189

Nova Hedwigia 75 1mdash2 189mdash200 Stuttgart August 2002

0029-5035 020075-0189 $ 300copy 2002 J Cramer in der Gebruumlder Borntraeger

Verlagsbuchha ndlung D-14129 Berlin middot D-70176 Stuttgart

DOI 101127 0029-5035 20020075-0189

New records of heterocystous cyanobacteriafrom Hong Kong rocky shores

by

Sanjay Nagarkar

Department of Ecology amp Biodiversity and Swire Institute of Marine ScienceThe University of Hong Kong Pokfulam Road Hong Kong PR China

Fax (852) 2517 6082Email snagarkahkusuahkuhk

With 10 figures

Nagarkar S (2002) New records of heterocystous cyanobacteria from Hong Kong rocky shores -Nova Hedwigia 75 189-200

Abstract The morphology and ecology of seven heterocystous cyanobacterial species collectedfrom various rocky shores around Hong Kong are described in the present study These areDichothrix cf baueriana Dichothrix cf spiralis Hapalosiphon cf welwitschii Mastigocoleustestarum Microchaete cf grisea Nostoc cf calcicola and Scytonema cf crustaceum All thesespecies are new records for Hong Kong and Dichothrix cf spiralis Hapalosiphon cf welwitschiiMicrochaete cf grisea Nostoc cf calcicola and Scytonema cf crustaceum are reported for thefirst time as marine epiliths Most of the species were recorded from the upper eulittoral andsupralittoral fringe and were present throughout the year These species are new additions to theexisting checklist from Hong Kong which now includes a total of 72 marine epilithic species fromthis area

Key words Cyanobacteria heterocysts rocky shore biofilm Hong Kong

Introduction

Intertidal epilithic biofilms are generally composed of cyanobacteria bacteriadiatoms microalgae protozoans and the spores and sporelings of macroalgae(Anderson 1995) Cyanobacteria are the dominant component of tropical intertidalepilithic biofilms (Cribb 1966 van den Hoek 1969 Potts 1980 Whitton amp Potts1980 Nagarkar amp Williams 1999) and being major primary producers form theenergy base of the epilithic food web and hence play an important role in structuring

190

intertidal assemblages (Nagarkar 1996 Williams et al 2000) Despite their ecologicalsignificance limited information is available on the species richness of marine epilithiccyanobacteria (but see Umezaki 1961 Gonzalez amp Parra 1975 Parra amp Gonzalez1976 Potts 1980 Hua amp Tseng 1984 Hoffmann amp Demoulin 1991 1993 Thajuddinamp Subramanian 1992 1994 Hussain amp Khoja 1993 Nagarkar 1998a b 2000 Silvaamp Pienaar 2000)

Hong Kong has a strongly seasonal monsoonal climate The summer months (May-September) are hot (mean air temperature 26-32degC mean surface seawater temperature24-29degC) and wet (monthly rainfall gt240 mm) due to the dominance of the SEmonsoon During this period typhoon conditions are common and low water tidesare ndash 06 m lower than in winter and occur during mid afternoon (Kaehler amp Williams1996) The winter months (November-March) are cool (mean air temperature 15-18degC mean surface seawater temperature 12-17degC) and dry (monthly rainfall lt70mm) due to the influence of the NE monsoon In winter wind speeds and thereforewave action is generally greater and the height of low water tides are higher than insummer (reviewed in Morton et al 1996) The months of April and October representtransition periods between monsoons (see Kaehler amp Williams 1996)

Rocky shores in Hong Kong support a variety of epilithic algal species dominatedby cyanobacteria which show distinct vertical zonation patterns (Kaehler amp Williams1996 Nagarkar amp Williams 1999) Information on cyanobacterial species richnessfrom Hong Kong rocky shores is limited representing an obstacle to ecologicalstudies on the intertidal epilithic biofilm So far only 65 epilithic cyanobacterialspecies have been recorded from the region of which only eight are heterocystousfilamentous species (Tseng 1936 Lee 1964 1966 Hodgkiss and Lee 1983 Kaehler1994 Nagarkar 1998a b 2000) To update the cyanobacterial species richness databasefrom the Hong Kong marine environment this paper describes the morphology andecology of seven new heterocystous filamentous cyanobacterial species which havenot been previously reported from this region

Materials and methods

A cyanobacterial species richness survey was conducted during winter (November 98-March 99)and summer (July 99-September 99) on various shores around Hong Kong (Fig 1) Each shore wasvisited between three to five times within each season Conspicuous cyanobacterial crusts werecollected from the supralittoral fringe upper mid- and lower eulittoral using a single-sided razorblade (Nagarkar 1998a) and transferred into plastic bags containing enriched seawater (Sweeney1954) The morphology of the fresh cyanobacteria samples was observed under the light microscope(Olympus BX 60) For species identification the classification system of Komaacuterek and Anagnostidis(1989) and Anagnostidis and Komaacuterek (1990) was followed and species were identified mainlyusing Geitler (1932) Freacutemy (1933) Desikachary (1959) and Umezaki (1961)

Results

Seven heterocystous cyanobacteria representing new taxon records for the marinerocky shores of Hong Kong were observed and characterized Six of the new recordshave morphologies identical or highly similar to taxa originally described from

191

freshwater or terrestrial habitats Despite their morphological similarity to thesespecies it is possible that the Hong Kong forms are sufficiently physiologically (andhence genetically) different from the type material upon which these taxa are basedto be considered new species Future culture work which will permit physiologicaland molecular characterization is planned for these taxa For now these taxa areindicated as being tentative identifications by use of the Latin term ldquocfrdquo Regardlessof final taxonomic status of these forms they still represent new records for HongKong rocky shores Descriptions of all seven taxa based on the Hong Kong materialare given below

Fig 1 Location of survey areas around Hong Kong rocky shores ( sampling site) Principle sitesare numbered as follows 1 Cape drsquoAguilar 2 Chung Hom Kok 3 Clear Water Bay 4 Heng FaChuen 5 Lei Yue Mun 6 Shek Mei Tau 7 Shek-O 8 Wah Fu

192

CYANOPHYTA

Nostocales

Rivulariaceae

Dichothrix Zanardini ex Bornet et Flahault

Dichothrix cf baueriana Bornet et Flahault Fig 2Geitler 1932 586 Desikachary 1959 546 Pl 111 Figs 1 3 4

Thallus caespitose mucilaginous expanded filaments flexuous false branched 15-20 microm wide sheath thin smooth yellowish-brown or hyaline trichomes blue-green5-72 microm wide gradually terminating in a hair constricted at the cross walls cells25-5 microm long cross walls not granulated protoplasm granular heterocyst basalsubspherical

The present species differs from the original material with respect to the habitat

ECOLOGY This species is epilithic in the mid- and lower eulittoral and present onlyduring winter Dichothrix cf baueriana is often associated with a thick matrix ofbiofilm mainly composed of various species of Gloeocapsa Lyngbya and Oscillatoria

LOCAL DISTRIBUTION This species is recorded from Cape drsquoAguilar Cheung ChauChung Hom Kok Clear Water Bay and Shek Mei Tau (Fig 1)

HABITAT Dichothrix baueriana and its similar morphological forms have been recordedfrom various habitats ie freshwater on the margin of springs epiphytic on aquaticplants on wood epilithic on moist stones marine epilithic on cliffs at sea coasts(Geitler 1932 Freacutemy 1933 Desikachary 1959)

Dichothrix cf spiralis Fritsch Fig 3Geitler 1932 592 Fig 373

Thallus olive-green mucilaginous filaments falsely branched olive-green 58-20 microm wide sheath pale-yellow or pale-brown unlamellated trichomes 2-3 in eachsheath spirally coiled ending in a long hair 42-9 microm wide constricted at the crosswalls cells as long as wide shorter or longer than wide 42-12 microm long heterocystbasal as well as intercalary basal heterocyst single cone-shaped 6-8 microm wide 9-10 microm long intercalary heterocyst spherical or oval 8-84 microm wide 10-112 micromlong

The Hong Kong species is marine epilithic which differs from the description ofGeitler (1932) with respect to the habitat

ECOLOGY This species is epilithic in the upper eulittoral and supralittoral fringe andpresent only in summer The species is visible as a black crust on the shore and isoften associated with Gloeocapsa spp and Mastigocoleus testarum Lagerheim exBornet et Flahault This is the first record of D cf spiralis as being epilithic fromthe marine environment

193

Figs 2-10 Marine epilithic cyanobacteria Fig 2 Dichothrix cf baueriana Fig 3 Dichothrix cfspiralis Fig 4 Microchaete cf grisea Figs 5 amp 6 Nostoc cf calcicola Fig 7 Scytonema cfcrustaceum Figs 8 amp 9 Hapalosiphon cf welwitschii Fig 10 Mastigocoleus testarumScale bars Fig 2 = 45 microm Fig 3 = 60 microm Fig 4 = 15 microm Fig 5 = 10 microm Fig 6 = 20 microm Figs 78 9 = 25 microm and Fig 10 = 40 microm

194

LOCAL DISTRIBUTION This species is recorded from Cheung Chau Lamma Island andLantau Island (Fig 1)

HABITAT Dichothrix spiralis and its similar morphological forms have been recordedfrom various habitats ie freshwater epiphyte on aquatic plant (Geitler 1932)marine (Thajuddin 1991)

Microchaetaceae

Microchaetoideae

Microchaete Thuret ex Bornet et FlahaultMicrochaete cf grisea Thuret ex Bornet et Flahault Fig 4

Geitler 1932 666 Fig 427 Desikachary 1959 510

Thallus caespitose dull-green mucilaginous formed by up to 1 mm long denselyentangled filaments filaments bent at the base swollen 6-7 microm wide sheath thinhyaline trichomes yellowish-brown 5-6 microm wide constricted at the cross wallscells 25-4 microm long cross walls not granulated protoplasm granular heterocystbasal spherical single

The present species differs from the description of the original material with respectto the habitat

ECOLOGY This species is epilithic in the upper eulittoral and present throughout theyear Microchaete cf grisea is visually conspicuous as a black crust on shores oftenassociated with Calothrix crustacea Thuret ex Bornet et Flahault Kyrtuthrix maculans(Gomont) Umezaki and Scytonema cf crustaceum Agardh ex Bornet et FlahaultThis species appears to be heat and desiccation tolerant and reproduces quickly insummer This is the first record of M cf grisea as being epilithic from the marineenvironment

LOCAL DISTRIBUTION This species is recorded from Cape drsquoAguilar Cheung ChauClear Water Bay and Shek Mei Tau (Fig 1)

HABITAT Microchaete grisea and its similar morphological forms have been recordedfrom various habitats ie freshwater epiphytic on algae epilithic (Geitler 1932Freacutemy 1933) marine on mussels shells planktonic in open sea and stagnant seawater(Thajuddin 1991 Thajuddin amp Subramanian 1992 Hussain amp Khoja 1993)

Nostocaceae

Nostoc Vaucher ex Bornet et Flahault

Nostoc cf calcicola Breacutebisson ex Bornet et Flahault Figs 5 6Geitler 1932 842 Fig 534 Desikachary 1959 384 Pl 68 Fig 1

Thallus olive-green or blue-green mucilaginous slightly diffluent expanded formedby loosely entangled filaments sheath very thin hyaline or yellowish-brown cells

195

blue-green barrel-shaped subspherical rarely longer than broad 25 microm wide 15-28 microm long heterocyst intercalary subspherical 3-45 microm wide

The present species differs from the original description with respect to the habitatNostoc calcicola was originally described from moist soil (see Geitler 1932Desikachary 1959) whilst the Hong Kong species is epilithic in the marineenvironment

ECOLOGY This species is epilithic in the mid- and lower eulittoral and present onlyduring winter It is visually conspicuous on the shore as a brown-green biofilmoften associated with a thick matrix of biofilm mainly composed of various speciesof Calothrix Lyngbya Oscillatoria and diatoms This is the first record of N cfcalcicola from the marine environment as epilithic

LOCAL DISTRIBUTION This species is recorded from Cape drsquoAguilar Cheung ChauChung Hom Kok Clear Water Bay Lamma Island Lantau Island and Shek-O (Fig 1)

HABITAT Nostoc calcicola and its similar morphological forms have been recordedfrom various habitats ie freshwater on moist soil on tree bark (Geitler 1932Desikachary 1959) marine planktonic in open sea (Thajuddin amp Subramanian 1992)

Scytonemataceae

Scytonema Agardh ex Bornet et Flahault

Scytonema cf crustaceum Agardh ex Bornet et Flahault Fig 7Geitler 1932 782 Figs 504 1a 1b Desikachary 1959 485 Pl 88 Fig 4 Pl 99Fig 1

Thallus cushion-like black mucilaginous expanded filaments 18-26 microm wide withshort and erect false branches false branches U-shaped extensions of the mainfilaments always in pairs united at the top free at the base sheath thick unevenyellow-brown lamellated divergent trichomes blue-green 6-8 microm wide constrictedat the cross walls cells subquadrate 4-6 microm long cross walls not granulatedprotoplasm granular heterocyst intercalary oblong

The Hong Kong species differs from the original material with respect to the habitat

ECOLOGY This species is epilithic in the upper eulittoral and supralittoral fringe andpresent throughout the year Scytonema cf crustaceum is visually conspicuous as ablack crust on the shore and is often associated with Chroococcus spp and Gloeocapsaspp This species appears heat and desiccation tolerant and reproduces quickly insummer

LOCAL DISTRIBUTION This species is recorded from Cheung Chau Heng Fa ChuenLei Yue Mun and Wah Fu (Fig 1)

HABITATS Scytonema crustaceum and its similar morphological forms have beenrecorded from various habitats ie epilithic on moist rock surface on moist soil(Geitler 1932 Freacutemy 1933 Desikachary 1959) marine (Thajuddin amp Subramanian1992)

196

Stigonematales

Mastigocladaceae

Mastigocladoideae

Hapalosiphon Naumlgeli ex Bornet et Flahault

Hapalosiphon cf welwitschii W et GS West Figs 8 9Geitler 1932 531 Fig 328a Desikachary 1959 588 Pl 137 Fig 5

Thallus blue-green mucilaginous expanded filaments flexuous with short lateralbranches 55-75 microm wide sheath thin hyaline trichomes blue-green or olive-green 45-65 microm wide cells spherical or elongate as long as wide or longer 45-75 microm long cells of the branches 3-10 microm long apical cells attenuated heterocystrare intercalary quadrate rounded or long cylindrical 6-62 microm wide 6-8 micromlong

The local species is different from the original material with respect to the habitat

ECOLOGY This species is epilithic in the upper eulittoral and supralittoral fringe andpresent only during summer It is not conspicuous on the shore often associatedwith Gloeocapsa spp and Kyrtuthrix maculans This is the first record of H cfwelwitschii as epilithic from the marine environment

LOCAL DISTRIBUTION This species is recorded from Cheung Chau Heng Fa Chuenand Lei Yue Mun (Fig 1)

HABITATS Hapalosiphon welwitschii and its similar morphological forms have beenrecorded from various habitats ie freshwater epiphyte on algae on moist brickson moist soil in marshes (Geitler 1932 Desikachary 1959) marine (Thajuddin1991)

Nostochopsidaceae

Mastigocoleus Lagerheim ex Bornet et Flahault

Mastigocoleus testarum Lagerheim ex Bornet et Flahault Fig 10

Geitler 1932 473 Fig 284 Desikachary 1959 575 Pl 122 Figs 1-5

Thallus perforating blue-green mucilaginous filaments curved with short and lat-eral branches 6-10 microm wide sheath is thin hyaline trichomes blue-green or red-brown 35-6 microm wide not constricted at the cross walls cells cylindrical orsubcylindrical 9-13 microm long cross walls not granulated protoplasm granularheterocyst terminal as well as lateral 67-7 microm wide 68-10 microm long

ECOLOGY This species is epilithic in the upper eulittoral and supralittoral fringe andpresent throughout the year Mastigocoleus testarum is visually conspicuous as ablack or brown crust often associated with Calothrix spp Gloeocapsa spp Kyrtuthrixmaculans and Scytonema cf crustaceum This species appears to be heat and desiccationtolerant and reproduces quickly in summer

197

LOCAL DISTRIBUTION The species is recorded from Cape drsquoAguilar Cheung ChauChung Hom Kok Clear Water Bay Lamma Island Lantau Island Shek Mei Tauand Shek-O (Fig 1)

HABITAT Marine on molluscan shells epilithic endolithic (Umezaki 1961 Thajuddinamp Subramanian 1992)

GEOGRAPHICAL DISTRIBUTION Atlantic coast of Europe Atlantic and Pacific coasts ofNorth America Bermuda Central America (Mexico) South America China IndiaJapan Mediterranean South East Asia (Thailand)

Discussion

Seven heterocystous filamentous cyanobacterial species from six genera belongingto six families and two orders are reported in the present study All the species arenew records for Hong Kong but Dichothrix cf spiralis Hapalosiphon cf welwitschiiMicrochaete cf grisea and Nostoc cf calcicola are also recorded for the first time asepiliths from the marine environment All the species were recorded from the uppereulittoral and supralittoral fringe except D cf baueriana and N cf calcicola whichwere recorded from the mid- and lower eulittoral Scytonema cf crustaceum andMastigocoleus testarum were a dominant component of the intertidal epilithic biofilmforming black and brown bands at Cheung Chau and Shek Mei Tau respectivelyOther species were common in the biofilm but did not form individual bands howeverthese species were associated with a variety of other cyanobacterial species in thebiofilm

Previous descriptions of Hong Kong cyanobacteria (Tseng 1936 Lee 1964 1966Hodgkiss amp Lee 1983 Kaehler 1994 Nagarkar 1998a b 2000) recorded 65 speciesof which only eight species were heterocystous namely Brachytrichia quoyi Bornetet Flahault Calothrix scopulorum Bornet et Flahault Calothrix contarenii Bornet etFlahault Calothrix crustacea Calothrix javanica de Wildeman Hormothamnionenteromorphoides Grunow ex Bornet et Flahault Kyrtuthrix maculans and Nodulariaspumigena Mertens ex Bornet et Flahault Kyrtuthrix maculans is the most abundantheterocystous cyanobacterium on Hong Kong rocky shores forming a characteristicblack band in mid- and upper eulittoral and is also widely distributed on tropicalrocky shores around the world (Williams 1993 Kaehler 1994 Kaehler amp Williams1996 Nagarkar 1996 Nagarkar amp Williams 1999) Calothrix scopulorum C con-tarenii and C crustacea are common on Hong Kong rocky shores and form blackleathery crusts on the lower mid- and upper eulittoral and are also widely distributedin various geographical areas (see Nagarkar 1996) Most of the species are widelydistributed around the world (Umezaki 1961 Thajuddin 1991 Thajuddin ampSubramanian 1992)

Whilst the addition of seven new species increases the species richness of heterocystouscyanobacteria from the region it is however still relatively low as compared toother geographic locations (eg Japan Umezaki 1961 Chile Parra amp Gonzalez1976 Red Sea Potts 1980 Aldabra Whitton amp Potts 1980 Saudi Arabia Hussainamp Khoja 1993)

198

Although all seven species have previously been recorded from the marineenvironment only Dichothrix cf baueriana and Mastigocoleus testarum were re-ported as marine epiliths In general rocky shores represent a most inhospitablehabitat due to the lack of nutrients tidal fluctuation and heat and desiccation stressesIn such stressful environments heterocystous species often dominate especially onthe high shore levels as they escape competition from less tolerant non-heterocystousspecies and are able to flourish due to their nitrogen fixation ability and stress toleranceThese attributes explain the diversity and abundance of heterocystous cyanobacteriaon rocky shores around the world especially in the high intertidal where the nutrientsupply is limited

Acknowledgements

I would like to thank Dr Gray A Williams Mr Aruna Weerasooriya (HKU) and Dr N Thajuddin(NFMC India) for their valuable comments on the manuscript Two anonymous referees and ProfJR Johansen also provided constructive criticisms Thanks to Prof R D Hill for translatingGerman and French literature for me This research was supported by a RGC grant to GAW (RGCproject no HKU 723198M)

References

ANAGNOSTIDIS K amp J KOMAacuteREK (1990) Modern approach to the classification system ofCyanophytes 5 ndash Stigonematales - Arch Hydrobiol Suppl 86 (Algol Stud 59) 1-73

ANDERSON MJ (1995) Variations in biofilms colonizing artificial surfaces seasonal effects andeffects of grazers - J Mar Biol Ass UK 75 705-714

CRIBB AB (1966) The algae of Heron Island Great Barrier Reef Australia Part 1 A generalaccount Vol 1 - In The University of Queensland paper Great Barrier Reef Committee HeronIsland Research Station 1-23 Univ of Queensland Press St Lucia

DESIKACHARY TV (1959) Cyanophyta - Indian Council of Agricultural Research New Delhi

FREacuteMY P (1933 reprinted 1972) Cyanophyceacutees des Cocirctes drsquoEurope - Meacutemoires de la SocieacuteteacuteNationale des Sciences Naturelles et Matheacutematiques de Cherbourg 41 1-236

GEITLER L (1932 reprinted 1985) Cyanophyceae - In L Rabenhorstrsquos Kryptogamen-Flora vonDeutschland Oumlsterreich und der Schweiz Akademische Verlags- Gesellschaft Leipzig Reprintedby Koeltz Scientific

GONZALEZ M amp OO PARRA (1975) Cianofitas marinas de Chile 1 Cianofitas del ambienteintermareal de la bahia de concepcion - Gayana Bot 31 1-69

HODGKISS IJ amp KY LEE (1983) Hong Kong Seaweeds - Urban Council Hong Kong

HOFFMANN L amp V DEMOULIN (1991) Marine Cyanophyceae of Papua New Guinea IILyngbya bouillonii sp nov a remarkable tropical reef-inhabiting blue-green alga - Belg J Bot124 82-88

HOFFMANN L amp V DEMOULIN (1993) Marine Cyanophyceae of Papua New Guinea III Thegenera Borzia and Oscillatoria - Bot Mar 36 451-459

HUA H amp CK TSENG (1984) Cyanophyta - In TSENG CK (ed) Common Seaweeds ofChina 13-41 Science Press Beijing

HUSSAIN MI amp TM KHOJA (1993) Intertidal and subtidal blue-green algal mats of open andmangrove areas in the Farasan Archipelago (Saudi Arabia) Red Sea - Bot Mar 36 377-388

190

intertidal assemblages (Nagarkar 1996 Williams et al 2000) Despite their ecologicalsignificance limited information is available on the species richness of marine epilithiccyanobacteria (but see Umezaki 1961 Gonzalez amp Parra 1975 Parra amp Gonzalez1976 Potts 1980 Hua amp Tseng 1984 Hoffmann amp Demoulin 1991 1993 Thajuddinamp Subramanian 1992 1994 Hussain amp Khoja 1993 Nagarkar 1998a b 2000 Silvaamp Pienaar 2000)

Hong Kong has a strongly seasonal monsoonal climate The summer months (May-September) are hot (mean air temperature 26-32degC mean surface seawater temperature24-29degC) and wet (monthly rainfall gt240 mm) due to the dominance of the SEmonsoon During this period typhoon conditions are common and low water tidesare ndash 06 m lower than in winter and occur during mid afternoon (Kaehler amp Williams1996) The winter months (November-March) are cool (mean air temperature 15-18degC mean surface seawater temperature 12-17degC) and dry (monthly rainfall lt70mm) due to the influence of the NE monsoon In winter wind speeds and thereforewave action is generally greater and the height of low water tides are higher than insummer (reviewed in Morton et al 1996) The months of April and October representtransition periods between monsoons (see Kaehler amp Williams 1996)

Rocky shores in Hong Kong support a variety of epilithic algal species dominatedby cyanobacteria which show distinct vertical zonation patterns (Kaehler amp Williams1996 Nagarkar amp Williams 1999) Information on cyanobacterial species richnessfrom Hong Kong rocky shores is limited representing an obstacle to ecologicalstudies on the intertidal epilithic biofilm So far only 65 epilithic cyanobacterialspecies have been recorded from the region of which only eight are heterocystousfilamentous species (Tseng 1936 Lee 1964 1966 Hodgkiss and Lee 1983 Kaehler1994 Nagarkar 1998a b 2000) To update the cyanobacterial species richness databasefrom the Hong Kong marine environment this paper describes the morphology andecology of seven new heterocystous filamentous cyanobacterial species which havenot been previously reported from this region

Materials and methods

A cyanobacterial species richness survey was conducted during winter (November 98-March 99)and summer (July 99-September 99) on various shores around Hong Kong (Fig 1) Each shore wasvisited between three to five times within each season Conspicuous cyanobacterial crusts werecollected from the supralittoral fringe upper mid- and lower eulittoral using a single-sided razorblade (Nagarkar 1998a) and transferred into plastic bags containing enriched seawater (Sweeney1954) The morphology of the fresh cyanobacteria samples was observed under the light microscope(Olympus BX 60) For species identification the classification system of Komaacuterek and Anagnostidis(1989) and Anagnostidis and Komaacuterek (1990) was followed and species were identified mainlyusing Geitler (1932) Freacutemy (1933) Desikachary (1959) and Umezaki (1961)

Results

Seven heterocystous cyanobacteria representing new taxon records for the marinerocky shores of Hong Kong were observed and characterized Six of the new recordshave morphologies identical or highly similar to taxa originally described from

191

freshwater or terrestrial habitats Despite their morphological similarity to thesespecies it is possible that the Hong Kong forms are sufficiently physiologically (andhence genetically) different from the type material upon which these taxa are basedto be considered new species Future culture work which will permit physiologicaland molecular characterization is planned for these taxa For now these taxa areindicated as being tentative identifications by use of the Latin term ldquocfrdquo Regardlessof final taxonomic status of these forms they still represent new records for HongKong rocky shores Descriptions of all seven taxa based on the Hong Kong materialare given below

Fig 1 Location of survey areas around Hong Kong rocky shores ( sampling site) Principle sitesare numbered as follows 1 Cape drsquoAguilar 2 Chung Hom Kok 3 Clear Water Bay 4 Heng FaChuen 5 Lei Yue Mun 6 Shek Mei Tau 7 Shek-O 8 Wah Fu

192

CYANOPHYTA

Nostocales

Rivulariaceae

Dichothrix Zanardini ex Bornet et Flahault

Dichothrix cf baueriana Bornet et Flahault Fig 2Geitler 1932 586 Desikachary 1959 546 Pl 111 Figs 1 3 4

Thallus caespitose mucilaginous expanded filaments flexuous false branched 15-20 microm wide sheath thin smooth yellowish-brown or hyaline trichomes blue-green5-72 microm wide gradually terminating in a hair constricted at the cross walls cells25-5 microm long cross walls not granulated protoplasm granular heterocyst basalsubspherical

The present species differs from the original material with respect to the habitat

ECOLOGY This species is epilithic in the mid- and lower eulittoral and present onlyduring winter Dichothrix cf baueriana is often associated with a thick matrix ofbiofilm mainly composed of various species of Gloeocapsa Lyngbya and Oscillatoria

LOCAL DISTRIBUTION This species is recorded from Cape drsquoAguilar Cheung ChauChung Hom Kok Clear Water Bay and Shek Mei Tau (Fig 1)

HABITAT Dichothrix baueriana and its similar morphological forms have been recordedfrom various habitats ie freshwater on the margin of springs epiphytic on aquaticplants on wood epilithic on moist stones marine epilithic on cliffs at sea coasts(Geitler 1932 Freacutemy 1933 Desikachary 1959)

Dichothrix cf spiralis Fritsch Fig 3Geitler 1932 592 Fig 373

Thallus olive-green mucilaginous filaments falsely branched olive-green 58-20 microm wide sheath pale-yellow or pale-brown unlamellated trichomes 2-3 in eachsheath spirally coiled ending in a long hair 42-9 microm wide constricted at the crosswalls cells as long as wide shorter or longer than wide 42-12 microm long heterocystbasal as well as intercalary basal heterocyst single cone-shaped 6-8 microm wide 9-10 microm long intercalary heterocyst spherical or oval 8-84 microm wide 10-112 micromlong

The Hong Kong species is marine epilithic which differs from the description ofGeitler (1932) with respect to the habitat

ECOLOGY This species is epilithic in the upper eulittoral and supralittoral fringe andpresent only in summer The species is visible as a black crust on the shore and isoften associated with Gloeocapsa spp and Mastigocoleus testarum Lagerheim exBornet et Flahault This is the first record of D cf spiralis as being epilithic fromthe marine environment

193

Figs 2-10 Marine epilithic cyanobacteria Fig 2 Dichothrix cf baueriana Fig 3 Dichothrix cfspiralis Fig 4 Microchaete cf grisea Figs 5 amp 6 Nostoc cf calcicola Fig 7 Scytonema cfcrustaceum Figs 8 amp 9 Hapalosiphon cf welwitschii Fig 10 Mastigocoleus testarumScale bars Fig 2 = 45 microm Fig 3 = 60 microm Fig 4 = 15 microm Fig 5 = 10 microm Fig 6 = 20 microm Figs 78 9 = 25 microm and Fig 10 = 40 microm

194

LOCAL DISTRIBUTION This species is recorded from Cheung Chau Lamma Island andLantau Island (Fig 1)

HABITAT Dichothrix spiralis and its similar morphological forms have been recordedfrom various habitats ie freshwater epiphyte on aquatic plant (Geitler 1932)marine (Thajuddin 1991)

Microchaetaceae

Microchaetoideae

Microchaete Thuret ex Bornet et FlahaultMicrochaete cf grisea Thuret ex Bornet et Flahault Fig 4

Geitler 1932 666 Fig 427 Desikachary 1959 510

Thallus caespitose dull-green mucilaginous formed by up to 1 mm long denselyentangled filaments filaments bent at the base swollen 6-7 microm wide sheath thinhyaline trichomes yellowish-brown 5-6 microm wide constricted at the cross wallscells 25-4 microm long cross walls not granulated protoplasm granular heterocystbasal spherical single

The present species differs from the description of the original material with respectto the habitat

ECOLOGY This species is epilithic in the upper eulittoral and present throughout theyear Microchaete cf grisea is visually conspicuous as a black crust on shores oftenassociated with Calothrix crustacea Thuret ex Bornet et Flahault Kyrtuthrix maculans(Gomont) Umezaki and Scytonema cf crustaceum Agardh ex Bornet et FlahaultThis species appears to be heat and desiccation tolerant and reproduces quickly insummer This is the first record of M cf grisea as being epilithic from the marineenvironment

LOCAL DISTRIBUTION This species is recorded from Cape drsquoAguilar Cheung ChauClear Water Bay and Shek Mei Tau (Fig 1)

HABITAT Microchaete grisea and its similar morphological forms have been recordedfrom various habitats ie freshwater epiphytic on algae epilithic (Geitler 1932Freacutemy 1933) marine on mussels shells planktonic in open sea and stagnant seawater(Thajuddin 1991 Thajuddin amp Subramanian 1992 Hussain amp Khoja 1993)

Nostocaceae

Nostoc Vaucher ex Bornet et Flahault

Nostoc cf calcicola Breacutebisson ex Bornet et Flahault Figs 5 6Geitler 1932 842 Fig 534 Desikachary 1959 384 Pl 68 Fig 1

Thallus olive-green or blue-green mucilaginous slightly diffluent expanded formedby loosely entangled filaments sheath very thin hyaline or yellowish-brown cells

195

blue-green barrel-shaped subspherical rarely longer than broad 25 microm wide 15-28 microm long heterocyst intercalary subspherical 3-45 microm wide

The present species differs from the original description with respect to the habitatNostoc calcicola was originally described from moist soil (see Geitler 1932Desikachary 1959) whilst the Hong Kong species is epilithic in the marineenvironment

ECOLOGY This species is epilithic in the mid- and lower eulittoral and present onlyduring winter It is visually conspicuous on the shore as a brown-green biofilmoften associated with a thick matrix of biofilm mainly composed of various speciesof Calothrix Lyngbya Oscillatoria and diatoms This is the first record of N cfcalcicola from the marine environment as epilithic

LOCAL DISTRIBUTION This species is recorded from Cape drsquoAguilar Cheung ChauChung Hom Kok Clear Water Bay Lamma Island Lantau Island and Shek-O (Fig 1)

HABITAT Nostoc calcicola and its similar morphological forms have been recordedfrom various habitats ie freshwater on moist soil on tree bark (Geitler 1932Desikachary 1959) marine planktonic in open sea (Thajuddin amp Subramanian 1992)

Scytonemataceae

Scytonema Agardh ex Bornet et Flahault

Scytonema cf crustaceum Agardh ex Bornet et Flahault Fig 7Geitler 1932 782 Figs 504 1a 1b Desikachary 1959 485 Pl 88 Fig 4 Pl 99Fig 1

Thallus cushion-like black mucilaginous expanded filaments 18-26 microm wide withshort and erect false branches false branches U-shaped extensions of the mainfilaments always in pairs united at the top free at the base sheath thick unevenyellow-brown lamellated divergent trichomes blue-green 6-8 microm wide constrictedat the cross walls cells subquadrate 4-6 microm long cross walls not granulatedprotoplasm granular heterocyst intercalary oblong

The Hong Kong species differs from the original material with respect to the habitat

ECOLOGY This species is epilithic in the upper eulittoral and supralittoral fringe andpresent throughout the year Scytonema cf crustaceum is visually conspicuous as ablack crust on the shore and is often associated with Chroococcus spp and Gloeocapsaspp This species appears heat and desiccation tolerant and reproduces quickly insummer

LOCAL DISTRIBUTION This species is recorded from Cheung Chau Heng Fa ChuenLei Yue Mun and Wah Fu (Fig 1)

HABITATS Scytonema crustaceum and its similar morphological forms have beenrecorded from various habitats ie epilithic on moist rock surface on moist soil(Geitler 1932 Freacutemy 1933 Desikachary 1959) marine (Thajuddin amp Subramanian1992)

196

Stigonematales

Mastigocladaceae

Mastigocladoideae

Hapalosiphon Naumlgeli ex Bornet et Flahault

Hapalosiphon cf welwitschii W et GS West Figs 8 9Geitler 1932 531 Fig 328a Desikachary 1959 588 Pl 137 Fig 5

Thallus blue-green mucilaginous expanded filaments flexuous with short lateralbranches 55-75 microm wide sheath thin hyaline trichomes blue-green or olive-green 45-65 microm wide cells spherical or elongate as long as wide or longer 45-75 microm long cells of the branches 3-10 microm long apical cells attenuated heterocystrare intercalary quadrate rounded or long cylindrical 6-62 microm wide 6-8 micromlong

The local species is different from the original material with respect to the habitat

ECOLOGY This species is epilithic in the upper eulittoral and supralittoral fringe andpresent only during summer It is not conspicuous on the shore often associatedwith Gloeocapsa spp and Kyrtuthrix maculans This is the first record of H cfwelwitschii as epilithic from the marine environment

LOCAL DISTRIBUTION This species is recorded from Cheung Chau Heng Fa Chuenand Lei Yue Mun (Fig 1)

HABITATS Hapalosiphon welwitschii and its similar morphological forms have beenrecorded from various habitats ie freshwater epiphyte on algae on moist brickson moist soil in marshes (Geitler 1932 Desikachary 1959) marine (Thajuddin1991)

Nostochopsidaceae

Mastigocoleus Lagerheim ex Bornet et Flahault

Mastigocoleus testarum Lagerheim ex Bornet et Flahault Fig 10

Geitler 1932 473 Fig 284 Desikachary 1959 575 Pl 122 Figs 1-5

Thallus perforating blue-green mucilaginous filaments curved with short and lat-eral branches 6-10 microm wide sheath is thin hyaline trichomes blue-green or red-brown 35-6 microm wide not constricted at the cross walls cells cylindrical orsubcylindrical 9-13 microm long cross walls not granulated protoplasm granularheterocyst terminal as well as lateral 67-7 microm wide 68-10 microm long

ECOLOGY This species is epilithic in the upper eulittoral and supralittoral fringe andpresent throughout the year Mastigocoleus testarum is visually conspicuous as ablack or brown crust often associated with Calothrix spp Gloeocapsa spp Kyrtuthrixmaculans and Scytonema cf crustaceum This species appears to be heat and desiccationtolerant and reproduces quickly in summer

197

LOCAL DISTRIBUTION The species is recorded from Cape drsquoAguilar Cheung ChauChung Hom Kok Clear Water Bay Lamma Island Lantau Island Shek Mei Tauand Shek-O (Fig 1)

HABITAT Marine on molluscan shells epilithic endolithic (Umezaki 1961 Thajuddinamp Subramanian 1992)

GEOGRAPHICAL DISTRIBUTION Atlantic coast of Europe Atlantic and Pacific coasts ofNorth America Bermuda Central America (Mexico) South America China IndiaJapan Mediterranean South East Asia (Thailand)

Discussion

Seven heterocystous filamentous cyanobacterial species from six genera belongingto six families and two orders are reported in the present study All the species arenew records for Hong Kong but Dichothrix cf spiralis Hapalosiphon cf welwitschiiMicrochaete cf grisea and Nostoc cf calcicola are also recorded for the first time asepiliths from the marine environment All the species were recorded from the uppereulittoral and supralittoral fringe except D cf baueriana and N cf calcicola whichwere recorded from the mid- and lower eulittoral Scytonema cf crustaceum andMastigocoleus testarum were a dominant component of the intertidal epilithic biofilmforming black and brown bands at Cheung Chau and Shek Mei Tau respectivelyOther species were common in the biofilm but did not form individual bands howeverthese species were associated with a variety of other cyanobacterial species in thebiofilm

Previous descriptions of Hong Kong cyanobacteria (Tseng 1936 Lee 1964 1966Hodgkiss amp Lee 1983 Kaehler 1994 Nagarkar 1998a b 2000) recorded 65 speciesof which only eight species were heterocystous namely Brachytrichia quoyi Bornetet Flahault Calothrix scopulorum Bornet et Flahault Calothrix contarenii Bornet etFlahault Calothrix crustacea Calothrix javanica de Wildeman Hormothamnionenteromorphoides Grunow ex Bornet et Flahault Kyrtuthrix maculans and Nodulariaspumigena Mertens ex Bornet et Flahault Kyrtuthrix maculans is the most abundantheterocystous cyanobacterium on Hong Kong rocky shores forming a characteristicblack band in mid- and upper eulittoral and is also widely distributed on tropicalrocky shores around the world (Williams 1993 Kaehler 1994 Kaehler amp Williams1996 Nagarkar 1996 Nagarkar amp Williams 1999) Calothrix scopulorum C con-tarenii and C crustacea are common on Hong Kong rocky shores and form blackleathery crusts on the lower mid- and upper eulittoral and are also widely distributedin various geographical areas (see Nagarkar 1996) Most of the species are widelydistributed around the world (Umezaki 1961 Thajuddin 1991 Thajuddin ampSubramanian 1992)

Whilst the addition of seven new species increases the species richness of heterocystouscyanobacteria from the region it is however still relatively low as compared toother geographic locations (eg Japan Umezaki 1961 Chile Parra amp Gonzalez1976 Red Sea Potts 1980 Aldabra Whitton amp Potts 1980 Saudi Arabia Hussainamp Khoja 1993)

198

Although all seven species have previously been recorded from the marineenvironment only Dichothrix cf baueriana and Mastigocoleus testarum were re-ported as marine epiliths In general rocky shores represent a most inhospitablehabitat due to the lack of nutrients tidal fluctuation and heat and desiccation stressesIn such stressful environments heterocystous species often dominate especially onthe high shore levels as they escape competition from less tolerant non-heterocystousspecies and are able to flourish due to their nitrogen fixation ability and stress toleranceThese attributes explain the diversity and abundance of heterocystous cyanobacteriaon rocky shores around the world especially in the high intertidal where the nutrientsupply is limited

Acknowledgements

I would like to thank Dr Gray A Williams Mr Aruna Weerasooriya (HKU) and Dr N Thajuddin(NFMC India) for their valuable comments on the manuscript Two anonymous referees and ProfJR Johansen also provided constructive criticisms Thanks to Prof R D Hill for translatingGerman and French literature for me This research was supported by a RGC grant to GAW (RGCproject no HKU 723198M)

References

ANAGNOSTIDIS K amp J KOMAacuteREK (1990) Modern approach to the classification system ofCyanophytes 5 ndash Stigonematales - Arch Hydrobiol Suppl 86 (Algol Stud 59) 1-73

ANDERSON MJ (1995) Variations in biofilms colonizing artificial surfaces seasonal effects andeffects of grazers - J Mar Biol Ass UK 75 705-714

CRIBB AB (1966) The algae of Heron Island Great Barrier Reef Australia Part 1 A generalaccount Vol 1 - In The University of Queensland paper Great Barrier Reef Committee HeronIsland Research Station 1-23 Univ of Queensland Press St Lucia

DESIKACHARY TV (1959) Cyanophyta - Indian Council of Agricultural Research New Delhi

FREacuteMY P (1933 reprinted 1972) Cyanophyceacutees des Cocirctes drsquoEurope - Meacutemoires de la SocieacuteteacuteNationale des Sciences Naturelles et Matheacutematiques de Cherbourg 41 1-236

GEITLER L (1932 reprinted 1985) Cyanophyceae - In L Rabenhorstrsquos Kryptogamen-Flora vonDeutschland Oumlsterreich und der Schweiz Akademische Verlags- Gesellschaft Leipzig Reprintedby Koeltz Scientific

GONZALEZ M amp OO PARRA (1975) Cianofitas marinas de Chile 1 Cianofitas del ambienteintermareal de la bahia de concepcion - Gayana Bot 31 1-69

HODGKISS IJ amp KY LEE (1983) Hong Kong Seaweeds - Urban Council Hong Kong

HOFFMANN L amp V DEMOULIN (1991) Marine Cyanophyceae of Papua New Guinea IILyngbya bouillonii sp nov a remarkable tropical reef-inhabiting blue-green alga - Belg J Bot124 82-88

HOFFMANN L amp V DEMOULIN (1993) Marine Cyanophyceae of Papua New Guinea III Thegenera Borzia and Oscillatoria - Bot Mar 36 451-459

HUA H amp CK TSENG (1984) Cyanophyta - In TSENG CK (ed) Common Seaweeds ofChina 13-41 Science Press Beijing

HUSSAIN MI amp TM KHOJA (1993) Intertidal and subtidal blue-green algal mats of open andmangrove areas in the Farasan Archipelago (Saudi Arabia) Red Sea - Bot Mar 36 377-388

191

freshwater or terrestrial habitats Despite their morphological similarity to thesespecies it is possible that the Hong Kong forms are sufficiently physiologically (andhence genetically) different from the type material upon which these taxa are basedto be considered new species Future culture work which will permit physiologicaland molecular characterization is planned for these taxa For now these taxa areindicated as being tentative identifications by use of the Latin term ldquocfrdquo Regardlessof final taxonomic status of these forms they still represent new records for HongKong rocky shores Descriptions of all seven taxa based on the Hong Kong materialare given below

Fig 1 Location of survey areas around Hong Kong rocky shores ( sampling site) Principle sitesare numbered as follows 1 Cape drsquoAguilar 2 Chung Hom Kok 3 Clear Water Bay 4 Heng FaChuen 5 Lei Yue Mun 6 Shek Mei Tau 7 Shek-O 8 Wah Fu

192

CYANOPHYTA

Nostocales

Rivulariaceae

Dichothrix Zanardini ex Bornet et Flahault

Dichothrix cf baueriana Bornet et Flahault Fig 2Geitler 1932 586 Desikachary 1959 546 Pl 111 Figs 1 3 4

Thallus caespitose mucilaginous expanded filaments flexuous false branched 15-20 microm wide sheath thin smooth yellowish-brown or hyaline trichomes blue-green5-72 microm wide gradually terminating in a hair constricted at the cross walls cells25-5 microm long cross walls not granulated protoplasm granular heterocyst basalsubspherical

The present species differs from the original material with respect to the habitat

ECOLOGY This species is epilithic in the mid- and lower eulittoral and present onlyduring winter Dichothrix cf baueriana is often associated with a thick matrix ofbiofilm mainly composed of various species of Gloeocapsa Lyngbya and Oscillatoria

LOCAL DISTRIBUTION This species is recorded from Cape drsquoAguilar Cheung ChauChung Hom Kok Clear Water Bay and Shek Mei Tau (Fig 1)

HABITAT Dichothrix baueriana and its similar morphological forms have been recordedfrom various habitats ie freshwater on the margin of springs epiphytic on aquaticplants on wood epilithic on moist stones marine epilithic on cliffs at sea coasts(Geitler 1932 Freacutemy 1933 Desikachary 1959)

Dichothrix cf spiralis Fritsch Fig 3Geitler 1932 592 Fig 373

Thallus olive-green mucilaginous filaments falsely branched olive-green 58-20 microm wide sheath pale-yellow or pale-brown unlamellated trichomes 2-3 in eachsheath spirally coiled ending in a long hair 42-9 microm wide constricted at the crosswalls cells as long as wide shorter or longer than wide 42-12 microm long heterocystbasal as well as intercalary basal heterocyst single cone-shaped 6-8 microm wide 9-10 microm long intercalary heterocyst spherical or oval 8-84 microm wide 10-112 micromlong

The Hong Kong species is marine epilithic which differs from the description ofGeitler (1932) with respect to the habitat

ECOLOGY This species is epilithic in the upper eulittoral and supralittoral fringe andpresent only in summer The species is visible as a black crust on the shore and isoften associated with Gloeocapsa spp and Mastigocoleus testarum Lagerheim exBornet et Flahault This is the first record of D cf spiralis as being epilithic fromthe marine environment

193

Figs 2-10 Marine epilithic cyanobacteria Fig 2 Dichothrix cf baueriana Fig 3 Dichothrix cfspiralis Fig 4 Microchaete cf grisea Figs 5 amp 6 Nostoc cf calcicola Fig 7 Scytonema cfcrustaceum Figs 8 amp 9 Hapalosiphon cf welwitschii Fig 10 Mastigocoleus testarumScale bars Fig 2 = 45 microm Fig 3 = 60 microm Fig 4 = 15 microm Fig 5 = 10 microm Fig 6 = 20 microm Figs 78 9 = 25 microm and Fig 10 = 40 microm

194

LOCAL DISTRIBUTION This species is recorded from Cheung Chau Lamma Island andLantau Island (Fig 1)

HABITAT Dichothrix spiralis and its similar morphological forms have been recordedfrom various habitats ie freshwater epiphyte on aquatic plant (Geitler 1932)marine (Thajuddin 1991)

Microchaetaceae

Microchaetoideae

Microchaete Thuret ex Bornet et FlahaultMicrochaete cf grisea Thuret ex Bornet et Flahault Fig 4

Geitler 1932 666 Fig 427 Desikachary 1959 510

Thallus caespitose dull-green mucilaginous formed by up to 1 mm long denselyentangled filaments filaments bent at the base swollen 6-7 microm wide sheath thinhyaline trichomes yellowish-brown 5-6 microm wide constricted at the cross wallscells 25-4 microm long cross walls not granulated protoplasm granular heterocystbasal spherical single

The present species differs from the description of the original material with respectto the habitat

ECOLOGY This species is epilithic in the upper eulittoral and present throughout theyear Microchaete cf grisea is visually conspicuous as a black crust on shores oftenassociated with Calothrix crustacea Thuret ex Bornet et Flahault Kyrtuthrix maculans(Gomont) Umezaki and Scytonema cf crustaceum Agardh ex Bornet et FlahaultThis species appears to be heat and desiccation tolerant and reproduces quickly insummer This is the first record of M cf grisea as being epilithic from the marineenvironment

LOCAL DISTRIBUTION This species is recorded from Cape drsquoAguilar Cheung ChauClear Water Bay and Shek Mei Tau (Fig 1)

HABITAT Microchaete grisea and its similar morphological forms have been recordedfrom various habitats ie freshwater epiphytic on algae epilithic (Geitler 1932Freacutemy 1933) marine on mussels shells planktonic in open sea and stagnant seawater(Thajuddin 1991 Thajuddin amp Subramanian 1992 Hussain amp Khoja 1993)

Nostocaceae

Nostoc Vaucher ex Bornet et Flahault

Nostoc cf calcicola Breacutebisson ex Bornet et Flahault Figs 5 6Geitler 1932 842 Fig 534 Desikachary 1959 384 Pl 68 Fig 1

Thallus olive-green or blue-green mucilaginous slightly diffluent expanded formedby loosely entangled filaments sheath very thin hyaline or yellowish-brown cells

195

blue-green barrel-shaped subspherical rarely longer than broad 25 microm wide 15-28 microm long heterocyst intercalary subspherical 3-45 microm wide

The present species differs from the original description with respect to the habitatNostoc calcicola was originally described from moist soil (see Geitler 1932Desikachary 1959) whilst the Hong Kong species is epilithic in the marineenvironment

ECOLOGY This species is epilithic in the mid- and lower eulittoral and present onlyduring winter It is visually conspicuous on the shore as a brown-green biofilmoften associated with a thick matrix of biofilm mainly composed of various speciesof Calothrix Lyngbya Oscillatoria and diatoms This is the first record of N cfcalcicola from the marine environment as epilithic

LOCAL DISTRIBUTION This species is recorded from Cape drsquoAguilar Cheung ChauChung Hom Kok Clear Water Bay Lamma Island Lantau Island and Shek-O (Fig 1)

HABITAT Nostoc calcicola and its similar morphological forms have been recordedfrom various habitats ie freshwater on moist soil on tree bark (Geitler 1932Desikachary 1959) marine planktonic in open sea (Thajuddin amp Subramanian 1992)

Scytonemataceae

Scytonema Agardh ex Bornet et Flahault

Scytonema cf crustaceum Agardh ex Bornet et Flahault Fig 7Geitler 1932 782 Figs 504 1a 1b Desikachary 1959 485 Pl 88 Fig 4 Pl 99Fig 1

Thallus cushion-like black mucilaginous expanded filaments 18-26 microm wide withshort and erect false branches false branches U-shaped extensions of the mainfilaments always in pairs united at the top free at the base sheath thick unevenyellow-brown lamellated divergent trichomes blue-green 6-8 microm wide constrictedat the cross walls cells subquadrate 4-6 microm long cross walls not granulatedprotoplasm granular heterocyst intercalary oblong

The Hong Kong species differs from the original material with respect to the habitat

ECOLOGY This species is epilithic in the upper eulittoral and supralittoral fringe andpresent throughout the year Scytonema cf crustaceum is visually conspicuous as ablack crust on the shore and is often associated with Chroococcus spp and Gloeocapsaspp This species appears heat and desiccation tolerant and reproduces quickly insummer

LOCAL DISTRIBUTION This species is recorded from Cheung Chau Heng Fa ChuenLei Yue Mun and Wah Fu (Fig 1)

HABITATS Scytonema crustaceum and its similar morphological forms have beenrecorded from various habitats ie epilithic on moist rock surface on moist soil(Geitler 1932 Freacutemy 1933 Desikachary 1959) marine (Thajuddin amp Subramanian1992)

196

Stigonematales

Mastigocladaceae

Mastigocladoideae

Hapalosiphon Naumlgeli ex Bornet et Flahault

Hapalosiphon cf welwitschii W et GS West Figs 8 9Geitler 1932 531 Fig 328a Desikachary 1959 588 Pl 137 Fig 5

Thallus blue-green mucilaginous expanded filaments flexuous with short lateralbranches 55-75 microm wide sheath thin hyaline trichomes blue-green or olive-green 45-65 microm wide cells spherical or elongate as long as wide or longer 45-75 microm long cells of the branches 3-10 microm long apical cells attenuated heterocystrare intercalary quadrate rounded or long cylindrical 6-62 microm wide 6-8 micromlong

The local species is different from the original material with respect to the habitat

ECOLOGY This species is epilithic in the upper eulittoral and supralittoral fringe andpresent only during summer It is not conspicuous on the shore often associatedwith Gloeocapsa spp and Kyrtuthrix maculans This is the first record of H cfwelwitschii as epilithic from the marine environment

LOCAL DISTRIBUTION This species is recorded from Cheung Chau Heng Fa Chuenand Lei Yue Mun (Fig 1)

HABITATS Hapalosiphon welwitschii and its similar morphological forms have beenrecorded from various habitats ie freshwater epiphyte on algae on moist brickson moist soil in marshes (Geitler 1932 Desikachary 1959) marine (Thajuddin1991)

Nostochopsidaceae

Mastigocoleus Lagerheim ex Bornet et Flahault

Mastigocoleus testarum Lagerheim ex Bornet et Flahault Fig 10

Geitler 1932 473 Fig 284 Desikachary 1959 575 Pl 122 Figs 1-5

Thallus perforating blue-green mucilaginous filaments curved with short and lat-eral branches 6-10 microm wide sheath is thin hyaline trichomes blue-green or red-brown 35-6 microm wide not constricted at the cross walls cells cylindrical orsubcylindrical 9-13 microm long cross walls not granulated protoplasm granularheterocyst terminal as well as lateral 67-7 microm wide 68-10 microm long

ECOLOGY This species is epilithic in the upper eulittoral and supralittoral fringe andpresent throughout the year Mastigocoleus testarum is visually conspicuous as ablack or brown crust often associated with Calothrix spp Gloeocapsa spp Kyrtuthrixmaculans and Scytonema cf crustaceum This species appears to be heat and desiccationtolerant and reproduces quickly in summer

197

LOCAL DISTRIBUTION The species is recorded from Cape drsquoAguilar Cheung ChauChung Hom Kok Clear Water Bay Lamma Island Lantau Island Shek Mei Tauand Shek-O (Fig 1)

HABITAT Marine on molluscan shells epilithic endolithic (Umezaki 1961 Thajuddinamp Subramanian 1992)

GEOGRAPHICAL DISTRIBUTION Atlantic coast of Europe Atlantic and Pacific coasts ofNorth America Bermuda Central America (Mexico) South America China IndiaJapan Mediterranean South East Asia (Thailand)

Discussion

Seven heterocystous filamentous cyanobacterial species from six genera belongingto six families and two orders are reported in the present study All the species arenew records for Hong Kong but Dichothrix cf spiralis Hapalosiphon cf welwitschiiMicrochaete cf grisea and Nostoc cf calcicola are also recorded for the first time asepiliths from the marine environment All the species were recorded from the uppereulittoral and supralittoral fringe except D cf baueriana and N cf calcicola whichwere recorded from the mid- and lower eulittoral Scytonema cf crustaceum andMastigocoleus testarum were a dominant component of the intertidal epilithic biofilmforming black and brown bands at Cheung Chau and Shek Mei Tau respectivelyOther species were common in the biofilm but did not form individual bands howeverthese species were associated with a variety of other cyanobacterial species in thebiofilm

Previous descriptions of Hong Kong cyanobacteria (Tseng 1936 Lee 1964 1966Hodgkiss amp Lee 1983 Kaehler 1994 Nagarkar 1998a b 2000) recorded 65 speciesof which only eight species were heterocystous namely Brachytrichia quoyi Bornetet Flahault Calothrix scopulorum Bornet et Flahault Calothrix contarenii Bornet etFlahault Calothrix crustacea Calothrix javanica de Wildeman Hormothamnionenteromorphoides Grunow ex Bornet et Flahault Kyrtuthrix maculans and Nodulariaspumigena Mertens ex Bornet et Flahault Kyrtuthrix maculans is the most abundantheterocystous cyanobacterium on Hong Kong rocky shores forming a characteristicblack band in mid- and upper eulittoral and is also widely distributed on tropicalrocky shores around the world (Williams 1993 Kaehler 1994 Kaehler amp Williams1996 Nagarkar 1996 Nagarkar amp Williams 1999) Calothrix scopulorum C con-tarenii and C crustacea are common on Hong Kong rocky shores and form blackleathery crusts on the lower mid- and upper eulittoral and are also widely distributedin various geographical areas (see Nagarkar 1996) Most of the species are widelydistributed around the world (Umezaki 1961 Thajuddin 1991 Thajuddin ampSubramanian 1992)

Whilst the addition of seven new species increases the species richness of heterocystouscyanobacteria from the region it is however still relatively low as compared toother geographic locations (eg Japan Umezaki 1961 Chile Parra amp Gonzalez1976 Red Sea Potts 1980 Aldabra Whitton amp Potts 1980 Saudi Arabia Hussainamp Khoja 1993)

198

Although all seven species have previously been recorded from the marineenvironment only Dichothrix cf baueriana and Mastigocoleus testarum were re-ported as marine epiliths In general rocky shores represent a most inhospitablehabitat due to the lack of nutrients tidal fluctuation and heat and desiccation stressesIn such stressful environments heterocystous species often dominate especially onthe high shore levels as they escape competition from less tolerant non-heterocystousspecies and are able to flourish due to their nitrogen fixation ability and stress toleranceThese attributes explain the diversity and abundance of heterocystous cyanobacteriaon rocky shores around the world especially in the high intertidal where the nutrientsupply is limited

Acknowledgements

I would like to thank Dr Gray A Williams Mr Aruna Weerasooriya (HKU) and Dr N Thajuddin(NFMC India) for their valuable comments on the manuscript Two anonymous referees and ProfJR Johansen also provided constructive criticisms Thanks to Prof R D Hill for translatingGerman and French literature for me This research was supported by a RGC grant to GAW (RGCproject no HKU 723198M)

References

ANAGNOSTIDIS K amp J KOMAacuteREK (1990) Modern approach to the classification system ofCyanophytes 5 ndash Stigonematales - Arch Hydrobiol Suppl 86 (Algol Stud 59) 1-73

ANDERSON MJ (1995) Variations in biofilms colonizing artificial surfaces seasonal effects andeffects of grazers - J Mar Biol Ass UK 75 705-714

CRIBB AB (1966) The algae of Heron Island Great Barrier Reef Australia Part 1 A generalaccount Vol 1 - In The University of Queensland paper Great Barrier Reef Committee HeronIsland Research Station 1-23 Univ of Queensland Press St Lucia

DESIKACHARY TV (1959) Cyanophyta - Indian Council of Agricultural Research New Delhi

FREacuteMY P (1933 reprinted 1972) Cyanophyceacutees des Cocirctes drsquoEurope - Meacutemoires de la SocieacuteteacuteNationale des Sciences Naturelles et Matheacutematiques de Cherbourg 41 1-236

GEITLER L (1932 reprinted 1985) Cyanophyceae - In L Rabenhorstrsquos Kryptogamen-Flora vonDeutschland Oumlsterreich und der Schweiz Akademische Verlags- Gesellschaft Leipzig Reprintedby Koeltz Scientific

GONZALEZ M amp OO PARRA (1975) Cianofitas marinas de Chile 1 Cianofitas del ambienteintermareal de la bahia de concepcion - Gayana Bot 31 1-69

HODGKISS IJ amp KY LEE (1983) Hong Kong Seaweeds - Urban Council Hong Kong

HOFFMANN L amp V DEMOULIN (1991) Marine Cyanophyceae of Papua New Guinea IILyngbya bouillonii sp nov a remarkable tropical reef-inhabiting blue-green alga - Belg J Bot124 82-88

HOFFMANN L amp V DEMOULIN (1993) Marine Cyanophyceae of Papua New Guinea III Thegenera Borzia and Oscillatoria - Bot Mar 36 451-459

HUA H amp CK TSENG (1984) Cyanophyta - In TSENG CK (ed) Common Seaweeds ofChina 13-41 Science Press Beijing

HUSSAIN MI amp TM KHOJA (1993) Intertidal and subtidal blue-green algal mats of open andmangrove areas in the Farasan Archipelago (Saudi Arabia) Red Sea - Bot Mar 36 377-388

192

CYANOPHYTA

Nostocales

Rivulariaceae

Dichothrix Zanardini ex Bornet et Flahault

Dichothrix cf baueriana Bornet et Flahault Fig 2Geitler 1932 586 Desikachary 1959 546 Pl 111 Figs 1 3 4

Thallus caespitose mucilaginous expanded filaments flexuous false branched 15-20 microm wide sheath thin smooth yellowish-brown or hyaline trichomes blue-green5-72 microm wide gradually terminating in a hair constricted at the cross walls cells25-5 microm long cross walls not granulated protoplasm granular heterocyst basalsubspherical

The present species differs from the original material with respect to the habitat

ECOLOGY This species is epilithic in the mid- and lower eulittoral and present onlyduring winter Dichothrix cf baueriana is often associated with a thick matrix ofbiofilm mainly composed of various species of Gloeocapsa Lyngbya and Oscillatoria

LOCAL DISTRIBUTION This species is recorded from Cape drsquoAguilar Cheung ChauChung Hom Kok Clear Water Bay and Shek Mei Tau (Fig 1)

HABITAT Dichothrix baueriana and its similar morphological forms have been recordedfrom various habitats ie freshwater on the margin of springs epiphytic on aquaticplants on wood epilithic on moist stones marine epilithic on cliffs at sea coasts(Geitler 1932 Freacutemy 1933 Desikachary 1959)

Dichothrix cf spiralis Fritsch Fig 3Geitler 1932 592 Fig 373

Thallus olive-green mucilaginous filaments falsely branched olive-green 58-20 microm wide sheath pale-yellow or pale-brown unlamellated trichomes 2-3 in eachsheath spirally coiled ending in a long hair 42-9 microm wide constricted at the crosswalls cells as long as wide shorter or longer than wide 42-12 microm long heterocystbasal as well as intercalary basal heterocyst single cone-shaped 6-8 microm wide 9-10 microm long intercalary heterocyst spherical or oval 8-84 microm wide 10-112 micromlong

The Hong Kong species is marine epilithic which differs from the description ofGeitler (1932) with respect to the habitat

ECOLOGY This species is epilithic in the upper eulittoral and supralittoral fringe andpresent only in summer The species is visible as a black crust on the shore and isoften associated with Gloeocapsa spp and Mastigocoleus testarum Lagerheim exBornet et Flahault This is the first record of D cf spiralis as being epilithic fromthe marine environment

193

Figs 2-10 Marine epilithic cyanobacteria Fig 2 Dichothrix cf baueriana Fig 3 Dichothrix cfspiralis Fig 4 Microchaete cf grisea Figs 5 amp 6 Nostoc cf calcicola Fig 7 Scytonema cfcrustaceum Figs 8 amp 9 Hapalosiphon cf welwitschii Fig 10 Mastigocoleus testarumScale bars Fig 2 = 45 microm Fig 3 = 60 microm Fig 4 = 15 microm Fig 5 = 10 microm Fig 6 = 20 microm Figs 78 9 = 25 microm and Fig 10 = 40 microm

194

LOCAL DISTRIBUTION This species is recorded from Cheung Chau Lamma Island andLantau Island (Fig 1)

HABITAT Dichothrix spiralis and its similar morphological forms have been recordedfrom various habitats ie freshwater epiphyte on aquatic plant (Geitler 1932)marine (Thajuddin 1991)

Microchaetaceae

Microchaetoideae

Microchaete Thuret ex Bornet et FlahaultMicrochaete cf grisea Thuret ex Bornet et Flahault Fig 4

Geitler 1932 666 Fig 427 Desikachary 1959 510

Thallus caespitose dull-green mucilaginous formed by up to 1 mm long denselyentangled filaments filaments bent at the base swollen 6-7 microm wide sheath thinhyaline trichomes yellowish-brown 5-6 microm wide constricted at the cross wallscells 25-4 microm long cross walls not granulated protoplasm granular heterocystbasal spherical single

The present species differs from the description of the original material with respectto the habitat

ECOLOGY This species is epilithic in the upper eulittoral and present throughout theyear Microchaete cf grisea is visually conspicuous as a black crust on shores oftenassociated with Calothrix crustacea Thuret ex Bornet et Flahault Kyrtuthrix maculans(Gomont) Umezaki and Scytonema cf crustaceum Agardh ex Bornet et FlahaultThis species appears to be heat and desiccation tolerant and reproduces quickly insummer This is the first record of M cf grisea as being epilithic from the marineenvironment

LOCAL DISTRIBUTION This species is recorded from Cape drsquoAguilar Cheung ChauClear Water Bay and Shek Mei Tau (Fig 1)

HABITAT Microchaete grisea and its similar morphological forms have been recordedfrom various habitats ie freshwater epiphytic on algae epilithic (Geitler 1932Freacutemy 1933) marine on mussels shells planktonic in open sea and stagnant seawater(Thajuddin 1991 Thajuddin amp Subramanian 1992 Hussain amp Khoja 1993)

Nostocaceae

Nostoc Vaucher ex Bornet et Flahault

Nostoc cf calcicola Breacutebisson ex Bornet et Flahault Figs 5 6Geitler 1932 842 Fig 534 Desikachary 1959 384 Pl 68 Fig 1

Thallus olive-green or blue-green mucilaginous slightly diffluent expanded formedby loosely entangled filaments sheath very thin hyaline or yellowish-brown cells

195

blue-green barrel-shaped subspherical rarely longer than broad 25 microm wide 15-28 microm long heterocyst intercalary subspherical 3-45 microm wide

The present species differs from the original description with respect to the habitatNostoc calcicola was originally described from moist soil (see Geitler 1932Desikachary 1959) whilst the Hong Kong species is epilithic in the marineenvironment

ECOLOGY This species is epilithic in the mid- and lower eulittoral and present onlyduring winter It is visually conspicuous on the shore as a brown-green biofilmoften associated with a thick matrix of biofilm mainly composed of various speciesof Calothrix Lyngbya Oscillatoria and diatoms This is the first record of N cfcalcicola from the marine environment as epilithic

LOCAL DISTRIBUTION This species is recorded from Cape drsquoAguilar Cheung ChauChung Hom Kok Clear Water Bay Lamma Island Lantau Island and Shek-O (Fig 1)

HABITAT Nostoc calcicola and its similar morphological forms have been recordedfrom various habitats ie freshwater on moist soil on tree bark (Geitler 1932Desikachary 1959) marine planktonic in open sea (Thajuddin amp Subramanian 1992)

Scytonemataceae

Scytonema Agardh ex Bornet et Flahault

Scytonema cf crustaceum Agardh ex Bornet et Flahault Fig 7Geitler 1932 782 Figs 504 1a 1b Desikachary 1959 485 Pl 88 Fig 4 Pl 99Fig 1

Thallus cushion-like black mucilaginous expanded filaments 18-26 microm wide withshort and erect false branches false branches U-shaped extensions of the mainfilaments always in pairs united at the top free at the base sheath thick unevenyellow-brown lamellated divergent trichomes blue-green 6-8 microm wide constrictedat the cross walls cells subquadrate 4-6 microm long cross walls not granulatedprotoplasm granular heterocyst intercalary oblong

The Hong Kong species differs from the original material with respect to the habitat

ECOLOGY This species is epilithic in the upper eulittoral and supralittoral fringe andpresent throughout the year Scytonema cf crustaceum is visually conspicuous as ablack crust on the shore and is often associated with Chroococcus spp and Gloeocapsaspp This species appears heat and desiccation tolerant and reproduces quickly insummer

LOCAL DISTRIBUTION This species is recorded from Cheung Chau Heng Fa ChuenLei Yue Mun and Wah Fu (Fig 1)

HABITATS Scytonema crustaceum and its similar morphological forms have beenrecorded from various habitats ie epilithic on moist rock surface on moist soil(Geitler 1932 Freacutemy 1933 Desikachary 1959) marine (Thajuddin amp Subramanian1992)

196

Stigonematales

Mastigocladaceae

Mastigocladoideae

Hapalosiphon Naumlgeli ex Bornet et Flahault

Hapalosiphon cf welwitschii W et GS West Figs 8 9Geitler 1932 531 Fig 328a Desikachary 1959 588 Pl 137 Fig 5

Thallus blue-green mucilaginous expanded filaments flexuous with short lateralbranches 55-75 microm wide sheath thin hyaline trichomes blue-green or olive-green 45-65 microm wide cells spherical or elongate as long as wide or longer 45-75 microm long cells of the branches 3-10 microm long apical cells attenuated heterocystrare intercalary quadrate rounded or long cylindrical 6-62 microm wide 6-8 micromlong

The local species is different from the original material with respect to the habitat

ECOLOGY This species is epilithic in the upper eulittoral and supralittoral fringe andpresent only during summer It is not conspicuous on the shore often associatedwith Gloeocapsa spp and Kyrtuthrix maculans This is the first record of H cfwelwitschii as epilithic from the marine environment

LOCAL DISTRIBUTION This species is recorded from Cheung Chau Heng Fa Chuenand Lei Yue Mun (Fig 1)

HABITATS Hapalosiphon welwitschii and its similar morphological forms have beenrecorded from various habitats ie freshwater epiphyte on algae on moist brickson moist soil in marshes (Geitler 1932 Desikachary 1959) marine (Thajuddin1991)

Nostochopsidaceae

Mastigocoleus Lagerheim ex Bornet et Flahault

Mastigocoleus testarum Lagerheim ex Bornet et Flahault Fig 10

Geitler 1932 473 Fig 284 Desikachary 1959 575 Pl 122 Figs 1-5

Thallus perforating blue-green mucilaginous filaments curved with short and lat-eral branches 6-10 microm wide sheath is thin hyaline trichomes blue-green or red-brown 35-6 microm wide not constricted at the cross walls cells cylindrical orsubcylindrical 9-13 microm long cross walls not granulated protoplasm granularheterocyst terminal as well as lateral 67-7 microm wide 68-10 microm long

ECOLOGY This species is epilithic in the upper eulittoral and supralittoral fringe andpresent throughout the year Mastigocoleus testarum is visually conspicuous as ablack or brown crust often associated with Calothrix spp Gloeocapsa spp Kyrtuthrixmaculans and Scytonema cf crustaceum This species appears to be heat and desiccationtolerant and reproduces quickly in summer

197

LOCAL DISTRIBUTION The species is recorded from Cape drsquoAguilar Cheung ChauChung Hom Kok Clear Water Bay Lamma Island Lantau Island Shek Mei Tauand Shek-O (Fig 1)

HABITAT Marine on molluscan shells epilithic endolithic (Umezaki 1961 Thajuddinamp Subramanian 1992)

GEOGRAPHICAL DISTRIBUTION Atlantic coast of Europe Atlantic and Pacific coasts ofNorth America Bermuda Central America (Mexico) South America China IndiaJapan Mediterranean South East Asia (Thailand)

Discussion

Seven heterocystous filamentous cyanobacterial species from six genera belongingto six families and two orders are reported in the present study All the species arenew records for Hong Kong but Dichothrix cf spiralis Hapalosiphon cf welwitschiiMicrochaete cf grisea and Nostoc cf calcicola are also recorded for the first time asepiliths from the marine environment All the species were recorded from the uppereulittoral and supralittoral fringe except D cf baueriana and N cf calcicola whichwere recorded from the mid- and lower eulittoral Scytonema cf crustaceum andMastigocoleus testarum were a dominant component of the intertidal epilithic biofilmforming black and brown bands at Cheung Chau and Shek Mei Tau respectivelyOther species were common in the biofilm but did not form individual bands howeverthese species were associated with a variety of other cyanobacterial species in thebiofilm

Previous descriptions of Hong Kong cyanobacteria (Tseng 1936 Lee 1964 1966Hodgkiss amp Lee 1983 Kaehler 1994 Nagarkar 1998a b 2000) recorded 65 speciesof which only eight species were heterocystous namely Brachytrichia quoyi Bornetet Flahault Calothrix scopulorum Bornet et Flahault Calothrix contarenii Bornet etFlahault Calothrix crustacea Calothrix javanica de Wildeman Hormothamnionenteromorphoides Grunow ex Bornet et Flahault Kyrtuthrix maculans and Nodulariaspumigena Mertens ex Bornet et Flahault Kyrtuthrix maculans is the most abundantheterocystous cyanobacterium on Hong Kong rocky shores forming a characteristicblack band in mid- and upper eulittoral and is also widely distributed on tropicalrocky shores around the world (Williams 1993 Kaehler 1994 Kaehler amp Williams1996 Nagarkar 1996 Nagarkar amp Williams 1999) Calothrix scopulorum C con-tarenii and C crustacea are common on Hong Kong rocky shores and form blackleathery crusts on the lower mid- and upper eulittoral and are also widely distributedin various geographical areas (see Nagarkar 1996) Most of the species are widelydistributed around the world (Umezaki 1961 Thajuddin 1991 Thajuddin ampSubramanian 1992)

Whilst the addition of seven new species increases the species richness of heterocystouscyanobacteria from the region it is however still relatively low as compared toother geographic locations (eg Japan Umezaki 1961 Chile Parra amp Gonzalez1976 Red Sea Potts 1980 Aldabra Whitton amp Potts 1980 Saudi Arabia Hussainamp Khoja 1993)

198

Although all seven species have previously been recorded from the marineenvironment only Dichothrix cf baueriana and Mastigocoleus testarum were re-ported as marine epiliths In general rocky shores represent a most inhospitablehabitat due to the lack of nutrients tidal fluctuation and heat and desiccation stressesIn such stressful environments heterocystous species often dominate especially onthe high shore levels as they escape competition from less tolerant non-heterocystousspecies and are able to flourish due to their nitrogen fixation ability and stress toleranceThese attributes explain the diversity and abundance of heterocystous cyanobacteriaon rocky shores around the world especially in the high intertidal where the nutrientsupply is limited

Acknowledgements

I would like to thank Dr Gray A Williams Mr Aruna Weerasooriya (HKU) and Dr N Thajuddin(NFMC India) for their valuable comments on the manuscript Two anonymous referees and ProfJR Johansen also provided constructive criticisms Thanks to Prof R D Hill for translatingGerman and French literature for me This research was supported by a RGC grant to GAW (RGCproject no HKU 723198M)

References

ANAGNOSTIDIS K amp J KOMAacuteREK (1990) Modern approach to the classification system ofCyanophytes 5 ndash Stigonematales - Arch Hydrobiol Suppl 86 (Algol Stud 59) 1-73

ANDERSON MJ (1995) Variations in biofilms colonizing artificial surfaces seasonal effects andeffects of grazers - J Mar Biol Ass UK 75 705-714

CRIBB AB (1966) The algae of Heron Island Great Barrier Reef Australia Part 1 A generalaccount Vol 1 - In The University of Queensland paper Great Barrier Reef Committee HeronIsland Research Station 1-23 Univ of Queensland Press St Lucia

DESIKACHARY TV (1959) Cyanophyta - Indian Council of Agricultural Research New Delhi

FREacuteMY P (1933 reprinted 1972) Cyanophyceacutees des Cocirctes drsquoEurope - Meacutemoires de la SocieacuteteacuteNationale des Sciences Naturelles et Matheacutematiques de Cherbourg 41 1-236

GEITLER L (1932 reprinted 1985) Cyanophyceae - In L Rabenhorstrsquos Kryptogamen-Flora vonDeutschland Oumlsterreich und der Schweiz Akademische Verlags- Gesellschaft Leipzig Reprintedby Koeltz Scientific

GONZALEZ M amp OO PARRA (1975) Cianofitas marinas de Chile 1 Cianofitas del ambienteintermareal de la bahia de concepcion - Gayana Bot 31 1-69

HODGKISS IJ amp KY LEE (1983) Hong Kong Seaweeds - Urban Council Hong Kong

HOFFMANN L amp V DEMOULIN (1991) Marine Cyanophyceae of Papua New Guinea IILyngbya bouillonii sp nov a remarkable tropical reef-inhabiting blue-green alga - Belg J Bot124 82-88

HOFFMANN L amp V DEMOULIN (1993) Marine Cyanophyceae of Papua New Guinea III Thegenera Borzia and Oscillatoria - Bot Mar 36 451-459

HUA H amp CK TSENG (1984) Cyanophyta - In TSENG CK (ed) Common Seaweeds ofChina 13-41 Science Press Beijing

HUSSAIN MI amp TM KHOJA (1993) Intertidal and subtidal blue-green algal mats of open andmangrove areas in the Farasan Archipelago (Saudi Arabia) Red Sea - Bot Mar 36 377-388

193

Figs 2-10 Marine epilithic cyanobacteria Fig 2 Dichothrix cf baueriana Fig 3 Dichothrix cfspiralis Fig 4 Microchaete cf grisea Figs 5 amp 6 Nostoc cf calcicola Fig 7 Scytonema cfcrustaceum Figs 8 amp 9 Hapalosiphon cf welwitschii Fig 10 Mastigocoleus testarumScale bars Fig 2 = 45 microm Fig 3 = 60 microm Fig 4 = 15 microm Fig 5 = 10 microm Fig 6 = 20 microm Figs 78 9 = 25 microm and Fig 10 = 40 microm

194

LOCAL DISTRIBUTION This species is recorded from Cheung Chau Lamma Island andLantau Island (Fig 1)

HABITAT Dichothrix spiralis and its similar morphological forms have been recordedfrom various habitats ie freshwater epiphyte on aquatic plant (Geitler 1932)marine (Thajuddin 1991)

Microchaetaceae

Microchaetoideae

Microchaete Thuret ex Bornet et FlahaultMicrochaete cf grisea Thuret ex Bornet et Flahault Fig 4

Geitler 1932 666 Fig 427 Desikachary 1959 510

Thallus caespitose dull-green mucilaginous formed by up to 1 mm long denselyentangled filaments filaments bent at the base swollen 6-7 microm wide sheath thinhyaline trichomes yellowish-brown 5-6 microm wide constricted at the cross wallscells 25-4 microm long cross walls not granulated protoplasm granular heterocystbasal spherical single

The present species differs from the description of the original material with respectto the habitat

ECOLOGY This species is epilithic in the upper eulittoral and present throughout theyear Microchaete cf grisea is visually conspicuous as a black crust on shores oftenassociated with Calothrix crustacea Thuret ex Bornet et Flahault Kyrtuthrix maculans(Gomont) Umezaki and Scytonema cf crustaceum Agardh ex Bornet et FlahaultThis species appears to be heat and desiccation tolerant and reproduces quickly insummer This is the first record of M cf grisea as being epilithic from the marineenvironment

LOCAL DISTRIBUTION This species is recorded from Cape drsquoAguilar Cheung ChauClear Water Bay and Shek Mei Tau (Fig 1)

HABITAT Microchaete grisea and its similar morphological forms have been recordedfrom various habitats ie freshwater epiphytic on algae epilithic (Geitler 1932Freacutemy 1933) marine on mussels shells planktonic in open sea and stagnant seawater(Thajuddin 1991 Thajuddin amp Subramanian 1992 Hussain amp Khoja 1993)

Nostocaceae

Nostoc Vaucher ex Bornet et Flahault

Nostoc cf calcicola Breacutebisson ex Bornet et Flahault Figs 5 6Geitler 1932 842 Fig 534 Desikachary 1959 384 Pl 68 Fig 1

Thallus olive-green or blue-green mucilaginous slightly diffluent expanded formedby loosely entangled filaments sheath very thin hyaline or yellowish-brown cells

195

blue-green barrel-shaped subspherical rarely longer than broad 25 microm wide 15-28 microm long heterocyst intercalary subspherical 3-45 microm wide

The present species differs from the original description with respect to the habitatNostoc calcicola was originally described from moist soil (see Geitler 1932Desikachary 1959) whilst the Hong Kong species is epilithic in the marineenvironment

ECOLOGY This species is epilithic in the mid- and lower eulittoral and present onlyduring winter It is visually conspicuous on the shore as a brown-green biofilmoften associated with a thick matrix of biofilm mainly composed of various speciesof Calothrix Lyngbya Oscillatoria and diatoms This is the first record of N cfcalcicola from the marine environment as epilithic

LOCAL DISTRIBUTION This species is recorded from Cape drsquoAguilar Cheung ChauChung Hom Kok Clear Water Bay Lamma Island Lantau Island and Shek-O (Fig 1)

HABITAT Nostoc calcicola and its similar morphological forms have been recordedfrom various habitats ie freshwater on moist soil on tree bark (Geitler 1932Desikachary 1959) marine planktonic in open sea (Thajuddin amp Subramanian 1992)

Scytonemataceae

Scytonema Agardh ex Bornet et Flahault

Scytonema cf crustaceum Agardh ex Bornet et Flahault Fig 7Geitler 1932 782 Figs 504 1a 1b Desikachary 1959 485 Pl 88 Fig 4 Pl 99Fig 1

Thallus cushion-like black mucilaginous expanded filaments 18-26 microm wide withshort and erect false branches false branches U-shaped extensions of the mainfilaments always in pairs united at the top free at the base sheath thick unevenyellow-brown lamellated divergent trichomes blue-green 6-8 microm wide constrictedat the cross walls cells subquadrate 4-6 microm long cross walls not granulatedprotoplasm granular heterocyst intercalary oblong

The Hong Kong species differs from the original material with respect to the habitat

ECOLOGY This species is epilithic in the upper eulittoral and supralittoral fringe andpresent throughout the year Scytonema cf crustaceum is visually conspicuous as ablack crust on the shore and is often associated with Chroococcus spp and Gloeocapsaspp This species appears heat and desiccation tolerant and reproduces quickly insummer

LOCAL DISTRIBUTION This species is recorded from Cheung Chau Heng Fa ChuenLei Yue Mun and Wah Fu (Fig 1)

HABITATS Scytonema crustaceum and its similar morphological forms have beenrecorded from various habitats ie epilithic on moist rock surface on moist soil(Geitler 1932 Freacutemy 1933 Desikachary 1959) marine (Thajuddin amp Subramanian1992)

196

Stigonematales

Mastigocladaceae

Mastigocladoideae

Hapalosiphon Naumlgeli ex Bornet et Flahault

Hapalosiphon cf welwitschii W et GS West Figs 8 9Geitler 1932 531 Fig 328a Desikachary 1959 588 Pl 137 Fig 5

Thallus blue-green mucilaginous expanded filaments flexuous with short lateralbranches 55-75 microm wide sheath thin hyaline trichomes blue-green or olive-green 45-65 microm wide cells spherical or elongate as long as wide or longer 45-75 microm long cells of the branches 3-10 microm long apical cells attenuated heterocystrare intercalary quadrate rounded or long cylindrical 6-62 microm wide 6-8 micromlong

The local species is different from the original material with respect to the habitat

ECOLOGY This species is epilithic in the upper eulittoral and supralittoral fringe andpresent only during summer It is not conspicuous on the shore often associatedwith Gloeocapsa spp and Kyrtuthrix maculans This is the first record of H cfwelwitschii as epilithic from the marine environment

LOCAL DISTRIBUTION This species is recorded from Cheung Chau Heng Fa Chuenand Lei Yue Mun (Fig 1)

HABITATS Hapalosiphon welwitschii and its similar morphological forms have beenrecorded from various habitats ie freshwater epiphyte on algae on moist brickson moist soil in marshes (Geitler 1932 Desikachary 1959) marine (Thajuddin1991)

Nostochopsidaceae

Mastigocoleus Lagerheim ex Bornet et Flahault

Mastigocoleus testarum Lagerheim ex Bornet et Flahault Fig 10

Geitler 1932 473 Fig 284 Desikachary 1959 575 Pl 122 Figs 1-5

Thallus perforating blue-green mucilaginous filaments curved with short and lat-eral branches 6-10 microm wide sheath is thin hyaline trichomes blue-green or red-brown 35-6 microm wide not constricted at the cross walls cells cylindrical orsubcylindrical 9-13 microm long cross walls not granulated protoplasm granularheterocyst terminal as well as lateral 67-7 microm wide 68-10 microm long

ECOLOGY This species is epilithic in the upper eulittoral and supralittoral fringe andpresent throughout the year Mastigocoleus testarum is visually conspicuous as ablack or brown crust often associated with Calothrix spp Gloeocapsa spp Kyrtuthrixmaculans and Scytonema cf crustaceum This species appears to be heat and desiccationtolerant and reproduces quickly in summer

197

LOCAL DISTRIBUTION The species is recorded from Cape drsquoAguilar Cheung ChauChung Hom Kok Clear Water Bay Lamma Island Lantau Island Shek Mei Tauand Shek-O (Fig 1)

HABITAT Marine on molluscan shells epilithic endolithic (Umezaki 1961 Thajuddinamp Subramanian 1992)

GEOGRAPHICAL DISTRIBUTION Atlantic coast of Europe Atlantic and Pacific coasts ofNorth America Bermuda Central America (Mexico) South America China IndiaJapan Mediterranean South East Asia (Thailand)

Discussion

Seven heterocystous filamentous cyanobacterial species from six genera belongingto six families and two orders are reported in the present study All the species arenew records for Hong Kong but Dichothrix cf spiralis Hapalosiphon cf welwitschiiMicrochaete cf grisea and Nostoc cf calcicola are also recorded for the first time asepiliths from the marine environment All the species were recorded from the uppereulittoral and supralittoral fringe except D cf baueriana and N cf calcicola whichwere recorded from the mid- and lower eulittoral Scytonema cf crustaceum andMastigocoleus testarum were a dominant component of the intertidal epilithic biofilmforming black and brown bands at Cheung Chau and Shek Mei Tau respectivelyOther species were common in the biofilm but did not form individual bands howeverthese species were associated with a variety of other cyanobacterial species in thebiofilm

Previous descriptions of Hong Kong cyanobacteria (Tseng 1936 Lee 1964 1966Hodgkiss amp Lee 1983 Kaehler 1994 Nagarkar 1998a b 2000) recorded 65 speciesof which only eight species were heterocystous namely Brachytrichia quoyi Bornetet Flahault Calothrix scopulorum Bornet et Flahault Calothrix contarenii Bornet etFlahault Calothrix crustacea Calothrix javanica de Wildeman Hormothamnionenteromorphoides Grunow ex Bornet et Flahault Kyrtuthrix maculans and Nodulariaspumigena Mertens ex Bornet et Flahault Kyrtuthrix maculans is the most abundantheterocystous cyanobacterium on Hong Kong rocky shores forming a characteristicblack band in mid- and upper eulittoral and is also widely distributed on tropicalrocky shores around the world (Williams 1993 Kaehler 1994 Kaehler amp Williams1996 Nagarkar 1996 Nagarkar amp Williams 1999) Calothrix scopulorum C con-tarenii and C crustacea are common on Hong Kong rocky shores and form blackleathery crusts on the lower mid- and upper eulittoral and are also widely distributedin various geographical areas (see Nagarkar 1996) Most of the species are widelydistributed around the world (Umezaki 1961 Thajuddin 1991 Thajuddin ampSubramanian 1992)

Whilst the addition of seven new species increases the species richness of heterocystouscyanobacteria from the region it is however still relatively low as compared toother geographic locations (eg Japan Umezaki 1961 Chile Parra amp Gonzalez1976 Red Sea Potts 1980 Aldabra Whitton amp Potts 1980 Saudi Arabia Hussainamp Khoja 1993)

198

Although all seven species have previously been recorded from the marineenvironment only Dichothrix cf baueriana and Mastigocoleus testarum were re-ported as marine epiliths In general rocky shores represent a most inhospitablehabitat due to the lack of nutrients tidal fluctuation and heat and desiccation stressesIn such stressful environments heterocystous species often dominate especially onthe high shore levels as they escape competition from less tolerant non-heterocystousspecies and are able to flourish due to their nitrogen fixation ability and stress toleranceThese attributes explain the diversity and abundance of heterocystous cyanobacteriaon rocky shores around the world especially in the high intertidal where the nutrientsupply is limited

Acknowledgements

I would like to thank Dr Gray A Williams Mr Aruna Weerasooriya (HKU) and Dr N Thajuddin(NFMC India) for their valuable comments on the manuscript Two anonymous referees and ProfJR Johansen also provided constructive criticisms Thanks to Prof R D Hill for translatingGerman and French literature for me This research was supported by a RGC grant to GAW (RGCproject no HKU 723198M)

References

ANAGNOSTIDIS K amp J KOMAacuteREK (1990) Modern approach to the classification system ofCyanophytes 5 ndash Stigonematales - Arch Hydrobiol Suppl 86 (Algol Stud 59) 1-73

ANDERSON MJ (1995) Variations in biofilms colonizing artificial surfaces seasonal effects andeffects of grazers - J Mar Biol Ass UK 75 705-714

CRIBB AB (1966) The algae of Heron Island Great Barrier Reef Australia Part 1 A generalaccount Vol 1 - In The University of Queensland paper Great Barrier Reef Committee HeronIsland Research Station 1-23 Univ of Queensland Press St Lucia

DESIKACHARY TV (1959) Cyanophyta - Indian Council of Agricultural Research New Delhi

FREacuteMY P (1933 reprinted 1972) Cyanophyceacutees des Cocirctes drsquoEurope - Meacutemoires de la SocieacuteteacuteNationale des Sciences Naturelles et Matheacutematiques de Cherbourg 41 1-236

GEITLER L (1932 reprinted 1985) Cyanophyceae - In L Rabenhorstrsquos Kryptogamen-Flora vonDeutschland Oumlsterreich und der Schweiz Akademische Verlags- Gesellschaft Leipzig Reprintedby Koeltz Scientific

GONZALEZ M amp OO PARRA (1975) Cianofitas marinas de Chile 1 Cianofitas del ambienteintermareal de la bahia de concepcion - Gayana Bot 31 1-69

HODGKISS IJ amp KY LEE (1983) Hong Kong Seaweeds - Urban Council Hong Kong

HOFFMANN L amp V DEMOULIN (1991) Marine Cyanophyceae of Papua New Guinea IILyngbya bouillonii sp nov a remarkable tropical reef-inhabiting blue-green alga - Belg J Bot124 82-88

HOFFMANN L amp V DEMOULIN (1993) Marine Cyanophyceae of Papua New Guinea III Thegenera Borzia and Oscillatoria - Bot Mar 36 451-459

HUA H amp CK TSENG (1984) Cyanophyta - In TSENG CK (ed) Common Seaweeds ofChina 13-41 Science Press Beijing

HUSSAIN MI amp TM KHOJA (1993) Intertidal and subtidal blue-green algal mats of open andmangrove areas in the Farasan Archipelago (Saudi Arabia) Red Sea - Bot Mar 36 377-388

194

LOCAL DISTRIBUTION This species is recorded from Cheung Chau Lamma Island andLantau Island (Fig 1)

HABITAT Dichothrix spiralis and its similar morphological forms have been recordedfrom various habitats ie freshwater epiphyte on aquatic plant (Geitler 1932)marine (Thajuddin 1991)

Microchaetaceae

Microchaetoideae

Microchaete Thuret ex Bornet et FlahaultMicrochaete cf grisea Thuret ex Bornet et Flahault Fig 4

Geitler 1932 666 Fig 427 Desikachary 1959 510

Thallus caespitose dull-green mucilaginous formed by up to 1 mm long denselyentangled filaments filaments bent at the base swollen 6-7 microm wide sheath thinhyaline trichomes yellowish-brown 5-6 microm wide constricted at the cross wallscells 25-4 microm long cross walls not granulated protoplasm granular heterocystbasal spherical single

The present species differs from the description of the original material with respectto the habitat

ECOLOGY This species is epilithic in the upper eulittoral and present throughout theyear Microchaete cf grisea is visually conspicuous as a black crust on shores oftenassociated with Calothrix crustacea Thuret ex Bornet et Flahault Kyrtuthrix maculans(Gomont) Umezaki and Scytonema cf crustaceum Agardh ex Bornet et FlahaultThis species appears to be heat and desiccation tolerant and reproduces quickly insummer This is the first record of M cf grisea as being epilithic from the marineenvironment

LOCAL DISTRIBUTION This species is recorded from Cape drsquoAguilar Cheung ChauClear Water Bay and Shek Mei Tau (Fig 1)

HABITAT Microchaete grisea and its similar morphological forms have been recordedfrom various habitats ie freshwater epiphytic on algae epilithic (Geitler 1932Freacutemy 1933) marine on mussels shells planktonic in open sea and stagnant seawater(Thajuddin 1991 Thajuddin amp Subramanian 1992 Hussain amp Khoja 1993)

Nostocaceae

Nostoc Vaucher ex Bornet et Flahault

Nostoc cf calcicola Breacutebisson ex Bornet et Flahault Figs 5 6Geitler 1932 842 Fig 534 Desikachary 1959 384 Pl 68 Fig 1

Thallus olive-green or blue-green mucilaginous slightly diffluent expanded formedby loosely entangled filaments sheath very thin hyaline or yellowish-brown cells

195

blue-green barrel-shaped subspherical rarely longer than broad 25 microm wide 15-28 microm long heterocyst intercalary subspherical 3-45 microm wide

The present species differs from the original description with respect to the habitatNostoc calcicola was originally described from moist soil (see Geitler 1932Desikachary 1959) whilst the Hong Kong species is epilithic in the marineenvironment

ECOLOGY This species is epilithic in the mid- and lower eulittoral and present onlyduring winter It is visually conspicuous on the shore as a brown-green biofilmoften associated with a thick matrix of biofilm mainly composed of various speciesof Calothrix Lyngbya Oscillatoria and diatoms This is the first record of N cfcalcicola from the marine environment as epilithic

LOCAL DISTRIBUTION This species is recorded from Cape drsquoAguilar Cheung ChauChung Hom Kok Clear Water Bay Lamma Island Lantau Island and Shek-O (Fig 1)

HABITAT Nostoc calcicola and its similar morphological forms have been recordedfrom various habitats ie freshwater on moist soil on tree bark (Geitler 1932Desikachary 1959) marine planktonic in open sea (Thajuddin amp Subramanian 1992)

Scytonemataceae

Scytonema Agardh ex Bornet et Flahault

Scytonema cf crustaceum Agardh ex Bornet et Flahault Fig 7Geitler 1932 782 Figs 504 1a 1b Desikachary 1959 485 Pl 88 Fig 4 Pl 99Fig 1

Thallus cushion-like black mucilaginous expanded filaments 18-26 microm wide withshort and erect false branches false branches U-shaped extensions of the mainfilaments always in pairs united at the top free at the base sheath thick unevenyellow-brown lamellated divergent trichomes blue-green 6-8 microm wide constrictedat the cross walls cells subquadrate 4-6 microm long cross walls not granulatedprotoplasm granular heterocyst intercalary oblong

The Hong Kong species differs from the original material with respect to the habitat

ECOLOGY This species is epilithic in the upper eulittoral and supralittoral fringe andpresent throughout the year Scytonema cf crustaceum is visually conspicuous as ablack crust on the shore and is often associated with Chroococcus spp and Gloeocapsaspp This species appears heat and desiccation tolerant and reproduces quickly insummer

LOCAL DISTRIBUTION This species is recorded from Cheung Chau Heng Fa ChuenLei Yue Mun and Wah Fu (Fig 1)

HABITATS Scytonema crustaceum and its similar morphological forms have beenrecorded from various habitats ie epilithic on moist rock surface on moist soil(Geitler 1932 Freacutemy 1933 Desikachary 1959) marine (Thajuddin amp Subramanian1992)

196

Stigonematales

Mastigocladaceae

Mastigocladoideae

Hapalosiphon Naumlgeli ex Bornet et Flahault

Hapalosiphon cf welwitschii W et GS West Figs 8 9Geitler 1932 531 Fig 328a Desikachary 1959 588 Pl 137 Fig 5

Thallus blue-green mucilaginous expanded filaments flexuous with short lateralbranches 55-75 microm wide sheath thin hyaline trichomes blue-green or olive-green 45-65 microm wide cells spherical or elongate as long as wide or longer 45-75 microm long cells of the branches 3-10 microm long apical cells attenuated heterocystrare intercalary quadrate rounded or long cylindrical 6-62 microm wide 6-8 micromlong

The local species is different from the original material with respect to the habitat

ECOLOGY This species is epilithic in the upper eulittoral and supralittoral fringe andpresent only during summer It is not conspicuous on the shore often associatedwith Gloeocapsa spp and Kyrtuthrix maculans This is the first record of H cfwelwitschii as epilithic from the marine environment

LOCAL DISTRIBUTION This species is recorded from Cheung Chau Heng Fa Chuenand Lei Yue Mun (Fig 1)

HABITATS Hapalosiphon welwitschii and its similar morphological forms have beenrecorded from various habitats ie freshwater epiphyte on algae on moist brickson moist soil in marshes (Geitler 1932 Desikachary 1959) marine (Thajuddin1991)

Nostochopsidaceae

Mastigocoleus Lagerheim ex Bornet et Flahault

Mastigocoleus testarum Lagerheim ex Bornet et Flahault Fig 10

Geitler 1932 473 Fig 284 Desikachary 1959 575 Pl 122 Figs 1-5

Thallus perforating blue-green mucilaginous filaments curved with short and lat-eral branches 6-10 microm wide sheath is thin hyaline trichomes blue-green or red-brown 35-6 microm wide not constricted at the cross walls cells cylindrical orsubcylindrical 9-13 microm long cross walls not granulated protoplasm granularheterocyst terminal as well as lateral 67-7 microm wide 68-10 microm long

ECOLOGY This species is epilithic in the upper eulittoral and supralittoral fringe andpresent throughout the year Mastigocoleus testarum is visually conspicuous as ablack or brown crust often associated with Calothrix spp Gloeocapsa spp Kyrtuthrixmaculans and Scytonema cf crustaceum This species appears to be heat and desiccationtolerant and reproduces quickly in summer

197

LOCAL DISTRIBUTION The species is recorded from Cape drsquoAguilar Cheung ChauChung Hom Kok Clear Water Bay Lamma Island Lantau Island Shek Mei Tauand Shek-O (Fig 1)

HABITAT Marine on molluscan shells epilithic endolithic (Umezaki 1961 Thajuddinamp Subramanian 1992)

GEOGRAPHICAL DISTRIBUTION Atlantic coast of Europe Atlantic and Pacific coasts ofNorth America Bermuda Central America (Mexico) South America China IndiaJapan Mediterranean South East Asia (Thailand)

Discussion

Seven heterocystous filamentous cyanobacterial species from six genera belongingto six families and two orders are reported in the present study All the species arenew records for Hong Kong but Dichothrix cf spiralis Hapalosiphon cf welwitschiiMicrochaete cf grisea and Nostoc cf calcicola are also recorded for the first time asepiliths from the marine environment All the species were recorded from the uppereulittoral and supralittoral fringe except D cf baueriana and N cf calcicola whichwere recorded from the mid- and lower eulittoral Scytonema cf crustaceum andMastigocoleus testarum were a dominant component of the intertidal epilithic biofilmforming black and brown bands at Cheung Chau and Shek Mei Tau respectivelyOther species were common in the biofilm but did not form individual bands howeverthese species were associated with a variety of other cyanobacterial species in thebiofilm

Previous descriptions of Hong Kong cyanobacteria (Tseng 1936 Lee 1964 1966Hodgkiss amp Lee 1983 Kaehler 1994 Nagarkar 1998a b 2000) recorded 65 speciesof which only eight species were heterocystous namely Brachytrichia quoyi Bornetet Flahault Calothrix scopulorum Bornet et Flahault Calothrix contarenii Bornet etFlahault Calothrix crustacea Calothrix javanica de Wildeman Hormothamnionenteromorphoides Grunow ex Bornet et Flahault Kyrtuthrix maculans and Nodulariaspumigena Mertens ex Bornet et Flahault Kyrtuthrix maculans is the most abundantheterocystous cyanobacterium on Hong Kong rocky shores forming a characteristicblack band in mid- and upper eulittoral and is also widely distributed on tropicalrocky shores around the world (Williams 1993 Kaehler 1994 Kaehler amp Williams1996 Nagarkar 1996 Nagarkar amp Williams 1999) Calothrix scopulorum C con-tarenii and C crustacea are common on Hong Kong rocky shores and form blackleathery crusts on the lower mid- and upper eulittoral and are also widely distributedin various geographical areas (see Nagarkar 1996) Most of the species are widelydistributed around the world (Umezaki 1961 Thajuddin 1991 Thajuddin ampSubramanian 1992)

Whilst the addition of seven new species increases the species richness of heterocystouscyanobacteria from the region it is however still relatively low as compared toother geographic locations (eg Japan Umezaki 1961 Chile Parra amp Gonzalez1976 Red Sea Potts 1980 Aldabra Whitton amp Potts 1980 Saudi Arabia Hussainamp Khoja 1993)

198

Although all seven species have previously been recorded from the marineenvironment only Dichothrix cf baueriana and Mastigocoleus testarum were re-ported as marine epiliths In general rocky shores represent a most inhospitablehabitat due to the lack of nutrients tidal fluctuation and heat and desiccation stressesIn such stressful environments heterocystous species often dominate especially onthe high shore levels as they escape competition from less tolerant non-heterocystousspecies and are able to flourish due to their nitrogen fixation ability and stress toleranceThese attributes explain the diversity and abundance of heterocystous cyanobacteriaon rocky shores around the world especially in the high intertidal where the nutrientsupply is limited

Acknowledgements

I would like to thank Dr Gray A Williams Mr Aruna Weerasooriya (HKU) and Dr N Thajuddin(NFMC India) for their valuable comments on the manuscript Two anonymous referees and ProfJR Johansen also provided constructive criticisms Thanks to Prof R D Hill for translatingGerman and French literature for me This research was supported by a RGC grant to GAW (RGCproject no HKU 723198M)

References

ANAGNOSTIDIS K amp J KOMAacuteREK (1990) Modern approach to the classification system ofCyanophytes 5 ndash Stigonematales - Arch Hydrobiol Suppl 86 (Algol Stud 59) 1-73

ANDERSON MJ (1995) Variations in biofilms colonizing artificial surfaces seasonal effects andeffects of grazers - J Mar Biol Ass UK 75 705-714

CRIBB AB (1966) The algae of Heron Island Great Barrier Reef Australia Part 1 A generalaccount Vol 1 - In The University of Queensland paper Great Barrier Reef Committee HeronIsland Research Station 1-23 Univ of Queensland Press St Lucia

DESIKACHARY TV (1959) Cyanophyta - Indian Council of Agricultural Research New Delhi

FREacuteMY P (1933 reprinted 1972) Cyanophyceacutees des Cocirctes drsquoEurope - Meacutemoires de la SocieacuteteacuteNationale des Sciences Naturelles et Matheacutematiques de Cherbourg 41 1-236

GEITLER L (1932 reprinted 1985) Cyanophyceae - In L Rabenhorstrsquos Kryptogamen-Flora vonDeutschland Oumlsterreich und der Schweiz Akademische Verlags- Gesellschaft Leipzig Reprintedby Koeltz Scientific

GONZALEZ M amp OO PARRA (1975) Cianofitas marinas de Chile 1 Cianofitas del ambienteintermareal de la bahia de concepcion - Gayana Bot 31 1-69

HODGKISS IJ amp KY LEE (1983) Hong Kong Seaweeds - Urban Council Hong Kong

HOFFMANN L amp V DEMOULIN (1991) Marine Cyanophyceae of Papua New Guinea IILyngbya bouillonii sp nov a remarkable tropical reef-inhabiting blue-green alga - Belg J Bot124 82-88

HOFFMANN L amp V DEMOULIN (1993) Marine Cyanophyceae of Papua New Guinea III Thegenera Borzia and Oscillatoria - Bot Mar 36 451-459

HUA H amp CK TSENG (1984) Cyanophyta - In TSENG CK (ed) Common Seaweeds ofChina 13-41 Science Press Beijing

HUSSAIN MI amp TM KHOJA (1993) Intertidal and subtidal blue-green algal mats of open andmangrove areas in the Farasan Archipelago (Saudi Arabia) Red Sea - Bot Mar 36 377-388

195

blue-green barrel-shaped subspherical rarely longer than broad 25 microm wide 15-28 microm long heterocyst intercalary subspherical 3-45 microm wide

The present species differs from the original description with respect to the habitatNostoc calcicola was originally described from moist soil (see Geitler 1932Desikachary 1959) whilst the Hong Kong species is epilithic in the marineenvironment

ECOLOGY This species is epilithic in the mid- and lower eulittoral and present onlyduring winter It is visually conspicuous on the shore as a brown-green biofilmoften associated with a thick matrix of biofilm mainly composed of various speciesof Calothrix Lyngbya Oscillatoria and diatoms This is the first record of N cfcalcicola from the marine environment as epilithic

LOCAL DISTRIBUTION This species is recorded from Cape drsquoAguilar Cheung ChauChung Hom Kok Clear Water Bay Lamma Island Lantau Island and Shek-O (Fig 1)

HABITAT Nostoc calcicola and its similar morphological forms have been recordedfrom various habitats ie freshwater on moist soil on tree bark (Geitler 1932Desikachary 1959) marine planktonic in open sea (Thajuddin amp Subramanian 1992)

Scytonemataceae

Scytonema Agardh ex Bornet et Flahault

Scytonema cf crustaceum Agardh ex Bornet et Flahault Fig 7Geitler 1932 782 Figs 504 1a 1b Desikachary 1959 485 Pl 88 Fig 4 Pl 99Fig 1

Thallus cushion-like black mucilaginous expanded filaments 18-26 microm wide withshort and erect false branches false branches U-shaped extensions of the mainfilaments always in pairs united at the top free at the base sheath thick unevenyellow-brown lamellated divergent trichomes blue-green 6-8 microm wide constrictedat the cross walls cells subquadrate 4-6 microm long cross walls not granulatedprotoplasm granular heterocyst intercalary oblong

The Hong Kong species differs from the original material with respect to the habitat

ECOLOGY This species is epilithic in the upper eulittoral and supralittoral fringe andpresent throughout the year Scytonema cf crustaceum is visually conspicuous as ablack crust on the shore and is often associated with Chroococcus spp and Gloeocapsaspp This species appears heat and desiccation tolerant and reproduces quickly insummer

LOCAL DISTRIBUTION This species is recorded from Cheung Chau Heng Fa ChuenLei Yue Mun and Wah Fu (Fig 1)

HABITATS Scytonema crustaceum and its similar morphological forms have beenrecorded from various habitats ie epilithic on moist rock surface on moist soil(Geitler 1932 Freacutemy 1933 Desikachary 1959) marine (Thajuddin amp Subramanian1992)

196

Stigonematales

Mastigocladaceae

Mastigocladoideae

Hapalosiphon Naumlgeli ex Bornet et Flahault

Hapalosiphon cf welwitschii W et GS West Figs 8 9Geitler 1932 531 Fig 328a Desikachary 1959 588 Pl 137 Fig 5

Thallus blue-green mucilaginous expanded filaments flexuous with short lateralbranches 55-75 microm wide sheath thin hyaline trichomes blue-green or olive-green 45-65 microm wide cells spherical or elongate as long as wide or longer 45-75 microm long cells of the branches 3-10 microm long apical cells attenuated heterocystrare intercalary quadrate rounded or long cylindrical 6-62 microm wide 6-8 micromlong

The local species is different from the original material with respect to the habitat

ECOLOGY This species is epilithic in the upper eulittoral and supralittoral fringe andpresent only during summer It is not conspicuous on the shore often associatedwith Gloeocapsa spp and Kyrtuthrix maculans This is the first record of H cfwelwitschii as epilithic from the marine environment

LOCAL DISTRIBUTION This species is recorded from Cheung Chau Heng Fa Chuenand Lei Yue Mun (Fig 1)

HABITATS Hapalosiphon welwitschii and its similar morphological forms have beenrecorded from various habitats ie freshwater epiphyte on algae on moist brickson moist soil in marshes (Geitler 1932 Desikachary 1959) marine (Thajuddin1991)

Nostochopsidaceae

Mastigocoleus Lagerheim ex Bornet et Flahault

Mastigocoleus testarum Lagerheim ex Bornet et Flahault Fig 10

Geitler 1932 473 Fig 284 Desikachary 1959 575 Pl 122 Figs 1-5

Thallus perforating blue-green mucilaginous filaments curved with short and lat-eral branches 6-10 microm wide sheath is thin hyaline trichomes blue-green or red-brown 35-6 microm wide not constricted at the cross walls cells cylindrical orsubcylindrical 9-13 microm long cross walls not granulated protoplasm granularheterocyst terminal as well as lateral 67-7 microm wide 68-10 microm long

ECOLOGY This species is epilithic in the upper eulittoral and supralittoral fringe andpresent throughout the year Mastigocoleus testarum is visually conspicuous as ablack or brown crust often associated with Calothrix spp Gloeocapsa spp Kyrtuthrixmaculans and Scytonema cf crustaceum This species appears to be heat and desiccationtolerant and reproduces quickly in summer

197

LOCAL DISTRIBUTION The species is recorded from Cape drsquoAguilar Cheung ChauChung Hom Kok Clear Water Bay Lamma Island Lantau Island Shek Mei Tauand Shek-O (Fig 1)

HABITAT Marine on molluscan shells epilithic endolithic (Umezaki 1961 Thajuddinamp Subramanian 1992)

GEOGRAPHICAL DISTRIBUTION Atlantic coast of Europe Atlantic and Pacific coasts ofNorth America Bermuda Central America (Mexico) South America China IndiaJapan Mediterranean South East Asia (Thailand)

Discussion

Seven heterocystous filamentous cyanobacterial species from six genera belongingto six families and two orders are reported in the present study All the species arenew records for Hong Kong but Dichothrix cf spiralis Hapalosiphon cf welwitschiiMicrochaete cf grisea and Nostoc cf calcicola are also recorded for the first time asepiliths from the marine environment All the species were recorded from the uppereulittoral and supralittoral fringe except D cf baueriana and N cf calcicola whichwere recorded from the mid- and lower eulittoral Scytonema cf crustaceum andMastigocoleus testarum were a dominant component of the intertidal epilithic biofilmforming black and brown bands at Cheung Chau and Shek Mei Tau respectivelyOther species were common in the biofilm but did not form individual bands howeverthese species were associated with a variety of other cyanobacterial species in thebiofilm

Previous descriptions of Hong Kong cyanobacteria (Tseng 1936 Lee 1964 1966Hodgkiss amp Lee 1983 Kaehler 1994 Nagarkar 1998a b 2000) recorded 65 speciesof which only eight species were heterocystous namely Brachytrichia quoyi Bornetet Flahault Calothrix scopulorum Bornet et Flahault Calothrix contarenii Bornet etFlahault Calothrix crustacea Calothrix javanica de Wildeman Hormothamnionenteromorphoides Grunow ex Bornet et Flahault Kyrtuthrix maculans and Nodulariaspumigena Mertens ex Bornet et Flahault Kyrtuthrix maculans is the most abundantheterocystous cyanobacterium on Hong Kong rocky shores forming a characteristicblack band in mid- and upper eulittoral and is also widely distributed on tropicalrocky shores around the world (Williams 1993 Kaehler 1994 Kaehler amp Williams1996 Nagarkar 1996 Nagarkar amp Williams 1999) Calothrix scopulorum C con-tarenii and C crustacea are common on Hong Kong rocky shores and form blackleathery crusts on the lower mid- and upper eulittoral and are also widely distributedin various geographical areas (see Nagarkar 1996) Most of the species are widelydistributed around the world (Umezaki 1961 Thajuddin 1991 Thajuddin ampSubramanian 1992)

Whilst the addition of seven new species increases the species richness of heterocystouscyanobacteria from the region it is however still relatively low as compared toother geographic locations (eg Japan Umezaki 1961 Chile Parra amp Gonzalez1976 Red Sea Potts 1980 Aldabra Whitton amp Potts 1980 Saudi Arabia Hussainamp Khoja 1993)

198

Although all seven species have previously been recorded from the marineenvironment only Dichothrix cf baueriana and Mastigocoleus testarum were re-ported as marine epiliths In general rocky shores represent a most inhospitablehabitat due to the lack of nutrients tidal fluctuation and heat and desiccation stressesIn such stressful environments heterocystous species often dominate especially onthe high shore levels as they escape competition from less tolerant non-heterocystousspecies and are able to flourish due to their nitrogen fixation ability and stress toleranceThese attributes explain the diversity and abundance of heterocystous cyanobacteriaon rocky shores around the world especially in the high intertidal where the nutrientsupply is limited

Acknowledgements

I would like to thank Dr Gray A Williams Mr Aruna Weerasooriya (HKU) and Dr N Thajuddin(NFMC India) for their valuable comments on the manuscript Two anonymous referees and ProfJR Johansen also provided constructive criticisms Thanks to Prof R D Hill for translatingGerman and French literature for me This research was supported by a RGC grant to GAW (RGCproject no HKU 723198M)

References

ANAGNOSTIDIS K amp J KOMAacuteREK (1990) Modern approach to the classification system ofCyanophytes 5 ndash Stigonematales - Arch Hydrobiol Suppl 86 (Algol Stud 59) 1-73

ANDERSON MJ (1995) Variations in biofilms colonizing artificial surfaces seasonal effects andeffects of grazers - J Mar Biol Ass UK 75 705-714

CRIBB AB (1966) The algae of Heron Island Great Barrier Reef Australia Part 1 A generalaccount Vol 1 - In The University of Queensland paper Great Barrier Reef Committee HeronIsland Research Station 1-23 Univ of Queensland Press St Lucia

DESIKACHARY TV (1959) Cyanophyta - Indian Council of Agricultural Research New Delhi

FREacuteMY P (1933 reprinted 1972) Cyanophyceacutees des Cocirctes drsquoEurope - Meacutemoires de la SocieacuteteacuteNationale des Sciences Naturelles et Matheacutematiques de Cherbourg 41 1-236

GEITLER L (1932 reprinted 1985) Cyanophyceae - In L Rabenhorstrsquos Kryptogamen-Flora vonDeutschland Oumlsterreich und der Schweiz Akademische Verlags- Gesellschaft Leipzig Reprintedby Koeltz Scientific

GONZALEZ M amp OO PARRA (1975) Cianofitas marinas de Chile 1 Cianofitas del ambienteintermareal de la bahia de concepcion - Gayana Bot 31 1-69

HODGKISS IJ amp KY LEE (1983) Hong Kong Seaweeds - Urban Council Hong Kong

HOFFMANN L amp V DEMOULIN (1991) Marine Cyanophyceae of Papua New Guinea IILyngbya bouillonii sp nov a remarkable tropical reef-inhabiting blue-green alga - Belg J Bot124 82-88

HOFFMANN L amp V DEMOULIN (1993) Marine Cyanophyceae of Papua New Guinea III Thegenera Borzia and Oscillatoria - Bot Mar 36 451-459

HUA H amp CK TSENG (1984) Cyanophyta - In TSENG CK (ed) Common Seaweeds ofChina 13-41 Science Press Beijing

HUSSAIN MI amp TM KHOJA (1993) Intertidal and subtidal blue-green algal mats of open andmangrove areas in the Farasan Archipelago (Saudi Arabia) Red Sea - Bot Mar 36 377-388

196

Stigonematales

Mastigocladaceae

Mastigocladoideae

Hapalosiphon Naumlgeli ex Bornet et Flahault

Hapalosiphon cf welwitschii W et GS West Figs 8 9Geitler 1932 531 Fig 328a Desikachary 1959 588 Pl 137 Fig 5

Thallus blue-green mucilaginous expanded filaments flexuous with short lateralbranches 55-75 microm wide sheath thin hyaline trichomes blue-green or olive-green 45-65 microm wide cells spherical or elongate as long as wide or longer 45-75 microm long cells of the branches 3-10 microm long apical cells attenuated heterocystrare intercalary quadrate rounded or long cylindrical 6-62 microm wide 6-8 micromlong

The local species is different from the original material with respect to the habitat

ECOLOGY This species is epilithic in the upper eulittoral and supralittoral fringe andpresent only during summer It is not conspicuous on the shore often associatedwith Gloeocapsa spp and Kyrtuthrix maculans This is the first record of H cfwelwitschii as epilithic from the marine environment

LOCAL DISTRIBUTION This species is recorded from Cheung Chau Heng Fa Chuenand Lei Yue Mun (Fig 1)

HABITATS Hapalosiphon welwitschii and its similar morphological forms have beenrecorded from various habitats ie freshwater epiphyte on algae on moist brickson moist soil in marshes (Geitler 1932 Desikachary 1959) marine (Thajuddin1991)

Nostochopsidaceae

Mastigocoleus Lagerheim ex Bornet et Flahault

Mastigocoleus testarum Lagerheim ex Bornet et Flahault Fig 10

Geitler 1932 473 Fig 284 Desikachary 1959 575 Pl 122 Figs 1-5

Thallus perforating blue-green mucilaginous filaments curved with short and lat-eral branches 6-10 microm wide sheath is thin hyaline trichomes blue-green or red-brown 35-6 microm wide not constricted at the cross walls cells cylindrical orsubcylindrical 9-13 microm long cross walls not granulated protoplasm granularheterocyst terminal as well as lateral 67-7 microm wide 68-10 microm long

ECOLOGY This species is epilithic in the upper eulittoral and supralittoral fringe andpresent throughout the year Mastigocoleus testarum is visually conspicuous as ablack or brown crust often associated with Calothrix spp Gloeocapsa spp Kyrtuthrixmaculans and Scytonema cf crustaceum This species appears to be heat and desiccationtolerant and reproduces quickly in summer

197

LOCAL DISTRIBUTION The species is recorded from Cape drsquoAguilar Cheung ChauChung Hom Kok Clear Water Bay Lamma Island Lantau Island Shek Mei Tauand Shek-O (Fig 1)

HABITAT Marine on molluscan shells epilithic endolithic (Umezaki 1961 Thajuddinamp Subramanian 1992)

GEOGRAPHICAL DISTRIBUTION Atlantic coast of Europe Atlantic and Pacific coasts ofNorth America Bermuda Central America (Mexico) South America China IndiaJapan Mediterranean South East Asia (Thailand)

Discussion

Seven heterocystous filamentous cyanobacterial species from six genera belongingto six families and two orders are reported in the present study All the species arenew records for Hong Kong but Dichothrix cf spiralis Hapalosiphon cf welwitschiiMicrochaete cf grisea and Nostoc cf calcicola are also recorded for the first time asepiliths from the marine environment All the species were recorded from the uppereulittoral and supralittoral fringe except D cf baueriana and N cf calcicola whichwere recorded from the mid- and lower eulittoral Scytonema cf crustaceum andMastigocoleus testarum were a dominant component of the intertidal epilithic biofilmforming black and brown bands at Cheung Chau and Shek Mei Tau respectivelyOther species were common in the biofilm but did not form individual bands howeverthese species were associated with a variety of other cyanobacterial species in thebiofilm

Previous descriptions of Hong Kong cyanobacteria (Tseng 1936 Lee 1964 1966Hodgkiss amp Lee 1983 Kaehler 1994 Nagarkar 1998a b 2000) recorded 65 speciesof which only eight species were heterocystous namely Brachytrichia quoyi Bornetet Flahault Calothrix scopulorum Bornet et Flahault Calothrix contarenii Bornet etFlahault Calothrix crustacea Calothrix javanica de Wildeman Hormothamnionenteromorphoides Grunow ex Bornet et Flahault Kyrtuthrix maculans and Nodulariaspumigena Mertens ex Bornet et Flahault Kyrtuthrix maculans is the most abundantheterocystous cyanobacterium on Hong Kong rocky shores forming a characteristicblack band in mid- and upper eulittoral and is also widely distributed on tropicalrocky shores around the world (Williams 1993 Kaehler 1994 Kaehler amp Williams1996 Nagarkar 1996 Nagarkar amp Williams 1999) Calothrix scopulorum C con-tarenii and C crustacea are common on Hong Kong rocky shores and form blackleathery crusts on the lower mid- and upper eulittoral and are also widely distributedin various geographical areas (see Nagarkar 1996) Most of the species are widelydistributed around the world (Umezaki 1961 Thajuddin 1991 Thajuddin ampSubramanian 1992)

Whilst the addition of seven new species increases the species richness of heterocystouscyanobacteria from the region it is however still relatively low as compared toother geographic locations (eg Japan Umezaki 1961 Chile Parra amp Gonzalez1976 Red Sea Potts 1980 Aldabra Whitton amp Potts 1980 Saudi Arabia Hussainamp Khoja 1993)

198

Although all seven species have previously been recorded from the marineenvironment only Dichothrix cf baueriana and Mastigocoleus testarum were re-ported as marine epiliths In general rocky shores represent a most inhospitablehabitat due to the lack of nutrients tidal fluctuation and heat and desiccation stressesIn such stressful environments heterocystous species often dominate especially onthe high shore levels as they escape competition from less tolerant non-heterocystousspecies and are able to flourish due to their nitrogen fixation ability and stress toleranceThese attributes explain the diversity and abundance of heterocystous cyanobacteriaon rocky shores around the world especially in the high intertidal where the nutrientsupply is limited

Acknowledgements

I would like to thank Dr Gray A Williams Mr Aruna Weerasooriya (HKU) and Dr N Thajuddin(NFMC India) for their valuable comments on the manuscript Two anonymous referees and ProfJR Johansen also provided constructive criticisms Thanks to Prof R D Hill for translatingGerman and French literature for me This research was supported by a RGC grant to GAW (RGCproject no HKU 723198M)

References

ANAGNOSTIDIS K amp J KOMAacuteREK (1990) Modern approach to the classification system ofCyanophytes 5 ndash Stigonematales - Arch Hydrobiol Suppl 86 (Algol Stud 59) 1-73

ANDERSON MJ (1995) Variations in biofilms colonizing artificial surfaces seasonal effects andeffects of grazers - J Mar Biol Ass UK 75 705-714

CRIBB AB (1966) The algae of Heron Island Great Barrier Reef Australia Part 1 A generalaccount Vol 1 - In The University of Queensland paper Great Barrier Reef Committee HeronIsland Research Station 1-23 Univ of Queensland Press St Lucia

DESIKACHARY TV (1959) Cyanophyta - Indian Council of Agricultural Research New Delhi

FREacuteMY P (1933 reprinted 1972) Cyanophyceacutees des Cocirctes drsquoEurope - Meacutemoires de la SocieacuteteacuteNationale des Sciences Naturelles et Matheacutematiques de Cherbourg 41 1-236

GEITLER L (1932 reprinted 1985) Cyanophyceae - In L Rabenhorstrsquos Kryptogamen-Flora vonDeutschland Oumlsterreich und der Schweiz Akademische Verlags- Gesellschaft Leipzig Reprintedby Koeltz Scientific

GONZALEZ M amp OO PARRA (1975) Cianofitas marinas de Chile 1 Cianofitas del ambienteintermareal de la bahia de concepcion - Gayana Bot 31 1-69

HODGKISS IJ amp KY LEE (1983) Hong Kong Seaweeds - Urban Council Hong Kong

HOFFMANN L amp V DEMOULIN (1991) Marine Cyanophyceae of Papua New Guinea IILyngbya bouillonii sp nov a remarkable tropical reef-inhabiting blue-green alga - Belg J Bot124 82-88

HOFFMANN L amp V DEMOULIN (1993) Marine Cyanophyceae of Papua New Guinea III Thegenera Borzia and Oscillatoria - Bot Mar 36 451-459

HUA H amp CK TSENG (1984) Cyanophyta - In TSENG CK (ed) Common Seaweeds ofChina 13-41 Science Press Beijing

HUSSAIN MI amp TM KHOJA (1993) Intertidal and subtidal blue-green algal mats of open andmangrove areas in the Farasan Archipelago (Saudi Arabia) Red Sea - Bot Mar 36 377-388

197

LOCAL DISTRIBUTION The species is recorded from Cape drsquoAguilar Cheung ChauChung Hom Kok Clear Water Bay Lamma Island Lantau Island Shek Mei Tauand Shek-O (Fig 1)

HABITAT Marine on molluscan shells epilithic endolithic (Umezaki 1961 Thajuddinamp Subramanian 1992)

GEOGRAPHICAL DISTRIBUTION Atlantic coast of Europe Atlantic and Pacific coasts ofNorth America Bermuda Central America (Mexico) South America China IndiaJapan Mediterranean South East Asia (Thailand)

Discussion

Seven heterocystous filamentous cyanobacterial species from six genera belongingto six families and two orders are reported in the present study All the species arenew records for Hong Kong but Dichothrix cf spiralis Hapalosiphon cf welwitschiiMicrochaete cf grisea and Nostoc cf calcicola are also recorded for the first time asepiliths from the marine environment All the species were recorded from the uppereulittoral and supralittoral fringe except D cf baueriana and N cf calcicola whichwere recorded from the mid- and lower eulittoral Scytonema cf crustaceum andMastigocoleus testarum were a dominant component of the intertidal epilithic biofilmforming black and brown bands at Cheung Chau and Shek Mei Tau respectivelyOther species were common in the biofilm but did not form individual bands howeverthese species were associated with a variety of other cyanobacterial species in thebiofilm

Previous descriptions of Hong Kong cyanobacteria (Tseng 1936 Lee 1964 1966Hodgkiss amp Lee 1983 Kaehler 1994 Nagarkar 1998a b 2000) recorded 65 speciesof which only eight species were heterocystous namely Brachytrichia quoyi Bornetet Flahault Calothrix scopulorum Bornet et Flahault Calothrix contarenii Bornet etFlahault Calothrix crustacea Calothrix javanica de Wildeman Hormothamnionenteromorphoides Grunow ex Bornet et Flahault Kyrtuthrix maculans and Nodulariaspumigena Mertens ex Bornet et Flahault Kyrtuthrix maculans is the most abundantheterocystous cyanobacterium on Hong Kong rocky shores forming a characteristicblack band in mid- and upper eulittoral and is also widely distributed on tropicalrocky shores around the world (Williams 1993 Kaehler 1994 Kaehler amp Williams1996 Nagarkar 1996 Nagarkar amp Williams 1999) Calothrix scopulorum C con-tarenii and C crustacea are common on Hong Kong rocky shores and form blackleathery crusts on the lower mid- and upper eulittoral and are also widely distributedin various geographical areas (see Nagarkar 1996) Most of the species are widelydistributed around the world (Umezaki 1961 Thajuddin 1991 Thajuddin ampSubramanian 1992)

Whilst the addition of seven new species increases the species richness of heterocystouscyanobacteria from the region it is however still relatively low as compared toother geographic locations (eg Japan Umezaki 1961 Chile Parra amp Gonzalez1976 Red Sea Potts 1980 Aldabra Whitton amp Potts 1980 Saudi Arabia Hussainamp Khoja 1993)

198

Although all seven species have previously been recorded from the marineenvironment only Dichothrix cf baueriana and Mastigocoleus testarum were re-ported as marine epiliths In general rocky shores represent a most inhospitablehabitat due to the lack of nutrients tidal fluctuation and heat and desiccation stressesIn such stressful environments heterocystous species often dominate especially onthe high shore levels as they escape competition from less tolerant non-heterocystousspecies and are able to flourish due to their nitrogen fixation ability and stress toleranceThese attributes explain the diversity and abundance of heterocystous cyanobacteriaon rocky shores around the world especially in the high intertidal where the nutrientsupply is limited

Acknowledgements

I would like to thank Dr Gray A Williams Mr Aruna Weerasooriya (HKU) and Dr N Thajuddin(NFMC India) for their valuable comments on the manuscript Two anonymous referees and ProfJR Johansen also provided constructive criticisms Thanks to Prof R D Hill for translatingGerman and French literature for me This research was supported by a RGC grant to GAW (RGCproject no HKU 723198M)

References

ANAGNOSTIDIS K amp J KOMAacuteREK (1990) Modern approach to the classification system ofCyanophytes 5 ndash Stigonematales - Arch Hydrobiol Suppl 86 (Algol Stud 59) 1-73

ANDERSON MJ (1995) Variations in biofilms colonizing artificial surfaces seasonal effects andeffects of grazers - J Mar Biol Ass UK 75 705-714

CRIBB AB (1966) The algae of Heron Island Great Barrier Reef Australia Part 1 A generalaccount Vol 1 - In The University of Queensland paper Great Barrier Reef Committee HeronIsland Research Station 1-23 Univ of Queensland Press St Lucia

DESIKACHARY TV (1959) Cyanophyta - Indian Council of Agricultural Research New Delhi

FREacuteMY P (1933 reprinted 1972) Cyanophyceacutees des Cocirctes drsquoEurope - Meacutemoires de la SocieacuteteacuteNationale des Sciences Naturelles et Matheacutematiques de Cherbourg 41 1-236

GEITLER L (1932 reprinted 1985) Cyanophyceae - In L Rabenhorstrsquos Kryptogamen-Flora vonDeutschland Oumlsterreich und der Schweiz Akademische Verlags- Gesellschaft Leipzig Reprintedby Koeltz Scientific

GONZALEZ M amp OO PARRA (1975) Cianofitas marinas de Chile 1 Cianofitas del ambienteintermareal de la bahia de concepcion - Gayana Bot 31 1-69

HODGKISS IJ amp KY LEE (1983) Hong Kong Seaweeds - Urban Council Hong Kong

HOFFMANN L amp V DEMOULIN (1991) Marine Cyanophyceae of Papua New Guinea IILyngbya bouillonii sp nov a remarkable tropical reef-inhabiting blue-green alga - Belg J Bot124 82-88

HOFFMANN L amp V DEMOULIN (1993) Marine Cyanophyceae of Papua New Guinea III Thegenera Borzia and Oscillatoria - Bot Mar 36 451-459

HUA H amp CK TSENG (1984) Cyanophyta - In TSENG CK (ed) Common Seaweeds ofChina 13-41 Science Press Beijing

HUSSAIN MI amp TM KHOJA (1993) Intertidal and subtidal blue-green algal mats of open andmangrove areas in the Farasan Archipelago (Saudi Arabia) Red Sea - Bot Mar 36 377-388

198

Although all seven species have previously been recorded from the marineenvironment only Dichothrix cf baueriana and Mastigocoleus testarum were re-ported as marine epiliths In general rocky shores represent a most inhospitablehabitat due to the lack of nutrients tidal fluctuation and heat and desiccation stressesIn such stressful environments heterocystous species often dominate especially onthe high shore levels as they escape competition from less tolerant non-heterocystousspecies and are able to flourish due to their nitrogen fixation ability and stress toleranceThese attributes explain the diversity and abundance of heterocystous cyanobacteriaon rocky shores around the world especially in the high intertidal where the nutrientsupply is limited

Acknowledgements

I would like to thank Dr Gray A Williams Mr Aruna Weerasooriya (HKU) and Dr N Thajuddin(NFMC India) for their valuable comments on the manuscript Two anonymous referees and ProfJR Johansen also provided constructive criticisms Thanks to Prof R D Hill for translatingGerman and French literature for me This research was supported by a RGC grant to GAW (RGCproject no HKU 723198M)

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HOFFMANN L amp V DEMOULIN (1993) Marine Cyanophyceae of Papua New Guinea III Thegenera Borzia and Oscillatoria - Bot Mar 36 451-459

HUA H amp CK TSENG (1984) Cyanophyta - In TSENG CK (ed) Common Seaweeds ofChina 13-41 Science Press Beijing

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Received 1 March 2001 accepted in revised form 2 January 2002