algae of terrestrial habitats

T H E B O T A N I C A L R E V I E W VOL. 55 APRIL-JUNE, 1 9 8 9 NO. 2

Algae of Terrestrial Habitats

LUCIEN HOFFMANN

Research Assistant of the National Fund for Scientific Research

Department of Botany, University of Lidge Sart Tilman B22, B-4000 Lidge, Belgium

I. Abstract ...................................................................................................................................................................... 77 R6sum6 ....................................................................................................................................................................... 78 Zusammenfassung .............................................................................................................................................. 78

II. Introduction ............................................................................................................................................................ 78 III. Soil Algae .................................................................................................................................................................. 79 IV. Lithophytic Algae ................................................................................................................................................ 82

A. Hypolithic Algae ......................................................................................................................................... 84 B. Chasmoendolithic Algae ....................................................................................................................... 85 C. Euendolithic Algae .................................................................................................................................... 85 D. Cryptoendolithic Algae .......................................................................................................................... 86 E. Epilithic Algae .............................................................................................................................................. 87

V. Cave Algae ............................................................................................................................................................... 89 VI. Snow and Ice Algae ........................................................................................................................................... 91

VII. Epiphytic Algae .................................................................................................................................................... 94 VIII. Epizooic Algae ....................................................................................................................................................... 96

IX. Acknowledgments ............................................................................................................................................... 97 X. Literature Cited .................................................................................................................................................... 97

I. A b s t r a c t

T h e p a p e r s u m m a r i z e s t h e p r e s e n t k n o w l e d g e o n t h e m o s t i m p o r t a n t

t e r r e s t r i a l h a b i t a t s f o r a l g a e a n d d e a l s w i t h so i l , l i t h o p h y t i c , c a v e , s n o w

a n d ice , e p i p h y t i c , a n d e p i z o o i c a lgae . F o r e a c h h a b i t a t t h e p h y s i c a l p a -

r a m e t e r s o f t h e e n v i r o n m e n t , t h e c h a r a c t e r i s t i c v e g e t a t i o n , a n d t h e f u n c -

t i o n i n g o f t h e e c o s y s t e m a r e d e t a i l e d .

Copies of this issue [55(2)] may be purchased from the Sci- entific Publications Department, The New York Botanical Gar- den, Bronx, NY 10458-5126 USA. Please inquire as to prices.

The Botanical Review 55: 77-105, Apr.-Jun., 1989 �9 1989 The New York Botanical Garden

78 THE B O T A N I C A L REVIEW

R~sum~

L'article pr6sente une revue de l'6tat actuel de nos connaissances sur les habitats terrestres les plus importants pour les algues et traite d'algues du sol, des rochers, des grottes, de la neige et de la glace, d'algues 6pi- phytiques et 6pizoiques. Pour chaque habitat les param~tres physiques de renvironnement, la v6g&ation caract6ristique et le fonctionnement de l'6cosyst6me sont d&aill6s.

Zusammenfassung

Der Artikel beschreibt den aktuellen Stand unserer Kenntnisse der wich- tigsten terrestrischen Standorte der Algen und behandelt Algen die im Boden, auf Felsen, in H/Shlen, auf Schnee und Eis, auf Pflanzen, und auf Tieren vorkommen. Fiir jeden Standort werden die physikalischen Pa- rametern, die charakterisfische Vegetation und das Funktionieren des (~kosystems geschildert.

II. Introduction

Although algae are generally known as freshwater and marine organisms, they also occupy a variety of terrestrial habitats, where their ecological importance is considerable. Terrestrial algae occur worldwide, including the most hostile environments like extreme arid, cold and hot deserts where they often are the only primary producers. A number of terrestrial niches are occupied by algae: most commonly, they occur either on the surface or at a depth of up to several centimeters in soil. In addition, they live in and on rocks and in caves, a habitat characterized by very low light intensities. Furthermore they inhabit permanent snow and ice fields and can also be found living on animals and plants.

Most terrestrial algal habitats represent extreme environments characterized by aridity, and/or by low or high levels of temperature or light intensity. In addition, in many of these habitats frequent fluctuations of environmental conditions occur, in sharp contrast with the mostly stable aquatic habitats. To cope with these stress situations, terrestrial algae developed morphological and physiological adaptations, and/or occupy sheltered microhabitats in which conditions are less severe. Among the different algal groups, the prokaryotic blue-green algae (cyanobacteria) and the eukaryotic green algae are generally the major constituents of terrestrial algal populations.

The study of terrestrial algae may present special problems. First, the ecological parameters are often difficult to evaluate. In the

microhabitats of terrestrial algae where macro- and mesoclimatic data are no longer valid, environmental factors such as light, temperature, and

ALGAE OF TERRESTRIAL HABITATS 79

humidity need to be considered at a micro- or even nanoclimatic level. The research and methodology of this field are just emerging (e.g., MeKay & Friedmann, 1985).

An additional set of problems arises from the uncertainty in identifying terrestrial algae: many of these organisms can generally not be observed in natural habitats; this is a notorious problem in soil algae, but may also be the case in other habitats. Information on the composition of these communities may therefore be based on enrichment cultures. The inherent disadvantage of this technique is that it discriminates between organisms, favoring ubiquitous "weeds" and suppressing specialists. Yet working with cultures is indispensable as the algae, especially in extreme habitats, may regularly occur in nature with reduced morphology and are thus identifiable in culture only.

The identification of some groups is difficult because of uncertainties in taxonomy. This is true primarily for blue-green algae (cyanobacteria) as the taxonomy of this group has recently been undergoing many changes (e.g., Friedmann & Borowitzka, 1982). As a consequence, species names are often used by different authors in widely different meanings.

The following survey, by no means complete, is an attempt to sum- marize present information on the most important terrestrial algal habitats, their vegetation and basic ecological characters.

We tried to include, whenever available, floristic as well as experimental data in our account. Both approaches are indeed essential elements to understand the ecology of algae (Round, 1981).

III. Soil Algae

The soil is the best studied terrestrial algal habitat. The biology and taxonomy of edaphic algae have been extensively reviewed (Bold, 1970; Gollerbakh & Shtina, 1969; Lund, 1962, 1967; Metting, 1981; Petersen, 1935; Shields & DurreU, 1964) and for more details and bibliography the reader is referred to these works.

Despite the numerous studies on soil algae it is still difficult to draw general conclusions on the diversity of the flora and on the functioning of this ecosystem. Comparisons of flora lists of soil algae by different authors are not easy due to the taxonomic uncertainties especially in the treatment of the green and blue-green algae as mentioned in the introduction. Estimates of the algal biomass in the soil populations differ greatly among authors as no standards exist for methods such as counting or use of enrichment media.

The most important environmental factors which control algal populations in soil seem to be light, humidity, temperature, availability of nutrients, and pH.

80 THE BOTANICAL REVIEW

As most algae are obligate photoautotrophs, the role of fight is evident from the vertical distribution of the algae in the soil: the density of algae is generally highest in the upper centimeters and falls offvery rapidly with depth (Petersen, 1935). Algae are often present far below the level of light penetration, yet it is questionable whether these organisms are actively metabolizing or are in a dormant state. Chemoheterotrophy in the dark has been reported in many green (Metting, 1981) and blue-green (Khoja & Whitton, 1975; Stanier, 1973) algae as well as in diatoms (Lewin, 1953). These algae thus could exist without the presence of light; it is, however, questionable whether they can effectively compete with obligate hetero- trophs for the limited supply of available organic matter. The fact that generally no algal species are found in deeper soil layers which are not present at the surface of the same soil is a further argument against the existence of an independent subterranean algal flora (Petersen, 1935). The occurrence of algae in such depths may be due to water seepage or to the burrowing activities of animals. Still, a few papers report that differences exist in the qualitative composition of the soil flora at different depths (Bolyshev, 1968; Gollerbakh, 1953). In general it seems that actively growing algal populations exist in the top layer of the soil and that heterotrophy is of minor importance in soil algal productivity.

Most soils are subjected to fluctuations in the level of humidity and soil algae are generally adapted to survive periods of desiccation: viable soil algae (e.g., Nostoc commune Vauch., Chlorococcum humicola (N/ig.) Rabenh., Stichococcus bacillaris N/ig.) have been recovered from up to 87- year-old herbarium specimens (Bristol, 1919; Lipman, 1941; Parker et al., 1969; Trainor, 1985). Seasonal changes in soil algal vegetation are generally quantitative, due to fluctuations in the availability of water, while the species composition remains constant over the year (Metting, 1981). Diurnal fluctuations in soil humidity have been shown to be, besides the feeding by protozoa and nematodes, the major cause for fluctuations of algal populations within a 24-hour period (Tchan & White- house, 1953).

Some desiccation-resistant soil algae form resting spores (e.g., Cylin- drospermum, Anabaena, Nostoc, Nodularia) while others can tolerate desiccation without apparent special morphological adaptations (e.g., Pra- siola crispa (Lightf.) Menegh., Hormidium flaccidum (Kiitz.) A. Br.).

Terrestrial algae are also resistant to low as well as to high temperatures, and live in cold and hot desert soils. According to laboratory experiments, temperature tolerance ranges from -195~ (Cameron & Blank, 1966) to 113~ (Booth, 1946).

The effect of the pH on the algal flora is difficult to evaluate as it is often correlated with other factors. Thus, arid soils are almost universally alkaline and many continuously wet soils acidic (Shields & Durrell, 1964).

A L G A E O F TERRESTRIAL HABITATS 81

The pH also depends on the calcium carbonate content of the soil. Among the different algal groups blue-green algae and diatoms generally prefer neutral and alkaline soils while green algae seem to tolerate a wider range of pH, so that they dominate the algal floras of acid habitats due to the absence of competition.

The role of algae in the soil ecosystem is manifold, the most important consequences being the input of nitrogen by nitrogen-fixing blue-green algae and of carbon. The formation of algal crusts on soil interferes with soil erosion, increases the storage of rainwater, and reduces the water loss by evaporation (Booth, 1941). They also provide organic matter and are responsible for soil formation which is especially important in deserts. Algae promote the release of nutrients from insoluble compounds (Ari- stovskaya et al., 1969; Smith et al., 1978) and the weathering of silicates by creating a slightly acidic environment.

The most common soil algae are green, blue-green algae, and diatoms, while xanthophytes, euglenophytes, and rhodophytes occur less fre- quently.

Green algae dominate the algal flora in acid soils, but are still numerous in neutral and alkaline environments. Species of the genera Ankistrodes- mus, Characium, Chlorella, Chlorococcum, Hormidium, Protococcus, Protosiphon, Stichococcus, and Ulothrix are widely encountered (Metting, 1981). Some, like Protosiphon species and Chlorococcum humicola are only found in soils, whereas others like Ulothrix also occur in freshwater. Both filamentous and coccoid forms are present; the latter seem to be more abundant in desert soils (Friedmann & Galun, 1974).

Blue-green algae, especially filamentous forms, are common in neutral to alkaline soils. Species ofMicrocoleus, Schizothrix, and Porphyrosiphon often form crusts on the soils (Durrell & Shields, 1961). Heterocystous nitrogen-fixing genera such as Nostoc, Anabaena, Tolypothrix, Scytonema, and Cylindrospermum are of great significance to the soil ecosystem. A peculiar association of blue-green algae which form small subterranean cushions is described by Schwabe (1960) from soil of the Atacama Desert. The two main species, Calothrix desertica Schwabe and Schizothrix atacamensis Schwabe, form joint colonies in which the lower part is formed by Schizothrix atacamensis and the top layer by Calothrix desertica.

In comparison to aquatic types, terrestrial soil diatoms tend to be of smaller size, and the difference in dimensions applies not only to species but to strains within the same species (Petersen, 1935). Diatoms generally occur in neutral or slightly alkaline soils. Most soil diatoms are pennate forms capable of active movements; prominent genera include Ach- nanthes, Cymbella, Fragilaria, Hantzschia, Navicula, Pinnularia, Stau- roneis, and Surirella (Metting, 1981).

In the xanthophycean algae, the genera Botrydiopsis, Bumilleria, Her-


erococcus, Bumilleriopsis, Heterothrix, and Pleurochloris seem to be the most abundant and widespread (Metting, 1981).

Among the euglenophytes, the genera Euglena and Peranema are reported from soils (Leedale, 1967).

The red algae are represented by the genera Cyanidium and Porphyridi- um. "Cyanidium caldariurn'" (Tilden) Geitl. [three species are presently distinguished under this name (Merola et al., 1982)] forms a characteristic vegetation in hot and extreme acid soils. It is the sole photosynthetic organism living at a pH lower than 5 and at a temperature superior to 40~ (Doemel & Brock, 1971; Smith & Brock, 1973). Porphyridium pur- pureum (Bory) Ross in Drew & Ross (=P. cruentum (Gray) N~ig.) forms gelatinous, red masses on generally polluted and ammonium rich soils (Geitler, 1944); it is desiccation resistant and prefers shaded habitats.

IV. Lithophytic Algae

Lithophytic algae live on or within rock substrates, expanding to a few mm below the rock surface. The following terminology, based on the one proposed by Golubi~ et al. (19 81), describes the different lithophytic habitats:

Epiliths Colonize the external exposed surface of rocks

Hypoliths Live under pebbles and small stones lying or buried in the soil

Endoliths Colonize the interior of rocks Chasmoendoliths Colonize fissures and cracks open to the

rock surface Cryptoendoliths Colonize structural cavities within porous

rocks Euendoliths Penetrate actively into the interior of

forming tunnels that conform with the shapes of their bodies (rock boring organisms)

Lithophytic algae generally colonize bare rock surfaces which are not covered by lichens or mosses. Thus they are characteristic of extreme climates such as hot and cold deserts and in temperate climates they occur in extreme microhabitats like steep rock faces in the high alpine regions. Here algae can compete successfully with lichens and mosses and are often the only autotrophic organisms colonizing the rocks. In response to the extreme ecological conditions and to the often frequent changes in the environment, lithophytic algae are adapted to switching their metabolism off and on: metabolic activity is limited to short periods when an appro- priate combination of temperature, light intensity, and humidity is pres-


ent. This period of metabolic activity may be as short as a few hundred hours in a year [e.g., in the Antarctic cold desert, Friedmann et al. (1987)]. In extreme arid environments only endolithic and hypolithic forms can exist. The microclimatic conditions seem to be more favorable inside and under the rocks than at the surface where frequent temperature oscillations (McKay & Friedmann, 1985), aridity, light intensity, and wind may pre- vent the establishment of an algal vegetation.

The most important factor concerning the ecology oflithophytic algae, especially in deserts, is water supply. In temperate regions rock inhabiting algae live in temporary water seepages and/or are regularly wetted by rainwater. In deserts, however, rain is scarce and more significantly un- evenly distributed, and organisms may utilize other water sources. In polar deserts occasional snow melts that imbibe the porous rocks seem to be the principal source of water (Friedmann, 1978). In hot deserts nightly dew condensation retained in the rocks may be the main source of water (Friedmann et al., 1967). In the case of endoliths, the surface crust of the rocks probably retards evaporation and the porous rock acts as a water trap (Friedmann, 1972). For hypolithic algae, pebbles lying on desert soil retard evaporation with small humidity islands persisting un- derneath (Vogel, 1955). Besides the physical structure of the microhabitat, the often gelatinous sheath of the algae acts in retaining humidity during droughts. At the same time desert blue-green algae are not able to pho- tosynthesize at lower water potentials and probably react to water stress by cessation of their metabolic activity, to rapidly restart again upon rewetting (Potts & Friedmann, 1981).

Rock algae are exposed to a wide range of light intensities varying from full sunlight for epilithic algae to very low intensities for endolithic and hypolithic algae.

The algae that are exposed to strong light often have colored sheath material. Hypo- and endolithic algae live under or in semitranslucent to translucent rocks where they occupy a well defined layer, most probably controlled by the steep gradient of light intensity penetrating into rock or soil. The rocks act as a filter and reduce the light intensity to 30-0.005% of the incidental irradiance for hypolithic algae (Berner & Evenari, 1978; Vogel, 1955) and to 0.1-0.01%, depending on the humidity of the rock, for cryptoendolithic algae (Friedmann & Ocampo-Friedmann, 1984).

Rock inhabiting algae are eurytherm as their environment undergoes great daily and annual temperature variations. In temperate regions the surface temperature can go up to 50~ in summer while during the winter the algae have to survive subzero temperatures in contrast to tropical regions where the temperature always remains above the freezing point. In polar regions algae are frozen for most of the year. During the summer, the temperature fluctuates between about - 1 0 ~ and + 10~ (McKay & Friedmann, 1985) resulting in daily freeze/thaw cycles.


The inorganic nutrients necessary for algal growth are probably found in the soil for hypolithic algae and in the rock for the other lithophytic algae. In part they may also be conveyed to the rocks by rain, snow, and dry atmospheric fallout. The source of nitrogen is of interest. In desert endolithic algal communities biological nitrogen fixation is non-existent or rare and the source of compound nitrogen is inorganically fixed in the atmosphere, reaching the rock surface by precipitation (rain or snow) or by dry fallout. In these communities productivity is low and the incoming fixed nitrogen results in an accumulation of surplus nitrate in the rocks. In contrast, the high productivity soil crusts are N-limited and thus nitrogen fixing (Friedmann & Kibler, 1980).

A. HYPOLITHIC ALGAE

The hypolithic vegetation consists of a thin layer of algae, mainly Cy- anophyceae, growing under generally translucent pebbles from near the soil surface down to about 4 cm. The algae are both in contact with the soil, providing the necessary mineral nutrients, and attached to the stone (pebble), which seems to create a favorable microclimate regarding light intensity and humidity.

Hypolithic algae are known from most deserts and semideserts in the world, but they seem to be absent in the extremely arid Atacama Desert (Friedmann, pers. comm.). Hypolithic algae are reported from the southwestern United States, South America, Middle East, southwestern Africa, Australia, and Antarctica (Berner & Evenari, 1978; Broady, 198 lc; Cam- eron, 1963; Friedmann et al., 1967; Fukushima, 1959; Hunt & Durrell, 1966; Shields & Drouet, 1962; Tchan & Beadle, 1955; Vogel, 1955). One report mentions this particular vegetation also from alpine regions in northern Europe (Kers, 1976).

The algal vegetation is formed by coccoid and filamentous blue-green and green algae which form a conspicuous green zone under the stones. For the Negev Desert, Friedmann et al. (1967) and R. Ocampo (unpubl.) list the following species: green algae--Bracteacoccus sp., Chlorosarci- nopsis negevensis Friedmann et Ocampo-Paus, Chlorosarcinopsis sp., Friedmannia israeliensis Chant. et Bold, Hormidium sterile Deason et Bold, Hormidium subtilissimum (Rabenh.) Mattox et Bold, Radiosphaera negevensis Ocampo-Paus et Friedmann, Stichococcus sp., Trebouxia sp., Trochiscia sp., and Ulothrix minuta Mattox et Bold; blue-green algae-- Chroococcidiopsis sp. as "Paracapsa sp.," Aphanocapsa sp., Aphanothece sp., Gloeocapsa spp., Lyngbya spp., Microcoleus chthonoplastes Thur., Myxosarcina sp., Nostoc spp., Plectonema sp., Schizothrix calcicola (Ag.) Gom., Schizothrix sp., Scytonema sp., and Tolypothrix byssoidea (Berk.) Kirchn. From the South African desert Vogel (1955) mentions the green algae Chlorella vulgaris Beyer., Cystococcus humicola N~ig., Coccomyxa


hypolithica Vogel and the blue-green algae Aphanocapsa biformis A. Br., A. cf. fuscolutea Hansg., ,4. pusilla Vogel, Aphanothece nidulans P. Richt. var. endophytica W. & G. S. West, A. saxicola N~ig., Chroococcus co- haerens (Br6b.) N~ig., Chroococcus sp., Gloeocapsa cf. punctata N~ig., Xenococcus kerneri Hansg., Myxosarcina minuta Vogel (probably Chroo- coccidiopsis sp.), Stigonema minutum (Ag.) Hass., Tolypothrix fragilis (Gardn.) Geitl. var. silicophila Vogel, Scytonema ocellatum Lyngbye, Nos- toc sphaericum Vauch., Oscillatoria cf. rupicola Hansg., O. cf. subtilissima Kiitz., O. gloeophila Grun., O. cf. neglecta Lemm. Broady (1981c) lists from Antarctica Aphanothece sp., Chroococcidiopsis sp., Lyngbya sp., Plectonema sp., Calothrix sp., Nodularia sp., Nostoc sp., Tolypothrix sp., Botrydiopsis sp., Heterothrix sp., Stichococcus sp., cf. Desmococcus sp., Prasiococcus calcarius (Pet.) Vischer, Navicula sp.

B. CHASMOENDOLITHIC ALGAE

Chasmoendolithic algae occupy spaces within the rocks that are open to the surface and that range from coarse cracks to microscopic fissures. The vegetation forms green belts in the cracks running a few mm deep parallel to the surface.

This type of vegetation mostly occurs in deserts and alpine regions. They are reported from deserts in Central Asia (Glazovskaya, 1950; Odintsova, 1941), Arctic (Gromov, 1957; Royzin, 1960), southwestern United States and Mexico (Friedmann, 1972), Negev (Danin & Garty, 1983; Friedmann et al., 1967), Namibia, Sinai, Central Australia, South America (Friedmann & Ocampo-Friedmann, 1984), Antarctica (Broady, 1981a; Friedmann, 1977, 1982). They are also found in alpine regions in Europe (Diels, 1914; Jaag, 1945), in North America (Friedmann, pers. comm.), and in less extreme environments, e.g., in Greece (Anagnostidis et al., 1983).

The chasmoendolithic vegetation is dominated by green and blue-green algae. Friedmann (1982) and Darling et al. (1987) also report the presence of Heterococcus, a xanthophycean filamentous alga, as a chasmoendolith in the Antarctic region.

As the cracks and fissures are in connection with the outer rock surface, debris carried by the air can accumulate in the wider spaces and constitute a sort of protosoil which makes the chasmoendolithic habitat similar to the hypolithic one, explaining why these niches often have a similar flora (Broady, 1981a, 1981c; Friedmann et al., 1967).

C. EUENDOLITHIC ALGAE

Euendolithic algae actively penetrate the rock substrate, forming chan- nels of the same contour as the boring organism. Limestone boring algae have been known for a long time in both freshwater and marine habitats


where they can play an important role in the destruction of coastal limestone (Golubi6 et al., 1975). Forms in terrestrial habitats, however, are still incompletely known.

Atmophytic euendolithic algae are reported from Central Europe (Bach- mann, 1915; Ercegovir, 1925; Palik, 1938), Middle East (Danin, 1983, 1986; Danin & Garty, 1983; Krumbein & Jens, 1981), and from tropical regions (Java: Koster, 1939; British West Indies: Folk et al., 1973; Man- gaia Island (South Pacific): Friedmann, pers. comm.).

So far only blue-green algae are reported as euendolithic terrestrial algae. In his study of limestone walls of Jerusalem, Danin (1983) determined that unicellular blue-green algae are penetrating the rock at a rate of 5 #m/year.

Limestone boring blue-green algae listed in the literature are Gloeocapsa spp., Scytonema sp., Chroococcus sp. (Bachmann, 1915), Chroococcus lithophilus Erceg., Aphanocapsa endolithica Erceg., Lithococcus ramosus Erceg., and Schizothrix coriacea var. endolithica Erceg. (Ercegovir, 1925).

An interesting geological formation, called phytokarst, resulting from the boring activities of blue-green algae is described by Folk et al. (1973) from the Cayman Islands. Here the attack of the boring algae that generally penetrate to 2 mm inside the rock results in jagged, grotesquely dissected, spongy pinnacles. A similar formation was found by Friedmann (pers. comm.) in the South Pacific island of Mangaia.

D. CRYPTOENDOLITHIC ALGAE

The rocks colonized by cryptoendolithic algae are limestone and sandstone which are primarily light colored and have a porous structure. Cryptoendolithic algae inhabit the spaces between the particles of porous rocks, at a depth of one to several mm where they form a 0.1-2.5 mm- wide distinct, colored layer. The rocks colonized are mostly light colored lime- and sandstone. The algal zone runs at a uniform depth following the contours of the rock surface: the upper and lower boundaries of the zone seem to be determined by the light intensity gradient.

Cryptoendolithic algae are so far reported only from extremely arid, hot and cold deserts and semi-deserts like the Negev (Friedmann, 1971; Friedmann et al., 1967), Antarctica (Friedmann, 1977, 1982; Friedmann & Ocampo, 1976), Sinai, southwestern United States (Bell et al., 1986; Friedmann & Ocampo-Friedmann, 1984), and Transvaal (Biidel, 1987).

So far only unicellular blue-green algae (Chroococcidiopsis sp., Chroo- coccus turgidus (Kiitz.) N~ig.) are reported living inside the rocks in hot deserts (Friedmann & Galun, 1974; Friedmann et al., 1967; Potts et al., 1983). In hot semi-deserts the cryptoendolithic flora is richer and eukaryotic algae occur besides blue-green algae. In sandstones in the southwestern United States (Colorado Plateau) the following taxa occur (Bell


et al., 1986): blue-green algae--Chroococcidiopsis spp., Gloeocapsa sp., Gloeothece sp., Synechococcus elongatus N/ig., Anabaena sp., Phormidium autumnale Gom.; green algae--Chlorococcum sphacosum Arch., C. are- nosum Arch., Myrmecia sp., Chlorella sp., Coccomyxa sp., Oocystis mars- sonii Lemm., Borodinella polytetras Mill., Chlorosarcinopsis minor Hernd., Fasiculochloris boldii McLean et Trainor, Friedmannia israeliensis Chant. et Bold, Tetracystis dissociata Brown et Bold, T. isobilateralis Brown et Bold, Klebsormidium sterile Silva, Mattox et Blackwell, Stichococcus bacillaris Niig. The photosynthetic rate of this community is about 0.48 mg CO2/mg chlorophyll a/hour (Bell & Sommerfeld, 1987). Extremely cold deserts seem to harbor a more complex cryptoendolithic ecosystem than extremely hot deserts since blue-green algae, eukaryotic algae, fungi, and lichens are found in this environment (Friedmann, 1977, 1982; Fried- mann & Ocampo, 1976). This indicates that hot deserts are a more severe environment than cold ones (Friedmann & Ocampo-Friedmann, 1984). In the Antarctic cold desert, cryptoendolithic algae are members of the complex community formed by lichens and other microorganisms. Among the free-living (non-lichenized) algae, unicellular blue-green algae (Gloeo- capsa sp., Chroococcidiopsis sp.), the unicellular green alga Hemichloris antarctica (Tschermak-Woess & Friedmann, 1985) and the xanthophycean Heterococcus endolithicus Darling et Friedmann (Darling et al., 1987) are present in this community.

E. EPILITHIC ALGAE

Epilithic algae inhabit the exposed rock surfaces as a crust or as a few mm-thick layer. They are generally the first photosynthetic organisms that colonize these surfaces (Fritsch, 1907; Treub, 1888) and often the only ones that can survive in this environment.

Epilithic algae occur mostly in habitats where environmental conditions are not too severe. They are infrequent in deserts and seem to be absent in extremely arid habitats where only crypto- and chasmoendolithic algae are able to exist (Friedmann & Ocampo-Friedmann, 1984). Here we will consider only algae inhabiting rock surfaces that are dry for the greater part of the year.

Most of the information available on these habitats from Central Europe is in Anagnostidis et al. (1983), Diels (1914), Ercegovi~ (1925), Fjerding- stad (1965), Fr6my (1925), Golubi~ (1967a), Hoffmann (1986), Jaag (1945), Messikommer (1942), Novfi~ek (1934), Schade (1923), Schorler (1914), from Northern Europe by Cedercreutz (1941, 1955), Hiiyr6n (1940), Jalas (1949), and Strom (1926). Less extensive studies report epilithic algae from South America (Golubi~, 1967b), North America (Johansen et al., 1983), Africa (Behre, 1953; Fr6my, 1930; Zehnder, 1953), Antarctica (Broady, 1981b), and Ceylon (Fritsch, 1907).


Blue-green algae followed by green algae are the most important organisms of the epilithic vegetation and other algal groups occur only occasionally in these habitats. Remarkable exceptions are the epilithic, bangioid red alga Rhodospora described by Geitler (1927, 1955) and the chrysophyte Ruttnera spectabilis Geitl. (Geitler, 1943a).

Light intensity and humidity seem to be the most important factors that determine the composition of an epilithic algal vegetation.

Schade (1923), based on the work of Schorler (1914), described the following algal associations on sandstone surfaces in Central Europe.

The Bacillarietum, often formed exclusively by diatoms, occurs on wet sandstones during the humid season and usually disappears in summer dryness. Important species are Fragilaria virescens Rolls., Pinnularia borealis Ehrh., P. appendiculata Ag., Melosira roeseana Rabenh., and Na- vicula rhomboides var. saxonica Rabenh.

Two green algal associations, the Mesotaenietum and the Gloeocyste- turn, form slimy coverings on rock surfaces; the Mesotaenietum and Gloeocystetum are often found in mountain valleys where air humidity is rather high. These algae have abundant, often pigmented sheath material. Important species are Mesotaenium braunii DBy., M. chlamydo- sporum DBy., M. micrococcum (Kiitz.) Kirchn., Gloeocystis rupestris (Lyngb.) Rabenh., Hormidium flaccidum A. Br., and Urococcus insignis (Hass.) Kiitz.

The Pleurococcetum, with Pleurococcus vulgaris (Grev.) Menegh. and Stichococcus bacillaris N~ig. as main species, covers the rock surfaces in dry and shadowed places. Here Trentepohlia species often form extensive orange patches.

The Gloeocapsetum dominated by species of the blue-green algal genus Gloeocapsa is found in water seepages on steep, bare rock surfaces. This association forms conspicuous black algal crusts that characterize the so called "Tintenstriche."

Jaag (1945) and Golubi6 (1967a) have studied in detail the algal associations dominated by blue-green algae.

In correlation with light intensity and humidity Golubi6 (1967a) distinguishes eight different associations (Fig. 1).

The Scytonemo-Gloeocapsetum, the most widespread association, is well developed on rock surfaces that are exposed to sunlight and wetted sporadically. The dominant blue-green algal species are Scytonema myochrous (Dillw.)Ag. em. Jaag and Gloeocapsa species with colored sheaths like Gl. sanguinea N~ig. em. Jaag, Gl. kuetzingiana Nfig. em. Jaag, Gl. compacta Kiitz. em. Golubi6, and Gl. biformis Erceg. In more shaded places this association is replaced by the Aphanocapso-Chroococcetum whose main species are Aphanocapsa muscicola (Menegh.) Wille, A. biformis A. Br., A. grevillei (Hass.) Rabenh., Aphanothece castagnei (Br6b.) Rabenh., and Chroococcus turgidus (Kiitz.) N~ig.


LIGHT INTENSITY,

Scytonemo- Gl~ocapsetum

Aphanocapso-

ChrOOeOecetum

~Tolypothricetum Dichothrieetum byssoideae ~ gypsophilae

Schizothricetum Schlzothricetum heufleri lardaceae

1

Calothricetum parietinae

Hydrocoleetum ho~eotrichl

HUMIDITY

Fig. 1. Occurrence ofepilithic blue-green algal associations in correlation with humidity and light intensity (after Golubi6, 1967a).

At high light intensity and increasing humidity, Scytonema myochrous is replaced by Tolypothrix byssoidea (Hass.) Kirchn., Dichothrix gyp- sophila (Kiitz.) Born. et Flah. and at the end of the series by Calothrix parietina Thur. characterizing the Tolypothricetum byssoideae, the Di- chothricetum gypsophilae, and the Calothricetum parietinae, respectively.

At low light intensity and increasing humidity the Scytonemo-Gloeo- capsetum is replaced by the Schizothricetum heufleri dominated by Schi- zothrix heufleri Grun. and Schizothrix affinis Lemm., then by the Schi- zothricetum lardaceae dominated by Schizothrix lardacea (Ces.) Gom., and finally by the Hydrocoleetum homoeotrichi characterized by Hydro- coleum homoeotrichum Kiitz. and Schizothrix penicillata (Kiitz.) Gom.

The role of epilithic algae in rock weathering is debated. While Jaag (1945) believed that they do not contribute to weathering, Krumbein (1972, 1973) and Marathe and Chaudhari (1975) reported considerable corrosion under epilithic algal mats.

Epilithic algae, especially blue-green algae, also play a role in rock formation by depositing carbonate crusts (tufts) on rock surfaces (Erce- govi6, 1925; Golubi6, 1967a; Jaag, 1945). Remarkably laminated, carbonate crust formation (desert stromatolites) is reported by Krumbein and Giele (1979) from deserts. Here the carbonate deposition is mainly achieved by the blue-green algae Pleurocapsa sp. and Plectonema gloeophilum Borzi (Krumbein & Ports, 1979). This crust may play a role in protecting the algae against too high light intensities and in retaining humidity in this otherwise hostile environment for epilithic algae.

V. Cave Algae

Cave algae may cover the surfaces of cave walls with a more or less dense cover, which extends from the entrance of the caves to the end of the photic zone.

Not only the geographic location, but also the configuration of the caves


determine the microclimatic conditions of the caves, especially that of temperature and humidity. The microclimate of caves is characterized by even temperatures throughout the year (which reflects the yearly av- erage temperature), an even level of humidity, and a pronounced light gradient. The latter is the key environmental factor which controls the composition of the algal vegetation.

Cave algae were reported from Hungary (Claus, 1955, 1962a, 1962b, 1964; Hajdu, 1966; Kol, 1966; Kom~iromy, 1977; Kom~iromy et al., 1985; Palik, 1960, 1964; Suba, 1957), France (Bourrelly & Dupuy, 1973; Leclerq et al., 1983), Israel (Friedmann, 1955, 1956, 1961, 1964), Germany (Do- bat, 1966, 1968, 1969a, 1969b, 1970, 1977), United States (Friedmann, 1979; Jones, 1964; Nagy, 1965), Italy (Abdelahad & Bazzichelli, 1988; Borzi, 1917; Skuja, 1970), Rumania (SerbAnescu & Decu, 1962), and Yugoslavia (Golubi6, 1967a).

The better illuminated wall surfaces near the entrance of caves are generally colonized by green and blue-green algae living in the neighboring areas (Dobat, 1968). Towards the depth of the cave, the algal vegetation becomes less and less dense.

Many limestone cave walls are colonized by calcifying filamentous blue- green algae which form a greyish, mold-like coat on the substrate. Near the cave entrance, Scytonema julianum (Kiitz.) Menegh. dominates the vegetation, whereas towards the less illuminated areas, Geitleria calcarea Friedm. becomes dominant and forms pure populations at the end of the photic zone. Geitleria calcarea occurs in caves in temperate and tropical regions and has a worldwide distribution [Israel, Rumania, Yugoslavia, Florida, South Pacific (Friedmann, 1979), France (Bourrelly & Dupuy, 1973; Cout6, 1982; Leclerq et al., 1983), Spain (Gracia Alonso, 1974), Italy (Abdelahad & Bazzichelli, 1988), Bahamas (Davis & Rands, 1981)]. A second species of the same genus, G. floridana, was described from caves in Florida, U.S.A. (Friedmann, 1979).

Chroococcidiopsis kashaii Friedm., a baeocyte forming unicellular blue- green alga, occurs in dry limestone caves in Israel (Friedmann, 1961) and seems to tolerate substrates with high nitrate concentrations (Friedmann, 1962).

Speleopogon cavarae Borzi is another filamentous blue-green algal species described from caves (Borzi, 1917). The genus also occurs in caves in Israel (Friedmann, pers. comm.).

The blue-green alga Gomontiella magyariana Claus was reported from caves in Hungary (Claus, 1960) and the United States (Jones, 1964).

The two blue-green algal genera Palikiella (Claus, 1962a, 1962b) and Baradleia (Hajdu, 1966; Palik, 1960) are only known from caves in Hun-

gary. The alga known as Cyanidium caldarium (Tilden) Geitler is known to


be characteristic of acid and hot environments. A morphologically iden- tical form occurs on the walls of limestone caves (Friedmann, 1964; Leclerq et al., 1983; Skuja, 1970). The cave inhabiting Cyanidium, unlike the acid hot spring forms, does not grow at low pH in culture and may represent a different species (Friedmann, unpubl.). Schwabe (1936) described a new species, Cyanidium chilense, from a cave in Chile.

The highly polymorphic bangioid red alga Phragmonema sordidum Zopf was first reported in greenhouses (Geitler, 1924; Zopf, 1882). Its natural habitat may, however, be caves (Friedmann, 1956; Geitler, 1943b; Sieminska, 1962) or other low light terrestrial habitats (Leclerq et al., 1983).

A remarkable ruderal vegetation is formed by algae living in the vicinity of artificial light sources in caves. Common atmophytic and freshwater algae often form a luxuriant vegetation here. Dobat (1966, 1968, 1969a, 1969b, 1970, 1977) has studied this "flora of the lamps" (Lampenflora). Recorded blue-green algae are Gloeocapsa alpina N~ig., G. dermochroa N~ig., G. sanguinea (Ag.) KiJtz., Tolypothrix rupestris Wolle, Nostoc mi- croscopicum Carm., Chroococcus varius A. Br., Chlorogloea microcystoides Geitl., Aphanocapsa fuscolutea Hansg., A. castagnei (Brrb.) Ra- benh., and A. saxicola N/ig. Common green algae are Pleurococcus naegelii Chod., Stichococcus bacillaris N~ig., Gloeocystis rupestris (Lyngb.) Ra- benh., G. vesiculosa Nag., Chlorella vulgaris Beyer., and Scotiella nivalis (Shuttlew.) Fritsch. In this particular niche blue-green algae sometimes occur in spherical aggregates (H~iufchenassoziationen), up to 1 cm in diameter. Dobat (1970) reports that in one cave these aggregates were almost exclusively composed of Gloeocapsa alpina N~ig. and Chroococcus varius A. Br. and in another ofAphanocapsafuscolutea Hansg. and Chlo- rogloea microcystoides Geitl.

Some reports in literature deal with algae isolated in culture from sam- ples taken from totally dark parts of caves (Claus, 1955, 1962b, 1964). A large variety of mostly common aquatic and terrestrial algae was iden- tified in these isolates, but no visible in situ growth of these species was recorded. Although the methodology of these studies may be beyond criticism, the presence of viable algal cells is not a necessary indication of a cave vegetation. Most likely these cells are introduced by ground water or air and animals.

VI. Snow and Ice Algae

Terrestrial snow and ice algae inhabit frozen water at the ice-air interface and are considered here as terrestrial organisms in contrast to marine cryobiontic algae which inhabit the ice-water interface and are therefore aquatic. These terrestrial cryobiontic algae occupy the spaces between the


ice crystals in the surface layers of snow and ice. They become visible only when they aggregate in large numbers near the surface or in horizontal bands leading to a coloration of the snow or the ice. Up to 400,000 cells/ ml of snow meltwater were counted in such colored snow patches (Hoham, 1975b).

Due to the extreme ecological conditions near the freezing point, cryobiontic algae can be active for a limited period of the year only, sometimes for no longer than a few weeks (Hoham, 1980) in which time they have to complete their life cycle. Blooms of snow algae occur when the air temperature remains above freezing for several consecutive days (Ho- ham, 1975a; Pollock, 1970; Stein & Amundsen, 1967). The increased presence of meltwater stimulates the growth of the algae by making nutrients and dissolved gases available to the algae. At the same time changes in the photoperiod and an increase of light penetration may initiate the germination of overwintering stages (Curl et al., 1972).

These algae need to be adapted to repeated freezing and thawing cycles. During the day the temperature in the colored snow patches may rise up to 1.3~ (Hoham, 1975a) due to the absorption of light by the pigments, whereas subzero temperatures are reached during the night. Experiments in pure culture show that obligative and facultative cryophytes can be distinguished (Hoham, 1975a) indicating that certain snow algae are op- timally suited to grow at temperatures near 0~

The light quantity and quality reaching the algae through the snow or ice layer varies: depending on the density of the snow, 1% of the surface value of total energy penetrates from 18 to 110 cm into the snow (Curl et al., 1972). The major portion of penetrating energy is found between 450 and 600 nm. The blue, red, and far red wavelengths are filtered out between 10 and 25 cm (Komfirek et al., 1973). The dust content of the snow also interferes with light transmission properties. The colored bands of Chloromonas pichinchae move up and down with changing light intensity, from near the surface at dawn to down to 10-15 cm below the surface at noon.

Nutrients do not seem to be limiting factors in this environment. Ko- m~rek et al. (1973) report nutrient concentrations similar to those in eutrophic lakes. Nutrients leaching from tree barks and litter influence the growth of snow algae and thus effect their overall distribution (Hoham, 1976, 1980).

Red carotenoids are produced by many of the snow algae. Czygan (1970) showed that in culture nitrogen deficiency can cause the accumulation of carotenoids in green algae; the influence of high light intensities, however, can not completely be ruled out (Hoham, 1980).

Cryobiontic algae occur worldwide in polar and alpine regions with long lasting and persistent ice or snow fields. They were reported from North


America, Greenland, Western and Eastern Europe, Siberia, Japan, South America, Antarctica (Kol, 1968, 1971, 1972, 1973), Central Australia (Marchant, 1982), New Guinea (Kol & Peterson, 1976), and Northern Europe (Kol & Eurola, 1973).

Kol (1968) distinguishes several types of colored snow and ice vege- tations, each characterized by dominant algal species:

a) red snow 1) Volvocales-type, caused by Chlamydomonas antarcticus Wille, Chl.

bolyaianus Kol, Chl. nivalis (Bau.) Wille, Chl. pichinchae Gerloff, Chl. sanguineus Lagerh., Smithsonimonas abbotii Kol, and Sphaerellopsis rubra Stein et Brooke.

2) Chlorococcales-type, caused by Scotiella nivalis (Shuttlew.) Fritsch, Sc. nivalis vat. californica Kol, Sc. nivalis vat. nipponica Kol, Sc. tatrae Kol, Trochiscia rubra Kol, and T. americana Kol.

b) green snow 1) Volvocales-type, caused by Carteria gyorffyi Kol, C. nivalis Kol, C

transsylvanica Kol, Chlamydomonas ballenyana Kol et Hint, Chl. caucasica (Kiss) Kol, and Chl. yellowstonensis Kol.

2) Chlorococcales-type, caused by Chlorella antarctica (Fritsch) Wille, Cryocystisjaponica Kol, and Ankistrodesmus antarcticus Kol et Hint.

3) Ulotrichales-type, caused by Hormidium flaccidum fo. cryophilum Kol, Koliella tatrae (Kol) Hindfik, K. tatrae var. fogarasensis (Kol) Hindfik, K. transsylvanica (Kol) Hindfik, K. viretii (Chod.) Hindfik, K. chodatii (Kol) Hind~k, K. bernina (Kol) Hindfik, K. nivalis (Chod.) Hind~k, Ra- phidonema nivale Lagerh., R. sabaudum Kol, and Stichococcus nivalis Chod.

c) yellow and yellow-brown snow 1) Volvocales-type, caused by Chlamydomonas flavovirens Rostaf. 2) Chlorococcales-type, caused by Cystococcus nivicolus Kol, Scotiella

antarctica Fritsch, and S. polyptera Fritsch.

d) blue snow Caused by the blue-green algae Dactylococcopsis caucasica Kiss, D.

hungarica Kol, and Gloeothece transsylvanica Kol.

e) purple brown ice Mesotaeniaceae-type, caused by A ncylonema nordensldoldii Berggr. and

Mesotaenium berggrenii (Wittr.) Lagerh.

Red snow is the most common snow type. It occurs in many of the world's alpine areas as well as in polar regions. The red snow is characteristic for locations exposed to high light intensities (Fukushima, 1963). The other snow types occur at more shadowed places.


From 354 species recorded from snow and ice (Kol, 1968), 46% belong to the Chlorophyta, most of these being unicellular flagellates of the family Chlamydomonadaceae, 26% to the Cyanophyceae, and 19% are diatoms. None of these diatoms occurs exclusively on snow or ice, whereas 58% of the green algae recorded are true cryobionts.

Many of the snow algae were recorded from only one or very few locations. It is difficult to determine how many of these are true endemic species as our information about taxonomy and distribution of these algae is still fragmentary. Thus it was only recently recognized that many of the algae described are only stages of other species. Many of the algae described as Chlorococcales seem to be zygotic stages of Volvocalean species; Hoham (1975b), Hoham and Mullet (1978), and Hoham et al. (1983) showed that many Scotiella species are resting spores of the genus Chloromonas. This makes the study of the developmental cycle in pure culture indispensable (Hoham, 1973, 1974a, 1974b).

Species with a wider distribution are generally restricted to either the northern or the southern hemisphere. Chlamydomonas nivalis is mostly responsible for the red snow on the northern hemisphere whereas Chla- mydomonas antarcticus causes the red snow in the Antarctic. Ancylonema nordenskioldii is restricted to the northern hemisphere where it causes purple ice blooms. Only a few species, such as Scotiella species, are found both in the Arctic and the Antarctic.

VII. Epiphytic Algae

Epiphytic algae commonly occur on higher plants either on tree bark (epiphloeic algae) or on leaves (epiphyllic algae). In certain cases free living species of epiphytic algae also participate in lichen associations (Tscher- mak-Woess, 1978).

The epiphytic algal vegetation seems to be controlled by physical factors rather than by host plant species. The epiphytic habitat is generally more arid than the soil and is subjected to periodic desiccation. Furthermore, the total amount of annual precipitation is usually much smaller on trees than on the ground. In the often windy tree bark habitat atmospheric humidity may be an important source of water supply (Barkman, 1958). Bark fissures may create a special microclimate as they are shady, retain moisture for a longer period, and are protected against the wind. For epiphloeic algae, nutrients are supplied by the dissolution of salts from the barks. The presence of sporopollenin in some of the epiphytic algae (Good & Chapman, 1978) may provide an effective protection against desiccation.

Epiphytic algae were studied in Europe in Switzerland (Brand & Stock- mayer, 1925; Jaag, 1945; Ochsner, 1928; Vischer, 1960), in Hungary (Felffldy, 1941), in Bohemia (Hilitzer, 1925), in The Netherlands (Bark-


man, 1958), in Belgium (Duvigneaud, 1942), in Africa (Fr6my, 1930; Marche-Marchad, 1980, 1981), in Southeast Asia (Fritsch, 1907; Jeeji- Bai, 1962; Kamat & Harankhedkar, 1976; Schmidle, 1897b, 1898; Van Oye, 1921), in Japan (Handa & Nakano, 1988; Suematu, 1957), in South America (Akiyama, 1971; Foerster, 1971; Kufferath, 1929; Schmidle, 1897a), in North America (Brunel, 1959; Cox & Hightower, 1972; LeBlanc, 1963; Wylie & Schlichting, 1973), and in Antarctica (Hickman & Vitt, 1973).

Barkman (1958) distinguishes three different associations of epiphloeic algae in Europe. The Pleurococcetum vulgaris forms a dull green, powdery, water repellent cover that loosely adheres to the bark on the shady side of trees. Pleurococcus vulgaris N~ig., Protococcus viridis Ag., and Chlorella vulgaris Beyer. are the major components. It occurs wherever the habitat is too harsh for the other associations and is generally the only association that can survive on city trees. It has a wide ecological amplitude and occurs on a great variety of trees. Its species are strongly nitrotolerant and are often present on the bases of trees manured by dogs.

A second association, the Prasioletum crispae, seems to be absent from more continental climates in Europe. It forms a velvety felt on tree barks, especially in alternatively wet and dry rain-tracks. The main species are Prasiola crispa (Lightf.) Menegh. and Hormidium flaccidum A. Br. This association develops at a certain age of the tree when the crown is able to procure sufficient water supply for the rain-tracks. It generally succeeds the Pleurococcetum and may in turn be replaced by bryophytes. The species of this association are also highly nitrotolerant.

A third association, the Trentepohlietum abietinae, forms orange cushions or crusts on trees. It prefers shady sites, such as Abies forests or the N and E side of isolated wayside trees in montane regions. It is absent in the maritime climate and is confined to subalpine regions of Central Europe. Trentepohlia abietina (Pers.) Hansg. and Tr. umbrina (Kiitz.) Born. are its representative species.

Whereas in temperate regions Trentepohlias occur only where the necessary degree of moisture exists, they are very common in humid tropical or subtropical climates. In tropical regions, blue-green algae form a major part of the epiphytic vegetation, besides Trentepohlia species (Fritsch, 1907). Fr6my (1930) found the following blue-green algae on tree barks in tropical Africa: Aphanocapsa naegelii Richt., Gloeocapsa aurata Stiz., Gl. ambigua Kirchn., Gl. lignicola (Kiitz.) Rabenh., Microcoleus tisserantii Fr6my, Schizothrix natans W. & G. S. West, Porphyrosiphon notarisii (Menegh.) Kfitz., Symploca muscorum (Ag.) Gom., S. muralis Kiitz., S. elegans Kiitz., S. parietina (A. Br.) Gom., Tolypothrix arboricola Fr6my, T. byssoidea (Berk.) Kirchn., Scytonema millei Born., S. javanicum (Kiitz.) Born., 5;. guyanense (Mont.) Born. & Flah., S. hofmannii Ag., S. my-


ochrous (Dillw.) Ag., S. crustaceum Ag., Nostoc sphaericum Vauch., N. macrosporum Menegh., Fischerella tisserantii Frrmy.

Epiphyllic algae are most commonly found in tropical regions. Some species like Phycopeltis arundinacea (Mont.) de Toni (Scannell, 1978), P. epiphyton Mill., and Cephaleuros virescens Kunze (Suematu, 1957) are also found in temperate regions. Besides the presence of blue-green algae, epiphyllic algae almost exclusively belong to the Chroolepidaceae (=Tren- tepohliaceae). In this group all transitional forms between epiphytic, en- dophytic, and parasitic algae exist (Oltmanns, 1922). Common epiphyllic genera are Trentepohlia, Phycopeltis (Printz, 1939), and Cephaleuros. Frr- my (1930) reports the blue-green algae Scytonemajavanicum (Kiitz.) Born., S. hofmannii Ag., Stigonema hormoides (Kiitz.) Born. & Flah., and St. minutum (Ag.) Hassal from leaves in equatorial Africa. Epiphyllic nitrogen fixing blue-green algae may play an important role in tropical rainforests (Bentley, 1987).

Epiphytic algae may also occur on ferns, mosses, and lichens. On mosses well developed diatom populations may occur. Thus Hickmann and Vitt (1973) report 47 species from Antarctica, the most common being Dia- tomella balfouriana Grev., Rhopalodia gibberula (Ehr.) O. Mull., R. gibba (Ehr.) O. Mull., Achnanthes lanceolata Brrb., Diploneis oblongella (N~tg. ex Kiitz.) Ross, and Mastogloia elliptica (Ag.) Cleve var. dansei (Thwaites) CI. Beger (1927) in his study of atmophytic diatoms mentions Melosira roeseana Rabenh., Navicula mutica Kiitz., Pinnularia borealis Ehrenb., Microneis minutissima (Kiitz.) Cleve, Hantzchia amphioxys (Ehr.) Grun., Fragilaria virescens Ralfs, and Navicula contorta Kitt. as most common moss inhabiting diatom species. Hustedt (1942) and Round (1957) also report diatom communities living on mosses.

VIII. Epizooic Algae

Various reports exist on the occurrence of algae on animals. Best known are the algae living on sloths [Bourrelly (1954, 1962); Kuhn (in Welcker, 1864); Thompson (1972); Weber van Bosse (1887); Wujek & Timpano (1986)]. Two algae, the filamentous green alga Trichophilus welckeri We- ber van Bosse (Chaetophorales) and a red alga, are often present on two- toed and three-toed sloths (Bradypus and Choleopus). Controversy exists about the correct name to apply to the red alga (Bourrelly, 1954; Thomp- son, 1972; Wujek & Timpano, 1986). According to Wujek & Timpano (1986) no name exists for this alga for which they propose the name Rufusia pilicola. Other algal genera present on sloths are Oscillatoria, Nostoc, Fischerella, Chroococcus, Pleurocapsa, Melosira, Trentepohlia, Stichococcus, Nannochloris, Dictyococcus, and Chlorococcum (Thompson,


1972). A new blue-green alga, Oscillatoria pilicola is described by Wujek & Lincoln (in press).

Lagerheim (1892) describes the green algal species Trichophilus neniae living on the shell of terrestrial snails in Ecuador. Trentepohliaceae were reported living on various animals, e.g., desert locusts (Ramchandra Rao, 1960) and spiders (Cribb, 1964). Gressitt et al. (1968) found tree bark algae growing on flightless weevils in tropical rainforests. A unicellular blue-green alga living inside of hairs of polar bears in zoos was recorded by Lewin & Robinson (1979). The greenish color of the fur of the pro- simian Galagoides is attributed by Sanderson (1957) to the presence of algae. Klintworth et al. (1968) report a case of human cutaneous infection caused by Prototheca, a colorless alga. The infection starts as a small lesion which then spreads slowly through the lymph glands, covering large areas of the body. In animals it can cause severe systemic infections leading to the death of the animal (Migaki et al., 1969).

Although algae living on animals appear to be infrequent, animals, e.g., insects (Gerson, 1976; Stewart & Schlichting, 1966) and birds (Schlichting et al., 1978), may serve as common substrate for algae playing a role in their dispersal.

IX. Acknowledgments

The work was started during a stay in the laboratory of Prof. E. I. Friedmann (Florida State Univ.) to whom I am grateful for many sug- gestions and for reading a preliminary draft of the manuscript. I am also thankful to Dr. V. Demoulin for reading the final manuscript. The stay at Florida State University was supported by NASA grant NSG-7337 and NSF grant DPP 83-14180 to Prof. E. I. Friedmann.

X. Literature Cited

Abdelahad, N. & G. Bazzichelli. 1988. Geitleria calcarea Friedmann, Cyanophyc6~ cavernicole nouvelle pour l'Italie. Nova Hedwigia 46: 265-270.

Akiyama, M. 1971. On some brazilian species of Trentepohliaceae. Mem. Fac. Educ., Shimane University 5:81-95.

Anagnostidis, K.,A. Economou-Amilli&M. Roussomoustakaki. 1983. Epilithicandchas- molithic microflora (Cyanophyta, Bacillariophyta) from marbles of the Parthenon (Acropolis--Athens, Greece). Nova Hedwigia 38: 227-287.

Aristovskaya, T. V., A. Y. Daragan, L. V. Zykina & R. S. Kutuzova. 1969. Microbiological factors in the movement of some mineral elements in the soil. Soviet Soil Sci. 5: 538- 546.

Bachmann, E. 1915. KalklSsende Algen. Ber. Deutsch. Bot. Ges. 33: 45-57, Taf. III. Barkman, J . J . 1958. Phytosociology and ecology of cryptogamic epiphytes. Koninklijke

Van Gorcum & Comp. N . V . G . A . Hak & Dr. H. J. Prakke. Assen, The Netherlands. 628 pp., 16 ph.

Beger, I-I. 1927. Beitr~ige zur Okologie und Soziologie der luftlebigen (atmophytischen) Kieselalgen. Ber. Deutsch. Bot. Ges. 45: 385--407.


Behre, K. 1953. Cyanophyceen iiberrieselter Felsen, von Herrn Vaillant vornehmlich in Algerien gesammelt. Bull. Soc. Hist. Nat. Afrique N. 44: 209-227.

Bell, R. A., P. V. Athey & M. R. Sommerfeld. 1986. Cryptoendolithic algal communities of the Colorado Plateau. J. Phycol. 22: 429--435.

- - & M. R. Sommerfeld. 1987. Algal biomass and primary production within a temperate zone sandstone. Amer. J. Bot. 74: 294-297.

Bentley, B.L. 1987. Nitrogen fixation by epiphylls in a tropical rainforest. Ann. Missouri Bot. Gard. 74: 234-241.

B e r n e r , T. & M. Evenari. 1978. The influence of temperature and light penetration on the abundance of the hypolithic algae in the Negev Desert of Israel. Oekologia 33: 255- 260.

Bold, H .C . 1970. Some aspects of the taxonomy of soil algae. Ann. New York Acad. Sci. 175: 601-616.

Bolyshev, N . N . 1968. "Vodorosli i ikh rol v obrazovanii pochv." (Algae and their role in the formation of soils.) Moscow University Press, Moscow. 83 pp.

Booth, W.E. 1941. Algae as pioneers in plant succession and their importance in erosion control. Ecology 22: 38--46.

�9 1946. The thermal death point of certain soil inhabiting algae. Proc. Montana Acad. Sci. 5/6: 21-23.

Borzi, A. 1917. Studi sulle Mixoficee. Nuovo Giorn. Bot. Ital. 24:100-112. B o u r r e l l y , P. 1954. Cyanoderma, algue des poils de Paresseux. Rev. Algol. N.S. 1: 122-

123. - - . 1962. Trichophilus, algue verte des poils de Paresseux. Revista Biol. 3: 201-204. - - & P. Dupuy. 1973. Quelques stations fran~aises de Geitleria calcarea, Cyanophyc6e

cavernicole. Schweiz. Z. Hydrol. 35: 136-140. Brand, F. & S. Stockmayer. 1925. Analyse der aerophilen Griinalgenanfliige, insbesondere

der proto-pleurococcoiden Formen. Arch. Protistenk. 52: 265-355. Bristol, B .M. 1919. On the retention of vitality by algae from old stored soils. New Phytol.

1 8 : 92-107. Broady, P .A. 1981 a. The ecology of chasmolithic algae at coastal locations of Antarctica.

Phycologia 20: 259-272. - - . 1981b. Ecological and taxonomic observations on subaerial epilithic algae from

Princess Elizabeth Land and MacRobertson Land, Antarctica. Brit. Phycol. J. 16: 257- 266.

- - . 1981 c. The ecology of sublithic terrestrial algae at the Vestfold Hills, Antarctica. Brit. Phycol. J. 16: 231-240.

Brunel, J . 1959. Le Trentepohlia arborum dans le Qu6bec. Naturaliste Canad. 86: 193- 198.

Biidel, B. 1987. Zur Biologic und Systematik der Flechtengattungen Heppia und Peltula im siidlichen Afrika. Biblioth. Lichenologica 23: 1-105.

Cameron, R.E. 1963. Algae of southern Arizona. Part I. Introduction--Blue-green algae. Rev. Algol. N.S. 6: 282-318.

- - & G. B. Blank�9 1966. Soil studies. Desert microflora. XI. Desert soil algae survival at extremely low temperatures. J.P.L. Space Programs Summary 37-37, IV: 174-181.

Cedercreutz, C. 1941. Beitrag zur Kenntnis der Felsenalgen in Finnland. Memoranda Soc. Fauna F1. Fenn. 17: 105-121.

- - . 1955. Vergleich zwischen der Algenvegetation an den Felsen Siid- und Mittelfinn- lands uod an den Felswiinden in der alpinen Region Lapplands. Acta Soc. Fauna Fl. Fenn. 72: 1-21.

Claus, G. 1955. Algae and their mode of life in the Baradla Cave at Aggtelek. Acta Bot. Acad. Sci. Hung. 2: 1-26.

�9 1960. Re-evaluation of the genus Gomontiella. Rev. Algol. N.S. 5:103-11 I. �9 1962a. Data on the ecology of the algae of Peace Cave in Hungary. Nova Hedwigia

4: 55-80, pl. 34-36. �9 1962b. Beitdige zur Kenntnis der Algenflora der Abaltigeter H6hle. Hydrobiologia

19: 192-222.


�9 1964. Algae and their mode of life in the Baradla Cave at Aggtelek II. Int. J. Speleol. 1: 13-17, pls. I, II.

Cout6, A. 1982. Ultrastructured'unecyanophyc6ea6riennecalcifi6ecavernicole: Geitleria calcarea Friedmann. Hydrobiologia 97: 255-274.

Cox, E. R. & J. Hightower. 1972. Some corticolous algae of McMinn County, Tennessee, U.S.A.J. Phycol. 8: 203-205.

Cribh, A.B. 1964. Notes on Trentepohlia from Queensland including one growing on a spider. University of Queensland Dept. Biol. Pap. 4: 99-108.

Curl, H., Jr., J . T. Hardy & R. Ellermeier. 1972. Spectral absorption of solar radiation in alpine snowfields. Ecology 53:1189-1194.

Czygan, F.-C. 1970. BlutregenundBlutschnee: Stickstoffmangel-ZellenvonHaematococ- cus pluvialis und Chlamydomonas nivalis. Arch. Microbiol. 74: 69-76.

Danin, A. 1983. Weathering of limestone in Jerusalem by cyanobacteria. Z. Geomorphol. N.F. 27: 413-421.

�9 1986. Patterns of biogenic weathering as indicators of palaeoclimates in Israel. Proc. Roy. Soc. Edinburgh 89B: 243-253.

- - & J. Garty. 1983. Distribution of cyanobacteria and lichens on hillsides of the Negev Highlands and their impact on biogenic weathering. Z. Geomorphol. N.F. 27: 423-444.

Darling, R. B., E. I. Friedmann & P. A. Broady. 1987. Heterococcus endolithicus sp. nov. (Xanthophyceae) and other terrestrial Heterococcus species from Antarctica: Morpho- logical changes during the life history and response to temperature. J. Phycol. 23: 598- 607.

Davis, J . S. & D. G. Rands. 1981. The genus Geitleria (Cyanophyceae) in a Bahamian cave. Schweiz. Z. Hydrol. 43: 63-68.

Diels, L. 1914. Die Algen Vegetation der siidtiroler Dolomitriffe. Ein Beitrag zur (~kologie der Lithophyten. Ber. Deutsch. Bot. Ges. 32: 502-526, Tar. XI.

Dobat, K. 1966. Die Kryptogamenvegetation der H6hlen und Halbhfhlen im Bereich der Schw~ibischen Alb. Abhandl. Karst--u. H6hlenkunde, Reihe E, 3:1-153.

- - . 1968. Die Pflanzen- und Tierwelt der Chaflottenh~Shle. Abhandl. Karst-u. H6h- lenkunde, Reihe A, 3: 37-50.

- - . 1969a. Die Lampenflora der B~irenh6hle. Pages 29-35 in G. Wagner (ed.), Die B~enhfhle bei Erpfingen. Erpfingen.

- - . 1969b. Ein biologischer Lehrgang durch die Schauh6hlen der Schw~ibischen Alb. Die Schulwarte 22: 439-456.

- - . 1970. Consid6rations sur la v6g6tation cryptogamique des grottes du Jura Souabe (Sud-ouest de l'Allemagne). Ann. Sp616ol. 25:871-907.

- - . 1977. Zur Oekogenese und Oekologie der Lampenflora deutscher Schauh6hlen. Pages 177-215 in W. Frey et al. (eds.), Beitr~ige zur Biologie der niederen Pflanzen. Gustav Fischer Verlag, Stuttgart, New York.

Doemel, W. N. & T. D. Brock�9 1971. The physiological ecology ofCyanidium caldarium. J. Gen. Microbiol. 67: 17-32.

Durrell, L. W. & L M. Shields. 1961. Characteristics of soil algae relating to crust formation. Trans. Amer. Microscop. Soc. 80: 73-79.

Dnvigneaud, P. 1942. Les associations 6piphytiques de la Belgique. Bull. Soc. Roy. Bot. Belg. 74: 32-53.

Ercegovi~, A. 1925. Litofitska vegetacija vapnenaca i dolomita u Hrvatskoj. (La v6g6tation des lithophytes sur les calcaires et les dolomites en Croatie). Acta Instituti Bot. R. Univ. Zagrebensis 1:64-114, tab. I-IV.

Felfiildy, L 1941. Die Epiphytenvegetation des Waldes "Nagyerdo" bei Debrecen. Acta Geobot. Hung. 4: 35-73.

Fjerdingstad, E. 1965. The algal flora of some "Tintenstriche" in the Alpes-Maritimes (France). Schweiz. Z. Hydrol. 27. 167-171.

Foerster, J . W . 1971. The ecology of an elfin forest in Puerto Rico. 14. The algae of Pico del Oeste. J. Arnold Arbor. 52: 86-109.


Folk, R. L., H�9 H. Roberts & C. H. Moore�9 1973. Black phytokarst from Hell, Cayman Islands, British West Indies. Bull. Geol. Soc. Amer. 84:2351-2360.

Frrmy, P. 1925. Essai sur l'rcologie des algues saxicoles, arriennes et subarriennes, en Normandie. Nuova Notarisia, ser. 36: 297-304.

�9 1930. Les Myxophycres de l 'Afrique l~quatoriale Fran~aise. Arch. Bot. Mrm. 3: 1-508.

F r i e d m a n n , E . I . 1971. Light and scanning electron microscopy of the endolithic desert algal habitat. Phycologia 10:411--428.

�9 1972. Ecology oflithophytic algal habitats in Middle Eastern and North American deserts. Pages 182-185 in L. E. Rodin (ed.), Ecophysiological foundation of ecosystems productivity in arid zones. Nauka, U.S.S.R. Acad. Sci., Leningrad.

�9 1977. Microorganisms in Antarctic desert rocks from dry valleys and Dufek Massif. Antarct. J. U.S. 12: 26-30.

�9 1978. Melting snow in the dry valleys is a source of water for endolithic microorganisms. Antarct. J. U.S. 13: 162-163.

�9 1979. The genus Geitleria (Cyanophyceae or Cyanobacteria): Distribution of G. calcarea and G. floridana n. sp. P1. Syst. Evol. 131: 169-178.

- - . 1982. Endolithic microorganisms in the Antarctic cold desert. Science 215: 1045- 1053.

- - & L. J . Borowitzka. 1982. The symposium on taxonomic concepts in blue-green algae: Towards a compromise with the bacteriological code? Taxon 31: 673-683.

- - & M. Galun. 1974. Desert algae, lichens, and fungi. Pages 165-212 in G. W. Brown (ed.), Desert biology 2. Academic Press, Inc., New York.

- - & A. P. Kibler. 1980. Nitrogen economy ofendoli thic microbial communities in hot and cold deserts. Microbial Ecol. 6: 95-108.

- - , Y. Lipkin & R. O. Pans. 1967. Desert algae of the Negev (Israel). Phycologia 6: 185-200.

- - , C. P. McKay & J. A. Nienow. 1987. The cryptoendolithic microbial environment in the Ross Desert of Antarctica: Satellite-transmitted continuous nanoclimate data, 1984 to 1986. Polar Biol. 7: 273-287.

- - & R. Ocampo. 1976. Endolithic blue-green algae in the dry valleys: Primary producers in the Antarctic desert ecosystem. Science 193: 1247-1249.

- - & R. Ocampo-Friedmann. 1984. Endolithic microorganisms in extreme dry environments: Analysis of a lithobiontic microbial habitat. Pages 177-185 in M. J. Klug & C. A. Reddy, Current perspectives in microbial ecology. American Society for Mi- crobiology, Washington, D.C.

F r i e d m a n n , I. 1955. Geitleria calcarea n. gen. and n. sp. Bot. Not. 108: 439--445. �9 1956. Beitr~ige zu Morphologie und Formwechsel der atmophytischen Bangioidee

Phragmonema sordidum Zopf. Oesterr. Bot. Z. 103:613-633. �9 1961. Chroococcidiopsis kashaii sp. n. and the genus Chroococcidiopsis. (Studies

on cave algae from Israel III.) Oesterr. Bot. Z. 108: 354-367. �9 1962. The ecology of the atmophytic nitrate-alga Chroococcidiopsis kashaii Fried-

mann. (Studies on cave algae from Israel IV.) Arch. Mikrobiol. 42: 42-45. �9 1964. Progress in the biological exploration of caves and subterranean waters in

Israel. Int. J. Speleol. 1: 29-33. Fritseh, F.E. 1907. A general consideration ofthe subaerial and freshwater algae ofCeylon.

Proc. Roy. Soc. London 79: 197-254. F u k u s h i m a , H. 1959. General report on fauna and flora of the Ongul Islands, Antarctica,

especially on freshwater algae. J. Yokohama Munic. University, Set. C, 31: 1-10, pls. 1-10.

�9 1963. Studies on cryophytes in Japan. J. Yokohama Munic. University, Ser. C, 43: 1-146.

Geitler, L. 1924. Lrber einige wenig bekannte Siisswasserorganismen mit roten oder blau- grfinen Chromatophoren. Rev. Algol. 4: 357-375.

�9 1927. Rhodospora sordida, nov. gen. et n. sp., eine neue, ,,Bangiacee" des Siiss- wassers. Oesterr. Bot. Z. 76: 25-28.


�9 1943a. Eine neue atmophytische Chrysophycee, Ruttnera spectabilis, nov. gen., nova spec. Int. Rev. Gesamten Hydrobiol. Hydrogr. 43: 100-109.

�9 1943b. Einigesel tenbeobachteteAlgenausLunz. Int. Rev. GesamtenHydrobiol . Hydrogr. 43: 98-99.

�9 1944. Furchungsbildung, simultane Mehrfachteilung, Lokomotion, Plasmotypse und Okologie der Bangiacee Porphyridium cruentum. Flora 37: 300-333.

�9 1955. Die atmophytische Bangioidee Rhodospora. Oesterr. Bot. Z. 102: 25-29. Gerson, U. 1976. The association of algae with arthropods. Rev. Algol. N.S. 11: 18-41,

213-234, 235-247. Glazovskaya, M . A . 1950. "Vyvetrivanie gornykh porod v nival 'nom poyase tsentral'nogo

Tyan-Shanya." (Rock weathering in the arable belt of central Tyan-Shan.) Trudy Pochv. Inst., Akad. Nauk SSSR 34: 28-48.

Gollerbakh, M . M . 1953. "Rol vodoreslei v pochvennykh protessakh." (The role of algae in soil processes.) Trudy Konf. Vop. Pochv. Mikrobiol. 1951: 98-108, 221-222.

- - & E . A . S h t i n a . 1969. "Pochvennyevodorosli ."(Soilalgae.)Izdatelystovo"Nauka," Leningrad. 228 pp.

Golubib~ S. 1967a. Algenvegetation der Felsen. In H. J. Elster & W. Ohle (eds.), Die Binnengewiisser 23. E. Schweizerbart'sche Vedagsbuchhandlung, Stuttgart. 183 pp.

�9 1967b. Die Algenvegetation an Sandsteinfelsen Ost-Venezuelas (Cumana). Int. Rev. Gesamten Hydrobiol. 52: 693-699.

, I. Friedmann & J. Schneider. 1981. The lithobiontic ecological niche, with special reference to microorganisms. J. Sediment. Petrol. 51: 475-478.

, R. D. Perkins & K. J . Lukas. 1975. Boring microorganisms and microborings in carbonate substrates. Pages 229-259 in R. W. Frey (ed.), The study of trace fossils. Springer-Verlag, New York.

Good, B. H. & R. L. Chapman�9 1978. The ultrastructure ofPhycopeltis (Chroolepidaceae: Chlorophyta). I. Sporopollenin in the cell walls. Amer. J. Bot. 65: 27-33.

Graeia Alonso, C . A . 1974. Geitleria calcarea Friedmann nueva alga cavernicola para Espana. Speleon 21: 133-136.

Gressitt, J . L., G. A. Samuelson & D. H. Vitt. 1968. Moss growing on living papuan moss- forest weevils. Nature 217: 765-767.

Gromov, B.V. 1957. The microflora of rock layers and primitive soils of some northern districts of the USSR. Mikrobiologya 26: 57-63.

Hajdu, L. 1966. Algological studies in the cave of Matyas Mount, Budapest, Hungary. Int. J. Speleol. 2: 137-149.

Handa, S. & T. Nakano. 1988. Some corticolous algae from Miyajunia Island, western Japan. Nova Hedwigia 46: 165-186.

Hilyrrn, E. 1940. Die Algenvegetation der Sickerwasserstreifen auf den Felsen in Siid- finnland. Commentat. Biol. 7: 1-19.

Hickman, M. & D. H. Vitt. 1973. The aerial epiphytic diatom flora of moss species from subantarctic Campbell Island. Nova Hedwigia 24: 443-458.

Hilitzer, A. 1925. La vrgrtation 6piphyte de la Bohrme. Publ. Fac. Sci. Univ. Charles, Prague, Cislo 41: 1-200.

Hoffman, L. 1986. Algues bleues arriennes et suba~riennes du Grand-Duch6 de Luxem- bourg. Bull. Jard. Bot. Nat. Belg. 56: 77-127.

Hoham, R.W. 1973. Pleiomorphism in the snow alga, Raphidonema nivale Lagerh. (Chlo- rophyta) and a revision of the genus Raphidonema Lagerh. Syesis 6: 255-263.

- - . 1974a. Chlain~176176176176176176176176 a revision of the snow alga, Trachelomonas kolii Hardy et Curl (Euglenophyta, Eu- glenales). J. Phycol. 10: 392-396.

�9 1974b. New findings in the life history of the snow alga, Chlainomonas rubra (Stein & Brooke) comb. nov. (Chlorophyta, Volvocales). Syesis 7: 239-247.

- - . 1975a. Opt imum temperatures and temperature ranges for growth of snow algae. Arctic and Alpine Res. 7 :13-24.

�9 1975b. The life history and ecology of the snow alga Chloromonas pichinchae (Chlorophyta, Volvocales). Phycologia 14: 213-226.


�9 1976. The effect of coniferous litter and different snow meltwaters upon the growth of two species of snow algae in axenic culture. Arctic and Alpine Res. 8: 377-386.

- - . 1980. Unicellular chlorophytes-snow algae. Pages 61-84 in E. Cox (ed.), Phyto- flagellates. Elsevier, North Holland, Inc., New York.

- - & J . E. Mullet. 1978. Chloromonas nivalis (Chod.) Hoh. & Mull. comb. nov., and additional comments on the snow alga, Scotiella. Phycologia 17: 106-107.

, - - & S. C. Raemer. 1983. The life history and ecology of the snow alga Chloromonaspolyptera comb. nov. (Chlorophyta, Volvocales). Canad. J. Bot. 61:2416- 2429.

Hunt, C. B. & L. W. Durrell. 1966. Distribution of fungi and algae. U.S. Geol. Surv., Prof. Pap. 509: 55-66.

Hustedt, F. 1942. Aerophile Diatomeen in der nordwestdeutschen Flora. Ber. Deutsch. Bot. Ges. 60: 55-73.

Jaag, O. 1945. Untersuchungen fiber die Vegetation und Biologie der Algen des nackten Gesteins in den Alpen, im Jura und im schweizerischen Mittelland. Beitr. Kryptoga- menfl. Schweiz 9: 1-560, 20 Taf.

Jalas, J . 1949. Algen yon einigen sonnenexponierten Osabh~ingen. Arch. Soc. Zool. Bot. Fenn. "Vanamo" 3: 52-59.

Jeeji-Bai, N. 1962. Trentepohlia monilia de Wildeman from Madras. Phykos 1: 79-83. Johansen, J. R., S. R. Rushforth, R. Orbendorfer, N . Fungladda & J. A. Grimes. 1983.

The algal flora of selected wet walls in Zion National Park, Utah, USA. Nova Hedwigia 38: 765-808.

dunes, H .d . 1964. Algological investigations in Mammoth Cave, Kentucky. Int. J. Speleol. 1: 491-516.

Kamat, N. D. & P. S. Harankhedkar. 1976. Bark algae of Nagpur, Maharashtra. Phykos 15: 53-57.

Kers, L .E . 1976. FSnsteralgvegetation i de svenska tjallen. (Vegetation with "stone win- dowed algae" in the high mountains of Sweden.) Svensk Bot. Tidskr. 70: 299-300.

Khoja, T. M. & B. A. Whitton. 1975. Heterotrophic growth of filamentous blue-green algae. Br. Phycol. J. 10: 139-148.

Klintworth, G. K., B. F. Fetter & H. S. Nielsen, J r . 1968. Protothecosis, an algal infection: Report of a case in man. J. Med. Microbiol. 1: 211-216.

Kol, E. 1966. Algal growth experiments in the Baradla Cave at Aggletek. Int. J. Speleol. 2: 457-474.

- - . 1968. Kryobiologie. In H. J. Elster & W. Ohle (eds.), Die Binnengewiisser 24. E. Schweizerbart'sche Verlagsbuchhandlung, Stuttgart. 216 pp.

- - . 1971. Green snow and ice from the Antarctica. Ann. Hist.-Nat. Mus. Natl. Hung. 63:51-56.

�9 1972. Snow algae from Signy Island (South Orkney Islands), Antarctica. Ann. Hist.-Nat. Mus. Natl. Hung. 64: 63-70.

�9 1973. Green snow from Haswell Island (Antarctica). Ann. Hist.-Nat. Nus. Natl. Hung. 65: 57-62.

- - & S. Eurola. 1973. Red snow in the Kilpisjarvi region, North Finland. Astarte 6: 75-86.

- - & J. A. Peterson. 1976. Cryobiology. Pages 81-91 in G. S. Hope et al. (eds.), The equatorial glaciers of New Guinea, results of the 1971-1973 Australian Universities' Expeditions to Irian Jaya: Survey, Glaciology, Meteorology, Biology and Palaeoenvi- ronments. Balkema, Rotterdam.

Komirek, J., F. Hind/tic & P. Javornick~. 1973. Ecology of green kryophilic algae from BeLanske Tarry Mountains (Czechoslovakia). Arch. Hydrobiol., Suppl. 41 (Algol. Stud. 9): 427-449.

Komiromy, Z.P . 1977. The algal flora of the ()rd6glyuk Cave at Szoplak (Hungary). Ann. Hist.--Natl. Mus. Natl. Hung. 69: 29-35.

, J . Padis/tk & M. Rajczy. 1985. Flora in the lamp-lit areas of the cave "Anna- barlang" near Lillafiired (Hungary). Ann. Hist.-Nat. Mus. Natl. Hung. 77: 103-122.

Koster, J . T . 1939. Notes on Javanese calcicole Cyanophyceae. Blumea 3: 243-247.


Krumbein, W . E . 1972. R61e des microorganismes dans la gen~se, la diagen~se et la d6gradation..des roches en place. Rev. Ecol. Biol. Sol 9:283-319.

�9 1973. UberdenEinflussvonMikroorganismenaufdieBausteinverwittertmg-eine ~kologische Studie. Ktmst-u. Denkmalpfl. 31:54-71.

- - & C. Giele. 1979. Calcification in a coccoid cyanobacterium associated with the formation of desert stromatolites. Sedimentol. 26: 593--604.

- - & K. Jens. 1981. Biogenic rock varnishes of the Nagev Desert (Israel): An ecological study of iron and manganese transformation by cyanobacteria and fungi. Oecologia 50: 25-38.

- - & M. Polls. 1979. Girvanella-like structures formed by Plectonema gloeophilum (Cyanophyta) from the Borrego desert in Southern California. Geomicrobiol. J. 1:211- 213.

Kufferath, H. 1929. Algues el Protistes muscicoles, corticoles et terrestres r6eolt6s sur la montagne de Barba (Costa-Rica). Ann. Cryptog. Exot. 2: 23-52.

Lagerheim, G. 1892. Trichophilus neniae Lagerh. n. sp., eine neue epizoische Alge. Ber. Deutsch. Bot. Ges. 10: 514-517.

LeBlne , F. 1963. Quelques soci6t6s ou unions d'6piphytes du sud du Qu6bec. Canad. J. Bot. 41: 591-638.

Leelerq, J . C., A. Cout~ & P. Dnpuy. 1983. Le climat annuel de deux grottes et d'une 6glise du Poitou, o4 vivent des colonies pures d'algues sciaphiles. Cryptogam., Algol. 4: 1-19.

Leed~e, G. 1967. Euglenoid flagellates. Prentice-Hall, Englewood Cliffs, New Jersey. 242 pp.

Lewin, J . C . 1953. Heterotrophy in diatoms. J. Gen. Microbiol. 9: 305-313. Lewin, R. A. & P. T. Robinson. 1979. The greening of polar bears in zoos. Nature 278:

445-447. Lipman, C.B. 1941. The successful revival of Nostoc communefrom a herbarium specimen

eighty-seven years old. Bull. Torrey Bot. Club 68: 664-666. Land, J . W . G . 1962. Soil algae. Pages 759-770 in R. A. Lewin (ed.), Physiology and

biochemistry of algae. Academic Press, New York. �9 1967. Soil algae. Pages 129-147 in A. Burger & F. Raw (eds.), Soil biology.

Academic Press, New York. Marathe, K. V. & P. R. Chaudhari. 1975. An example of algae as pioneers in the lithosphere

and their role in rock corrosion. J. Ecol. 63: 65-70. Marehant, H . J . 1982. Snow algae from the Australian Snowy Mountains. Phycologia 21:

178-184. Marehe-Marchad, J . 1980. l~tude6cologiquedesorganismes6piphyllesetsous-cuticulaires

d'Anacardium occidentale L. au S6n6gal. Rev. Gen. Bot. 87: 3-71, 143-202, 209-260. - - . 1981. Quelquesdonn6es6cologiquessurCephaleurosvirescensKanzeetleslichens

dont il est la gonidie. Cryptogam., Algol. 2: 289-301. McKay, C. P. & E. I. Friedmann. 1985. The cryptoendolithic microbial environment in

the Antarctic cold desert: Temperature variations in nature. Polar Biol. 4: 19-25. Merola, A., R. Castaldo, P. De Luea, R. Gambardella, A. Musaechio & R. Taddei. 1982.

Revision of Cyanidium caldarium. Three species of acidophilic algae. G. Bot. Ital. 115: 189-195.

Messikommer, F. 1942. Beitrag zur Kenntnis der Algenflora mad Algenvegetation des Hochgebirges im Davos. Beitr. Geobot. Landesaufn. Schweiz 24: 1-452.

Metting, B. 1981. The systematics and ecology of soil algae. Bot. Rev. 47: 195-312. Migaki, G., F. M. Garner & G. D. Imes. 1969. Bovine protothecosis. Pathol. Vet. 6: 444-

453. Nagy, J .P . 1965. Preliminary notes on the algae of Crystal Cave, Kentucky. Int. J. Speleol.

1: 479-490. Novh~elq F. 1934. Epilithick~ sinice serpentinfi Mohelensk~ch. Arch. Svazu Ochr. Pfir

moravskol 3:1-178. Oehsner, F. 1928. StudienuberdieEpiphytenvegetati~

Naturwiss. Ges. 63: 1-106.


Odintsova, S .V. 1941. Nitre formation in deserts. Dokl. Akad. Nauk. SSSR 32: 578-580. Oltmanns, F. 1922. Morphologie and Biologie der Algen, Bd. 1. Gustav Fischer Vedag,

Jena. 459 pp. Palik, P. 1938. Adatok a Bukk-Hegys6g Lithophyta Algaveget~ti6jithoz. (Beitriige zur

Kenntnis der Lithophyten Algenvegetation des Biikkgebirges.) Index Horti Bot. Univ. Budapest 3: 3-10.

�9 1960. A new blue-green alga from the cave Baradla near Aggtelek. Ann. Univ. Sci. Budapest. Rolando Eotvos, Sect. Biol. 3: 275-285.

- - . 1964. Uber die Algenwelt der H/Shlen in Ungarn. Int. J. Speleol. 1: 35-43. Parker, B. C., N. Schamem & R. Renner. 1969. Viable soil algae from the herbarium of

the Missouri Botanical Garden. Ann. Missouri Bot. Gard. 56:113-119. Petersen, J . B . 1935. Studies on the biology and taxonomy of soil algae. Dansk. Bot. Ark.

8: 1-180. Pollock, R. 1970. What colors the mountain snow? Sierra Club Bull. 55: 18-20. Potts, M . & E . I . Friedmann. 1981. Effectsofwaterstressoncryptoendolithiccyanobacteila

from hot desert rocks. Arch. Microbiol. 130: 267-271. , R . Ocampo-Friedmann, M. A. Bowman & B. Tozun. 1983. Chroococcus $24 and

Chroococcus N41 (cyanobacteria): Morphological, biochemical and genetic character- ization and effects of water stress on ultrastructure. Arch. Microbiol. 135:81-90.

Printz, H. 1939. Vorarbeiten zu einer Monographie der Trentepohliaceen. Nyt. Mag. Naturvidensk. 80:137-210.

Ramchandra Rao, Y. 1960. The desert locust in India. Monogr. Indian Council Agr. Res., New Delhi, No. 21 (cited in U. Gerson).

R o u n d , F .E . 1957. The diatom community of some Bryophyta growing on sandstone. J. Linn. Soc., Bot. 55: 657-661.

�9 1981. The ecology of algae. Cambridge University Press, Cambridge. 653 pp. Royzin, M . B . 1960. "Mikroflora skal i primitivnykh pochv vysokogornoi arkticheskoi

pustyni." (Microflora of the rocks and primitive soils in the high mountain arctic desert.) Bot. Zurn. (Leningrad)45: 997-1008.

Sanderson, I .T. 1957. The monkey kingdom: Introduction to the pilmates. ChiltonBooks, Philadelphia. 200 pp.

Scannell, M. J . P . 1978. Phycopeltis arundinacea Mont. en Europe. Rev. Algol. N.S. 13: 41-42.

Schade, A. 1923. Die kryptogamischen Pflanzengesellschaften an den Felsw~inden der S~iehsischen Schweiz. Ber. Deutsch. Bot. Ges. 41: (49)--(59).

Sehlichting, H . E . , J r . , B . J . Spez ia le&R.M. Zink. 1978. Dispersal ofalgae and protozoa by antarctic flying birds. Antarct. J. U.S. 13: 147-149.

Sehmidle, W. 1897a. Vier neue yon Professor Lagerheim in Ecuador gesammelte Baum- algen. Ber. Deutsch. Bot. Ges. 15: 456-459.

- - . 1897h. Epiphylle Algen nebst einer Pithophora und Dasya aus Neu-Guinea. Flora 33: 304.

�9 1898. Ober einige yon Prof. Lagerheim in Ecuador und Jamaika gesammelte Blattalgen. Hedwigia 37:61-64.

Schorler, B. 1914. Die Algenvegetation an den Felsw/inden des Elbsandsteingebirges. Abh. Naturw. Ges. "Isis" Dresden 1: 3-27.

Schwabe, G .H. 1936. Uber einige Blaualgen aus dem mittleren und siidlichen Chile. Verh. Deutsch. Wissenschaftl. Ver. Santiago (Chile), N.F. 3:113-174.

- - . 1960. Blaualgen aus ariden B6den. Forsch. & Fortschr. 34: 194-197. Serb~nescu, M. & V. Decu. 1962. To the knowledge of cavernicolous algae of Oltenia. I.

Rev. Biol. 7" 201-214. Shields, L. M. & F. Drouet. 1962. Distribution of terrestrial algae within the Nevada test

site. Amer. J. Bot. 49: 547-554. - - & L. W. Durrell. 1964. Algae in relation to soil fertility. Bot. Rev. 30: 92-128. Sieminska, J . 1962. TheredalgaPhragmonemasordidumintheSibylCavenearbyNaples.

Acta Hydrobiol. 4: 225-227. Skuja, H. 1970. Alghe cavernicole helle zone illuminate delle grotte di Castellana (Murge

di Bail). Le Grotte d'Italia, Ser. 4, 2: 193-202.


Smith, D. W. & T. D. Brock. 1973. The water relations of the alga Cyanidium caldarium in soil. J. Gen. Microbiol. 79: 219-231.

Smith, E. A., C. I. Mayfield & P. T. S. Wong. 1978. NaturaUy-occurring apatite as a source of orthophosphate for growth of bacteria and algae. Microbial Ecol. 4 :105-118.

Stanier, R .Y. 1973. Autotrophy and heterotrophy in unicellular blue-green algae. Pages 501-518 in N. G. Carr & B. A. Whitton (eds.), The biology of blue-green algae. Bot. Monogr. 9. Blackwell Sci. Publ., Oxford.

Stein, J. R. & C. C. Amundsen. 1967. Studies on snow algae and fungi from the Front Range of Colorado. Canad. J. Bot. 45: 2033-2045.

Stewart, K. W. & H. E. Schlichting, Jr . 1966. Dispersal of algae and protozoa by selected aquatic insects. J. Ecol. 54:551-562.

Str tm, K . M . 1926. Norwegian mountain algae. Skr. Norske Vidensk.-Akad. Oslo, Mat.- Naturvidensk. K1. 6: 22-24.

Suba, E. 1957. Die Algen dcr Palvolgyer H6hle in Ungarn. Verh. Zool.-Bot. Ges. Wien 97: 97-109.

Suematu, S. 1957. Notes on Cephaleuros and Phycopeltis, parasitic and epiphytic aerial- algae III. Lists of infected plants. Bot. Mag. (Tokyo) 7 0 : 2 7 6 - 2 8 1 .

Tchan, Y . T . & N . C . W . Beadle. 1955. Nitrogen economy in semi-arid plant communities. Proc. Linn. Soc. New South Wales 80: 97-104.

- - & J. A. Whitehouse. 1953. Study of soil algae. II. The variation of the algal population in sandy soils. Proc. Linn. Soc. New South Wales 78: 160-170.

Thompson, R.H. 1972. Algae from the hair of the sloth Bradypus. J. Phycol. 8 (Suppl.): 8. Trainor, F .R . 1985. Survival of algae in a desiccated soil: A 25 year study. Phycologia

24: 79-82. Treub, M. 1988. Notice sur la nouvelle flore de Krakatau. Ann. Jard. Bot. Buitenzorg 7:

221-223. Tschermak-Woess , E. 1978. Myrmecia reticulata as a phycobiont and free-living--Free-

living Trebouxia--The problem of Stenocybe septata. Lichenologist 10: 69-79. - - & E. I. Friedmann. 1985. Hernichloris antarctica, gen. et sp. nov. (Chlorococcales,

Chlorophyta), a cryptoendolithic alga from Antarctica. Phycologia 23: 443-454. Van Oye, P. 1921. Influence des facteurs climatiques sur la r6partition des 6piphytes ~ la

surface des troncs d'arbres ~ Java. Rev. Gen. Bot. 33: 16i-176. Vischer, W. 1960. Reproduktion und systematische Stellung einiger Rinden- und Boden-

algen. Schweiz. Z. Hydrol. 22: 330-349. Vogel, S. 1955. Niedere "Fensterpflanzen" in der siidafrikanischen Wiiste. Beitr. Biol.

Pflanzen 31: 45-135. Weber van Bosse, A. 1887. ]~tude sur les algues parasites des Paresseux. Natuurk. Verh.

Holl. Maatsch. Wetensch. Haarlem III, 5: 1-24, tab. I-III. Weleker, H. 1864. Haut und des Haares bei Bradypus nebst Mittheilungen fiber eine in

Inneren des Faultierhaares lebende Alge. Abh. Naturf. Ges. Halle 9: 1-72. Wujek, D. E. & T. A. Lincoln. (In press). Ultrastructure and taxonomy of Oscillatoria

pilicola, a new species of blue-green alga from sloth hair. Brenesia 27. - - & P. Timpano. 1986. Rufusia (Porphyridales, Phragmoncmataceae), a new red alga

from sloth hair. Brenesia 25/26: 163-168. Wylie, P. A. & H. E. Schlichting. 1973. A floristic survey of corticolous subaerial algae

in North Carolina. J. Elisha Mitchell Sci. Soc. 89: 179-183. Zehnder, A. 1953. Bcitrag zur Kenntnis yon Mikroklima und Algenvegetation des nackten

Gesteins in den Tropen. Ber. Schweiz. Bot. Ges. 63: 5-26. Zopf, W. 1882. Zur Kenntnis der Spaltalgen (Schizophyceae). Bot. Zentralbl. 10: 32-36.

algae of terrestrial habitats

Documents