the lagoon of orbetello

111

The Orbetello lagoon

THE LAGOON OF ORBETELLO Mauro Lenzi

1, Francesca Birardi

1, Silvia Boddi

2, Rugiada Roffilli

1, Duccio Solari

1,

Gianfranco Sartoni 2

1 Lagoon Ecology and Aquaculture Laboratory, OPL s.r.l, Orbetello, 2 Dipartimento di

Botanica, Università di Firenze

Riassunto

Si riporta una revisione della flora sommersa della laguna di Orbetello a partire

dagli anni ’70, confrontando la successione di associazioni e specie dominanti

in relazione ai cambiamenti avvenuti durante le attività di recupero cominciate

nei primi anni ’90. Gli elenchi floristici ottenuti durante i tre studi principali

condotti negli anni ’70 e ’80 sono paragonati con due liste, più recenti ma non

pubblicate, elaborate dopo le operazioni di recupero ambientale. Il fondo mobile

fangoso-argilloso di questa laguna è per la maggior parte colonizzato da specie

pleustofitiche, tra le quali un’associazione dominata da Rhodophyta

(prevalentemente Gracilariaceae) si alterna ad un’associazione dominata dalla

Chlorophyta Chaetomorpha linum. La flora comprende diverse specie epifite,

principalmente comuni epifite delle fanerogame che sono distribuite entro tutta

la laguna, ad eccezione delle Chordariales Cladosiphon zosterae e

Corynophlaea flaccida, che rappresentano nuove segnalazioni per le coste

toscane e per il Tirreno settentrionale. Attualmente, le due fanerogame presenti,

Ruppia cirrhosa e Nanozostera noltii sono abbondanti. L’ambiente della laguna

di Orbetello non è, al momento, completamente risanato, poiché risulta

potenzialmente eutrofico, ma potrebbe essere recuperato con interventi solleciti

ma onerosi.

Abstract

Distribution of submerged vegetation of Orbetello lagoon is reviewed since the

1970s, comparing the succession of associations and dominant species and

changes occurring during remediation activities which began in the early 1990s.

Lists of the flora from the three main studies carried out in the 1970s and 1980s

are compared with two, more recent, unpublished lists, compiled after

environmental restoration operations. The soft silt-clay bottom of this lagoon is

largely dominated by unattached species, where an association dominated by

Rhodophyta (Gracilariaceae) alternates with one dominated by the Chlorophyta

Chaetomorpha linum. The flora includes several epiphytic species, mainly

common seagrass epiphytes which are widespread throughout the lagoon,

except for the Chordariales Cladosiphon zosterae and Corynophlaea flaccida,

that are new reports for the coast of Tuscany and the northern Tyrrhenian Sea.

Angiosperms are currently abundant and consist mainly of Ruppia cirrhosa and

Nanozostera noltii. The lagoon environment is not yet completely restored,

being potentially eutrophic, but can be managed by prompt albeit onerous

interventions.

112

Flora and Vegetation of the Italian TWS

Key-words: Angiosperms, Cladosiphon zosterae, Corynophlaea flaccida,

Orbetello lagoon, Mediterranean Sea, Seaweeds, Transitional waters, Tuscany,

Tyrrhenian Sea

1 Introduction

The lagoon of Orbetello, situated on the southern Tuscan coast of Italy (42°25’-

42°29’N, 11°10’-11°17’E), has been the subject of many studies. Research on

water physico-chemical properties began in the 1920s (Anselmi 1929).

Descriptive studies of social, technical and economic aspects, from which it is

possible to extract information on submerged vegetation and environmental

conditions, have been carried out since the early 1900s (Del Rosso 1905). The

first exhaustive biological description of this lagoon environment was promoted

by the Tuscan Regional Administration and Orbetello municipality (Cognetti et

al. 1978) in the 1975-76. That study was performed during major lagoon

changes, namely the transition from a typical mesotrophic coastal water body to

a hyper-eutrophic environment because of the summer tourist increase and the

establishment of land-based fish-farms (Lenzi 1992). After 1978, other studies

were carried out dealing with water quality (Lenzi and Angelini 1984, Caprioli et

al. 1988, Cartei et al.1997), human impact (Lenzi 1992), phytoplankton (Tolomio

and Lenzi 1996, Nuccio et al. 2003) and macrophytobenthos (Lenzi 1984,

Naviglio et al. 1988, Lenzi et al. 2003). These studies were sometimes repetitive

because the research was never coordinated or directed at the less studied

aspects of this environment.

2 Description of the site

Orbetello lagoon covers a total area of 25.25 km2 and consists of two

communicating (western and eastern) basins having areas of 15.25 km2 and

10.00 km2, respectively (Fig. 1). The soft silt-clay bottom has an average depth

of 1 m. Three artificial canals, 0.5-2 km long and 10-15 m wide, two in the

western and one in the eastern basin, connect the lagoon with the sea (Fig. 1).

Because they are small shallow canals, water turnover is poor and depends

mainly on wind force and direction, as the Tyrrhenian tide range is narrow. The

fresh water inputs come from both precipitation and the Albegna river estuary

where one of the three canal is located (Fig. 1), however input from the Albegna

is low and mainly autumnal. Thus lagoon salinity ranges from 28 to 45 psu,

depending on evaporation. Owing to the low water renewal, sea water is

pumped into the lagoon to promote water turnover (Fig. 1). The pumping station

was potentiated in 1996 and about 15,000 m3 s

-1 of water is now circulated by

the two western pumping stations through the lagoon and the eastern canal into

the sea in the warm season. This input creates a continuous one-way flow,

ensuring water turnover in the stagnating central areas of the two basins.

Like many other coastal environments, Orbetello Lagoon is subject to

considerable macroalgal proliferation (Bombelli and Lenzi 1996). The

phenomenon is anthropogenic, due to tourism, intensive aquaculture in four

land-based fish-farms (Lenzi 1992) and recently an oyster-farm in the western

lagoon (Fig. 1). Since the 1970s, the water column has suffered hypoxia-anoxia,

113


with low Eh values and a high range of pH due to high primary production and

fast decay of macroalgal biomass. Increasing eutrophication has gradually led

to qualitative and quantitative changes from seagrass to seaweed dominance

with extensive cyclic growth of opportunistic green seaweeds. When these

macroalgae die in spring and summer, they cause massive decomposition

processes in the lagoon (Bombelli and Lenzi 1996). These processes were

reversed by remediation carried out after the long dystrophic crisis of 1992-93

(Lenzi 1998, Lenzi et al. 1998, 2003). However, eutrophication persists and

dystrophic crises are still possible, depending on accumulation of organic matter

in the lagoon sediment. In fact, most of the eutrophic wastewater of the land-

based fish-farms, about 200,000 m3 d

-1, estimated to be equivalent to 265 kg of

nitrogen (N) and 13 kg of phosphorus (P) per day, continue to be discharged

into the lagoon (Lenzi et al. 2003). As a consequence of the restoration

interventions, the primary production is again equally distributed between

seagrasses and seaweeds with occasional phytoplankton contributions. The

water column is now usually clear, except in the period of macroalgal biomass

decay, when it becomes dark with bacteria and Dinophyceae blooms.

As far as dissolved nutrients are concerned, according to Lenzi et al. (2003), the

central lagoon areas showed fairly similar trends, with high inorganic nitrogen

(DIN: 12.0−85.1 µM with ammonium accounting for >80%) and soluble reactive

Fig. 1 – Orbetello lagoon,

contained by two sandy bars,

Italian continent and Mont

Argentario promontory.

114


phosphorus (SRP: 0.1− 0.9 µM) concentrations. The DIN:SRP atomic ratio

widely ranged between 40 and 851 with large differences between the warm

and cold season. In surface sediment the mean total nitrogen and total

phosphorus were 0.13 ± 0.02% and 0.08 ± 0.07 % dw, respectively, in the

eastern basin, and 0.45 ± 0.12% and 0.06 ± 0.05 % dw, respectively, in the

western basin. The mean N:P atomic ratio in the whole lagoon was 26 ± 19

(Lenzi et al. 2003). During a study carried out in 2005 and 2006, sediment

organic matter (evaluated as loss on ignition at 400 °C for 3 hours) ranged

between 8.62% and 14.67% (Lenzi unpublished data).

According to Lenzi et al. (2003), the N:P atomic ratio in macroalgal thalli ranged

between 41 and 123, showing strong P limitation and high N availability.

Differences in nutrient contents of various species were found between eastern

and western basins.

3 Macroalgae

Tab. 1 shows the macroalgal list of the taxa recorded by Cognetti et al. (1978),

Lenzi (1984), Naviglio et al. (1988) and unpublished observations of Lenzi in the

period 1999-2002 and Birardi, Lenzi, Sartoni and Sfriso between 2005 and

2006. Tab. 2 enumerates the species that have recently disappeared. The

macroalgal standing crop (MSC) as well as the percentages of dominant

species from 1983 to 2006 were estimated by the method in Lenzi and Solari

(2007) and varied between 23,000 tonnes wet weight in 1983 (November) for

Gracilariaceae to 77,759 in 2006 (June) for Chaetomorpha linum. The species

composition, biomass and dominance of macroalgal vegetation widely varied

over the years. The total number of taxa was reported to be 35, 41, 40, 37 and

62, by Cognetti et al. (1978), Lenzi (1984), Naviglio et al. (1988) and surveys

carried out in 1999-2002 and 2005-2006, respectively. Recent observations

(1999-2006) indicate a total Rhodophyta/Chlorophyta (R/C) ratio of 1.4,

calculated from all the taxa listed in Tab. 1, according to Sfriso et al. (2005).

This ratio is higher than that calculated for the same lagoon in 2004-2005 based

on four stations (Sfriso et al. 2006). A R/C of ca. 1.7 was recently calculated for

the Venice lagoon (Sfriso et al. 2005, 2006).

As shown in Tab. 1, there were 21 unattached species and 44 epiphytes. The

main associations observed were multi-species unattached communities

dominated by either Chaetomorpha linum or Gracilariaceae. The former was

mostly represented by a dominant facies of Chaetomorpha linum, only recently

coupled with the co-dominance of Valonia aegagropila. This latter disappeared

towards the end of the 1970s, returning only after the environmental restoration

began in 1994. Since 1999, a new population has established near the

Giannella spit (Fig. 1). That species was initially present with low density

between beds of Chaetomorpha linum and Gracilariopsis longissima and in

meadows of Ruppia cirrhosa. Since 2002, V. aegagropila increased to 4-5 kgww

m-2

over about an hectare and is now widespread in the western basin, probably

due to wind transport from the Giannella, since the thalli form floating balls. In

the eastern basin it is still rare, being found mainly near the canal between the

two basins (Fig. 1). In the association dominated by Gracilariaceae,

115


Gracilariopsis longissima and Gracilaria bursa-pastoris are the dominant

species. Alsidium corallinum and Cystoseira barbata can also be found in both

basins, as well as Ulva prolifera which is abundant in summer. These

pleustophytic species form small dense masses disposed in patches among the

Gracilariaceae, especially in summer. Ulva prolifera exhibits very fine filaments

that only in culture increase in lumen size and develop lateral branches. These

species were a major component of the MSC, especially in the western basin.

In the eastern one, an unattached mat consisting of large and densely tangled

thalli developed in an area of 50 ha. It consisted of a floating bed of

Gracilariaceae, 10-15 cm thick, further compacted by a framework of vertical

tubules of the Polychaeta Ficopomatus enigmaticus Fauvel, constituting 20-

30% of the mat weight. Other species found in the drifting mat included

Polysiphonia sertularioides, Polysiphonia denudata, Ceramium spp. and

Spyridia filamentosa. This association was present in the lagoon almost

continuously from the mid 1980s to the mid 1990s. Now it appears sporadically

and tends to disappear in summer and autumn. Finally, the aptophyta

Acetabularia acetabulum grows on shells in June and July. It has been

observed in both basins, mainly inshore, especially in areas devoid of

vegetation and with large deposits of shells.

The Charophyta Lamprothamnion papulosum and the Chlorophyta Caulerpa

prolifera have been the most significant disappearances (Tab. 2). The former is

a pioneer species (Ferrari et al. 1972) that establishes in areas with freshwater

input and sandy bottoms with little organic matter. It was abundant until the

1970s and was last recorded in 1987 in residual areas, failing to survive the

subsequent dystrophic crises. Despite remediation interventions, this species

has not reappeared. On the other hand, Caulerpa prolifera prefers substrates

rich in organic detritus with better water turnover as it occurs in the centre of the

lagoon. It was abundant near the sea canals but has not be recorded in these

areas since 1993.

In the lagoon, dystrophic crises are often associated with macroalgal blooms

and once occurred for two consecutive years. In that occasion, Gracilariaceae

and Chlorophyceae alternated as dominant species in these algal masses. At

present, high biomasses of Gracilariaceae are situated in the central areas of

both basins, relatively far from the remaining anthropogenic nutrient sources.

On the other hand, Chaetomorpha linum is largely found inshore close to

nutrient sources (in and around the oyster farm and near the outlets of urban

treatment plants and intensive fish-farms, Fig. 1), where it may exceed 20 kgww

m-2

. Most of the algal mats degenerated between May and August (21,620

TWW), this period being critical for the lagoon environment. Since the MSC

subsequently decreased, most macroalgal production occurs between March

and May. This cycle is substantially the same from year to year and is

influenced by weather conditions. The percentages of the main species

composing the MSC in 2005 include the Briozoa Ctenostomata Zoobotryon

verticillatum delle Chiaje (2.8 tonnes wet weigth) and the Polychaeta

Phycopomatus enigmaticus Fauvel (7.5 tonnes wet weigth), both often

intimately mixed with the macrophyte biomass and forming an essential part of

116


the associations. The two basins showed different macrophyte and macrofauna

growth. Specifically, P. enigmaticus strongly proliferated in the eastern lagoon in

autumn. With regard to macroalgae, C. linum was dominant in the western

lagoon in spring; Gracilariaceae were always dominant in the east, spreading to

the western lagoon in autumn. In 2005 and 2006, dense floating mats of Ulva

spp. (>10 kgww m-2

) developed again close to the fish-farms and the town of

Orbetello. These taxa reached high percentages with respect to total biomass,

especially in the eastern lagoon.

Under conditions of low water turnover, the dominant species was

Chaetomorpha linum sometimes together with Valonia aegagropila. When

environmental conditions deteriorated this association, it was replaced by the

Ulvaceae and by Cladophora spp.

The variability of populations of opportunistic macroalgae heavily depends on

nutrient availability, their chemical species and the DIN:SRP atomic ratio.

Settling of organic matter from macrophyte decomposition onto surface

sediments causes high fluxes of orthophosphates because of Eh lowering

(Fenchel and Riedl 1970). This favours opportunistic phosphorus-hungry

Chlorophyceae, such as Chaetomorpha linum (Lavery and McComb 1991) and

many species of the genus Cladophora (Lapointe and O’Connell 1989, Planas

et al. 1996). On the other hand, oxidized sediments with relatively high Eh lead

to retention of orthophosphate linked to ferric hydroxides (Golterman 1995),

carbonate detritus and clays (Dodge et al. 1984, De Jonge and Villerius 1989).

Under these conditions P-limitation is established favouring species that tolerate

reduced availability of P, such as Gracilariaceae.

The soft silt-clay bottoms of both basins, with an average depth of about 1 m,

are clearly unfavourable for the development of diversified macrobenthic

vegetation. From a structural point of view, the algal communities found in

Orbetello lagoon are largely dominated by pleustophytic species. Nevertheless,

the flora check-list includes several epiphytic species, mainly seagrass

epiphytes. Most are common species, widespread along the neighbouring

shores, but from a floristic point of view two recent findings are noteworthy:

Cladosiphon zosterae and Corynophlaea flaccida. These two Chordariales,

previously only recorded along the coasts of Sardinia (Cossu et al. 1992), are

new reports for the coasts of Tuscany and the northern Tyrrhenian Sea.

4 Angiosperms

The taxa recorded in Orbetello lagoon are listed in Tab. 1. Their distribution

varied in relation to environmental crises and remediation. Nanozostera noltii

and Ruppia cirrhosa were recently the most abundant species, and were often

found together forming dense meadows in the eastern and western lagoons.

Bottoms in the central parts of the basins were less colonized by angiosperms,

mainly R. cirrhosa distributed in small isolated patches. Settlements of C.

nodosa were recently observed only in the western lagoon in areas with sandy

bottoms along the Giannella and Argentario, near the Nassa canal (Fig. 1).

Inflorescences of C. nodosa were never observed, whereas the other two

117


species bloomed between June and July, bearing fruit in August-September. In

the past, angiosperm communities were situated far from urban centres, and

the continuous decrease of meadows in the 1970s and 1980s led to their

marginalization along the sandy stretches of the Giannella and Feniglia (Fig. 1).

As reported in Bombelli and Lenzi (1996) seagrasses almost disappeared in the

early 1990s, reappearing after remediation, first in small clusters and then over

larger areas. Since July 2000, they have covered more than 50% of the lagoon

soft bottoms. Unlike in the past, angiosperm soft bottom coverage now includes

the area close to Orbetello. That colonisation by angiosperm probably due to

the complete elimination of urban wastewater from this part of the lagoon, as

angiosperm remains distant from the new drain water outlets. The angiosperm

standing crops estimated between May 1999 and February 2000 showed the

highest values in August and consisted largely of fruit-bearing stems. Estimates

of standing crops in July-August 1998-2005 showed a fast increase up to 2002,

when populations were colonising the bottoms. The colonisation was followed

by an initial meadow retreat and then by stable conditions since the last anoxia

recorded, particularly in the eastern lagoon.

Conclusions

The increase in species observed in 2005-2006 probably reflects a real

increase in species number due to an overall improvement in environmental

conditions since 1996-1997, and not only the more precise identification of the

species themselves. Besides, previous studies were ecological rather than

strictly botanical, as shown by the absence of certain information, such as data

on reproductive phenology.

Improved conditions led to the reappearance of angiosperm which occupied

60% of the lagoon substrate in 2001, and consequently an increase in

biodiversity and recolonisation by epiphytes. The lagoon is still potentially

eutrophic due to deposition of nutrients in the sediment layers. Indeed, floating

macroalgal mats can still develop when environmental conditions enable

release of these nutrients. Fluctuations in nutrient availability and

weather/climate influence the dynamics of populations, which may vary widely

in both quantity and quality from one year to another, broadly alternating

between dominant associations of Chlorophyta and Gracilariaceae.

Management of the lagoon environment by pumped water turnover and

harvesting of algae is made particularly onerous by the logistic problems, high

costs of transporting algae to storage sites and their subsequent treatment and

disposal in landfills. Two aspects need specific attention, namely the possible

industrial use of this material (hitherto impracticable) and management aimed at

reducing macroalgal development, for example by artificial limitation of nutrient

availability (Lenzi et al. 2005). For the latter aspect, it will be necessary to obtain

more detailed knowledge of dominant species and local strains, as well as their

nutrient requirements.

118


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Tab. 1 - List of macrophytobenthos taxa recorded in the Orbetello lagoon. (*)

taxa reported in previous papers with other name and/or other Authorities. m=

male gametophyte; f= female gametophyte; s= sporophyte; p= propagules; a= attached; u=

unattached; e= epiphyte .

Taxa

Rep

rod

uc

tive

ph

en

olo

gy

Sett

lem

en

t sta

tus

References

m f s p e a u

RHODOPHYTA

Alsidium corallinum C. Agardh + 15, 23, Lenzi pers. obs., Birardi et al. pers. obs.

Antithamnion piliferum Cormaci et G. Furnari

+ Birardi et al. pers. obs.

Audouinella sp. + 15*, Birardi et al. pers. obs.

Bangia fuscopurpurea (Dillwyn) Lyngbye

+ 5*

Callithamnion sp. + 15, Birardi et al. pers. obs.

Ceramium codii (H. Richards) Feldmann-Mazoyer

+ 15, 23, Lenzi pers. obs., Birardi et al. pers. obs.

Ceramium gaditanum (Clemente) Cremades

+ + Birardi et al. pers. obs.

Ceramium siliquosum (Kützing) Maggs et Hommersand


Ceramium virgatum Roth + 15, Lenzi pers. obs., Birardi et al. pers. obs.

Ceramium sp. + 23

Chondria pygmaea Garbary et Vandermeulen


Chondria sp. + Lenzi pers. obs., Birardi et al. pers. obs.

Chroodactylon ornatum (C. Agardh) Basson

+ 5*

Crouania attenuata (C. Agardh) J. Agardh


Dasya corymbifera J. Agardh + Birardi et al. pers. obs.

Erythrotrichia carnea (Dillwyn) J. Agardh

+ Lenzi pers. obs., Birardi et al. pers. obs.

Gayliella mazoyerae T.O. Cho, Fredericq et Hommersand

+ Birardi et al. pers. obs. as Ceramium flaccidum (Kütz.) Ardissone

Gracilaria bursa-pastoris (S.G. Gmelin) P.C. Silva


Gracilariopsis longissima (S.G. Gmelin) Steentoft, L.M. Irvine et Farnham

+ + 5*, 15

*, 23

*, Lenzi pers. obs., Birardi

et al. pers. obs.

Herposiphonia secunda (C. Agardh) Ambronn


Hydrolithon boreale (Foslie) Y.M. Chamberlain


121


Taxa

Rep

rod

uc

tive

ph

en

olo

gy

Sett

lem

en

t sta

tus

References

m f s p e a u

Hydrolithon farinosum (J.V. Lamouroux) Penrose et Y.M. Chamberlain

+ 5*

Jania adhaerens J.V. Lamouroux + Birardi et al. pers. obs.

Pneophyllum fragile Kützing + 5*

Polysiphonia breviarticulata (C. Agardh) Zanardini


Polysiphonia denudata (Dillwyn) Greville ex Harvey

+ + + 23*, Lenzi pers. obs.,Birardi et al.

pers. obs.

Polysiphonia scopulorum Harvey + Birardi et al. pers. obs.

Polysiphonia sertularioides (Grateloup) J. Agardh


Polysiphonia stricta (Dillwyn) Greville

+ 15*, Lenzi pers. obs.

Polysiphonia subulifera (C. Agardh) Harvey


Seirospora sphaerospora Feldmann


Spyridia filamentosa (Wulfen) Harvey

+ + 5, 15, 23, Lenzi pers. obs., Birardi et al. pers. obs.

Stylonema alsidii (Zanardini) K.M. Howe

+ 15*, 23

*, Lenzi pers. obs., Birardi et

al. pers. obs.

Wrangelia penicillata (C. Agardh) C. Agardh


TOTAL RHODOPHYTA=34

OCHROPHYTA

Acinetospora crinita (Carmichael) Sauvageau


Cladosiphon zosterae (J. Agardh) Kylin


Corynophlaea flaccida (C. Agardh) Kützing


Cystoseira barbata (Stackhouse) C. Agardh

+ + 15, 23, Lenzi pers. obs., Birardi et al. pers. obs.

Cystoseira barbata (Stackhouse) C. Agardh f. repens Zinova et Kalugina

+ 5*, 15, 23, Lenzi pers. obs., Birardi et

al. pers. obs.

Dictyota dichotoma (Hudson) J.V. Lamouroux v. dichotoma


Dictyota dichotoma (Hudson) J.V. Lamouroux v. intricata (C. Agardh) Greville

+ + Lenzi pers. obs., Birardi et al. pers. obs.

Dictyota spiralis Montagne + + 15*, 23

*, Lenzi pers. obs., Birardi et

al. pers. obs.

Ectocarpus siliculosus (Dillwyn) Lyngbye


122


Taxa

Rep

rod

uc

tive

ph

en

olo

gy

Sett

lem

en

t sta

tus

References

m f s p e a u

Padina pavonica (Linnaeus) J.V. Lamouroux


Petalonia fascia (O.F. Müller) Kuntze


Scytosiphon lomentaria (Lyngbye) Link

+ + + 15, Lenzi pers. obs., Birardi et al. pers. obs.

Stictyosiphon adriaticus Kützing + + + 15, 23, Lenzi pers. obs., Birardi et al. pers. obs.

TOTAL OCHROPHYTA=13

CHLOROPHYTA

Acetabularia acetabulum (Linnaeus) P.C. Silva

+ 5, 15, 23, Lenzi pers. obs., Birardi et al. pers. obs.

Anadyomene stellata (Wulfen) C. Agardh


Blidingia minima (Nägeli ex Kützing) Kylin


Bryopsis plumosa (Hudson) C. Agardh

+ + + 15, 23, Lenzi pers. obs., Birardi et al. pers. obs.

Bryopsis sp. + 15, 23, Lenzi pers. obs., Birardi et al. pers. obs.

Chaetomorpha linum (O.F. Müller) Kützing


Cladophora prolifera (Roth) Kützing

+ 5, Lenzi pers. obs., Birardi et al. pers. obs.

Cladophora rupestris (Linnaeus) Kützing

+ + Lenzi pers. obs.

Cladophora vadorum (Areschoug) Kützing

+ + + Birardi et al. pers. obs.

Cladophora vagabunda (Linnaeus) C. Hoek

+ + + 5, 15, 23, Lenzi pers. obs., Birardi et al. pers. obs.

Rhizoclonium tortuosum (Dillwyn) Kützing

+ 23*, Lenzi pers. obs., Birardi et al.

pers. obs.

Ulothrix flacca (Dillwyn) Thuret + + 5*, 23, Lenzi pers. obs., Birardi et al.

pers. obs.

Ulothrix implexa (Kützing) Kützing + + Birardi et al. pers. obs.

Ulva compressa Linnaeus + + 5*, 15

*, 23

*, Lenzi pers. obs.

Ulva curvata (Kützing) De Toni + Birardi et al. pers. obs.

Ulva intestinalis Linnaeus + + 5*, 15

*, 23


et al. pers. obs.

Ulva laetevirens Areschoug + + 5*, 15

*, 23


et al. pers. obs.

Ulva prolifera O.F. Müller + + 5*, Lenzi pers. obs., Birardi et al.

pers. obs.

Ulva rotundata Bliding + Birardi et al. pers. obs.

123


Taxa

Rep

rod

uc

tive

ph

en

olo

gy

Sett

lem

en

t sta

tus

References

m f s p e a u

Ulvella lens P. et H. Crouan + 5, 15, Lenzi pers. obs., Birardi et al. pers. obs.

Valonia aegagropila C. Agardh + 5, 23, Lenzi pers. obs., Birardi et al. pers. obs.

TOTAL CHLOROPHYTA=21

CHRYSOPHYTA

Nematochrysopsis marina (J. Feldmann) C. Billard


TOTAL CHRYSOPHYTA=1

TOTAL SPECIES=69

ANGIOSPERMAE fruits flowers

Cymodocea nodosa (Ucria) Ascherson


Nanozostera noltii (Hornemann) Tomlinson & Posluzny


Ruppia cirrhosa (Petagna) Grande + + 5, 15, 23, Lenzi pers. obs., Birardi et al. pers. obs.

TOTAL ANGIOSPERMAE=3

Tab. 2 - List of disappeared seaweed species in the Orbetello lagoon (*) taxa

reported in previous papers with other name and/or others Authorities.

e=epiphyte, a=attached, u=unattached, i=invasive, ni=non-invasive.

Taxa

Sett

lem

en

t sta

tus

References

e a u

RHODOPHYTA

Anotrichium furcellatum (J. Agardh) Baldock

+ 5

Ceramium deslongchampsii Chauvin ex Duby

+ 5

Chondria capillaris (Hudson) M.J. Wynne + 5

Chondria dasyphylla (Woodward) C. Agardh

+ 5

Chylocladia sp. + + 15, 23

Halopithys incurva (Hudson) Batters + 15

Heterosiphonia crispella (C. Agardh) Wynne

+ 5

Laurencia obtusa (Hudson) J.V. Lamouroux + + 15, 23

124


Taxa

Sett

lem

en

t sta

tus

References

e a u

Palisada papillosa (C. Agardh) K.W. Nam + 5*, 15* as Chondrophycus papillosus

Polysiphonia pulvinata (Roth) Sprengel [T.i.]

+ + 15, 23

Polysiphonia sanguinea (C. Agardh) Zanardini

+ 15, 23

Polysiphonia subulata (Ducluzeau) P. et H. Crouan

+ + 5

Porphyra sp. + 23

Pterocladiella capillacea (S.G. Gmelin) Santelices et Hommersand

+ 15

TOTAL RHODOPHYTA=14

OCHROPHYTA

Arthrocladia villosa (Hudson) Duby + + 15

Cystoseira compressa (Esper) Gerloff et Nizamuddin

+ 15*

Feldmannia paradoxa (Montagne) Hamel + 23*

Stilophora tenella (Esper) Silva + 23*

TOTAL OCHROPHYTA=4

CHLOROPHYTA

Acrochaete geniculata (N.L. Gardner) O’Kelly

+ 5

Blastophysa rhyzopus Reinke + 5

Bryopsis pennata J.V. Lamouroux + 5

Caulerpa prolifera (Forsskål) J.V. Lamouroux

+ 15, 23

Chaetosiphon moniliformis Huber + 5

Cladophora battersii C. Hoek + + 5

Cladophora fracta (O.F. Müller ex Vahl) Kützing

+ 5

Cladophora laetevirens (Dillwyn) Kützing + 23

Cladophora liniformis Kützing + + 5

Cladophora socialis Kützing + 5

Entocladia viridis Reinke + 5

Lamprothamnion papulosum (Wallroth) J. Groves

+ 5, 15, 23

Ochlochaete hystrix Thwaites + 5

Ulva linza Linnaeus + + 23*

TOTAL CHLOROPHYTA=14

TOTAL SPECIES=32

the lagoon of orbetello

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