Biological Components of Greek Lagoonal Ecosystems: an Overview

Mediterranean Marine Science Volume 6/2, 2005, 31-50

Biological components of Greek lagoonal ecosystems: an overview

A. Nicοlaidou1, S. Reizopoulou.2, D. Koutsoubas3, S. Orfanidis4 and T. Kevrekidis5

1 University of Athens, Department of Zoology-Marine Biology, Panepistimiopolis, 15784 Athens, Greece

2 Hellenic Centre for Marine Research, Institute of Oceanography, P.O.Box 712, 190 13 Anavissos, Greece

3 University of the Aegean, Department of Marine Science, University Hill, 81100 Mytilini, Greece

4Fisheries Research Institute of Kavala, Nea Peramos, 64007 Kavala, Greece

5 Democritus University of Thrace, Department of Education-Primary level, 68100 Alexandroupoli, Greece e-mail: [email protected]

Abstract

The paper summarises the available information on the main biological components – phytoplankton, zooplankton, phytobenthos, zoobenthos and fish – of Greek lagoonal ecosystems. Meiobenthos was also studied in one of the lagoons. All components show great variability both in space and time, which is attributed to the variability of environmental conditions. The most important variable influencing species distribution and diversity is the degree of communication with the sea and the nutrient load introduced through fresh water inputs. Certain new methods, which have been applied for evaluation of the ecological quality state of the lagoons, are also presented.

Keywords: Lagoons; Benthos; Plankton; Fish; Pollution; Mediterranean.

Introduction openings allowing limited water exchange with Coastal lagoons are transitional areas between the sea. Due to their formation, they are shallow land and sea, formed, in most cases, in river del- areas, sheltered from strong waves and currents, tas (ZALIDIS & MANTZAVELAS, 1994). They with muddy or sandy bottoms often covered by are enclosed water bodies separated from the sea macrophytes. Since there are no significant tides, by depositional barriers with one or more narrow the water circulation in the lagoons is mostly con-

Medit. Mar. Sci, 6/2, 2005, 31-50 31 Fig. 1: Map of Greece showing main transitional coastal ecosystems (estuaries and lagoons). Dark symbols indicate ecosystems for which detailed information exists and are treated in this paper. 1: Kalamas Est. 13: Aitoliko Lag. (●) 25: Aliakmonas Est. 37: Karatza Lag. 2: Acherontas Est. 14: Messolonghi Lag. (●) 26: Axios Est. 38: Alyki Lag. 3: Mazoma Lag. (●) 15: Kleisova Lag. (●) 27: Gallikos Est. 39: Ptelea Lag. 4: Tsopeli Lag. (●) 16: Evinos Est. 28: Epanomi Lag. 40: Elos Lag. 5: Louros Est. 17: Papas Lag. (●) 29: Strymonas Est. 41: Laki Lag. (●) 6: Rodia Lag. (●) 18: Kotychi Lag. 30: Vassova Lag. (●) 42: Drana Lag. (●) 7: Arachthos Est. 19: Gialova Lag. (●) 31: Erateino Lag. (●) 43: Monolimni Lag. (●) 8: Logarou Lag. (●) 20: Evrotas Est. 32: Agiasma Lag. (●) 44: Evros Est. (▲) 9: Tsoukalio Lag. (●) 21: Vivari Lag. (●) 33: Keramoti Lag. (●) 45: Alyki Kallonis Lag. 10: Stenou Lefkadas Lag. 22: Vouliagmeni Lag. 34: Nestos Est. 46: Vouvaris Est. 11: Koutavos Lag. 23: Spercheios Est. 35: Porto Lagos Lag. 47: Alyki Polychnitou Lag. 12: Acheloos Est. 24: Pineios Est. 36: Fanari or Xsirolimi Lag. (●) trolled by meteorological conditions, especially cated in Western and Northern Greece (Fig. 1). intensity and direction of the wind. The most important are protected under the The most extensive lagoonal systems are lo- Ramsar convention or are part of the Natura

32 Medit. Mar. Sci, 6/2, 2005, 31-50 communication with the sea is greater, as 2000 network (Table 1). Almost all are used for in Logarou, the prevalent species are dia- the extensive culture of fish. The Greek lagoons toms, such as Rhizosolenia fragilissima and are not all equally explored scientifically. More Nitzchia closterium and the dinoflagellates attention has been paid to the lagoons of Am- Scrippsiella trochoidea and Procentrum vrakikos Bay (NICOLAIDOU & KARLOU, scutellum (CHRISTAKI & GOTSIS-SKRE- 1983; NICOLAIDOU et al. 1985; NICOLAID- TAS, 1990). In semi-enclosed lagoons, such OU & KARAKIRI, 1989, REIZOPOULOU et as Gialova (DOUNAS & KOUTSOUBAS, al. 1998; CHRISTAKI & GOTSIS-SKRETAS, 1996) the diatoms are rather few, restricted 1990; KORMAS et al. 2001, REIZOPOULOU to the marine channels, while dinoflagellates & NICOLAIDOU, 2004, NICOLAIDOU et (Oxyrrhis marina, Goiniodoma sphaericum, al. 2006) while the most comprehensive study Peridinium depressum and Gymnodinium was carried out in Gialova, on the Southwest heterostriatum) are quite well represented es- Peloponnese (ARVANITIDIS et al. 1999; pecially in the innermost part of the lagoon. PETIHAKIS et al. 1999; KOUTSOUBAS et The abundance of phytoplankton varies al. 2000a,b; McARTHUR et al. 2000, TRIAN- not only between lagoons and seasons but TAFYLLOU et al. 2000) (Table 2). Different also between stations in the same lagoon. aspects of the numerous eastern Macedonian Maximum concentrations are observed at and Thrace lagoons, such as phytobenthos (OR- the end of winter, beginning of spring. To- FANIDIS et al., 2000, 2001a,b; MALEA et al., tal phytoplankton abundance usually ranges between 3x104 to 2x106cells/l but concen- 2003, 2004), zoobenthos (KEVREKIDIS, 1997, 7 2004a; GOUVIS & KOUKOURAS, 1993, trations of up to 4.4x10 cells/l, belonging mostly to nannoplankton, have been report- GOUVIS et al, 1997) and fishes (KOUTRAKIS ed under slightly polluted conditions. Such & TSIKLIRAS, 2003) were also explored. blooms tend to be monospecific and local- This paper gives an account of the availa- ised (GOTSIS-SKRETAS & SATSMADJIS, ble information on the main biological com- 1989/90). ponents of Greek lagoonal ecosystems in an Qualitative and quantitative variability in effort to highlight the distribution of species lagoonal phytoplankton is attributed to vari- and their variability in space and time. Cer- ability of environmental conditions, such as tain new methods which have been applied salinity and nutrient concentrations, which for evaluation of the ecological quality state are related to freshwater inputs and mix- of the lagoons are also presented. A summa- ing with seawater (GOTSIS-SKRETAS & ry can also be found in SoHelME (2005). SATSMADJIS, 1989/90). Phytoplankton Zooplankton In terms of species composition, phy- Spatial and temporal variability, both in toplankton in lagoons is poorer than neritic terms of numbers of species and individuals, phytoplankton. It is frequently enriched by is also observed in the zooplankton commu- benthic diatoms, which, due to the small nity. In the mesozooplankton, density ranges depth of the lagoons, are put to suspension from few individuals per m3 to approximate- by the wind. In addition, neritic species ly 4500 indiv./m3 (SIOKOU-FRANGOU, enter passively from the sea and remain in 1986). Copepods are the dominant group. the lagoon for a period of time. Thus, in the In the inner parts of lagoons the zooplank- most enclosed lagoons, for example in Ro- ton consists of brackish water species, such dia of Amvrakikos, cryptophytes, such as as Calanipeda aquaedulcis, accompanied, or Rhodomonas sp. and Cryptomonas sp, are replaced depending on the season, by eury- the most abundant genera, while, where

Medit. Mar. Sci, 6/2, 2005, 31-50 33 - -

sopeli, D ** ** *** *** F, AE F, 0.2 - 0.4 - 0.2 1.3 - 0.4 4.0 - 25.0 - 4.0 12.6 - 24.5 - 12.6 147 - 208* - 147 RAMSAR Evros Delta Evros Evros Delta Evros T =

* F F 1.9 - E = D rainage) RAMSAR 0.2 - 3.0 - 0.2 6.1 - 3.2 2.0 - 31.5 - 2.0 15.2 - 4.3 19.3 - 34.2 - 19.3

* ** Ke 1,0 F, AE F, RAMSAR - Va 0.2 - 4.0 - 0.2 7.8 - 2.2

* 2.0 - 31.5 - 2.0 22.0 - 4.2 ** 26.1 - 34.6 - 26.1 Ag 3.9 F, AE F, Eastern Macedonia & Thrace & Macedonia Eastern RAMSAR

* E ** G 3,0 F, AE F, 14 - 31 - 14 4.5 - 9.1 - 4.5 5.0 - 0.2 Eastern Macedonia & Thrace & Macedonia Eastern 0.3 - 1.2 - 0.3 RAMSAR 13.0 - 60.0 - 13.0 94.7 - 14.5 Ionian Sea Ionian

* ** Va 0.8 F, AE F, P RAMSAR RAMSAR 0.2 - 1.5 - 0.2 9.3 - 1.2 5.6 - 2.9 20.0 - 42.5 - 20.0 32.0 - 10.0 98.0 - 23.0 * * G ** 2.5 DC *** *** F, AE F, NATURA Ionian Sea Ionian A 2.4 ulf G 4.5 - 7.3 - 4.5 9.1 - 11.1 - 9.1 0.3 - 30.0 - 0.3 18.5 - 23.5 - 18.5 25.3 - 15.5

3 * P ** DC *** *** F, AE F, NATURA atraikos atraikos ., 2006; Patraikos Gulf: BOGDANOS & DIAPOULIS 1984; Ionian Sea: KOUTSOU ulf P Me G soukalio, Va=Vassova). soukalio, 4.2 - 7.9 - 4.2 5.1 - 0.9 et al 0.20 - 2.0 - 0.20 76.8 - 2.0 37.0 - 45.0 - 37.0 27.9 - 24.5

* A s= T 26 ** DC *** *** F, AE F, Table 2 Table T Table 1 Table RAMSAR atraikos atraikos P K

* sopeli, 0.2 - 2.0 - 0.2 6.7 - 5.0 3.6 - 1.6 ** Me 100 *** *** 23.0 - 41.0 - 23.0 21.6 - 20.5 35.6 - 19.9 F, AE F, RAMSAR T = L

L ** *** *** 25.7 0.7 - 1.0 - 0.7 3.5 - 2.2 9.1 - 28.1 - 9.1 12.1 - 4.5 32.0 - 6.4 15.8 - 48.6 - 15.8 RAMSAR F, AE, ASI AE, F, reek lagoons. characteristics of G reek E nvironmental R=Rodia, C haracteristics of lagoons and parameters studied.

R ** ** *** *** R 13.5 ulf 2.9 - 5.2 5.2 - 2.9 5.0 - 1.2 RAMSAR F, AE, ASI AE, F, 5.0 - 35.0 - 5.0 29.1 - 8.9 10.8 - 3.5 G 12.0 - 77.5 - 12.0 ulf G

(Sampling frequency: * =occasional, ** =seasonal, *** =seasonal, more than one year) * =occasional, ** =seasonal, *** more (Sampling frequency: Ts ** ., 1997; KEVREKIDIS, 2004a; MOGIAS & 2005; MOGIAS 2005. *** *** 16.5 Ts RAMSAR F, AE, ASI AE, F, et al. 1.6 - 5.2 - 1.6 5.1 - 1.3 8.6 - 30.0 - 8.6 10.6 - 4.6 79.0 - 8.3 14.0 - 36.5 - 14.0 Amvrakikos Amvrakikos Amvrakikos Amvrakikos

1 T ** *** *** RAMSAR ogarou, Ma= Mazoma, Me=Messolonghi, P = apas, Ma= Mazoma, Me=Messolonghi, (A=Aetoliko, E = ratino, G ialova, K=Klissova, L ogarou, F, AE, ASI AE, F, T 2.8 - 9.8 - 2.8 5.3 - 1.1 0.2 - 1.5 - 0.2 8.0 - 29.0 - 8.0 66.3 - 6.7 21.0 - 38.0 - 21.0

* * * 1.6 Ma AE, F AE, RAMSAR - - Ma ystrophic crisis, D DC = D ystrophic I =Semi-intensive aquaculture, AS A E = xtensive aquaculture, ( F = isheries, Va=Vassova). soukalio, 1.0 - 2.0 - 1.0 6.8 - 4.8 9.0 - 13.0 - 9.0 oo- 23.0 - 27.0 - 23.0 NS hyto- Z lankton P Abiotic s= T benthos benthos P Fishfauna

l., 2000b, Evros Delta: GOUVIS

GOO

arameters studied arameters A P C) Size (km) Size o uman impact impact uman L Exploitation et a Conservation H agoons T ( T S (psu) S L Org. C % C Org. Coarse % Coarse O2 (mg/l) O2 Depth (m) Depth ogarou, Ma= Mazoma, Me=Messolonghi, P = apas, R=Rodia, Ma= Mazoma, Me=Messolonghi, L = ogarou, Ag=Agiasma, E = ratino, F anari, G ialova, Ke=Keramoti, (A=Aetoliko, * =Median diameter (φ) Amvrakikos Gulf: REIZOPOULOU & NICOLAIDOU, 2004; NICOLAIDOU Basic sources: BAS

34 Medit. Mar. Sci, 6/2, 2005, 31-50 haline species such as Acartia latisetosa, A. of which the most abundant is G. bursa-pas- clausi and Centropages kroyeri and inverte- toris. Other abundant Rodophyceae are Chon- brate larvae of barnacles, molluscs, decapods dria tenuissima and Polysiphonia elongata. and polychaetes. In the outer parts euryha- During summer and autumn the species of line species including Acartia latisetosa, A. tropical affinity Hypnea musciformis and clausi, A. discaudata and Oithona nana are Acanthophora najadiformis are recorded. dominant. These copepods are often accom- Characteristic Chlorophyceae are species of panied by meroplanktonic larvae and ben- the genera Ulva, Chaetomorpha and Clado- thic amphipods. Close to the sea, typically phora. The most characteristic of Phaeophyc- marine species, such as Temora stylifera, eae is the species Cystoseira barbata. Oithona plumifera, Paracalanus parvus and The Charophyceae, regarded as a class Clausocalanus furcatus enter the lagoons of the Chlorophyta, despite their highly dis- with currents. tinctive thallus and reproductive organs, are Micro-zooplankton in coastal lagoons is represented by the genus Lamprothamnion represented mostly by ciliates such as Strom- recorded in the Amvrakikos Gulf. bidium spp., Lohmaniella oviformis and The diversity varies seasonally and is Tintinopsis spp. Densities vary considerably higher during summer and autumn due to and range from 0.1 to 50 X 106 indiv./m3, the growth of tropical affinity species in the depending on the prevailing environmental Vassova lagoon, Nestos Delta (ORFANIDIS conditions, season and distance from the et al., 2001b). By contrast, biomass values point of communication with the sea (DOU- are higher during winter (max. dry biomass NAS & KOUTSOUBAS, 1996). 1276 g/m2) possibly due to higher loads of nutrients during this period. Phytobenthos Angiosperms Benthic vegetation in lagoons consists The angiosperms, annual or perennial of a small number of species and associa- rooted flowering plants, recorded in Greek tions. The dominant phytobenthic species transitional waters, belong mainly to the are shown in Table 3. The following five genera Ruppia, Zostera, Cymodocea and associations (sensu the “Zürich-Montpellier Zannichellia (Table 3). School”) are considered most important: Ruppia is a cosmopolitan genus, charac- 1. Association with Ruppia cirrhosa and/or teristic of many coastal brackish waters and Ruppia maritima inland salt-water habitats. Its tolerance to sa- 2. Association with Zostera noltii linity fluctuations (total range ca. 3 to 101psu) 3. Association with Cymodocea nodosa is enormous (VERHOEVEN, 1979). Two 4. Association with Cystoseira barbata, different species of Ruppia were recorded in Gracilaria spp., Cladophora spp. and the Greek lagoons: R. cirrhosa and R. mariti- Ulva spp. ma. They form dense submerged meadows in 5. Association with Lamprothamnion papu- many lagoons, especially in Macedonia and losum Thrace. The growth of R. maritima meadows 6. Association with Zannichellia palustris in Evros Delta is regulated by temperature, being maximum during the warm period of Seaweeds the year (MALEA et al., 2004). The four main classes of seaweeds (15 Zostera noltii is the only species of this Chlorophyceae, 1 Charophyceae, 4 Phaeo- genus inhabiting Greek lagoons. It has a rela- phyceae, 24 Rodophyceae) are recorded in the tively restricted distribution, found mainly in Greek lagoons (Table 3). Characteristic Rodo- the lagoons of the Amvrakikos Gulf. phyceae are species of the genus Gracilaria, Cymodocea nodosa is a characteristic

Medit. Mar. Sci, 6/2, 2005, 31-50 35

D (Continued) * * * * * * * Mo Evros Delta Evros * * * * * * * * * * * * * * * L a * F

* Ke * * * Ag * * * * * E Eastern Macedonia & Thrace Eastern Macedonia & * * * * * * * * * Va * P

A soukalio, Va=Vassova). soukalio, P atraikos G ulf * * * * * Me aki, Ma= Mazoma, Me=Messolonghi, Mo=Monolimni, Mo=Monolimni, Mazoma, Me=Messolonghi, L a= aki, Ma= = L ogarou, s= T T

* L Table 3 Table sopeli,

R T =

T Amvrakikos G ulf

Ma resence of common benthic macrophytes at each lagoon. of common benthic macrophytes P resence P = apas, R=Rodia, * dominant species, (absence of a mark does not indicate absence the sp ecies) (C. Agardh) Wynne Agardh) (C. L agoons (Delile) Papenfuss (Gmelin) Silva Reinsch (Dillwyn) Kjellman (Lightfoot) Roth (Kόtzing) J. Agardh (Kόtzing) J. (Dillwyn) J. Agardh (Dillwyn) J. (Hudson) Papenfuss (Goodenough &Woodward) C. Agardh C. (Goodenough &Woodward) (Kόtzing) Ardissone (Kόtzing) (Woodward) C. Agardh C. (Woodward) (Wulfen) Lamouroux (Wulfen) C. Agardh C. (Hudson) C. Agardh (Hudson) C. (C. Agardh) J. Agardh Agardh) J. (C. (Stackhouse) Le Jolis (Hudson) Lamouroux (Zanardini) Drew sp. sp. spp. sp. sp. sp. (A=Aetoliko, Ag=Agiasma, D = rana, E ratino, F anari, Ke=Keramoti, L (A=Aetoliko, Species Cystoseira barbata Ectocarpus silicolosus Ectocarpus Feldmania Rhodophyceae Acanthophora najadiformis Ceramium flaccidum Ceramium rubrum Ceramium circinatum Ceramium diaphanum Ceramium Stylonema alsidii Stylonema cornu-cevri Gelidium pusillum Bangia carnea Erithrotrichia Chondria tenuissima Chondria dasiphylla Gracilaria armata Gracilaria bursa-pastoris Gracilaria verrucosa Herposiphonia secunda f. tenella Nitophyllum Hypnea musciformis obtusa Laurencia Laurencia P haeophyceae

36 Medit. Mar. Sci, 6/2, 2005, 31-50 * * D , 2003; et al. * * * * * * * * * * * * Mo Evros Delta Evros * * * * * * * * * * * ogarou, L a= aki, = L ogarou, L a * * * * F * * * * * * * Ke * * * * * * Ag soukalio, Va=Vassova). soukalio, * * E s= T T Eastern Macedonia & Thrace Eastern Macedonia & * * * * * * * * Va sopeli, * * P T = * * * * A

P atraikos G ulf * * * * Me * * * * * * * * L ., 2002), Partaikos Gulf (BOGDANOS & DIAPOULIS, 1984), Evros Delta (MALEA ., 2002), Partaikos Gulf (BOGDANOS & DIAPOULIS, 1984), Evros Delta (MALEA * * * R able 3 (continued) et al T * * * Ts * * T Amvrakikos G ulf * Ma ., 2001) et al * dominant species, (absence of a mark does not indicate absence the sp ecies) (Kόtzing) Kόtzing L agoons Ma= Mazoma, Me=Messolonghi, Mo=Monolimni, P = apas, R=Rodia, (Linnaeus) Greville ., 2003). Basic sources: Amvrakikos Gulf (LAZARIDOU ., 2003). Basic sources: (Linnaeus) Silva (O.F. Mόller) J. Agardh Mόller) J. (O.F. (Wulfen ex Roth) J. Agardh ex Roth) J. (Wulfen (Hudson) Sprengel Kόtzing Linnaeus (Roth) Kόtzing (O.F. Mόller) Kόtzing (O.F. (Linnaeus) Kόtzing (Dillwyn) Kόtzing et al (Linnaeus) J. Agardh (Linnaeus) J. (Ucria) Aschers (Ucria) sp. Linnaeus (Petagna) Grande spp. spp. sp. Hornem sp. spp. spp. Species Lophosiphonia Polysiphonia elongata Polysiphonia Chlorophyceae Acetabularia acetabulum Chaetomorpha aerea Chaetomorpha mediterranea Chaetomorpha linum Chaetomorpha Cladophora liniformis rupestris Clarophora Cladophora prolifera Cladophora flexuosa Enteromorpha compressa Enteromorpha prolifera Enteromorpha linza Enteromorpha Enteromorpha Ulva Charophyceae Lamprothamnion Cymodocea nodosa Ruppia cirrhosa Ruppia maritima Zostera noltii Zannichellia palustris P otamogetonales anari, Ke=Keramoti, L Ag=Agiasma, D = rana, E ratino, F anari, Ke=Keramoti, at each lagoon. (A=Aetoliko, of common benthic macrophytes P resence *(see also HAYDEN *(see also HAYDEN Thrace ORFANIDIS 2004), Eastern Macedonia &

Medit. Mar. Sci, 6/2, 2005, 31-50 37 angiosperm of several Greek coasts form- MOGIAS & KEVREKIDIS, 2005). The ing extensive meadows from the sea surface most abundant species in each lagoon are down to 10 m depths. A recent attempt to limit shown in Table 4. freshwater inflow in the lagoons, as a measure Four main groups of benthic inverte- against eutrophication, increased their water brates are found in coastal brackish water salinity and may have favored the growth of lagoons, depending on their hydrologic and this species (ORFANIDIS et al. 2001a). trophic status: i) fresh water species, ii) eury- The freshwater genus Zannichellia has haline brackish water species iii) marine spe- been found in the Evros Delta. cies preferring shallow sheltered areas, and iv) opportunistic species. The first group is Meifauna represented by chironomid larvae and oligo- chaetes and it is found in areas isolated from Meiobenthos has only been studied in Gi- the sea with increased fresh water input. The alova lagoon, where 18 meiofaunal taxa were typically euryhaline brackish water species found (McARTHUR et al., 2000). These are: include the molluscs Cyclope neritea, Abra foraminiferans, ciliates, cnidarians, turbelar- segmentum, Mytilaster minimus, and Ceras- ians, gnathostomulids, gastrotrichs, nema- toderma glaucum, the polychaete Hediste todes, nemertines, rotifers, gastropod and bi- diversicolor, and the crustacean Gammarus valve molluscs, annelids, amphipods, harpac- aequicauda. They are the most widely dis- ticoid copepods, dipteran larvae, bryozoans, tributed and highly abundant species. Char- holothuroids and ascidians. Densities ranged acteristic marine species of shallow areas from 17 to over 2.000 individuals per 10 are the mollusc Loripes lacteus, the polycha- cm2, with nematodes and copepods being the ete Nephthys hombergii and the amphipod most abundant taxa. The distribution pattern Corophium insidiosum. Finally the oppor- of the meiofaunal community varied both tunistic species, commonly found in abun- across the lagoon and over the seasons. On dance in organically enriched areas, include the basis of the spatial differences a meiofau- the polychaete species Capitella capitata, nal coenocline, correlated with the degree of Heteromastus filiformis, Polydora ciliata isolation, was observed, composed of mainly and Hydroides dianthus. Apart from the hy- two zones: one comprising the area close to drological and trophic status of the lagoon, the marine channel and the other the more the relative importance of each group of spe- isolated area in the inner lagoon. Meiofaunal cies varies according to season and the life distribution pattern, however, was not clearly cycle of the dominant species. correlated to a single environmental vari- Some of the dominant species have re- able: apart from purely physical and chemi- ceived special attention in relation to their cal characteristics it was also associated with life-cycle and population dynamics. They food supply. are the polychaete Streblospio shrubsolii (KEVREKIDIS, 2005), the bivalve mol- Zoobenthos luscs Abra segmentum (NICOLAIDOU & KOSTAKI-APOSTOLOPOULOU, 1988; Macrozoobenthos is the ecosystem com- KEVREKIDIS & KOUKOURAS, 1992; ponent most studied in Greek lagoons (e.g. GONTIKAKI et al., 2003), Mytilaster min- NICOLAIDOU et al., 1983, 1985, 2006; imus (NICOLAIDOU & ANAGNOSTAKI, DOUNAS et al., 1998; ARVANITIDIS et al., 1983) and the amphipods Gammarus aequi- 1999; KOUTSOUBAS et al., 2000a; GOU- cauda (KEVREKIDIS & LAZARIDOU- VIS & KOUKOURAS, 1993; KEVREKIDIS DIMITRIADOU 1988, KEVREKIDIS & 1997, 2004a; KEVREKIDIS et al., 2000; KOUKOURAS, 1988-89, 1989), G. insen- REIZOPOULOU & NICOLAIDOU, 2004; sibilis, Dexamine spinosa, Microdeutopus

38 Medit. Mar. Sci, 6/2, 2005, 31-50 Table 4 Dominant benthic animal species at each lagoon. (A= Aetoliko, C=Coast, D=Drana, G=Gialova, I=Isolated shallows, K=Klissova, La=Laki, L=Logarou, Ma= Mazoma, Me=Messolonghi, Mo=Monolimni, P=Papas, R=Rodia, T=Tsopeli, Ts=Tsoukalio, V=Vivari). * dominant species, + locally or occasionally important species (absence of a mark does not indicate absence of the species)

Lagoons Amvrakikos Gulf Patraikos Ionian Aegean Evros Delta Gulf Sea Sea Species Ma T Ts R L K Me A P G V C La Mo D I Mollusca Abra alba + + Abra segmentum * * * * * * * * * * * * * * * Bittium reticulatum + Cerastoderma glaucum + * * * * * + * Cerithium vulgatum * Cyclope neritea * + + + Haminoea hydatis * Hydrobia acuta * Hydrobia ulvae + Hydrobia ventrosa + + Ventrosia maritima * * * * * Loripes lacteus * * + Mytilaster minimus * + * * * * Mytilus galloprovincialis * Pirenella conica * Tapes decussatus + Polychaeta Armandia cirrosa * + * Capitella capitata + + + * * Chaetozone sp. * Exogone hebes + Exogone verrugera + Harmothoe spinifera + Hediste diversicolor + * * + * * * * * Heteromastus filiformis * + + + * Hydroides dianthus * Lumbrinereis latreilli + + Malacoceros fuliginosus * * + Microspio mecznikowianus + + Nainereis laevigata * + + Neanthes caudata + * Neodexiospira * pseudocorrugata Nephtys hombergi * + * + * Notomastus latericeus * + Ophiodromus pallidus * Owenia fusiformis + Perinereis cultifera * Platynereis dumerilii + (continued) Medit. Mar. Sci, 6/2, 2005, 31-50 39 Table 4. (continued)

Lagoons Amvrakikos Gulf Patraikos Ionian Aegean Evros Delta Gulf Sea Sea Species Ma T Ts R L K Me A P G V C La Mo D I Phyllodoce sp. + Polydora ciliata + Polyophthalmus pictus + Protoaricia oerstebii + * Streblospio shrubsolii + * * Syllis prolifera * Crustacea Cirripedia * Corophium acherusicum + Corophium insidiosum * + Corophium orientale * * * Ericthonius brasiliensis + Ericthonius difformis * Gammarus aequicauda + * * * Gammarus crinicornis + Gammarus insensibilis * + + Gammarus subtypicus + Idotea baltica * + + * * Iphinoe serrata * * * Leptochelia savignyi + + Melita palmata + Microdeutopus anomalus + * Microdeutopus gryllotalpa + + * * + Microdeutopus sp. + + Phtisica marina + Sphaeroma ghigii * + Sphaeroma serratum * Tanais cavolinii * Upogebia litoralis + Miscellanea Amphipholis squamata * Actiniaria * + + + + + + Chironomidae + * * + + * * Nematoda + + Nemertea + + + Oligochaeta * * + * * Ophiuroidea + Phoronis muelleri +

Basic sources: Amvrakikos Gulf: REIZOPOULOU et al., 1996; REIZOPOULOU & NICOLAIDOU, 2004; NICO- LAIDOU et al., 2006; Patraikos Gulf: BOGDANOS & DIAPOULIS, 1984; NICOLAIDOU et al., 1983; Ionian Sea: KOUTSOUBAS et al., 2000b; Evros Delta: GOUVIS et al., 1997; KEVREKIDIS, 1997; KEVREKIDIS et al., 2000; KEVREKIDIS, 2004a; MOGIAS & KEVREKIDIS, 2005.

40 Medit. Mar. Sci, 6/2, 2005, 31-50 Fig. 2: Biological Zonation in Gialova lagoon, according to the scheme proposed by GUELORGET & PERTHUISOT (1992) for Mediterranean lagoons. gryllotalpa (KARAKIRI & NICOLAIDOU, tion with the sea, or confinement, described 1987), Corophium insidiosum (KARAKIRI & by GUELORGET & PERTHUISOT (1992) NICOLAIDOU, 1987; KEVREKIDIS, 2004b) as the time required for a lagoon to renew and Corophium orientale (KEVREKIDIS et its marine elements. Six zones, as described al., 2004; KEVREKIDIS in press). in the model, have been found in Greek la- It is worth mentioning the dominance of goons: Zone I, which is a continuation of the mudsnail Ventrosia maritima, a typical the sea, with strictly marine species, Zone II, lagoonal species, found mainly in isolated where the more stenohaline marine species areas of Evros Delta. This mud-snail was are lost, Zone III, with mixed species, Zone only known from the Black Sea. However, IV, with strictly brackish water species, utilizing DNA sequencing and phyloge- Zone V with only vagile fauna and freshwa- netic analyses, the occurrence of this spe- ter (hypohaline) or evaporitic (hyperhaline) cies was recently ascertained in the Evros species and finally, Zone VI, which shows Delta. The first detailed data concerning almost total colonisation of substratum by the ecology and distribution of Ventrosia Cyanobacteria. Some or all of the zones are maritima in a lagoon system, its life cycle, present in each lagoon, as shown in Figure population dynamics and productivity, were 2 for the lagoon Gialova. The limits of the given by KEVREKIDIS et al. (2005) and zones may show seasonal shifts indicating KEVREKIDIS & WILKE (2005). the dynamic character of the lagoonal envi- The most important variable shaping spe- ronment (KOUTSOUBAS et al., 2000b). cies composition and macrobenthic commu- The degree of confinement affects com- nity structure is the degree of communica- munity diversity (REIZOPOULOU & NICO-

Medit. Mar. Sci, 6/2, 2005, 31-50 41 part of the lagoonal systems where salinity, temperature, dissolved oxygen as well as other environmental variables present strong fluctuations. The migratory marine/estuarine species are also found in the inner parts of the lagoons but only during the most stable period, from spring to autumn. In accordance with other biotic components of the lagoonal system, fish fauna is Fig. 3: Regression of diversity against confinement characterized by spatial and temporal vari- (based on data from the lagoons of Amvrakikos, Mes- ability, both in terms of numbers of species solonghi, Papas, Vivari, and Gialova). and individuals. Although temporal patterns vary significantly from lagoon to lagoon or even in the same lagoon inter-annually, there LAIDOU, 2004). There is a negative correla- is a general tendency to have the most rich tion (p=0.0001) between confinement and di- fish fauna, both in terms of species numbers versity (Fig. 3). Lowest diversity is observed and density, from spring to autumn, while in enclosed lagoons, most isolated from the during winter very few species and low den- marine environment, while in lagoons with sities are observed. an important marine element and good water Most lagoons in Greece are used for the circulation, diversity is high. Such differenc- extensive culture of various fish species es in diversity may be observed in the same the majority of which belong to the migra- lagoon where the inner parts show the lowest tory marine/estuarine species. Mean annual diversity and the canals of communication production varies significantly depending with the sea the highest. on the size of the lagoon while differences are also observed in the fish catch composi- Fishfauna tion 10t in Gialova lagoon during 1986 to 2003 - mostly various species of grey mul- More than 30 fish species have been re- let (Liza saliens, L. aurata, L. ramada), sea corded from the Greek lagoonal systems un- bream (Sparus aurata) and sea bass (Dicen- der consideration (Table 5). They could be trarchus labrax); 45t in Papas lagoon during divided in three different categories: i) typical 1996 to 2000 – mostly the species referred lagoonal species, which complete their whole above for Gialova and additionally eel (An- life-cycle in lagoons such as Aphanius fascia- guilla anguilla) ZOULIAS, 2003; over 200t tus and Atherina boyeri ii) migratory marine/ in Messolonghi lagoon during 1988 to 1996 estuarine species which reproduce in the sea, – mostly the aforementioned species and ad- but which spend a period of their life in brack- ditionally Chelon labrosus and Mugil cepha- ish waters, for example Sparus aurata, Di- lus) (DIMITRIOU et al., 1997). centrarchus labrax, Anguilla anguilla, Mugil cephalus, Chelon labrosus, Liza saliens, Modelling L. aurata, L. ramada, Diplodus sargus and Solea solea and iii) marine species which are The simulation of lagoon ecosystem dy- normally distributed in the sea and are occa- namics has an increased level of complexity sionally or accidentally found in the lagoons compared with the simulation of open sea e.g. Gobius spp., Blennius spp., Diplodus an- systems. Therefore, application of ecologi- nularis, D. puntazzo, Lithognathus mormyrus, cal models is required. Such an approach has and Salpa salpa. The marine species extend been performed in Gialova lagoon where the in a narrow zone, influenced by the sea, while European Regional Seas Ecosystem Model the permanent species occupy the innermost

42 Medit. Mar. Sci, 6/2, 2005, 31-50 Table 5. Fish species found in Greek Transitional Ecosystems. (A=Aetoliko, Amv= Amvrakikos, D=Drana, G=Gialova, La=Laki, Me= Messolonghi, Nest=Western Macedonia and Thrace, P=Papas)

Transitional Species Category Common name (Greek/English) Com. Ecosystem Alburnus alburnus (Linnaeus, 1758) Freshwater Sirko/Bleak D La, Nest, P, G, Anguilla anguilla Linnaeus, 1758 Marine/Estuarine Cheli/Eel + Me, A, Amv Aphanius fasciatus Nardo, 1827 Lagoonal Kounoupopsaro/Killifish G, Me, A, La, D Atherina boyeri Risso, 1810 Lagoonal Atherina/Big-scale sand smelt P, G, La, D Blennius sp. Marine Saliara/Blenny P Carassius auratus (Linnaeus, 1758 ) Freshwater Italiko/Goldfish La, D Nest, P, G, Me, A, Chelon labrosus Risso, 1826 Marine/Estuarine Velanissa/ Thicklip grey mullet + Amv Nest, P, G, Me, A, Dicentrarchus labrax Linnaeus, 1758 Marine/Estuarine Lavraki/Sea bass + Amv La, P, G, Me, A, Diplodus annularis Linnaeus, 1758 Marine Sparos/Annular seabream + Amv Diplodus puntazzo Cetti, 1777 Marine Mytaki/Sharpsnout seabream P, G , Me, A, Amv + Diplodus sargus Linnaeus, 1758 Marine/Estuarine Sargos/White seabream P, G, Me, A, Amv + Sargopapas/Common two-banded Diplodus vulgaris Linnaeus, 1758 Marine P, Me, A, Amv + seabream Epinephelus aeneus (Geofroy, 1817) Marine Sfirida/White grouper P + Gaidropsarus mediterraneus (Linnaeus, Marine Shore rockling La 1758) Gambusia affinis (Baird & Girard, 1853) Freshwater Kounoupopsaro/Mosquitofish La Gobius geniporus Valenciences, 1837 Marine Govios/Slender gobby G Gobius sp. Marine Govios/Gobby P, Me, A Knipowitschia caucasica (Kawrajsky in Berg, Lagoonal Pontogovios/ Gobby La, D 1916) Lepomis gibbosus (Linnaeus, 1758) Freshwater Eliopsaro/Pumpkinseed D Lithognathus mormyrus Linnaeus, 1758 Marine Mourmoura/Striped seabream P, Me, A + La, Nest, P, G, Liza aurata Risso, 1826 Marine/Estuarine Mixsinari/ Golden grey mullet + Me, A, Amv Nest, P, G, Me, A, Liza ramada Risso, 1826 Marine/Estuarine Mavraki/ Thinllip mullet + Amv La, Nest, P, G, Liza saliens Risso, 1810 Marine/Estuarine Gastros/Leaping mullet + Me, A, Amv Nest, P, G Me, A, Mugil cephalus Linnaeus,1758 Marine/Estuarine Kefalos/Flathead grey mullet + Amv Mullus barbatus Linnaeus, 1758 Marine Koutsomoura/Red mullet P, Me, A + Mullus surmuletus Linnaeus, 1758 Marine Barbouni/Striped red mullet P, G + Oedechilus labeo (Cuvier, 1829) Marine/Estuarine Grentzos/ Boxllip mullet P, G + Parablennius sanguinolentus (Pallas, 1811) Marine Rusty blenny La Pomatoschistus marmoratus(Risso, 1810) Marine/Estuarine Govios/Marbled goby La, D Salpa salpa Linnaeus, 1758 Marine/Estuarine Salpa/Salema P, Me, A + Solea vulgaris Quensel, 1806 Marine Glossa/Common sole P, Me, A, Amv + Nest, P, G, Me, A, Sparus aurata Linnaeus, 1758 Marine/Estuarine Tsipoura/Sea bream + Amv Spondyliosoma cantharus (Linnaeus, 1758) Marine Skathari/Black seabream G + Syngnathus acus Linnaeus, 1758 Marine/Estuarine Greater pipefish La Zosterisessor ophiocephalus (Pallas, 1811) Marine/Estuarine Grass goby La

Basic sources: ANANIADIS, 1984; DOUNAS & KOUTSOUBAS, 1996; DIMITRIOU et al., 1997; KEVREKIDIS et al., 1990; MOGIAS et al., 2002; MOGIAS, 2005.

Medit. Mar. Sci, 6/2, 2005, 31-50 43 (ERSEM), initially designed for the open reaction, commonly called eutrophication sea, has been usefully applied with minimum (CLOERN, 2001). It starts with an increase modifications. Model results depicting the in growth (organic production) and a shift in seasonal variation of nutrients and Chl-a in dominance of primary producers from an- the water column (PETIHAKIS et al., 1999), giosperms to opportunistic seaweeds, and as well as three benthic functional groups culminates to a dystrophic crisis with exten- (suspension feeders, deposit feeders, and sive algal blooms, severe anoxia and mass benthic carnivores), were validated with in killings of both fish and invertebrate fauna situ data (TRIANTAFYLLOU et al., 2000). (SCHRAMM & NIENHUIS, 1996). Such The modelled pelagic ecosystem exhibits a events are not uncommon in some Greek la- microbial foodweb, characterised by com- goons. In Papas and Vassova the opportunistic petition for nutrients between bacteria and seaweeds Ulva and Gracilaria have increased phytoplankton, which was broadly in agree- their dominance at the cost of angiosperms, ment with the observations made in the la- in the last decades, due to nutrient excess in goon. The heterotrophic biomass was larger the water (KARYOTIS et al., 2005). Some than the autotrophic biomass and there was a areas of Papas, Aetoliko and Gialova become strong benthic-pelagic coupling in the mod- completely defaunated, especially during el, as would be expected in a shallow system summer or early autumn (REIZOPOULOU rich in detrital material. The seasonal vari- & NICOLAIDOU, 2004; KOUTSOUBAS ations in the benthic flux of nutrients were et al., 2000b). The sedentary infauna is more tightly coupled to the phytoplankton nutrient affected than vagile organisms, such as crus- demand and hence the supply of detritus in tacea and fish, which are able to migrate. Re- the sediments. The likely effect of a techni- covery is generally rapid, as organisms soon cal intervention (river input) increasing the recolonize the affected areas. Papas lagoon, freshwater nutrient inputs on the lagoonal for example, which was affected by summer ecosystem functioning was also investigated. dystrophic crisis with extensive mortality of Model experiments indicated the shift of the fish and benthic invertebrates, recovered the ecosystem from nitrate limitation to predator same autumn. A similar trend has also been control with external inputs. Model experi- observed in Gialova lagoon. ments also revealed a significant increase in The degree of pollution in Greek lagoons the amount of carbon entering the benthic has been assessed by an array of methods, system through the activity of filter feeders including Abundance Biomass Comparison when river inputs were implemented. The (ABC) curves and plotting of Geometric successful application of ERSEM to Gialova Abundance Classes, which are widely used lagoon has highlighted the potential utility of for pollution assessment in the fully marine a model as an operational tool to support en- environment (REIZOPOULOU et al., 1996). vironmental management decisions in such However, due to the naturally stressed con- ecosystems. dition of the lagoons, these methods were ineffective as was Shannon diversity index. Pollution Conversely, the application of recently de- veloped rapid biodiversity assessment tech- Lagoons are nutrient rich areas as a result niques (WARWICK & CLARKE, 1998; of input of nutrients by rivers and recycling CLARKE & WARWICK, 2001) in certain between sediment and water column facili- Greek lagoons was proved useful and ef- tated by their shallowness. Nutrient excess ficient (ARVANITIDIS et al., 2004). Fur- and hydrological changes, often accelerated thermore, two new indices –the Ecological by human intervention, in the lagoons, result Evaluation Index, based on macrophytes, al- in a non-linear and self-accelerating chain gae and angiosperms, and the Size Distribu-

44 Medit. Mar. Sci, 6/2, 2005, 31-50 Fig. 4: Ecological Evaluation Index (EEI) in com- Fig. 5: Index of Size Distribution (ISD) in three parison to diversity indices in five Greek lagoons. Greek lagoons. Higher values correspond to the most Line bars indicate 95% confidence intervals. disturbed lagoon, Papas, and low to the less affected, Tsopeli (REIZOPOULOU & NICOLAIDOU, in press). tion Index, based on the size distribution of expertise. An application of the ΙSD to three macrobenthic animals - have been proposed Greek lagoons is shown in Figure 5. for the estimation of the ecological condition of lagoonal ecosystems. Conclusions

Ecological Evaluation Index. (EEI) was The research carried out so far in Greek la- designed to estimate the ecological status of goons confirms the variability of the envi- transitional and coastal waters as shifts, due ronment, demonstrated also for other coastal to anthropogenic stress, from the pristine lagoons in the Mediterranean. Differences state dominated by late successional species exist not only among lagoons but also within (EEI=10) to the degraded state dominated by the same lagoon, both in space and time. The opportunistic species (EEI=2) (ORFANIDIS degree of communication with the sea affects et al., 2001, 2003). Its application in five most of the other environmental variables, Greek lagoons and the comparison with di- playing a prominent role in shaping the bio- versity indices, considered inappropriate for logical communities. Inflow of fresh water ecological assessment, is shown in Figure 4. is also very important in the differentiation of biota. However, neither of the above has Index of Size Distribution (ΙSD) is based on been directly quantified so far. The zonation the observations that, with increasing organ- of confinement is based on the end result- the ic load the community size structure changes species distribution- rather than the causative (REIZOPOULOU & NICOLAIDOU, in factor-the water circulation and exchange. press). Due to the dominance of small sized An independent evaluation of confinement, opportunistic species and the decline of large based on physical predictors rather than on bodied specimens (mainly suspension-feed- the fauna, might provide a better understand- ers and carnivores), smaller and fewer size ing of its role. The input of fresh water and classes are present, thus, size class distribu- the contributed organic matter and nutrients, tion is skewed towards the smaller size class- would give a clearer picture of the terrestrial es. The value of skewness of the curve is influence. used as a measure of environmental quality. Finally, it is demonstrated that variability It has the advantage of a good discrimination between and within lagoons concerns mostly power and of not requiring a high taxonomic the dominance of species and not the pres-

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