Proceedings of the Second Mediterranean Symposium on Marine

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<strong>of</strong>fs (group B; Fig. 2). The lagoons <strong>of</strong> Delta Nestos are divided in several sub-basins and receive considerable amounts <strong>of</strong> urban and agricultural run-<strong>of</strong>fs from drainage channels and <strong>the</strong> old bed <strong>of</strong> <strong>the</strong> Nestos River. There, R. cirrhosa grew in relative restricted areas alone or in coexistence with seaweed populations (group A). In sites or lagoons where angiosperms were scarce or absent, <strong>the</strong> seaweeds species Gracilaria bursa-pastoris, Ulva sp. and Cystoseira barbata were dominated (group C). These results indicate <strong>the</strong> existence <strong>of</strong> a eutrophication gradient (Harlin, 1995; Schramm and Nienhuis, 1996) between two stable equilibrium states (see Scheffer et al., 2001), <strong>the</strong> oligotrophicpristine (group B) and <strong>the</strong> eutrophic-degrated (group C). The dominance <strong>of</strong> Ruppia cirrhosa, a late-successional angiosperm, indicates <strong>the</strong> oligotrophic state, which is characterized by low nutrient and clear water conditions. By contrast, <strong>the</strong> dominance <strong>of</strong> opportunistic seaweeds indicates <strong>the</strong> eutrophic state, which is characterized by high nutrients and turbid conditions. These conditions favor rapid growth and/or colonization ability <strong>of</strong> seaweeds to exclude angiosperms (Sommer and Worm, 2002). The absence <strong>of</strong> angiosperm could also be attributed to high organic content (>6%) <strong>of</strong> <strong>the</strong> sediment. Seaweed and angiosperm coexistence (group A) indicate intermediate conditions. A similar pattern was evident by using <strong>the</strong> EEI. The lagoon Fanari was indicated as a sustainable ecosystem and a possible reference condition lagoon for Macedonia & Thrace region (Orfanidis et al., 2003). The Nestos Delta lagoons were indicated as ecosystems to be restored to a higher ESC, with only Agiasma to be classified as moderate and <strong>the</strong> o<strong>the</strong>rs as low. Water parameters in <strong>the</strong> Vassova lagoon showed a seasonal variability across a winter to summer axis (Table 1). Maximum nitrate values in winter coincided with adverse climatic and hydrographic conditions (high precipitation, strong NE to E winds and low tide) that overload <strong>the</strong> lagoon with freshwaters. Dissolved phosphorus variability indicated, beside freshwaters, also sediment as a possible P-source. The analysis <strong>of</strong> seaweed community indicated a more complex pattern (Fig. 3). Fish farming practices hinder water circulation at site 2 in winter and caused <strong>the</strong> Ulva bloom that self-accelerated <strong>the</strong> rest <strong>of</strong> <strong>the</strong> year. Site 3 samples were grouped mainly in a winter to summer axis due to high winter Gracilaria biomass. The analysis at a species-level separated spring from summer and winter, due to high growth <strong>of</strong> Cystoseira barbata under <strong>the</strong> clear water prevailing conditions. Noticeably, analysis at <strong>the</strong> species-level grouped autumn with summer, whereas at <strong>the</strong> functional level grouped autumn with winter. First classification is due to species <strong>of</strong> tropical affinity grew in summer and autumn, whereas <strong>the</strong> second due to seaweed responses to relative similar environmental conditions prevailing in autumn and winter. The macrophyte community showed considerable seasonal changes. Then, <strong>the</strong> macrophyte based water quality estimations should, principally include long-term seasonal investigations. The seasonal monitoring <strong>of</strong> <strong>the</strong> Vassova lagoon showed similar water quality estimations, when summer or 4 seasonal samples were used (Fig. 4). Since summer is also <strong>the</strong> main growing season <strong>of</strong> marine angiosperms in <strong>the</strong> lagoons (Schramm and Nienhuis, 1996), one could suggest summer as an adequate sampling period in low budget monitoring programs. ACTES DU DEUXIEME SYMPOSIUM MEDITERRANEEN SUR LA VEGETATION MARINE (ATHENES, 12-13 DECEMBRE 2003) 191
PROCEEDINGS OF THE SECOND MEDITERRANEAN SYMPOSIUM ON MARINE VEGETATION (ATHENS, 12-13 DECEMBER 2003) 192 CONCLUSION Marine benthic macrophytes have been successfully used as bioindicators <strong>of</strong> eutrophication in Eastern Macedonian & Thrace lagoons. They provide readable signal with analyses based on functional group composition providing powerful support to traditional species-level analyses. Although this paper is dealing specifically with eutrophication, it is clear that <strong>the</strong> use <strong>of</strong> benthic macrophytes as bioindicators has widespread applicability in <strong>the</strong> monitoring <strong>of</strong> water quality. A cost-effective monitoring system to cover <strong>the</strong> demands <strong>of</strong> WFD could include summer destructive samplings, functional-form classification, and use <strong>of</strong> <strong>the</strong> EEI. REFERENCES Anderson A. (1999) - My bioindicator or yours? Making <strong>the</strong> selection. J. Insect Conser., 3: 61-64. De Jonge V. N., Elliott M., Orive E. (2002) - Causes, historical development, effects and future challenges <strong>of</strong> a common environmental problem: eutrophication. Hydrobiol., 475/476: 1-19. Duarte C. M. (1995) - Submerged aquatic vegetation in relation to different nutrient regimes. Ophelia, 41: 87-112. Harlin M. M. (1995) - Changes in major plant groups following nutrient enrichment. In: Mc Comb A. J. (ed), Eutrophic shallow estuaries and lagoons, Institute for Environmental Science, Murdoch University, CRC Press, Murdoch, Australia: 173-187. Littler M. M., Littler D. S. (1980) - The evolution <strong>of</strong> thallus form and survival strategies in benthic marine macroalgae: field and laboratory tests <strong>of</strong> a functional form model. Am. Nat., 116: 25-44. Orfanidis S., Panayotidis P., Stamatis N. (2001) - Ecological evaluation <strong>of</strong> transitional and coastal waters: a marine benthic macrophytes model. Mar. Medit. Sc. 2 (2): 46-65. Orfanidis S., Panayotidis P., Stamatis N. (2003) - An insight to <strong>the</strong> ecological evaluation index (EEI). Ecol. Indic., 3: 27-33. Scheffer M., Carpenter S., Foley J. A., Folke C., Walker B. (2001) - Catastrophic shifts in ecosystems. Nature, 413: 591-596. Schramm W., Nienhuis P. H. (eds) (1996) - Marine benthic vegetation: recent changes and <strong>the</strong> effects <strong>of</strong> eutrophication. Ecological studies 123. Springer-Verlag: 470 pp. Sommer U., Worm B. (eds) (2002) - Competition and coexistence. Ecological studies 161. Springer- Verlag: 221 pp.
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United Nations Environment Programm
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PROCEEDINGS OF THE SECOND MEDITERRA
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CONTENTS/SOMMAIRE Programme .......
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ORFANIDIS S., TSIAGGA E. & STAMATIS
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Friday 12 December 2003 09:00 Openi
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Discussion Discussion - Littoral be
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MAPPING MARINE VEGETATION DISTRIBUT
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1984; Boudouresque et al., 1985b; M
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Elbu cove, Scandula nature 1/ 1190
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features of P. oce
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Belsher T., Houlgatte E. (2000) - E
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Gloux B. (1984) - Méthodes acousti
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Pasqualini, V., Pergent-Martini, C.
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Here, we will firstly delineate wha
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Fig. 2. The tree of</strong
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In the same way, "
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While the
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COASTAL DEVELOPMENT The destruction
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invaders, overfishing and climate c
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At the end <strong
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to be built up, this disappearance
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Boudouresque C.F., Ribera M.A. (199
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Marchand M. (1981) - Amoco Cadiz. B
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FLORISTIC SIMILARITY AND DISCONTINU
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871 accepted taxa (Table 1). Howeve
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Fig. 2. Hystogram showing t
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4 (1.6%) and 2 (1.1%) at Spain; 5 (
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characteristics of
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Fig. 9. Hystogram showing t
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Fig. 11. Dendrogram depicting mutua
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REFERENCES Agardh C. A. (1822-1823)
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De Toni G. B. (1905) - Sylloge Alga
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Langenbach G. (1873) - Die Meeresal
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SESSION «BIOLOGY, ECOLOGY AND INVE
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SESSION ‘MAPPING MARINE VEGETATIO
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Page 141 and 142: PROCEEDINGS OF THE SECOND MEDITERRA
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Mr Baris AKÇALI D.E.U. Institute <
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Mr Francesco Saverio CIVILI MED POL
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Mr Jamel KSOURI Laboratoire de Biod
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Mr Frédéric PLATINI Accord RAMOGE
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Ms Eleni TRYFON Natural Environment
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