Hard Bottom Benthic Communities: Towards A New Concept In Assessing And Monitoring Marine Biodiversity

Figure 1. Hard substratum benthic communities from Greece characterised by dense growths of sponges.

Studying benthic invertebrates is considered a valuable tool for the marine environment quality assessment, since these organisms have the ability to 'integrate' and thus reflect the long-term environmental conditions to which they are subjected (Bilyard, 1987; Gray, 1980; EMaPS, 1998). Several researchers have underlined the advantages of studying hard bottom epibenthic assemblages as they are spatially fixed and therefore easily monitored and manipulated. (Christie, 1980; Hartnoll & Hawkins, 1980; Fraschetti et al 2001a). The importance of the marine rocky habitats is further strengthened by the fact that 85% of the benthic species have been characterized as endangered by the Protocol for the Marine Biodiversity in the Mediterranean Sea occur in hard substrata (EEA, 1999). In Greece, whereas rocky shores represent the largest part of the extensive coastline (16,000 km, including the islands), scientific knowledge of the indigenous hard-bottom benthic communities is still in a rather impoverished state. Although there are several phytobenthic studies (Chryssovergis & Panayotidis, 1995; Haritonidis, 1978; Lazaridou, 1994; Orfanidis et al 2001), seldom are they efficiently replicated in space and time. As regards zoobenthic communities, plenty of information exists on soft-bottom fauna composition (Simboura & Nikolaidou 1994, 2001; Pancucci, 1996; Zenetos, 1993; Zenetos et al, 1991; Koutsoubas et al, 1992; Karakassis & Eleftheriou, 1997; Arvanitidis, 2000) but very little is known about hard-bottom species and assemblages (but see Koukouras et al 1995, 1996; Vafidis et al 1997; Antoniadou & Chintiroglou, 2001). Due to the logistic difficulties that are inherent to rocky sublittoral sampling (e.g. laborious, costly, time-consuming) there is comparatively little information on the ecology and dynamics of these particular ecosystems. At the same time, Marine Protected Areas are being continuously established along the Mediterranean rocky shores (Fraschetti et al 2001a). As a result, there is an increasing need for a new concept in assessing and monitoring the biodiversity status of rocky coastal areas.

Developing rapid bio-assessment techniques is becoming a major common goal in the field of marine biology. Recent approaches give priority to surrogate or key species (Ward et al 1998; EEC, 2000) to obtain a fast but efficient tool for biodiversity conservation and management action. Various visual census techniques are developed and widely used by many marine biologists around Europe (Garrabou et al 1998; Roberts et al 1998; Fraschetti et al 2001b; Pagola-Carte et al 2002; Terlizzi et al 2002). Such methods can provide us with the capability of effective qualitative and quantitative sampling over large areas with low effort and within short periods of time. At the same time, their non-destructive character renders them invaluable tools especially when it comes to the biological assessment of marine protected areas or rare and endangered species.

In this preliminary study both destructive and non-destructive (photographic) sampling was performed on phytobenthic populations of the Saronikos Gulf in order to compare and inter-calibrate these two methods. Three sampling stations were chosen in the upper sublittoral zone between 0.5 and 1m, the one situated at a degraded area near the sewage discharge of the Attica Treatment Plant, while the other two at putatively unimpacted sites. An Ecological Evaluation Index (EEI) developed by Orfanidis et al (2001) was applied to data collected by each method. The analyses showed that the -anticipated- loss in taxonomic information by the photographic method did not correspond to loss of ecological quality information and that identification to genera level can be as informative as identification to functional form group when it comes to the ecological assessment of a marine ecosystem.

Further studies are imperative in order to verify the method's robustness to greater temporal and spatial variability. In addition, there is a need to integrate zoobenthic data, starting by testing whether invertebrate species regarded as bioindicators in the Western Mediterranean (eg. Ballesteros, 1982; Bellan et al 1994; Perez et al 2000) show similar responses and can thus be used in the Aegean Sea. Besides, this study is expected to bring in a considerable amount of new information concerning the hard-bottom benthic fauna and thereupon the marine biodiversity of Greek waters. 

References 

Arvanitidis C., 2000. Polychaete fauna of the Aegean Sea: inventory and new information. Bull. Mar. Sci., 60(1): 73-96. 

Antoniadou C. & C. Chintiroglou, 2001. Colonization pattern of the infralittoral hard substrate communtiy in the North Aegean Sea (Chalkidiki, Greece). Preliminary results. Rapp. Comm. Int. Mer. Medit. 36, 351p. 

Ballesteros E., 1982. Primer intento de tipificacion de la vegetacion marina y litoral sobre substrato rocoso de la Costa Brava. Oecol. Aquat., 6: 163-173. 

Bellan G., D. Soltan, V. Gravez, 1994. Les indicateurs biologiques et ecologiques de la qualite des eaux littorales en Mediterranee: Faune Benthique et Algues. In: Etat de Connaissances Operationnelles sur la contamination et les indicateurs de pollution chimique toxique du milieu marin. Analyse Bibliographique, COM Technical Report, 50p. 

Bilyard, G.R., 1987. The value of benthic infauna in marine pollution monitoring studies. Mar. Poll. Bull.,18: 581-585. Christie H., 1980. Methods for ecological monitoring: Biological interactions in a rocky subtidal community. Helgol. Meer., 33, 473-483. 

Chryssovergis F. & P. Panayotidis, 1995. Communities of macrophytobenthos along a eutrophication gradient (Maliakos gulf, Aegean Sea, Greece). Oceanol. Acta 18(6): 649-658. 

EEA, 1999. State and pressures of the marine and coastal Mediterranean environment. Env. Ass. Ser., 5, 137p. 

EEC, 2000. Council Directive for a legislative frame and actions for the water policy, 2000/60/EC, Official Journal of the E.C., 22/12/2000. 

EMaPS, 1998. A European science plan on marine biodiversity. Heip C., R. Warwick & L. d' Ozouville (eds). EMaPS Position Paper 2, 20p. Fraschetti S., A. Terlizzi, F. Micheli, L. Benedetti Cecchi, F. Boero, 2001a. A proposal for measuring effectiveness in Marine Protected Areas. Rapp. Comm. Int. Mer. Medit., 36: 385. 

Fraschetti S., N. Bianchi, A. Terlizzi, G. Fanelli, C. Morri & F. Boero, 2001b. Spatial variability and human disturbance in shallow sutidal hard substrate assemblages: a regional approach. Mar. Ecol. Prog. Ser., 212: 1-12. 

Garrabou J., J. Riera & M. Zabala, 1998. Landscape pattern indices applied to Mediterranean subtidal rocky benthic communities. Landscape Ecol., 13: 225-247. 

Gray J.S., 1980. Why Do Ecological Monitoring? Mar. Poll. Bull., 11(3): 62-65. 

Haritonidis S., 1978. Contribution to the research of marine plant macrophyceae (Chloro-, Phaeo-, and Rodophyceae) of the Thermaikos Gulf. PhD Thesis, Aristotle University of Thessaloniki (in Greek). 

Hartnoll R.G. & S.J. Hawkins, 1980. Monitoring rocky shore communities: a critical look at spatial and temporal variation. Helgol. Meer., 33: 484-494. 

Karakassis J. & Eleftheriou A., 1997. The continental shelf of Crete: structure of macrobenthic communities. Mar. Ecol. Progr. Ser., 160: 185-196. 

Koukouras A., E. Voultsiadou-Koukoura, Th. Kevrekidis & D. Vafidis, 1995. Ascidian fauna of the Aegean Sea with a checklist of the eastern Mediterranean and Black Sea species. Ann. Inst. Oceanogr., 71(1): 19-34. 

Koukouras A., A. Russo, E. Voultsiadou-Koukoura, C. Arvanitidis & D. Stefanidou, 1996. Macrofauna associated with sponge species of different morphology. PSZNI: Mar. Ecol., 17(4): 569-582. 

Koutsoubas D., Koukouras A., Karakassis I. & C. Dounas, 1992. Contribution to the knowledge of Gastropoda and Bivalvia (Mollusca) of Crete Island (S. Aegean Sea). Boll. Malacol., 28: 69-82. 

Lazaridou E., 1994. Systematics, bionomy and ecological study of the marine phytobenthos of Milos Island (Cyclades). PhD Thesis, Aristotle University of Thessaloniki (in Greek) 

Orfanidis S., P. Panayotidis, N. Stamatis, 2001. Ecological evaluation of transitional and coastal waters: A marine benthic macrophytes-based model. Med. Mar. Sci., 2(2): 45-65. 

Pagola-Carte S., J. Urkiaga-Alberdi, M. Bustamante, J.I. Saiz-Salinas, 2002. Concordance degrees in macrozoobenthic monitoring programmes using different sampling methods and taxonomic resolution levels. Mar.Poll.Bull. 44: 63-70. 

Pancucci M.A., 1996. Fauna Greciae: Echinodermata. Hellenic Zoological Society, Athens, 162p. 

Perez T., S. Sartoretto, D. Soltan, S. Capo, M. Fourt, E. Dutrieux, J. Vacelet, J.G. Harmelin & P. Rebouillon, 2000. Etude bibliographique sur les bioindicateurs de l' etat du milieu marin. In: System d' evaluation de la Qualite des milieux littoraux -Volet biologique. Rapport Agences de l'eau, 4 fasiscules, 642p. 

Roberts D.E., A. Smith, P. Ajani & A.R. Davis, 1998. Rapid changes in encrusting marine assemblages exposed to anthropogenic point-source pollution: a 'Beyond BACI' approach. Mar. Ecol. Prog. Ser., 163: 213-224. 

Simboura N. & A. Nicolaidou, 1994. Checklist and bibliography of Polychaetes from Greece with some recent additions. Abstract in: Actes de la 4eme Conference Internationale des Polychetes. Mem. Mus. Natn. Hist. Nat., 162: 640. 

Simboura, N. & A. Nicolaidou, 2001. The Polychaetes (Annelida, Polychaeta) of Greece: checklist, distribution and ecological characteristics. Accepted for publications in: Monographs on Marine Sciences, Series no 4. NCMR. 

Terlizzi A., S. Fraschetti, P. Guidetti, F. Boero, 2002. The effects of sewage discharge on shallow hard substrate sessile assemblages. Mar. Poll. Bull., 44: 544-550. 

Vafidis D., A. Koukouras & E. Voultsiadou-Koukoura, 1997. Actiniaria, Corallimorpharia and Scleractinia (Hexacorallia, Anthozoa) of the Aegean Sea, with a checklist of the Eastern Mediterranean and Black Sea species. Isr. J. Zool., 43: 55-70. 

Ward T., R.A. Kenchington, D.P. Faith & C.R. Margules, 1998. Marine BioRap Guidelines: Rapid Assessment of Marine Biological Diversity. CSIRO Perth, 1998, 52p. 

Zenetos A., 1993. Infralittoral macrobenthos in the Patras Gulf and Ionian Sea. Bivalvia Mollusca. Malacol. Rev., 26: 51-62. 

Zenetos A., E. Papathanassiou & J.J. Van Aartsen, 1991. Analysis of benthic communities in the Cyclades plateau (Aegean Sea) using ecological and plaeoecological data sets. PSZN: Mar. Ecol., 12 (2): 123-137.