A PILOT RIVER BASIN NETWORK FOR SUSTAINABLE MANAGEMENT OF NATURAL RESOURCES

A PILOT RIVER BASIN NETWORK FOR SUSTAINABLE MANAGEMENT OF NATURAL RESOURCES G. Bidoglio, N. Murray, J.M. Zaldivar, F. Bouraoui Institute for Environment and Sustainability, Joint Research Centre, European Commission, Ispra (VA), Italy Issues such as agriculture, land degradation/desertification, water availability, urban growth are key elements of environmental strategies for sustainable development, which requires appropriate integration of land use, soil and water protection legislative frameworks. To this end, watersheds form meaningful landscape units where actions can be taken, because of the shared functional relationships that exist within their boundaries. Many National Action Programmes developed in the context of the UN-Convention to Combat Desertification mention among their priorities the protection of watersheds as core measures for achieving their objectives. Watersheds are also the basic territorial units for many monitoring and information system initiatives, and are embedded in the concept of the River Basin Management Plans (RBMP) being introduced by the EU Water Framework Directive (WFD). In this lecture, the Observational Network of Watersheds developed at the Joint Research Centre (JRC) will be discussed, together with European Commission initiatives in this context that by linking policy and research aspects aim at the protection of soil and water resources. The uses made of all major European watersheds have long-term and wide-ranging impacts not only on soil and freshwater resources, but also on the quality and quantity of water runoff to coastal areas. Although the management of water systems has often followed river basin approaches to environmental planning and regulation, until now they have not been developed in a uniform manner across the EU, and have led to large variations in resulting application. In order to overcome this deficiency, one of the underpinning principles of the Water Framework Directive is to place river basin management in a comprehensive and statutory context. To facilitate the development of such an integrated approach, a pilot project for testing guidance documents developed under the Common Implementation Strategy (CIS) of the WFD has been launched. For this purpose, Member States and Candidate Countries have set-up a network of Pilot River Basins (PRBs) covering a wide range of climatic, environmental and socio-economic conditions. The network has been established using strict selection criteria, including the commitment and availability of resources, the implication of the PRBs in on-going research projects, the strong involvement of NGOs, practitioners and stakeholders. At present, the network is made up of 5 river basins from different countries. A multi-phase approach has been proposed to conduct the integrated testing to take into consideration the legal requirements of the Member States to comply with reporting obligation under the WFD, but also the need to develop, in the near term, programmes of measures and river basin management plans. This network serves the purpose of feeding practitioners experience into the policy making process. Since direct feedback is needed 3

also from the research side in order to improve the science-basis of the policy support, the JRC has complemented the PRB network with an additional number of river catchments in Europe, with case-study areas in, among others, Finland, France, Greece, Italy, Spain, UK. Activities at each node of the network aim at establishing relationships between anthropogenic activities and the loads of chemicals to soils, inland and coastal waters, and to assess the impact of preventive and remedial measures on these loads. Particular attention in the research network is given to diffuse sources of agricultural origin, a re-emerging priority in Europe, to respond to policy needs of EU agri-environmental programmes. Using several examples, the presentation will illustrate as well the different modelling approaches applied to derive nutrient losses and how, in some cases, the implementation of the strictest technical solution to environmental pressure does not always yield the expected outcomes. In this context it is of primary importance to dispose of appropriate and harmonized quantification and reporting procedures allowing source allocation to different land uses and pathways. The focus on nutrients facilitates intercomparison of different approaches, because data for nutrients are in general more widely available in Europe than for other types of contaminants. However, the methodologies that are currently used in EU Member States and Candidate Countries for quantifying diffuse nutrient losses differ profoundly in their level of complexity, their representation of system processes and pathways, and resource requirements. With many nations using different approaches/methodologies, there is a need for an intercomparison of these contrasting methodologies in order to form an objective judgement of their performance and cost-effectiveness under different agricultural, geophysical and hydrological conditions throughout Europe. It is also necessary to develop and evaluate at the local scale methodologies that could be used to upscale environmental assessment of small watersheds to larger river basins watersheds. 4

FISHERIES AND RELATED INDICATORS OF FISHERIES RESOURCES AND ECOSYSTEMS: TOWARDS AN APPLICATION IN THE MEDITERRANEAN Jacques A. Bertrand IFREMER - Rue de l Ile d Yeu, BP 05, 443 Nantes cedex 03, France e-mail: bertrand@ifremer.fr INTRODUCTION Since a long time, fishery research has developed tools aiming to characterize fish resources dynamics and applied them in view of fishery management support. In this scope, very deep theory and concepts have been produced. Nevertheless, despite the efforts and progress, the state of the sector is far to be satisfying in a lot of intensively fished areas. From this situation, deeper analyses have been done, and new ways for fishery management, particularly its integration in marine ecosystem management, have been investigated. This research has been also stimulated by the general concerns about the utilization of the marine resources all over the world particularly since the 980s with the Convention on the law of the Sea (98), and the Convention on biological diversity (99) which extend the question of management at the scale of the whole ecosystems. To report on the effects of human uses on marine services, various forms of state of the environment reporting have been proposed with the aim of integrating the different components of the ecosystem. This approach requires the availability of information on an amount of parameters much more larger than the ones needed for the previous fishery assessments mainly based on single species dynamics. This paper intends to remind some general topics related to this evolution, to discuss some directions to be potentially relevant for the Mediterranean, and to present a few first attempts on characterizing resources and ecosystem at a large scale in this area. THEORY OF INDICATORS IN RELATION WITH ECOSYSTEM From the very abundant literature related to the concept of sustainable development, some principles established at the Bellagio Conference (996, Italy) may be highlighted. Notably, these principles include the need for (i) a guiding vision and clear goals, in a holistic perspective and adequate scope, with long enough time scales and wide enough spatial scales, a limited number of key issues and (ii) standardized indicators comparing targets, reference values, range, and thresholds, effective communication with a diversified audience, institutional capacity improving the data collection and analysis. All these principles would be integrated in a conceptual framework of sustainability including environment, resources, people and technology, managed through institutions towards objectives of human well-being and environment well-being (Garcia et al. 000a), and able to characterize the state of the system, the pressure it is suffering and 5

the response it gives to the applied management. Historically, fishery research has been mainly oriented to the biological aspects of this framework, and particularly towards the assessment of the mainly exploited resources. If the new approach requires the upholding of a high level of expertise in this domain, it also implies the building of knowledge on less or not exploited resources, and on more ecological topics including ecosystem structuring and functioning. Only these biological aspects will be considered below. Concerning the environment subsystem, it is generally admitted that the global objectives of ecosystem fishery management would be (i) the upholding of the target resources characteristics at levels capable of ensuring its natural and continuous exploitation under ecologically acceptable conditions, and (ii) the confidence that the environment conditions should be protected, maintained and enhanced (where appropriate) to ensure the maintenance of resource productivity (Garcia et al. 000a). The first objective implies that the criteria for the target resources relate to resource quality, diversity, and availability. Related indicators would need to reflect total biomass, resource size and age structure, spawning biomass, recruitment index, extension of distribution area, species composition, etc. The second objective implies that related ecosystem criteria would include the state of the ecosystem: structure, productivity, environment, biodiversity, population structure and food chain integrity. The related indicators would need to reflect the following: water quality, critical habitat, species composition, diversity and resilience. Because exploited communities are complex systems, finding single indicators that measure the effect of fishing would be unrealistic. Hence, multiple indicators are necessary to build a representation of the state of the system. Various available indices may be useful to improve knowledge on the ecosystem characteristics and functioning. Nevertheless, to be really relevant as good indicators, the candidate indices should encompass the following criteria: policy priorities, practicality/feasibility, data availability, cost-effectiveness, understandability, accuracy and precision, robustness to uncertainty, scientific validity, acceptability to users/stakeholders (consensus among parties), ability to communicate information, timeliness, formal (legal) foundation, and adequate documentation (FAO 999). An important question is to consider the scales at which the system is considered. The definition of an operational scale may be based on various geographical and biological references (Caddy 998). For an ecosystem approach, they may refer to the concept of large marine ecosystems (Anon. 00). Whatever the scale, the observation system would include mapping of the spatial distribution of the species (eventually at different life stages), and of the habitat structuring. Once relevant indices have been selected, the question is on how to summarise the information provided by a set of indicators. Efficient synthetic representations based on reference or target points are usually applied for assessment of monospecific resources, e.g. in the U.S.A. (Dayton et al. 00) or in the ICES with precautionary approach plots (Anon. 00a). For ecosystem indicators, different ways have been proposed, such as kites and barometers (Garcia et al. 000b), multivariate analyses (Pitcher et al. 998) or composite indices like the indices of biological integrity (IBIs) used for freshwater monitoring. In any case, fundamental difficulties lie in the necessary weighting of indicators. Finally, comparative approaches by gathering estimates of indicators from various systems may be powerful (Rochet et al. 003), particularly when they consider neighbouring areas with contrasted exploited rates. 6

INDICATORS FROM FISHERIES Classically, the majority of stock assessments have been done to monospecific stocks. They are mainly derived from applications of (i) analytical (including length-based methods) and production models, and (ii) swept area estimates of abundance. The first class of methods is based on a very structured fishery theory extended by consistent formulation of tools for analysing the relations between yield and exploitation (see Beverton et al. 957; Gulland 977; Ricker 958). The reference points mainly refer to the concept of maximum sustainable yield (MSY) (Caddy et al. 996). Nevertheless in a lot of cases the applications are moderated by the large amount of basic information they require, and the poor quality of the data often available from the fishery sector, which drastically conditioned the results. Furthermore, comparison between areas is often restricted due to the wide diversity of the fishery sector (gear, effort, quality of the data, etc.) making difficult standardization of the results. Trawl-surveys are less prone to the biases affecting commercial catch data (Hutchings et al. 994), but they are subject to greater measurement error due to a smaller sample size. Furthermore, their cost had limited their utilization in a lot of areas for long time and therefore the research effort towards methodologies from the information produced by such surveys, despite their usefulness not only for assessment but also to integrate spatiality and in view of ecosystem approaches. Despite these limits, a significant development of surveys has been made in different areas during the last few decades to produce data independent of those coming from the fishery (in the North Atlantic and the Mediterranean more than twenty survey series are presently in course, most of them existing since the 980s). These surveys are mainly devoted to the production of abundance and biomass indices. Basically, most of them have been used to calibrate abundance indices for stock assessments. They may also constitute a fantastic base to implement indicators to measure the impact of fisheries on the ecosystems. Hence candidate indicators have been sought at population level, for assemblages (that is to say sets of population living together in a biotope, ignoring interactions), and for communities, e.g. trough the trophic levels (Christensen 000). In a recent review of these kinds of indices, authors (Rochet et al. 003) have selected height populations indices, twelve related to assemblages and ten related to communities, most of them calculable from standard trawl surveys. Nevertheless, these authors underline that few of the large variety of the proposed indicators have been validated, and very few have associated reference points (Trenkel et al. 003). The most operational ones are those for populations. As the art of assessing the impact of fishing on biological communities is still in its infancy, all of the community indices need much theoretical and analytical work to design reference points. SOME APPROACHES IN THE MEDITERRANEAN The Mediterranean is an intensively exploited marine system. After a maximum at about million tonnes during the 980s, the capture fishery production in the Mediterranean and Black Sea remained at about. million tonnes in the 990s (Anon. 00b). This general trend hides very various situations from one species to the other, in the different subareas. For instance, from an analysis of 45 years time series (945-994) of landings related to 960 species/areas in the western and eastern Mediterranean, it has been shown (Fiorentini et al. 997) that about 50% of the series were rising or recovering, and about 6% were declining, the others being distributed between new, dome-shaped, stable, intermittent, and collapsed. This variability is linked with the fact that most of the stocks are demersal species, mainly located on the shelves, and constituting 7

local stocks. As underlined by these authors, landings are not enough to fully characterize a fishery, as this information mixes information of changes in the fishery and in the underlying environment, and may hidden a lot of combined factors. However, in case of very few information is available, it could be useful for identifying the priorities in the perspective of stock assessment, e.g. those showing strong short-term decline and those showing long-term decline. A lot of assessments of fishery resources applying methods based on estimates of population parameters from commercial fishery data have been done for a large amount of exploited stocks in the Mediterranean. They are supported by extensive research on the biological parameters related to these species. Most often, these assessments are referring to local case studies. Apart from few regional syntheses, as it has been done for the Central Mediterranean (Relini et al. 999), the information is widely spread in the literature, making difficult a global view of the situation and comparisons. One of the larger scale standardized approaches in the Mediterranean is the one produced through the international bottom trawl survey (Medits) programme (Bertrand et al. 00; Ber- trand et al. 000). This programme is based on the carrying out of yearly standardized bottom trawl surveys on the shelves and upper slopes in the Mediterranean Sea. For the time being, the programme covers mainly the North Mediterranean, from Gibraltar to the Aegean Sea, with one survey (about 00 hauls) every year since 994. Different indices have been built from these surveys. The first ones were abundance indices and length distribution of the sampled species in the different subareas (Abello et al. 00). Deeper analyses of dynamics parameters (Lembo 00) on 8 species in 6 geographical units gave extensive information on biological (length distribution, sex ratio, size at maturity) and demographic parameters (average size at age, growth, mortality, exploitation rate) at the population level, and on multispecies size spectra as an indicator of the effect of fishing on the whole community. In most of the cases, the series was to short (994-999) for identifying time trends. But it made possible comparisons between subareas. For instance, not any geographical trend was detected from cumulative density and biomass of the 8 studied species. However, the ratio between biomass and density indices of the slope highlighted the occurrence of larger average size in some areas. The analysis among the geographical units showed rather variable exploitation rates according to the species and areas. A longer series of data in the Gulf of Lions (983-00, including the Medits data from 994 to 00) showed significant trends of the biomass and density indices for some species, particularly Raja clavata and Scyliorhinus canicula, both species for which most of the decline occurred before 994. A systematic analysis of a large range of population, assemblage and community indices (Rochet et al. 003) is in progress from the French Medits data. For the time being, all these indices have yet to be tested so as to identify their relevance and their sensibility, notably regarding the potential fishery impact. The whole Medits survey data might be a very appropriate case study to enlarge the test, due to high level of sampling standardisation of the survey, and the wide diversity of ecosystems covered by the surveys. CONCLUSION A large range of indicators of exploitation and state of ecosystems have been proposed for fishery management from an ecosystem perspective. However, the experience with fishery indicators in the scope of ecosystem approach is very short, and the available indicators need still to be evaluated according to objective requirements by defining appropriate criteria. The Mediterranean may constitute a very exiting case study for such an approach, due to the deep knowledge 8

of the biology of the exploited resources and associated ecosystems, the large variety of subsystems, and the availability of basic data. Such evaluation should be a first steep in progressing towards ecosystem management. The expected results could help the definition of an integrated monitoring system on clearly defined objectives, within a systemic management framework to be underpinned from communication with all stakeholders (Grieve et al. 003). The development of theoretical research on the functioning of the ecosystem should also give new guides for the improvement of the existing survey methodologies. References Abello P., J.A. Bertrand, L. Gil de Sola, C. Papaconstantinou, G. Relini & A. Souplet eds, 00. Marine demersal resources of the Mediterranean: the MEDITS International trawl survey (994-999). Sci. Mar. Vol. 66: 80 p. Anon., 00. Large Marine Ecosystems of the World. An Introduction to LME s. http://www.edc.uri.edu/ lme/intro.htm. Anon., 00a. Cod in Subarea IV (North Sea), Division VIId (Eastern Channel), and Division IIIa (Skagerrak). ICES C. R. R. (55): 9-7. Anon., 00b. Part. World review of fisheries and aquaculture. In The state of world fisheries and aquaculture 00. FAO: 3-5. Bertrand J.A., L. Gil de Sola, C. Papaconstantinou, G. Relini & A. Souplet, 00. The general specifications of the Medits surveys. In Mediterranean Marine Demersal Resources: The MEDITS International Trawl Survey (994-999). P. Abello, J. Bertrand, L. Gil de Sola, C. Papaconstantinou, G. Relini & A. Souplet eds. Sc. Mar. 66: 9-7. Bertrand J.A. & G. Relini eds, 000. Demersal resources in the Mediterranean. Proceedings of the symposium held in Pisa, 8- March 998. Actes de Colloques. Vol. 6. Ifremer, Plouzané: 38 p. Beverton R.J.H. & S.J. Holt, 957. On the dynamics of exploited fish and populations. Fish. Invest.,, 9. 533 p. Caddy J. & R. Mahon, 996. Points de référence en aménagement des pêcheries. FAO. Doc. technique sur les pêches. 0 p. Caddy J.F., 998. Issues in Mediterranean fisheries management: geographical units and effort control. Studies and Reviews. GFCM-FAO (70): 56 p. Christensen V., 000. Indicators for marine ecosystems affected by fisheries. Mar. Freshwater Res. 5: 447-450. Dayton P.K., S. Thrush & F.C. Coleman, 00. Ecological effects of fishing in marine ecosystems of the United States. PEW Oceans commission. 5 p. FAO, 999. Indicators for sustainable development of marine capture fisheries. FAO tech. guidelines for responsible fisheries No. 8. 68 p. Fiorentini L., J. Caddy & J.I. de Leiva, 997. Long- and short-term trends of Mediterranean fishery resources. Studies and Reviews. GFCM-FAO (69): 7. Garcia S.M. & D.J. Staples, 000a. Sustainability reference systems and indicators for responsible marine capture fisheries: a review of concepts and elements for a set of guidelines. Mar. Freshwater Res. 5: 385-46. Garcia S.M. & D.J. Staples, 000b. Sustainable indicators in Marine Capture Fisheries: introduction to the special issue. Mar. Freshwater Res. 5: 38-384. Grieve C., N. Sporrong, C. Coffey, S. Moretti & N. Martini, 003. Review and gap analysis of environmental indicators for fisheries and aquaculture. IEEP, Report to English Nature. 63 p. Gulland J.A., 977. Fish population dynamics. Wiley & sons, New York: 37 p. Hutchings J.A. & M.S. Myers, 994. What can be learned from the collapse of a renewable resource? Atlantic cod, Gadus morhua, of Newfoundland and Labrador. Can. J. Fish. Aquat. Sci. 5: 7-46. Lembo G. ed 00. SAMED Stock assessment in the Mediterranean. EC project n 99/047. COISPA, Italy. Pitcher T., S. Mackinson, M. Vasconcellos, L. Nøttestad & D. Preikhost, 998. Rapid appraisal of the status of fisheries for small pelagics using multivariate, multidisciplinary ordination. In Lowell Wakefield 9

Fisheries Symposium. F. Funk, T.J. Quinn II, J. Heifetz, J.N. Ianelli, J.E. Powers, J.F. Schweigert, P.J. Sullivan & C.-I. Zhang, eds, Anchorage, Alaska. Relini G., J. Bertrand & A. Zamboni eds, 999. Sintesi delle conoscenze sulle risorce da pesca dei fondi del Mediterraneo centrale (Italia e Corsica). Synthesis of the knowledge on bottom fishery resources in central Mediterranean (Italy and Corsica). Biol. Mar. Medit. Vol. 6: 868 p. Ricker W.E., 958. Handbook of computations for bioloogical statistics of fish populations. Bull. Fish. Res. Board Can. 9: 300. Rochet M.J. & V. Trenkel, 003. Which community indicators can measure the impact of fishing? A review and proposals. Can. J. Fish. Aquat. Sci. 60: 86-99. Trenkel V. & M.J. Rochet, 003. Performance of indicators derived from abundance estimates for detecting the impact of fishing on a fish community. Can. J. Fish. Aquat. Sci. 60: 67-85. 0

DISTINGUISHING ANTHROPOGENIC FROM NATURAL CHANGES IN MARINE BIODIVERSITY Richard M. Warwick Plymouth Marine Laboratory, Prospect Place, West Hoe, Plymouth PL 3DH, UK. Anthropogenic threats to marine biodiversity are many and varied, and operate on a range of spatial and temporal scales ranging from local short-term pollution incidents or fishing activities to regional long-term effects of eutrophication or climate change. These effects of Man s activities are often quite subtle and difficult to detect against a background of natural variability in biodiversity resulting from differences in natural environmental variables such as bottom sediment type, salinity, turbidity or primary productivity. At the organismal level, the most widely used biodiversity measures are those based on the number of species present, perhaps adjusted for the number of individuals sampled. Recently alternative measures of biodiversity have been proposed, based not on species richness but which measure features of the overall taxonomic spread. Average taxonomic distinctness (Δ + ) is a measure of the degree to which the species are related taxonomically to each other, and is the average path length between every pair of species traced through a taxonomic tree. The degree to which certain taxa from the regional species pool are over- or under-represented is another biodiversity attribute of ecological relevance. This is reflected in variability of the full set of pairwise distinctness weights making up the average, termed variation in taxonomic distinctness (Λ + ). Unlike species richness measures, both these indices have the distinct advantage of being unbiased by sample size or sampling effort, but in the present context they have the additional advantage of being largely insensitive to natural environmental variability whist remaining sensitive to anthropogenic perturbations. For example, in the UK traditional measures like species diversity have been shown to vary significantly between samples of macrobenthos from estuarine compared with coastal sites. Thus, for many of these measures the setting of reference conditions might be problematic. Average taxonomic distinctness did not vary significantly with habitat type, suggesting that a common set of reference conditions may be a possibility for this index. For both estuarine and coastal sites average taxonomic distinctness was correlated with TOC, whereas the number of species, Shannon diversity and evenness were not. In the estuaries, this was also true for heavy metal concentrations. In another example, the taxonomic distinctness of free-living nematodes is shown not to vary significantly between widely different habitat types, but is significantly depressed in areas subjected to anthropogenic perturbation. Because of their robustness to natural environmental variability on the one hand, and their sensitivity to anthropogenic perturbations on the other, taxonomic distinctness measures are beginning to find application in broad scale geographical comparisons of biodiversity, in environmental impact assessment, in evaluation of surrogates for biodiversity estimation, and also for

predicting the effect of long term (e.g. climate) change on biodiversity. Some examples of these applications, using macrobenthos, fish and mollusc assemblages are illustrated:. Abundances of macrobenthic species have monitored twice yearly at 6 locations in Tees Bay, NE England, between 973 and 996. In the Bay there was a major shift in community composition between 986 and 988 and inter-annual variability in community composition was significantly greater after 987 than before 987 in all areas. Although there was no clear pattern of change in the number of species present over the sampling period, a dramatic increase in Shannon diversity (H ) occurred after 987, due to an increase in evenness that resulted from the reduction of a few previously dominant species, notably the small polychaete Spiophanes bombyx. Although biodiversity measures describing the taxonomic breadth of the species assemblages also showed a marked step change in 987, this was one of reduced diversity, average taxonomic distinctness (D + ) decreasing and the variation in taxonomic distinctness (L + ) increasing. These abrupt, detrimental, changes coincided with a well-documented change in a variety of components of the North Sea ecosystem in the same period. Traditional species diversity measures such as H therefore gave a false impression of improving environmental quality over this period, given that the average taxonomic spread was reduced, certain taxa were under-represented with respect to others, and community composition as measured by a multivariate stability index (MSI) became less stable. H also failed to distinguish putatively impacted areas close to the estuary mouth compared with those more distant, despite clear differences in D +, L + and in community stability (MSI).. Concern over the impact of beam trawling on the biodiversity of demersal fish assemblages in the North Sea, Irish Sea and English Channel has prompted a comparison of nine large sea areas that are subjected to different levels of fishing effort. Average taxonomic distinctness was shown to be significantly reduced in some areas that are subjected to heavy fishing pressure, whilst remaining at expected levels in other less heavily fished areas. 3. There is increasing concern about the effects of global warming on biological diversity. Community level changes on decadal timescales cannot be predicted from short term experiments, and currently there is little predictive ability regarding the effects of global climate change on the marine biota. A useful approach to predicting the effects of future climatic scenarios on marine biodiversity is by an analysis of biodiversity patterns where such conditions currently pertain. However, this may be rather too simplistic. For example, we would not expect coastal biodiversity in Britain to become equivalent to that of the Mediterranean if temperature rose to a comparable level, because other environmental factors (tidal regime, range of habitats etc.) differ considerably between the two. Another possibility, for taxa with a good fossil record, is to compare current patterns of biodiversity with fossil death assemblages in the same region laid down under different climatic conditions to the present. This will of course depend on whether the death assemblages are fully representative of the biodiversity of the regional living species pool. The death assemblage of molluscs (gastropods and bivalves) from a sandy beach at Harlyn Bay, North Cornwall, UK, has been shown to be fully representative of the biodiversity of the regional species pool from all habitat types, in terms of D + and L +. A late Pliocene fossil assemblage of molluscs from St Erth Pits, north Cornwall, UK, is also not significantly different in biodiversity from the present-day regional species pool. The climate in the late Pliocene was similar to the present-day Mediterranean, suggesting that predicted changes in climate, by the end of this century, will not affect molluscan biodiversity, although the species composition will undoubtedly change.

References Brown B.E., Clarke K.R. & Warwick R.M. 00. Serial patterns of biodiversity change in corals across shallow reef flats in Ko Phuket, Thailand, due to the effects of local (sedimentation) and regional (climatic) perturbations. Marine Biology 4, -9. Clarke, K.R. & Warwick, R.M. 998. A taxonomic distinctness index and its statistical properties. Journal of Applied Ecology 35, 53-53. Clarke, K.R. & Warwick, R.M. 00. A further biodiversity index applicable to species lists: variation in taxonomic distinctness. Marine Ecology Progress Series 6, 65-78 Hall, S.J. & Greenstreet, S.P. 998. Taxonomic distinctness and diversity measures: responses in marine fish communities. Marine Ecology Progress Series 66, 7-9. Harper, J.L. & Hawksworth, D.L. 994. Biodiversity: measurement and estimation. Preface. Philosophical Transactions of the Royal Society of London Series B, 345, 5-. Piepenburg, D., Voss, J. & Gutt, J. 997. Assemblages of sea stars (Echinodermata: Asteroidea) and brittle stars (Echinodermata: Ophiuroidea) in the Weddell Sea (Antarctica) and off Northeast Greenland (Arctic): A comparison of diversity and abundance. Polar Biology 7, 305-3. Price, A.R.G., Keeling, M.J. & O Callaghan, C.J. 999. Ocean-scale patterns of biodiversity of Atlantic asteroids determined from taxonomic distinctness and other measures. Biological Journal of the Linnean Society 66, 87-03. Rogers, S.I., Clarke, K.R. & Reynolds, J.D. 999. The taxonomic distinctness of coastal bottom-dwelling fish communities of the North-east Atlantic. Journal of Animal Ecology 68, 769-78. Warwick, R.M. & Clarke, K.R. 998. Taxonomic distinctness and environmental assessment. Journal of Applied Ecology 35, 53-543. Warwick, R.M. & Clarke, K.R. 00. Practical measures of marine biodiversity based on relatedness of species. Oceanography and Marine Biology: an annual Review 39, 07-3 Warwick, R.M. & Light, J. 00. Death assemblages of molluscs on St. Martin s Flats, Isles of Scilly: a surrogate for regional biodiversity? Biodiversity and Conservation, 99-. Warwick R.M., Ashman C.M., Brown A.R., Clarke K.R., Dowell B., Hart B., Lewis R.E., Shillabeer N., Somerfield P.J. and Tapp J.F. 00. Inter-annual changes in the biodiversity and community structure of the macrobenthos in Tees Bay and the Tees estuary, UK, associated with local and regional environmental events. Marine Ecology Progress Series 34, -3. Warwick, R.M. & Turk, S.M. 00. Predicting climate change effects on marine biodiversity: comparison of recent and fossil molluscan death assemblages. Journal of the Marine Biological Association of the United Kingdom 8, 847-850. 3

GAS HYDRATES, THEIR FUTURE AS ENERGY RESOURCE AND THEIR IMPACT ON GLOBAL ENVIRONMENTAL CHANGES John Woodside Faculty of Earth and Life Sciences, Vrije Universiteit, De Boelelaan 085, 08 HV Amsterdam, the Netherlands (email: john.woodside@falw.vu.nl) Natural gas hydrates (GH), also known as clathrates (from the Latin indicating furnished with a lattice or encaged ), are solids composed of water molecules forming a rigid lattice which contains molecules of light hydrocarbons, predominantly methane. Not only is a good supply of the gas necessary but the pressure and temperature conditions must be right for formation of the icy hydrate structure. Because of this, methane hydrate, the commonest gas hydrate, is unstable in our normal working environment and therefore very difficult to study because it rapidly dissociates into free gas and water at standard temperature and pressure. A cubic metre of methane hydrate could render 64 cubic metres of gas at standard conditions, as well as about 0,8 cubic metres of water. The potentially large concentrations of methane in a relatively small space make them interesting to people exploring for energy resources; however, the possibility of releasing large volumes of a potent greenhouse gas like methane from destabilised clathrates also makes them a potential threat to society. WHERE ARE THEY? Gas hydrates are found in nature mainly in Artic permafrozen sediments where conditions are cold, or below about 500 m depth in the oceans where the pressure is high and the temperature is generally low. The phase boundary between the solid hydrate form and free methane and water is also a function of impurities in the water: thus, elevated concentrations of sodium chloride or nitrogen in the water reduce the stability of the gas hydrates but the presence of hydrogen sulphide, carbon dioxide, or other light hydrocarbons makes the hydrate form stable at slightly higher temperatures or lower pressures. Moreover, methane, ethane, propane, isobutane, normal butane, carbon dioxide, and hydrogen sulphide can occur in hyrated form. In ocean sediments, a gas hydrate stability zone (GHSZ) can be defined, usually between the seafloor (at appropriate depths/pressures and bottom water temperatures) and a depth where the geothermal gradient, the normal increase of temperature with depth into the earth, brings the local sediments to temperatures above those where hydrates would be stable at that depth/pressure. There may or may not be gas hydrates within the gas hydrate stability zone. This depends on the concentration and availability of the gas. 4

SOURCE Methane is usually produced in the sediments by microbial processing of organic matter (giving biogenic methane) but it can also come in much smaller quantities from the same geological kitchen that produces other natural hydrocarbons from organic matter in the deeper hotter sediments (giving thermogenic gas and oil). The isotopic signature of the carbon can usually indicate whether the source is one or the other, or a mixture. When migrating methane from below enters the gas hydrate stability zone, it can form gas hydrates in the sediment. It is likely that there is therefore a concentration of gas hydrates near the base of the GHSZ, and the concentration of methane hydrates is a function of the flux into and through the zone. Higher concentrations of gas hydrates near the base of the GHSZ are also promoted by the upward migration of the base of the stability zone as a result of the addition of seafloor sediments through normal depositional processes. The gas hydrate tends to form small crystals in pore spaces in the sediments (possibly the commonest form), developing possibly (and less commonly) into nodules or lenses, veins and laminae, and occasionally the more massive forms that have been found in several places in the world (e.g. Hydrate Ridge of western USA, Blake Ridge off eastern USA). ASSESSING THE QUANTITY Estimates of how much methane is trapped in hydrate form are still poorly constrained and vary by at least two orders of magnitude: between about x 0 4 m 3 and 0 5 m 3 according to Soloviev compared to x 0 6 m 3 according to Kvenvolden (see Henriet and Mienert, 998), with many other estimates in between by others. Most estimates assume a thickness of the GHSZ based on the theoretical stability curves, as well as concentrations and form of the gas hydrates in the sediments; however, the concentrations and extent of gas hydrates in the environment are still poorly known. Estimating gas hydrate volume involves mapping, sampling, and modeling, all of which are busy areas of research at this moment. Mapping of gas hydrates usually makes use of indirect geophysical methods which need to be calibrated with samples from the seafloor sediments. If there are indications of gas in the sediments, with further indications of active advection through the sediments, then gas hydrates may be present within the GHSZ. Such indications of seafloor methane fluxes and gassy sediments include seafloor pockmarks observed on sidescan sonar records, acoustic anomalies in subbottom profiles (i.e. acoustic voids, acoustic wipe-outs, acoustic curtains and plumes, etc), and thriving chemosynthetic communities as observed in seafloor photographs, videos, or direct observation from submersible. Direct indication of methane hydrates is inferred from bottomsimulating reflectors (BSR) in seismic profiles. These BSRs are observed at the base of the gas hydrate stability zone as strong reflectors that are roughly parallel to the seafloor (because they may be considered to follow a roughly isobaric surface) and are seen to cross natural stratification in the sediments. The strong reflector and its accompanying polarity inversion (compared to the polarity of the seafloor reflector) both occur because higher seismic velocities in the gas hydrates contrast strongly with the lower seismic velocities in underlying sediments containing elevated concentrations of free gas. Analysis of the sediments containing gas hydrates is important to understand the relationship between hydrate form and concentration and the sediment grain size, porosity, and permeability. Unfortunately this is not possible in general because the gas hydrates dissociate quickly when sediment samples containing them are brought to the surface; and their sedimentological struc- 5

ture is permanently destroyed in the process. As a result, most knowledge of formation of gas hydrates in sediments comes from experiments in which they are formed artificially in simple sedimentary mixtures, or through modeling. Within the last few years, however, new sampling equipment has provided the possibility to bring sediment samples from the GHSZ under in situ pressures for analysis. This technique has been used successfully by the Ocean Drilling Program (ODP) and has been adapted for use from smaller research vessels employing relatively simple coring methods. Thus we are still in relatively early stages of making a proper assessment of methane gas hydrates as potential energy resource or possible cause of climate change because we are still collecting the necessary data base to refine estimates of their volume and distribution. USEFUL RESOURCE? A great deal of money is being spent on research into exploiting the energy of methane hydrates as an extended hydrocarbon resource. It has been estimated by Kvenvolden that more than half the total organic carbon on earth (not counting the vast amounts of dispersed organic carbon such as kerogen and bitumen) is locked up in gas hydrates (0 9 g), which is twice the amount found in all recoverable and non-recoverable fossil fuels (coal, oil, natural gas). Two major unanswered questions are () do gas hydrates form a sufficiently concentrated resource to make exploitation feasible? and () is it an economically viable prospect to mine the methane from the gas hydrates? Concentrated deposits have not yet been found in more than say half a dozen places on earth, partly because of both the lack of sufficient seafloor surveying and of predictions of likely locations to find them, based on modeling and knowledge of the sedimentological controls. Exploitation of these concentrated deposits as a natural resource has been proposed using methods of dissociating the hydrates and collecting the resulting gas; but these are either too expensive or still difficult to realize. Heating the gas hydrates using hot water or steam injection, or injection of a fluid such as methanol or glycol, have been considered for destabilizing the gas hydrates but rejected as impractical both economically and environmentally. Depressurising the gas hydrates might be a promising way to proceed if other problems of collecting the gas are addressed and solved. As a natural phenomenon, formation of gas hydrates has been considered as a means of solving the problem of excess emissions of carbon dioxide by industrialised societies. It has been proposed to store surplus carbon dioxide in hydrate form in the deep sea as a method of limiting further addition of this greenhouse to the atmosphere. The stability of these deposits might cause worry of longer term problems. CLIMATIC INFLUENCE? Release of methane into the environment from dissociating gas hydrates has been considered not only as a possible geological hazard but also a potential source of climate change. Methane is a powerful greenhouse gas that is 5 times more efficient than carbon dioxide at trapping heat, although it has a shorter atmospheric residence time. Methane gas hydrates are a possibly large methane sink; but their relatively rapid dissociation into gas and water when they are made unstable by elevated temperatures or lower pressures make them also a potentially important source of atmospheric methane. They may thus act as a gigantic CH 4 buffer in dynamic equilibrium with environmental conditions. Reduction of hydrostatic/lithostatic pressure in the GHSZ could 6

occur, for example, following the removal of overlying sediments by a submarine slide or by sea level fall, and temperature changes in ocean bottom water is a similarly normal natural process. Over the last two decades, for example, deep-water warming has occurred in the eastern Mediterranean. It has been proposed that massive dissociation of gas hydrates in the past has liberated enough methane to cause major climatic perturbations, for example, at the end of the Paleocene (e.g. Dickens et al., 997). Evidence supporting this is the depleted content of 3 C in the carbon record. The Late Paleocene Thermal Maximum (65 Ma) appears as a sharp excursion (about 0.6 %o in the δ 8 O) indicating a potential increase in ocean temperature of over two degrees. This correlates exactly with an excursion of.5 %o in the δ 3 C, which is shown by modeling to be consistent with a release of.x0 8 g of methane from gas hydrates over a period of about 0 4 years (Dickens et al., 997). POSTSCRIPT Gas hydrate build-ups in pipelines transporting hydrocarbons have been an annoyance to oil companies, and gas hydrate concentrations in sedimentary environments have been heralded both as a resource and a hazard. Such hazards might include, besides potential climatic effects caused by release of gas from the hydrates, also submarine slides (with their accompanying tsunamis) and destabilization of seafloor constructions (e.g. pumping of warm hydrocarbons from deep sources through the GHSZ can destabilise the gas hydrates and structures like oil platforms based in the overlying sediments). Research into all these related phenomena in recent years has made a gas hydrates a very hot topic. Suggested reading DICKENS, G.R., CASTILLO, M.M., and WALKER, J.C.G., 997, A blast of gas in the latest Paleocene: simulating first-order effects of massive dissociation of oceanic methane hydrate. Geology, 5, 59-6. HENRIET, J.-P., and MIENERT, J., (editors), 998, Gas Hydrates: Relevance to World Margin Stability and climate Change. Geological Society, London, Special Publications, 37, 338. PAULL, C., and DILLON, W.P., (editors), 00, Natural Gas Hydrates: Occurrence, Distribution, and Detection. American Geophysical Union, Geophysical Monograph Series, 4, 35. 7

ΜΕΛΕΤΗ ΤΗΣ ΚΑΤΑΚΡΑΤΗΣΗΣ ΒΑΡΕΩΝ ΜΕΤΑΛΛΩΝ ΚΑΤΑ ΤΗΝ ΠΡΩΤΟΒΑΘΜΙΑ ΚΑΘΙΖΗΣΗ ΣΤΟ ΚΕΝΤΡΟ ΕΠΕΞΕΡΓΑΣΙΑΣ ΛΥΜΑΤΩΝ ΤΗΣ ΨΥΤTΑΛΕΙΑΣ Γ. Φιρφιλιώνης, Β. Παρασκευοπούλου, Γ. Βιλιώτη & Μ. Δασενάκης Πανεπιστήμιο Αθηνών, Τμήμα Χημείας, Εργαστήριο Περιβαλλοντικής Χημείας Πανεπιστημιόπολη, 577, Αθήνα, e-mail: edasenak@cc.uoa.gr ΕΥΔΑΠ, Κέντρο Επεξεργασίας Λυμάτων Ψυττάλειας Είναι γενικά γνωστή η σημασία, από περιβαλλοντική και οικολογική σκοπιά, του προσδιορισμού των επιπέδων και των μορφών των βαρέων μετάλλων που εισέρχονται στη θάλασσα. Σκοπός της παρούσας μελέτης είναι να προσδιορισθεί η ικανότητα κατακράτησης μετάλλων της πρωτοβάθμιας καθίζησης του Κέντρου Επεξεργασίας Λυμάτων Ψυττάλειας (ΚΕΛΨ). Επίσης να διερευνηθεί η κατανομή των μετάλλων σε επιμέρους μορφές (διαλυτές, σωματιδιακές) και οι αλληλεπιδράσεις-μετατροπές μεταξύ των μορφών αυτών κατά την επεξεργασία των λυμάτων. Τα μέταλλα που εξετάστηκαν ήταν: Pb, Cu, Zn, Cr, Ni. Για την έρευνα αυτή λαμβάνονταν δύο δείγματα από το ΚΕΛΨ σε μηνιαία βάση, ένα στην είσοδο της πρωτοβάθμιας καθίζησης και ένα στην έξοδο, αμέσως πριν από την είσοδο του επεξεργασμένου λύματος στον αγωγό που οδηγεί στη θάλασσα. Στην πειραματική διαδικασία περιλαμβάνονταν: διαδοχική διήθηση σε προζυγισμένους ηθμούς Millipore 8μm και 0,45μm, για διαχωρισμό του αιωρούμενου υλικού σε λεπτόκοκκο και χονδρόκοκκο κλάσμα, χώνευση των ηθμών με πυκνό νιτρικό οξύ και τελικά μέτρηση των βαρέων μετάλλων, στο διήθημα και στο προϊόν της χώνευσης, με φασματομετρία ατομικής απορρόφησης με φλόγα και φούρνο γραφίτη. Τα αποτελέσματα έδειξαν μεγάλες διακυμάνσεις στα ποσοστά των κατακρατήσεων, γεγονός που οφείλεται πιθανώς στη διαφοροποίηση των χαρακτηριστικών ποιότητας των εισερχόμενων λυμάτων. Ένας σχετικά αξιόπιστος μέσος όρος κατακράτησης είναι 30-40 %. Η κύρια μορφή των μετάλλων είναι η χονδρόκοκκη σωματιδιακή (>8μm), ενώ παρατηρήθηκε μετακίνηση μετάλλων από τη διαλυτή στη σωματιδιακή φάση. A STUDY OF THE RETENTION OF TRACE METALS DURING THE PRIMARY SEDIMENTATION OF WASTEWATER AT THE TREATMENT PLANT OF PSITALIA, SARONICOS GULF G.Firfilionis, V. Paraskevopoulou, G. Vilioti & M. Dassenakis University of Athens, Department of Chemistry, Laboratory of Environmental Chemistry, Panepistimioupoli, 577, Athens EYDAP, The Wastewater treatment plant of Psitalia The determination of the levels and forms of heavy metals discharged in seawater is important from an environmental and an ecological point of view. The aim of the present study was to determine the retention ability of the primary sedimentation at the Psitalia Wastewater Treatment Plant. Also, there was an effort to investigate the distribution of trace metals between dissolved and particulate forms, and the interactions-conversions between these forms during the treatment. The metals examined were: Pb, Cu, Zn, Cr, Ni. The experimental part of the study included: (a) monthly sampling of untreated and treated effluents at the inflow and outflow of the primary sedimentation system, (b) successive filtration of the samples through pre-weighed Millipore 8μm και 0,45μm filters, in order to separate the suspended material into two fractions, (c) digestion of the filters with concentrated nitric acid and 3

(d) determination of trace metals, in the filtrate and the digestion product, with flame and graphite furnace atomic absorption spectrometry. The results showed significant fluctuation in the retention of metals, probably due to the variation in the composition of incoming wastewater. Average retention was between 30 and 40%. The highest percentage of metals was determined in the suspended particles with a diameter of over 8 μm. We also found that the conditions in the treatment tanks favor the conversion of dissolved forms into particulate. 33

ΟΙ ΡΟΕΣ ΝΕΡΟΥ ΚΑΙ ΘΡΕΠΤΙΚΩΝ ΑΛΑΤΩΝ ΣΤΗ ΔΙΟΔΟ ΣΑΛΑΜΙΝΑΣ-ΑΙΓΙΝΑΣ Χ. Κοντογιάννης, Α. Παυλίδου & Ι. Σιώκου-Φράγκου Εθνικό Κέντρο Θαλασσίων Ερευνών, Τ.Θ. 7, 903 Ανάβυσσος Αττικής, e-mail: hk@ncmr.gr Με βάση τα χημικά δεδομένα και τις ρευματομετρήσεις κατά μήκος της διόδου Σαλαμίνας Αίγινας, εκτιμώνται οι παροχές νερού και θρεπτικών διαμέσου της διόδου σε τέσσερις εποχιακούς πλόες στο Σαρωνικό κόλπο την περίοδο 000-00. Οι ολοκληρωμένες τιμές παροχής νερού έχουν προσεγγιστικό μέγεθος ~0-30 (x0 3 ) m 3 /sec. Tην περίοδο ομογενοποίησης, όταν η ροή έχει μικρές μόνο μεταβολές με το βάθος (Δεκέμβριος 000, Μάρτιος 00) οι ολοκληρωμένες τιμές αντιπροσωπεύουν είσοδο νερού προς τον Εσωτερικό Σαρωνικό και είσοδο θρεπτικών με σημαντικότερες αυτές των πυριτικών και νιτρικών μεγέθους ~500 Μmol/yr και ~800 Μmol/yr αντιστοίχως. Την περίοδο στρωμάτωσης (Μάιος 000, Αύγουστος 000), όταν η ροή κάτω από το θερμοκλινές είναι αντίστροφη αυτής του επιφανειακού στρώματος, παρατηρείται συνολική έξοδος (~30 x0 3 m 3 /sec) προς τη Δυτική Λεκάνη κατά το Μάιο 000 και συνολική είσοδος (~0 x0 3 m 3 /sec) προς τον Εσωτερικό Σαρωνικό κατά τον Αύγουστο 000. Οι ολοκληρωμένες παροχές θρεπτικών και στις δύο αυτές περιόδους στρωμάτωσης αντιπροσωπεύουν έξοδο για όλα τα θρεπτικά με σημαντικότερες αυτές των πυριτικών (~500 Μmol/yr) για το Μάιο 000, και των πυριτικών (~700 Μmol/yr) και νιτρικών (~500 Μmol/yr) για τον Αύγουστο 000. Λόγω της ύπαρξης μαιανδρισμών στην κυκλοφορία, συχνά οι μεταφορές νερού ή θρεπτικών οφείλονται σε επανακυκλοφορία στην περιοχή της διόδου και όχι σε καθαρή ανταλλαγή μεταξύ του Εσωτερικού Σαρωνικού και της Δυτικής Λεκάνης. THE WATER AND NUTRIENT FLUXES THROUGH THE SALAMINA-AEGINA PASSAGE IN THE SARONIKOS GULF H. Kontoyiannis, A. Pavlidou & I. Siokou-Frangou National Centre for Marine Research. P.O. Box 7, 903 Avavyssos, Attica Based on chemical data and ADCP current measurements along the Salamina -Aegina section, the water and nutrient fluxes through the section are estimated during four seasonal cruises in the Saronikos Gulf in 000-00. The section-integrated values of water transport range in general between 0-30 (x0 3 ) m 3 /sec. During winter (December 000, March 00), when the flow is barotropic, there is a net water and nutrient transport towards the Inner Saronikos Gulf. The most important nutrient fluxes are those of silica and nitrate of approximate magnitude ~500 Μmol/yr and ~800 Μmol/yr respectively. In the stratification period (May 000, August 000), when the flow under the pycnocline is reversed with respect to the flow of the upper layers, there is a net outflow (~30 x0 3 m 3 /sec) to the west sub-basin in May 000 and a net inflow (~0 x0 3 m 3 /sec) towards the Inner Gulf in August 000. The nutrient fluxes in both the May and August cruises show a net outflow to the west for all nutrients; the most important of them are those for silica, of ~500 Μmol/yr in May 000 and of ~700 Μmol/yr in August 000, and for nitrate of ~500 Μmol/yr in August 000. Due to closed loops and meandering in the circulation, the water and nutrient transports are often influenced by re-circulation in the Salamina-Aegina passage and they do not represent a net exchange between the Inner Saronikos and the west sub-basin. 34

EΠΙΔΡΑΣΗ ΤΟΥ ΑΓΩΓΟΥ ΛΥΜΑΤΩΝ ΤΗΣ ΨΥΤΤΑΛΕΙΑΣ ΣΤΟ ΙΣΟΖΥΓΙΟ ΟΡΓΑΝΙΚΟΥ ΑΝΘΡΑΚΑ ΤΟΥ ΕΣΩ-ΣΑΡΩΝΙΚΟΥ ΚΟΛΠΟΥ. ΠΡΟΚΑΤΑΡΚΤΙΚΗ ΕΚΤΙΜΗΣΗ Χ. Ζέρη & Χ. Κοντογιάννης Εθνικό Κέντρο Θαλασσίων Ερευνών, Τ.Θ. 7, 903 Ανάβυσσος Αττικής, e-mail: chris@ncmr.gr Στην παρούσα εργασία επιχειρείται μια πρώτη προσέγγιση υπολογισμού του ισοζυγίου οργανικού άνθρακα στον έσω-σαρωνικό κόλπο. Οι υπολογισμοί βασίζονται σε δεδομένα συγκεντρώσεων ολικού οργανικού άνθρακα (TOC) κατά τη διάρκεια δύο μηνών (Αύγουστος 000 και Μάρτιος 00) στην εν λόγω περιοχή. Επίσης λαμβάνονται υπόψη οι εισροές TOC από τον αγωγό λυμάτων της Ψυττάλειας κατά την αντίστοιχη χρονική περίοδο. Οι ανταλλαγές με τον υπόλοιπο Σαρωνικό κόλπο στηρίζονται στις ρευματομετρήσεις των αντίστοιχων χρονικών περιόδων. Οι υπολογισμοί συμπληρώνονται από βιβλιογραφικά δεδομένα σε ό,τι αφορά τις εισροές οργανικού άνθρακα από τα ιζήματα και τη βροχή. Τόσο τον Αύγουστο του 000 όσο και το Μάρτιο του 00 φαίνεται ότι οι εισροές TOC στον έσω-σαρωνικό υπερτερούν των εκροών (ΔTOC:.7 ktonnes C /month και 0.96 ktonnes C /month αντίστοιχα), δηλαδή δεν γίνεται εξαγωγή οργανικού άνθρακα προς τον ευρύτερο Σαρωνικό κόλπο. Αυτό το αποτέλεσμα υποδεικνύει ότι στον έσω-σαρωνικό κόλπο έχουμε έλλειμμα οργανικού άνθρακα και στις δύο περιόδους που μελετήθηκαν, που σημαίνει ότι στην περιοχή γίνεται κατανάλωση του οργανικού άνθρακα και ενισχύονται οι ετερότροφες διεργασίες. Γενικά τα αποτελέσματα έδειξαν ότι η παρουσία του αγωγού λυμάτων της Ψυττάλειας δεν παίζει ιδιαίτερα σημαντικό ρόλο στο ισοζύγιο του οργανικού άνθρακα του έσω- Σαρωνικού κόλπου. EFFECT OF THE PSITTALIA SEWAGE OUTFLOW ON THE ORGANIC CARBON BUDGET OF THE INNER SARONIKOS GULF. PRELIMINARY APPROXIMATION C. Zeri & H. Kontoyiannis National Centre for Marine Research. P.O. Box 7, 903 Avavyssos, Attica In this work we report a first approximation of the organic carbon budget in the inner Saronikos gulf. The calculations are based on total organic carbon (TOC) data obtained during August 000 and March 00 in the area. TOC inputs from the Psittalia sewage outflow, during the same period, are also taken into consideration. The exchange flows with the outer Saronikos gulf are based on both TOC data and the corresponding water flows as measured during the two periods. Supplementary data from the literature are used concerning organic carbon fluxes from the sediments and rain. During both study periods TOC inputs to the inner Saronikos gulf were found greater than the outputs (ΔTOC:.7 ktonnes C /month in August 000 and 0.96 ktonnes C /month in March 00). This finding suggests that there is no organic carbon export towards the outer Saronikos gulf, but on the contrary there is an organic carbon deficit during both study periods, i.e. organic carbon consumption and heterotrophic processes are enhanced. Moreover, our results showed that the Psittalia sewage outflow does not play an important role in the organic carbon budget of the inner Saronikos gulf. 35

ΣΥΓΚΡΙΤΙΚΗ ΜΕΛΕΤΗ ΟΠΤΙΚΩΝ ΚΑΙ ΣΥΜΒΑΤΙΚΩΝ ΜΕΘΟΔΩΝ ΔΕΙΓΜΑΤΟΛΗΨΙΑΣ ΦΥΤΟΒΕΝΘΟΥΣ ΣΚΛΗΡΟΥ ΥΠΟΣΤΡΩΜΑΤΟΣ: ΠΡΟΚΑΤΑΡΚΤΙΚΑ ΑΠΟΤΕΛΕΣΜΑΤΑ ΑΠΟ ΤΗΝ ΠΕΡΙΟΧΗ ΤΟΥ ΣΑΡΩΝΙΚΟΥ ΚΟΛΠΟΥ Μ. Σαλωμίδη & Π. Παναγιωτίδης Εθνικό Κέντρο Θαλασσίων Ερευνών, Τ.Θ. 7, 903 Ανάβυσσος Αττικής, e-mail: msal@ncmr.gr Η ανάγκη για άμεση και ταχεία εκτίμηση της οικολογικής ποιότητας των ακτών εμφανίζεται ολοένα και πιο επιτακτική στον τομέα της θαλάσσιας βιολογίας. Το βασικό πλεονέκτημα ανάπτυξης και εφαρμογής τέτοιων μεθόδων είναι η δυνατότητα ποιοτικών και ποσοτικών δειγματοληψιών σε μεγάλα χωρικά και σύντομα χρονικά διαστήματα. Με στόχο τη σύγκριση αποδοτικότητας μεταξύ των δύο μεθόδων, πραγματοποιήθηκε δειγματοληψία μακροφυτοβενθικών πληθυσμών της ανώτερης υποπαράλιας ζώνης (0,5-,0 μέτρα βάθος) με τη χρήση τόσο συμβατικών (καταστροφικών) όσο και οπτικών (φωτογραφικών) τεχνικών. Τέσσερις σταθμοί δειγματοληψίας επιλέχθηκαν κατά μήκος μίας διαβάθμισης ρύπανσης στο Σαρωνικό κόλπο, από την εκβολή του αγωγού της Ψυττάλειας (στον εσωτερικό Σαρωνικό) έως την περιοχή του Αγίου Νικολάου Αναβύσσου (στον εξωτερικό Σαρωνικό). Η ανάλυση των δειγμάτων έδειξε ότι η απώλεια ταξινομικής πληροφορίας από τη φωτογραφική μέθοδο δεν υπήρξε ανασταλτικός παράγοντας για την ορθή εκτίμηση της οικολογικής ποιότητας του παράκτιου περιβάλλοντος, καθώς η αναγνώριση των φυτοβενθικών πληθυσμών ακόμη και σε επίπεδο λειτουργικής ομάδας φάνηκε να είναι εξίσου διαφωτιστική με την αναγνώρισή τους σε επίπεδο είδους. A COMPARATIVE STUDY BETWEEN VISUAL AND DESTRUCTIVE SAMPLING METHODS ON HARD BOTTOM PHYTOBENTHOS: PRELIMINARY RESULTS FROM THE SARONIKOS GULF M. Salomidi & P. Panayotidis National Centre for Marine Research. P.O. Box 7, 903 Avavyssos, Attica Developing rapid bio-assessment techniques is becoming a major common goal in the field of marine biology. 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. In this study both destructive and non-destructive (photographic) samplings were performed on macrophytobenthic populations of the upper infralittoral zone (between 0.5 and m depth) in order to compare and inter-calibrate these two methods. Four sampling stations were chosen along a pollution gradient from the Inner Saronikos Gulf (near the sewage discharge of the treatment plant) to the Outer Saronikos Gulf (a putatively unimpacted site). Data analysis showed that, in terms of Ecological Status Evaluation, the loss in taxonomic information by the photographic method did not correspond to loss of ecological quality information, and that identification to the functional group level could be quite as informative as identification to the species level. 36