| ||N° 38 - July 2003|
| MEDITERRANEAN – BLACK SEA - Europe's troubled seas
The Mediterranean's delicate health has long been at the centre of European environmental research. The Black Sea has not been ignored either and has been the subject of a number of studies and remedial measures. Now, with the approaching accession of Romania and Bulgaria (planned for 2007), the European Union will land itself an extensive shoreline along this landlocked sea, which is in a particularly critical state. The IASON initiative, launched in the spring of 2003 at a major scientific conference under the Greek presidency, aims to set up transnational and multidisciplinary co-operation networks to treat and protect these two crucially important maritime basins.
A fast-growing population
Time is short. These two seas which form Europe's southern border are currently undergoing radical change. In addition to their relatively small size, they also have the common characteristic of being virtually landlocked, with the Straits of Gibraltar, the Dardanelles and the Bosphoros considerably impeding water circulation.
This is exacerbating the effects of a rapidly expanding population. 'In the 1960s, the population of the countries bordering the Mediterranean was 246 million. Today it is over 450 million,' points out Michael Scoullos of Athens University, who is also secretary of the Office for Information on the Mediterranean (MOI-ECDSE). 'Then there is the seasonal influx of tourists to be taken into account, totalling some 150 million. All the forecasts indicate that these figures are set to increase further.'
Half of the 25 000 km Mediterranean coastline is already heavily urbanised. The water treatment stations built in response to this population increase are often too old and too small, and not all coastal inhabitants are connected to them. Moreover, the impact of humanity on the marine environment is growing all the time – partly due to technological progress.
'The transnational and multidisciplinary environmental problems of the Black Sea and Eastern Mediterranean have not yet been assessed in an integrated way, one taking advantage of all the existing data and liaising with existing efforts,' says Achilleas Mitsos, director-general of research at the European Commission. 'Such an integrated approach could lead to solutions, policy actions and proposals for long-term strategies for sustainable development.'
There is also the question of air pollution – which is often under-estimated when speaking of the sea – generated by cars, household waste incinerators, industry, and so on. '[The] impact is, however, concentrated in the air masses of coastal areas and exchanges between these and surface waters. This phenomenon is exacerbated by the absence of tides, which greatly reduces the mixing effect,' notes Alexandros Theoharis of the Greek National Center for Marine Research. 'The concentration gradients, as well as pH gradients, for various molecules are, therefore, very intense, with marked consequences on marine biocenoses.'
The sea itself is now being used more intensively than ever before. There has been a major increase in sea transport, especially of hydrocarbons, which can cause such devastating and lasting pollution. Every year 100 000 tonnes of hydrocarbons pass through the Black Sea alone. Fishing fleets are having a greater impact too, even if the number of vessels has remained virtually stable. Fish farming has also expanded considerably, and this too will have major ecological repercussions.
The combined effect of this environmental pressure is that a number of sustainability indicators are now on maximum alert. A high and increasing mortality rate among marine animals in the Black Sea, for which there is as yet no clear explanation, has been observed over the past three decades, with losses estimated at tens of millions of tonnes.
Fish catches have plummeted by 80% in recent years and, of the 26 species previously fished commercially, only six remain in sufficient numbers. At the same time, populations of jellyfish and other gelatinous animal species have increased significantly, probably due to eutrophication and/or the accidental introduction by ships of foreign species.
Reduced catches have also been recorded in the Mediterranean for more than a decade. 'What is more, the overfishing of large carnivorous species has upset the structure and functioning of the ecosystem. At many locations, fisheries are now obliged to make do with smaller varieties which are more sensitive to environmental variations,' points out Jacques Bertrand of the French Institute for Marine Research (IFREMER).
These major changes to the Mediterranean ecosystem are all the more worrying as it is a sea with a high level of endemism (the presence of exclusively local and, hence, irreplaceable species). The Mediterranean represents just 1% of the world's seas but contains 7.5% of all aquatic species. Among the various indicators of disturbed ecological balances, there is a clear trend towards 'tropicalisation' as many species from warmer waters are proliferating to the point where they are threatening their indigenous cousins, whether plants (such as the famous predatory seaweed Caulerpa taxifolia), molluscs, shellfish or other types of fish. This worrying and complex phenomenon is probably due to the combined effect of inflows of water and increased shipping traffic through the Suez Canal and the Straits of Gibraltar, and may be further exacerbated by global warming.
Most of the processes at work – and consequently the possible solutions – are transnational and require multidisciplinary approaches. This explains the range of expertise represented at the IASON conference, where oceanologists and climatologists rubbed shoulders with specialists in biology, marine genetics, fishing, economics and modelling. The gathering drew scientists from throughout the Union, as well as delegates from Albania, Croatia, Russia, Turkey, Georgia, Bulgaria, Egypt, Cyprus, Romania, Ukraine, Israel and the United States. It is only through such a spirit of co-operation that a sustainable future for these two precious seas can be achieved.
Making data accessible
A mass of oceanographical data has been gathered over the years by scientists working on the Mediterranean and Black Sea. A recent project (MEDAR/MEDATLAS) – supported by institutions in 20 countries, the European Commission and UNESCO – has now made readily available a large proportion of this data in the form of an easy-to-use database, available through the Internet or in the form of four CD-ROMS. This usefully supplements the multidisciplinary database previously compiled by the MTP/MATER, an EU-backed project studying the Mediterranean. MEDAR/MEDATLAS provides high quality data sets, based on extensive sampling of parameters such as temperature, salinity, dissolved oxygen, pH, as well as ion concentrations.
This impressive information source includes maps, graphs and diagrams, all accessible free of charge. The database is updated continuously and extended regularly to include new factors and parameters.
The waters of the Mediterranean are naturally poor in nutrients and, thus, in algae, which is why they are so blue and transparent. But the results of the EU-backed Interpol project suggest that this equilibrium is now being seriously upset in certain places by human waste with its high density of phosphate, nitrate and other nutrients. This waste – originating in the leaching of agricultural fertilisers and the inflow of urban or industrial waste water – is causing eutrophication reflected in the intense development of unicellular algae and the micro-organisms which feed off them. In deeper waters, it is causing disoxygenation.
These changes are impacting on the ecosystem as a whole, sometimes resulting in the virulent proliferation of certain species of planktonic algae which produce 'red tides' (or tides of other colours depending on the species of plankton). These proliferations can be viscous and foul smelling, with disastrous effects for regions where beach tourism is a source of vital revenues. They can even be toxic, causing high mortality among marine species. Several European research projects, such as FATE, are trying to understand the mechanism at work in these proliferations and, in particular, the nutrient thresholds at which they are triggered.
Eutrophication is even more of a problem in the Black Sea than in the Mediterranean, especially in the north-west corner into which water flows from the 'four Ds': the Danube, Dnieper, Dniester and Don. For its size, the Black Sea is the final destination for a very large volume of human, agricultural and industrial waste. Algal blooms are frequent, intense and extensive, resulting in acute disoxygenation, which causes high mortality among shellfish and benthic molluscs. A number of marine species have disappeared, while the proliferation of jellyfish and Noctiluca scintillans (a type of plankton) has worsened what is already a seriously disrupted ecosystem. Fortunately, some easing of the effects of eutrophication has been observed recently.
The sustainable management of marine resources is a delicate art. Fish farming – often presented as an alternative to overfishing – requires vast quantities of fish meal. In addition, uneaten food debris and excrement build up around the breeding enclosures and can place a considerable burden on the surrounding ecosystems.
The sustainable management of fishing means defining exactly what catches a given stock can support. This must be based on a complex series of demographic indicators –population size, age pyramid, number of reproducers, etc. This requires a major scientific monitoring exercise. The creation of fishing reserves as a tool of stock management involves a judicious choice of location, geographical limits and the implementation of precise rules.
These are all challenging tasks for researchers whose opinions are often questioned by professionals.
The biodiversity capital
It is difficult to put a monetary value on marine biodiversity, although research is looking into possible ways of doing so. One example of the economic importance of this natural 'capital' is the vast numbers of species of bacteria, known as thermophilic or hyperthermophilic, which are able to live at temperatures of over 100°C and which are now the subject of close study. These bacteria live in hydrothermal springs and the molecules found in their metabolism can withstand temperatures which are incompatible with the functioning of ordinary biological processes.
Some of these molecules – enzymes, sugars, antiseptic or antifungal agents – are thermostable which makes them of great interest to industry, especially the paper, detergent, agri-foodstuffs and textile industries. Research into these fields has resulted in many products which are already commercially available.