MARBENA e-conference on Baltic Sea marine biodiversity (June 2003)
Topic 3: "Where is the 'Cutting Edge Science' in the Baltic marine biodiversity?"
Author: Prof. Erik Bonsdorff, Environmental and Marine Biology, Abo Akademi University, Finland
Dear colleagues,
"Marine Biodiversity" has been given many definitions, fitting the purposes of a variety of prerequisites for research and/or understanding of the problem. For the scientific scene around the Baltic Sea, this is a critical issue, as this non-tidal, low-saline brackish water basin in so many ways differs significantly from most other marine systems in the world. In fact, referees for international journals still tend to question the justification in publishing results from the Baltic Sea in the top ranked journals, as they claim these "lack generality within marine research" (quotation from referee statement in May 2003). Scientists within the Baltic Sea system have traditionally responded to the outside scientific world in two ways: (i) keeping to themselves, and presenting their data and knowledge within the Baltic marine science community at specially dedicated symposia and workshops published as separate proceedings-volumes, and (ii) by primarily testing general hypotheses utilizing the specific (species-poor) characteristics of the Baltic biota to validify or develop our (marine) ecological thinking, thus gradually increasing the awareness and knowledge of the Baltic Sea, as a valuable model for general (global) marine ecology and biology. The first approach was vital in the strive to encompass the (former) eastern Baltic countries into the family of (western) research, and also in the work to map, monitor and ultimately improve the ecological state of the heavily impacted Baltic Sea ecosystem. For this purpose the Helsinki Commission for the Protection of the Baltic Sea (HELCOM) was started already some 30 years ago (see: http://www.helcom.fi). Subsequently HELCOM has published a large number of assessment reports of the environmental state, and this effort has been of paramount importance for our current knowledge and understanding of the Baltic Sea as an ecosystem, also form a biodiversity-point of view. Similarly, the (sometimes small-scale) experimental approaches by individual scientists (or groups of scientists) working with both planktonic and benthic ecosystems has gained international recognition of the species-poor Baltic Sea as a perfect natural laboratory for the developing marine biodiversity paradigms, and it is my conviction that both these approaches have been equally important for our currently broad and detailed knowledge. Today much of our efforts are pooled through EU-financed projects, involving partners from all around Europe, and it is self-evident that we compare our marine ecosystem to any other on equal terms (perhaps at the cost of loosing individual creativity?).
This relatively simple system (low species numbers, few species per ecological function) offers ample opportunities to study and analyse functional aspects of biodiversity, linking population-, community- and systems-ecology. Further, numerical modelling including also biological effect parameters can be done at a reasonably accurate level. Thus, there is every reason for us to promote and conduct marine biodiversity research in the Baltic Sea.
There are to my mind some factors that should be kept in mind when tackling the biodiversity of the Baltic Sea, and I hope these issues will be discussed during this MARBENA e-conference on marine biodiversity: 1) the post-glacial history of the Baltic Sea: the system is young on geological, evolutionary and ecological time scales, and natural succession has not yet reached a level of "dynamic equilibrium" with immigration and extinction rates balancing each other, 2) the extremely steep environmental gradients from south (fully marine, no ice cover in winter etc) to north (almost limnic, arctic ice conditions annually, etc) reduce the number of potential natural immigrants, keeping numerical diversity low, 3) the enclosed status of the sea, with marine inflow (and hence species recruitment) only through the Danish straits: The distance from the potential species pool (currently the North Sea and Skagerrak) with its specific conditions to the inner Baltic Sea, is long and hazardous, including problems with salinity-and hypoxia-gradients. The potential glacial immigration corridor(s) from NE (the White Sea) could be considered in terms of genetic similarity and geological history. Also, potential historic "ecological refugia" offer an interesting approach (why arae some populations "Baltic"; why are some genetically close to the White Sea biota, etc), 4) current inflow of "alien" species aided by man breaking down the structures and functions evolved during the past 8500 years: some 100 introductions (ranging from unicellular planktonic species to coastal mammals) have been recorded, but perhaps only 30% of these have actually established themselves with self-sustaining populations, and little is known on actual effects on biodiversity (increasing species composition and ecosystem functioning; no known extinctions caused by these "invaders"), with the possible exceptions of highly pre-stressed environments, such as harbors and some semi-enclosed embayments or lagoons, 5) the anthropogenic environmental stress on the system, where climate change and eutrophication are the overshadowing factors, with over-fishing, transport of hazardous substances, traffic, physical modifications of (primarily coastal) habitats and habitat fragmentation, toxic substances in the environment and in the organisms etc, as very important additional stressors.
Against these aspects, it is evident that the successional patterns that during the past millennia have lead to the ecosystem structure and function described around the mid 20th century, have been radically interferred with, causing problems for the biota of such a magnitude that it is safe to say that the marine biodiversity (species composition and their functioning) is changing at a far higher ratio than could be anticipated purely based on the successional history of the Baltic Sea ecosystem.
In this respect it is vital that scientists from all countries and political systems bordering our common Baltic Sea are given the same premises and platforms to work from in order to further our knowledge of this delicate ecosystem |
