Altogether 18 scientists participated in the discussions concerning Topic No 1: L. Ignatiades, J. M. Weslawski, S. Cornell, I. Sousa Pinto, M. A. Kendall, T. Radziejewska, V. Panov, H. Ojaveer, E. Karasiova, F. Boero, M. Szymelfenig, L. Stempniewicz,E. Wlodarczyk, E. Bonsdorff, D. Uzars, L. Postel, K. Jadzewski, J. Morozinska-Gogol

As described in the opening statements, the participants addressed the ecosystem of the Baltic Sea as an unique young brackish-water species-poor system, which involves a number of subsystems. To improve the biodiversity assessments and include all habitats of different ecosystem components, it was proposed to carry out studies on transects starting from the shallow coastal zone to the deep parts of every subsystem (H. Ojaveer, K. Jadzewski). The leading role of taxonomy in the biodiversity research was strongly stressed (K. Jadzewski, L. Ignatiades, M. Szymelfenig, L. Stempniewicz, F. Boero). The importance of continuation and improvement of the quality of the long-term data sets for the investigation of the Baltic ecosystem was indicated by L. Postel. The influence of ecological factors (functional aspects of biodiversity) were suggested to be taken into consideration in the biodiversity assessments (D. Uzars, E. Bonsdorff).

The second part of the topic provoked an animated discussion that lasted up to the final comments. L. Ignatiades, J. M. Weslawski, S. Cornell, K. Jadzewski, I. Sousa Pinto, M. A. Kendall, T. Radziejewska, V. Panov, and F. Boero contributed to the discussions. It was confirmed that important data on the Baltic Sea systems exist published in languages other than English, or unpublished. The problem could be divided into two parts:

1. The data on the biota in the Baltic Sea have been published for more than one and a half centuries. A number of works by S. Segerstrale, K. Demel, W. Mankowski and other well-known scientists contain basic information on the ecosystems. They were mainly written in the so-called non-Congressional languages. Also, e.g. a very important monograph by the late A. Jarvekulg, published in Russian, and a number of similar other works belong to such literature, as during the Soviet occupation publication in other languages was almost out of question.
   In certain fields serious scientific work is not possible without using earlier publications. Correct evaluation of changes in the Baltic ecosystems needs expertise in the usage of historical data for comparison. As up to now this expertise has included knowledge in some languages, then not all scientists have been in the position for drawing valid conclusions in this very important section of science.
   Therefore, a more balanced attitude towards the literature sources, published in the languages other than English, would be justified. The sources should not be evaluated on the basis of the languages they are published in, but by the value of their scientific content. It would be beneficial if the most important publications of the past could be made available for a wide scientific community.
2. The involvement into the general databases of scientific data from the unpublished or recently published sources of the Baltic east-coast countries is of substantial importance. In this process plagiarism should be avoided. The main practical suggestions:
   1. the publication (in English) of the data by the data-owners should be encouraged;
   2. the data should be exploited and published in the framework of scientific collaboration.

Evald Ojaveer has clearly summarized our discussion in Topic 1, so just few words from my side.
An answer to the question - What is the Baltic contribution to the European marine biodiversity ? - would be : Baltic Sea is an interesting, unique and therefore worth studying example how the marine biodiversity decreases along the salinity gradient - first very steep in Kattegat and Danish straits, then, in the Baltic proper, rather slowly reaching oligohaline/freshwater state in the innermost bays and lagoons. Quite recent (last 2 decades) invasions of alien, mostly Ponto-Caspian, but also North American species, especially in the Baltic lagoons (mass occurrence of Pontogammarus, Obesogammarus, Gammarus tigrinus), but also in more open waters (Marenzelleria, Neogobius, Cercopagis) deserve special attention and monitoring - we still do not know the level of ecological impact of these newcomers, however we can expect that it may be a serious one.

I would hesitate to answer the second question - What is the marine diversity knowledge in NAS countries?
In my opinion this knowledge is not bad, but also not satisfactory. I think that we need to create a solid databases, at least for several better known Baltic sub-basins (like, for instance Gulf of Riga or Bay of Puck). These databases would encompass both the names of species ever recorded in such a basin, as well as the references dated as far back as possible and published in any possible "Baltic language".

Finally I wish to thank all colleagues for their contribuions. I was really pleased to hear so many advocates of the importance of taxonomy for other branches of the biology. I think that it is really a good idea to use the EU-FP-6 framework programme (for instance Marie Curie actions) for special courses training people in taxonomy (determination) of particular animal (and plant) groups.

With many greetings
Krzysztof Jazdzewski

Jonne Kotta, Andrzej Witkowski and Brygida Wawrzyniak-Wydrowska opened the topic with an introduction discussing the role of physical and biological factors on the dynamics of the Baltic Sea ecosystem at various temporal and spatial scales. It was pointed out that besides eutrophication, biological pollution significantly affects the diversity of the Baltic Sea. It was concluded that although the Baltic Sea is considered the most studied sea area in the world, the majority of evidence about various processes is circumstantial. Our knowledge is based on the spatial distribution or temporal trends of the biota whereas the experimental studies are in minority.

Main topics of the discussion were as follows:

• Physically controlled biodiversity in Baltic as contrast to biologically controlled in full saline seas
• Sea of change (more saline and fresher periods) - consequences to biodiversity
• Availability of results from archival and paleo-oceanography research
• What is the role of alien and invasive species?
• How much the Baltic biodiversity depends from external driving forces - the role of global dimensions?
• Long-lasting eutrophication and its consequences to biodiversity.
• What is the role of other uses of the sea?

Erik Bonsdorff pointed out that the Baltic Sea is under the continuous change and therefore it is not possible to describe the typical biota of the Baltic. Nevertheless the rationale of protecting the biota of the Baltic Sea is due to the following considerations: uncertainly of the future, ethic obligations towards our surrounding environment, including its inhabitants, and we do not know how a completely altered food web will function, i.e. we run the risk of loosing our own food source by disrupting the ecosystem.

Jonne Kotta provided the example that the relationship between the nutrient load and the state of biota is not necessarily straightforward. As an example, prior to the 1990s the Gulf of Riga was strongly influenced by municipal and agricultural discharge. Following the economic recession of the Baltic States in the 1990s the intensity of agriculture and consequently the nutrient content in the basin have substantially reduced (Suursaar, 1995). Following the improvement of the water quality in the Gulf of Riga, the mass development of the benthic filamentous macroalgae and the formation of the drift algal mats were observed (Kotta et al., 2000). Despite of the signs of improvement in terms of nutrient load we are fully aware that the Gulf of Riga is still more polluted basin than the Baltic Sea on average. Hence, the changes are likely reflecting the instability of ecosystems due to the abrupt changes in the nutrient levels.

Henn Ojaveer stressed that alien species are an important component of the Baltic food-web at various trophic levels (e.g., phytoplankton, zooplankton, zoobenthos, fish). It means that human activities continuously play very important role in evolution of the Baltic biota. Hence, it is difficult to agree with the statement that 'the biodiversity in the Baltic Sea is primarily controlled by historical and abiotic factors, that man can do very little about!'. Alien species have caused biodiversity increase in the Baltic Sea. There are many examples showing how alien species have changed composition of the Baltic biota (e.g., Leppäkoski et al. 2002; Ojaveer et al. 2002).

Erik Bonsdorff argued that the discussion about the effect of alien species on the structural or functional biodiversity of the Baltic Sea bases on no scientific knowledge. That was also noted by Jonne Kotta who stressed that the majority of evidence about various processes in the Baltic Sea (including the effect of aliens) is circumstantial and despite of that much is talked about the significant effects of alien species on the ecosystem functioning. There exist only a few exceptions where the impacts of aliens on the native communities were experimentally studied (e.g. Kotta et al., 2001; Panov et al., 2002; Kotta & Òlafsson, 2003).

Henn Ojaveer argued that several case studies confirm that some species (e.g., Marenzelleria viridis, Cercopagis pengoi, Neogobius melanostomus) continue to increase in population size and by colonising new areas continue to cause declines in distribution area and population size of native species. As more alien species are expected to be transported into the Baltic, more profound impacts are to be predicted. However, which species is the next to come is almost impossible to say as such predictions (made in other regions) have generally failed. The same is valid for the potential ecological impacts caused by alien species - these are often unpredictable both in magnitude and direction. But what should be agreed with the above statement by Andrzej Witkowski in terms of alien species is that abiotic factors certainly also control the Baltic xenodiversity (=alien species diversity) allowing successful establishment of species tolerating changeable brackish-water environment.

Ewa Wlodarczyk was concerned about the increased diversity of the Baltic Sea caused by the successful invasion of non-indigenous species. In this respect the Baltic again confirmed its uniqueness by using to its advantage what is considered a world wide threat to biodiversity, i.e. non-native species. Nowadays, an increased (or at least conserved) biodiversity seems to be one of the major aims of an ecosystem-based approach to the management of human activities. Hence, there is a need to weigh the financial burden of ballast water treatment against the "slight" danger (or even benefit?) of invasion by alien species. Vadim Panov reported the negative effects of alien species in the Baltic Sea coastal waters, including replacement of native species (i.e. the decline of the native diversity) (Panov et al., 2002).

Finally Ferdinando Boero suggested that comparing the Baltic and the Mediterranean is a very profitable exercise as a low-diversity basin and a high-diversity basin should respond differently to biological invasions? He believes that it is time to synthesise all this knowledge and start to make comparisons.

Papers cited by the participants

Kotta, J., Ólafsson, E., 2003. Competition for food between the introduced exotic polychaete Marenzelleria viridis and the resident native amphipod Monoporeia affinis in the Baltic Sea. J. Sea Res. (in press)
Kotta, J., Orav, H., Sandberg-Kilpi, E. 2001. Ecological consequence of the introduction of the polychaete Marenzelleria viridis into a shallow water biotope of the northern Baltic Sea. J. Sea Res., 46, 273-280.
Kotta, J., Paalme, T., Martin, G., Mäkinen, A. 2000. Major changes in macroalgae community composition affect the food and habitat preference of Idotea baltica. Internat. Rev. Hydrobiol., 85, 693-701.
Leppäkoski, E., Gollasch, S., Gruszka, P., Ojaveer, H., Olenin, S. and Panov, V. The Baltic - a sea of invaders. Canadian Journal of Fisheries and Aquatic Sciences, 59: 1209- 1228.
Ojaveer, H., Leppäkoski, E., Olenin, S., and Ricciardi, A. 2002. Ecological impacts of Ponto-Caspian invaders in the Baltic Sea, European inland waters and the Great Lakes: an inter-ecosystem comparison. In (eds. E. Leppäkoski, S. Gollasch and S. Olenin) Invasive Aquatic Species of Europe: Distribution, Impacts and Management. Kluwer Scientific Publishers, Dorthrecht, The Netherlands, pp. 412-425.
Panov V.E., A. F. Alimov, S. M. Golubkov, M.I. Orlova, I.V. Telesh 2002. Environmental problems and challenges for the coastal zone management in the Neva estuary (eastern Gulf of Finland). In: G. Schernewski & U. Schiewer (eds.): Baltic Coastal Ecosystems: Structure, Function and Coastal Zone Management. CEEDES-Series, Springer Publ., Berlin, 171-184.
Suursaar, Ü. 1995. Nutrients in the Gulf of Riga. In Ecosystem of the Gulf of Riga between 1920 and 1990 (Ojaveer, E., ed.), pp. 41-50, Estonian Academy Publishers, Tallinn.

Below you can find a few general remarks/conclusions referring to some plots of discussion on topic three.

[1] "All men by nature desire to know." (Aristotle, Metaphysics, Book I, Part 1) The man desires to understand the biotic and abiotic nature, i.e. not just to know "how it is" but also "why it is". He desires to know it not necessary for some utilitarian ends or any other advantages. The man wants to know truth.

[2] In order to develop properly (in the biological, psychological, intellectual, and spiritual sense) we - human beings - need "diversity": the different living forms in our surroundings, the differentiated landscapes, the starry sky, ..... We need the Baltic Sea with its lower number of species and biota, and the Mediterranean Sea with its higher number of species and biota.

[3] We cannot judge a priori or arbitrarily on the importance of a given living form for biocenosis (i.e. for community of organisms) or ecosystem. Before we undertake decision "to protect" or "leave unprotected", "to introduce" or "reintroduce" a given species, "to change" or "not to change" its habitat, we must learn this living form - its niche, its adaptive potential, its relation to other organisms, etc.

[4] We are trying to know and to protect concrete living forms and their habitats. Actually we do not observe, monitor and protect the so called "functional groups" - but we do observe living forms. The so called "primary producers", "consumers", "decomposers", "semi terrestrial detriphagous", etc. are just mental abstracts, i.e. a kind of intellectual "tools". They are quite useful in conceptualization and arrangement of our knowledge. But the primary object of our study is life - in its various, fascinating forms.

[5] We have to study biodiversity, i.e. diversity of living forms, inhabiting different environments. In our research we should not ignore the developmental and adaptive potential of a particular living forms. In our work we should not become discouraged because our publications, our papers are not always impressive in terms of impact factor or because our investigations are not "fitting" to the currently trendy topics. I repeat - we are pursuing science in order to know, and not necessary for any utilitarian end. We do not seek knowledge only for the sake of any other advantage, but the joy of knowing the truth, the beauty and the goodness of nature.

Jolanta Koszteyn

Dear MARBENA colleagues,

I wish to apologize for not having played an active role in the MARBENA e-Conference. During the conference I was traveling along the Baltic coast aboard the M/S Ocean Monarch taking part in a symposium entitled The Baltic Sea - Common Heritage, Shared Responsibility, which was organized under the auspices of the Religion, Science and Environment program of the of Metropolitan of Constantinople, HAH Bartholomew. This initiative was related to the protection of God's creation - the Baltic Sea. The message from this symposium to MARBENA can be paraphrased by the symposium title BIODIVERSTY - Common Heritage, Shared Responsibility.

Just by chance, this symposium coincides well with Topic 4 of our e-Conference (The socioeconomic and cultural dimension and conservation status of marine biodiversity in the Baltic Sea). The public, as well as decision makers, should be thinking about why biodiversity is our common heritage. What does shared responsibility mean in practice? Decision makers should be advised on how to protect and manage biodiversity, if, indeed, biodiversity can be managed at all. Let me raise some issues in the form of questions (even if we know the answers). Who, if not scientists, should teach the public and decision makers about biodiversity and what humankind's relationship with it should be ? Who, if not scientists, should provide scientific advice to managers on how to conserve and manage biodiversity? We all know the answers: scientists have other duties than just research. Biodiversity has many other dimensions than just scientific (Oksanen 1997), and it is the responsibility of scientists to bring these to the attention of the public and decision makers.

From my experience with HELCOM EC NATURE (presently HELCOM HABITAT) and HELCOM BMP (presently HELCOM MONAS), it appears that scientists are not really capable of, or perhaps even interested in providing adequate advice to managers on how to protect biodiversity. Questions such as how to monitor and asses biodiversity remain essentially unanswered, and they must be answered by scientists. It must also be borne in mind that only limited financial resources are available for research and monitoring and that decision makers have limited time available for reading scientific advice. No manager has the time to read scientific papers and reports, and this is why they keep requesting simple, indicative reports.

Therefore, I will repeat what I said in the opening statement: "A number of practical questions are to be answered in relation to the preservation of biological diversity in the Baltic Sea and in fulfilling the BD Convention. They should be considered within the context of existing international organizations and ongoing monitoring and research programs. Thus, it is the duty of scientists to develop appropriate science-based tools for the assessment of biodiversity and to offer them to managers".

Finally, in view of the establishment of a new ICES Study Group on the Ecosystem Health of the Baltic Sea, I am personally interested on how to use biodiversity as an indicator of ecosystem health, and I offer my assistance to those scientists who would like to participate in this ICES Study Group.

I would like to extend my thanks to all those who participated in the discussion under Topic 4.

Kind regards

References
Oksanen M. "The Moral Value of Biodiversity". Ambio Vol. 26 No. 8, Dec. 1997.

Altogether 6 scientists participated in the discussions concerning Topic No 5: S. Olenin, V. Panov, K. Skóra, JM Weslawski, E. Karasiova, Z. Piesik.

The Baltic Sea have been described as EU "village pond", internal water body, with concerned citizens living at its shores. Great level of collaboration and coordinated monitoring runs through HELCOM system, regular international contacts and highly integrated scientific community makes almost ideal framework for the best use of knowledge for the good of the region. However it turns out, that we are still having problems with communication to the end users and general public. Decision makers want to have simple indicators of the state of the environment (and the biodiversity), furthermore they use to have the static concept of the Nature: "when I was young there was a pike in this bay, and that it should be forever". Because of this static concept, number of regulations and actions are undertaken - like fight against erosion, attempts to stop the immigrating species, attempts to restore the species locally extinct etc. Besides this "maintanance of the village pond" there are also actions to reshape the environment for the current interest. Here belong ideas and attempts of creating artificial reefs, digging out the new lagoons, manipulations with river mouths and coastal marshes. Our problem is to understand the natural evolution of the system from the man-induced, and consequently differentiate actions taken in areas which has been severely disturbed (e.g. harbours) from areas which are undergoing natural changes (e.g. invasions of pontocaspian crustaceans via riverine system). Most of scientists believe that we have the good reason to manipulate the disturbed environments, while we shall keep hands off the areas with no acute environmental problems. The biodiversity is an important issue in planned and current human interventions in the Baltic. Those who want to intervene shall keep in mind that this temperate, brackish sea has very limited potential to accept new species (euryhaline, resistant species are not very numerous in the North Atlantic species pool).