Returning to the Baltic Proper: More questions than answers?

Abstract

Data collection and thus also possibilities to have direct information on the marine environment situation in the Latvian Baltic Proper which is covering the Eastern Gotland Basin was stopped in 1994. The real alterations of ecosystem were not estimated, as only indirect data were available. Thanks to the start of National research program KALME, three the most representative sampling locations were visited again in 2007, actually repeating the sampling program of 1994, including basic hydrological observations, nutrient concentrations, abundance and species composition of phyto- and zooplankton and macrozoobenthos. The obtained information on vertical profiles of physico-chemical parameters and the structure of biological variables allows to have a scenery what has happened during 14-15 years - in a period when the environment of the Baltic Sea has been changing under the large-scale climatic pressure and its local variations. This study is discussing the observed changes in the plankton and benthic communities of the Baltic Proper both in the light of numerical values and biological diversity. Taking into account the development of knowledge on the processes in the Baltic Sea and also the current needs for elaboration of the ecosystem-based management we have tried to estimate the adequacy of sampling approach and quality of the obtained data.