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Baltic Associated Investigators: Related Time Series: Zooplankton samples were collected within the Baltic Sea HELCOM Combine Monitoring Programme. The Maritime Branch of the Institute of Meteorology and Water Management is responsible for collecting the samples along the southern coast of the Baltic Sea (in the Polish EEZ), however, over those thirty years, zooplankton was analyzed by several experts working in various institutions. In the Bornholm Basin the data series started in 1979. Frequency of sampling varied in time (3-6 time per year) but the spring and summer conditions can be described for each year. Data from years 1998 and 2000-2001 are still missing in the database. In addition, zooplankton samples were not taken at the station located in the Bornholm Basin during the period of 2002-2006. Samples were taken following the guidelines of the Manual for Marine Monitoring in the COMBINE Programme of HELCOM (especially Annex C-7: Mesozooplankton) which means that the vertical hauls of the WP-2 net with 100 µm mesh size were used. Stratified samples (all presented here) were collected in the layers from the bottom to the halocline (included); from the top of halocline to the thermocline (included); and from the top of thermocline to the surface. Preservation (4% formaldehyde solution) as well as sub-sampling and lab analyses were carried out according to the HELCOM guidelines. Total abundance and biomass is presented for the last nine years only (2007-2010) as the earlier data are being still verified. Trends in surface salinity and temperature are not obvious. Nevertheless, since the beginning of 1990s we are observing mostly negative anomalies in salinity with the possible reversed trend over the last few years. Positive anomalies in temperature dominated in the last decade. Despite the observed year-to-year variation, trends in copepod abundance and biomass are similar to those observed in the Gdańsk Basin and the Southern Gotland Basin. Acknowledgements Presented data were collected within the Polish National Monitoring Programme and permission to demonstrate them was granted by the Chief Inspector of Environmental Protection ( https://www.gios.gov.pl/) |