Maria Iwona Żmijewska

Spatio-temporal variability of mesozooplankton from the Gulf of Gdańsk (Baltic Sea) in 1999-2000

Spatio-temporal variability of mesozooplankton from the Gulf of Gdańsk (Baltic Sea) in 1999-2000 The spatio-temporal variability of mesozooplankton in the Gulf of Gdańsk was studied using samples collected in the western part of this basin every month in the 1999-2000 period. The investigation indicated that the qualitative composition of zooplankton was typical of this area and was comprised of Copepoda, Cladocera, Rotatoria, Appendicularia, and meroplankton. Acartia bifilosa and Temora longicornis were present permanently, while Cladocera, Acartia tonsa, Centropages hamatus, Eurytemora sp., the genus Keratella, as well as Mollusca and Balanus improvisus larvae exhibited clear preferences for warmer months. Acartia longiremis, Pseudocalanus elongatus, and Fritillaria borealis were encountered in the cooler season (from November to April). Synchaeta spp. dominated among Rotatoria and Polychaeta larvae among meroplankton. The presence of Brachionus calyciflorus indicated the presence and influence of riverine water from the Vistula.

Spatiotemporal distribution of copepod populations in the Gulf of Gdansk (southern Baltic Sea)

In the present study, we used a 3D Coupled Ecosystem Model of Baltic Sea version 1 (3D CEMBSv1) coupled with a copepod model to examine the spatiotemporal distribution of two representative copepod populations in the Gulf of Gdansk (southern Baltic Sea) including Acartia spp. and Pseudocalanus minutus elongatus. The annual cycles simulated for 2000 under realistic weather and hydrographic conditions were studied with the three-dimensional version of the coupled ecosystem-copepod model in the south-eastern Baltic Sea. The paper presents the comparison of simulated and observed copepod development at two stations in the Gulf of Gdansk. A validation of influential state variables gives confidence that the model is able to calculate reliably the stage development of dominant species in the southern Baltic Sea. The number of generations was one for P. m. elongatus and 3–5 for Acartia spp.. A mean of five generations for the latter species per year were estimated in the coastal region and ca. three generations at the Gdansk Deep (in the open sea). Food concentration and temperature as the main factors controlling the development of the investigated copepods as well as salinity as a masking factor (i.e. salinity modifies the rate of their development) in the case of Pseudocalanus minutus elongatus are included in the present study.

Population dynamics of Pseudocalanus minutus elongatus in the Gulf of Gdansk (southern Baltic Sea) – experimental and numerical results

The seasonal and spatial distribution of the pelagic calanoid copepod Pseudocalanus minutus elongatus was studied in the Gulf of Gdansk (southern Baltic Sea) between January 2006 and December 2007 based on experimental data (from six stations) and numerical simulations. Numerical calculations were performed using a structured zooplankton population model that was adapted to this species and coupled to the ecosystem model. Spatiotemporal distribution of this species depends on salinity as a masking factor. Highest abundances at station J23, an open sea site, were observed in July 2006 and March 2007 (10,050 and 11,000 ind. m−3, respectively) and resulted from the large numbers of earlier copepodites C1–C3 in 2006 and nauplii in 2007. In shallow stations abundances declined. Our results show that only one complete generation of this copepod species developed during the year in this region. Differences in development between the experimental and numerical data are analysed.

Pelagic coelenterates in the Atlantic sector of the Arctic Ocean − species diversity and distribution as water mass indicators

Abstract Marginal seas of the Arctic Ocean are well recognized as one of the richest ecosystems in the world’s ocean, being at the same time the most vulnerable to climate change. Such vulnerability affects the distribution of water masses, thus influences the pelagic species dispersal and local diversity. For certain reasons some plankton species can be used as indicators of water mass distribution. Although the use of copepods and chaetognaths in such a manner is well documented, still little is known about the potential of pelagic Coelenterata as possible indicator species; they are still poorly investigated in this part of the Arctic Ocean. Therefore, a survey of these gelatinous animals was conducted in a transect between the Norwegian, Greenland, and Barents Seas in summer 2011. A total of 21 taxa were encountered and the most abundant was Aglantha digitale. Species distribution coupled with hydrological analysis of the investigated area enabled us to establish the water mass indicator taxa. Therefore, A. digitale was connected with the Atlantic Water Mass, while Bougainvillia superciliaris and large numbers of ctenophores were correlated with the Arctic Water Mass. The results presented herein may provide the basis for developing new tools to analyze changes in the Arctic Ocean.

Population dynamics of the main copepod species in the Gulf of Gdansk (the Southern Baltic Sea): abundance, biomass and production rates

Abstract The aim of this study was to describe the production biomass and abundance dynamics of the major Baltic calanoid copepods (Acartia spp., Temora longicornis and Pseudocalanus sp.) in the Gulf of Gdansk (the southern Baltic Sea) during a three-year period from March 2010 to December 2012. The data were collected at six stations located in the western part of the gulf. Acartia spp. was the most abundant taxon throughout the study period. The observed differences in the weighted mean depth for the investigated species were >2 m between nauplii and adults of Acartia spp., >5 m between nauplii and adults of Temora longicornis and 3 m between nauplii and younger copepodites of Pseudocalanus sp. The highest values of the secondary production rates were determined for Acartia spp. - almost 17.55 mg C m-2 d-1 (summer 2011), while Temora longicornis reached 3.80 mg C m-2 d-1 in spring 2010 and Pseudocalanus sp. had the highest secondary production values in summer 2011 - about 1.28 mg C m-2 d-1.