Abundance and biomass of sub-ice mesozooplankton in the Pechora and Kara Seas in January-April 2000

Zooplankton communities under continuous ice cover in the Kara Sea and near the ice edge in the Pechora Sea were studied. Sampling was carried out from onboard nuclear ice breakers in the period January-April 2000. Breeding of a small-size opportunist species Pseudocalanus acuspes under continuous fast ice of the Gulf of Yenisei began as early as in April, though total mesozooplankton biomass (0.8 mg/m**3) was characteristic of winter condition of community. A classical spring pattern of polychaete and barnacle larvae hatching and euphausiid spawning was observed. Such conditions of the zooplankton community near the ice edge had been described earlier, but this was the first observation of a planktonic community under continuous ice of the Kara Sea

Table 3: Comparison of freshwater species in Ob and Yenisei during the 1997 cruise

Phytoplankton biomass distribution (chlorophyll a, chl. a) and species composition (cell numbers) were investigated during three expeditions to the Kara Sea with "Akademik Boris Petrov" (BP) in 1997, 1999, and 2000. The distribution of biomass in the estuaries of Ob and Yenisei showed a similar range in 1997 (0.2 to 3.2 µg/l) and 2000 (0.4 to 3.5 ug/l); higher chl. a concentrations during these two years were found in Yenisei than in Ob. In 1999, phytoplankton biomass in the Ob and Ob Estuary was much higher than in 1997 and 2000, with maximum values above 10.0 ug chl. a/l. In 1999, biomass in Yenisei was lower (1.5 to ~5 ug/l) than in Ob but slightly higher than in 1997 and in 2000. During the expedition in 2000, the research area extended farther to the north, here, lowest phytoplankton biomass during all three years was found. Typical summer values for integrated chl.a biomass (surface to bottom) ranged between 6 and 20 mg m**-2. Strong differences existed in species composition in both rivers, the estuaries, and the open Kara Sea. In general, three or four different populations could be distinguished in surface waters: (1) freshwater diatoms together with bluegreen algae in both rivers, (2) centric and small pennate diatoms mainly brackish species in the estuaries, (3) north of 74°N, brackish/marine species dominated, i.e. in 1999 Thalassiosira cfpunctigera and Chaetoceros spp prevailed in the phytoplankton bloom in Ob. (4) At the northernmost, almost marine stations, a region with a more heterogeneous composition of unicellular plankton was encountered. We assume, we found different seasonal signals of phytoplankton development during 1997/2000 and 1999, respectively. However, the yearly fluctuation of freshwater runoff of both rivers seems to have the strongest influence on the timing and duration of phytoplankton blooms, species compositions and biomass standing stocks during summer

Oceanographic characteristics and microplankton in the Murmansk coastal pelagic zone in March 1998

From March 13 to March 29,1998 a multi-disciplinary expedition of the Murmansk Marine Biological Institute carried out investigations of microplankton in marginal basins of the Murmansk coast (Kola Peninsula). In addition to water sampling the expedition carried out a study of bottom communities of the littoral zone (macrobenthos and littoral foraminifers), sampling of snow, littoral soil, and macrophytes for testing contents of heavy metals and radionuclides

Community Structure and Abiotic Characteristics of Pelagic Microalgal in Adjacent Areas of the Barents Sea and Kara Sea

This study aimed to confirm the hypothesis of a floristic identity between the southeastern Barents Sea and the southwestern Kara Sea. We conducted integrated studies of pelagic microalgae communities including microscope cell counting and taxonomical identification as well as photosynthetic pigments determination and defining of hydrological and hydrochemical characteristics during a cruise in late August and the first half of September 2020. As far as we are concerned, no such observations had been carried out in this region at this time of the year before. During our observations, 35 species were identified, 14 (40%) of which were present in both water bodies. The communities of both regions were in a state corresponding to the autumn stage of the annual succession cycle. In the southeastern Barents Sea, the mean abundance of organisms in the water column varied from 10.650 to 41.840 cells per liter with a biomass of 71.04 to 300.55 µg/L. In the southwestern Kara Sea, these values were 3.510–28.420 cell/L and 16.31–66.96 µg/L, respectively. In general, the results of a comparative analysis suggest that the pelagic algal communities in the regions under comparison, despite the difference in hydrological parameters, demonstrate similar qualitative and quantitative characteristics and thus may belong to the same phytogeographic region