Daria Martynova

Selected quantitative characteristics of the feeding of the mass species of the White Sea copepods such as Acartia bifilosa (Giesbrecht, 1882), Centropages hamatus (Lilljeborg, 1853), and Temora longicornis (O.F. Müller, 1792) were examined, and their relationships with selected biotic and abiotic factors were determined. The rates of filtration and ingestion for all three species of copepods reliably depended on the species to which the copepod belongs and on its maturity stage. The ingestion rate ranged from 1.17 0.60 10frame03 mg dry weight/ind./h (copepodites CI–CIII, A. bifilosa) to 8.59 0.43 10frame13 mg dry weight/ind./h in the C.hamatus females. The filtration rate was from 0.21 0.08 (copepodites CII–CIII of T. longicornis) to 2.03 1.13 ml/ind./h (C. hamatus females). The light conditions have a reliable effect on the rate of ingestion. High values of the rate are observed when C. hamatus and T. longicornis feed in dark containers. A. bifilosa demonstrates the same relations...

Size and weight characteristics of pellets produced by the mass White Sea copepod species Acartia bifilosa (Giesorecht, 1882), Centropages hamatus (Lilljeborg, 1853), and Temora longicornis (O.F. Müller, 1792) are estimated. The pellet length and width vary from 97 to 168 and 13 to 23 µm, respectively. The average volume and weight range from 0.013 mm3 and 0.3 10–3 mg to 0.067 mm3 and 1.1 10–3mg in A. bifilosa (the CIII copepodite stage) and C. hamatus females, respectively. The pellet length-to-width ratio varies from 7.45 to 8.78. The pellet length and volume increase with the prosoma length in the relevant copepod individual. The pellet dry weight depends on its volume. The subsidence rate of pellets averages 2.5 m/h. The duration of pellet formation is a few tens of minutes, decreasing during onthogenesis. The highest rates are noted for A. bifilosa. The faecal pellet flux varies during the season and within separate areas, depending on the structure of pelagic community in the ...

Data on the zooplankton community structure, gut evacuation rate and carbon content of zooplankton faecal pellets were used for assessing the contribution of zooplankton to vertical carbon fluxes in the White and Kara Seas. The results revealed strong regional and seasonal variations of pellet carbon input related to differences in structure and dynamics of the zooplankton communities in the regions studied. In the deep regions of the White Sea, maximum daily pellet carbon flux from the 0-50 m layer was observed in the spring. It reached 98 mg Corg m-2 day-1 and coincided with a strong predominance of the large arctic herbivorous copepod Calanus glacialis in the surface layers. In summer and fall, it decreased by 1 to 2 orders of magnitude due to migration of this copepod to its overwintering depths. In contrast, in the shallow coastal regions, the pellet production was low in spring, gradually increased during summer and reached its maximum of 138 mg Corg m-2 day-1 by late summer t...

The species composition, cell concentration (N), and biomass (B) of the phytoplankton, as well as the chlorophyll a (Chl a) concentration, primary production (PP), and the concentrations of the dissolved inorganic micronutrients (phosphorus, silica, nitrogen as nitrite), were estimated for Kandalaksha Bay (KB), Dvina Bay (DB), and the basin (Bas) of the White Sea in August of 2004. The micronutrient

... 2010). This life history strategy is consid-© Inter-Research 2011 · www.int-res.com *Email: daase@npolar.no Effects of food quality on naupliar development in Calanus glacialis at subzero temperatures Malin Daase1, 2,*, Janne E. Søreide1, Daria Martynova3 ...

ABSTRACT We hypothesize that shifts in the annual pattern of the environmental parameters may affect the phenology of the zooplankton especially in temperate and polar areas. Five species (cold-water: Calanus glacialis, warm-water: Centropages hamatus, Temora longicornis, Acartia longiremis, and Evadne nordmanni) were tested with regard to the annual pattern of the water temperature using the dataset of 50-year-long monitoring in the White Sea (1961–2010). The hydrological summer duration increased by 20 days during the last 50 years, as it has been tracked by an earlier warming up of 0–10-m water layer in spring. Calanus glacialis responded to these changes by the appearance of CI copepodites earlier in the season. We suggest that the earlier start and longer period of ice melt may cause a longer phytoplankton bloom and thus may promote better trophic conditions during the period of Calanus reproduction and its early development. In contrast to cold-water C. glacialis, the phenology and abundance of warm-water copepods have not changed significantly. Both the timings of autumn cooling and average summer temperature remained relatively stable since the beginning of observations resulting in steady conditions during the reproductive period of warm-water species. Prolongation of summer had no effect on their reproduction.