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Interannual variability in the population dynamics of the main mesozooplankton species in the Gulf of Gdańsk (southern Baltic Sea): Seasonal and spatial distribution

Dzierzbicka-Głowacka L., Kalarus M., Żmijewska M. I.

Oceanologia

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2013

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No. 55 (2)

409-434

EN

The paper characterizes the population dynamics of the major Baltic calanoid copepod species (Acartia spp., Temora longicornis and Pseudocalanus sp.) in the Gulf of Gdańsk (southern Baltic Sea) from January 2006 to December 2007. The data were collected at six stations (M2, S1, S2, S3, S4, J23) located in the western part of the Gulf of Gdańsk. The objective of this research was to describe and compare the seasonal and spatial distributions of these three major copepod species. Their distributions in the study area are largely similar, although there are some exceptions regarding Pseudocalanus sp. Copepoda development in the Gulf was at its most intense from May to September, peaking in July. The abundance of these species was the least at the shallowest stations. Based on these results, the weighted mean depth WMD per developmental stage was calculated for Pseudocalanus sp., Acartia spp. and T. longicornis. The paper also compares the abundance (in indiv. m-2) of the copepodite stages of these species in two regions of the Baltic Sea (the Gulf of Gdańsk and the Gotland Basin). Except for Pseudocalanus sp., the abundance of these copepodite stages (ΣCII-CVI) in the Gulf of Gdańsk in 2006 was similar to that in the Gotland Basin in the mid-1990s; in spring/summer 2007, however, their abundances were significantly higher (ca 2-4 times) in the former region.

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Equivalence of rates of growth and egg production of Pseudocalanus

Dzierzbicka-Głowacka L.

Oceanological and Hydrobiological Studies

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2005

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Vol. 34, No.4

19--32

EN

The equivalence of rates of growth and egg production is analyzed for well-fed females of Pseudocalanus from Puget Sound (Washington, USA) and from the southern North Sea. The hypothesis is tested using published data on the Pseudocalanus species. The growth rates of the copepodite stages for species from these two regions as a function of temperature and food concentration were used. Quantitative expressions describing the effects of temperature and the cephalothorax length of females on potential reproductive rate were compared. Food-saturated egg production was computed as the mean number of eggs per sac divided by 1.25 times the embryonic duration at the given temperature. The calculations were done based on experimental data from the literature for some geographically separate populations of Pseudocalanus from southwest Baffin Island, Nova Scotia, Long Island Sound, Scotland, and the southern North Sea and adjacent waters. These values were compared with the average number of eggs produced per day by one female obtained here as a function of growth rate, i.e., multiplying exp gmax – 1 from the growth rate equation by Wfemale/Wegg. The combined effect of food concentration and temperature as a function of these two parameters on egg production (reduced by food limitation) was also established for Pseudocalanus from Puget Sound. These assumptions and estimations appear to predict the temperature-length of female dependent daily rates of egg production of well-fed females of Pseudocalanus spp. for the above waters. Suggestions are made as to how to obtain and present data to test this hypothesis more thoroughly.

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The dependence of body weight in copepodite stages of Pseudocalanus spp. on variations of ambient temperature and food concentration

Dzierzbicka-Głowacka L.

Oceanologia

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2004

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No. 46 (1)

45-63

EN

Quantitative expressions are presented describing the effects of temperature and food concentration on the mean body weight of copepodite stages of Pseudocalanus spp. The calculations were made on the basis of experimental data from the literature for three geographically separate populations of Pseudocalanus from Puget Sound (Washington, USA), from the southern North Sea and the Baltic Sea. Relationships were obtained between the coefficient of daily exponential growth of body weight of Pseudocalanus sp. from Puget Sound and temperature in the 8-15.5oC range and food concentrations from 10 mgC m-3 to excess, as well as for Pseudocalanus elongatus from the southern North Sea at high food concentrations and in the 4-15oC temperature range. Also computed was the mean body weight for stages CII to CV of P. elongatus from the southern Baltic Sea at 5oC. The empirical models presented here can be used with good precision in mathematical models of pelagic communities. The results presented here indicate that Pseudocalanus sp. from Puget Sound (a species resembling Pseudocalanus minutus) is similar to P. elongatus from the southern North Sea and the English Channel with respect to growth parameters in the studied range of temperatures for excess food. P. elongatus collected in the Baltic Sea (Gulf of Gdańsk) differs from P. elongatus from the southern North Sea.

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Potential rate of reproduction for some geographically separate populations of Pseudocalanus spp.

Dzierzbicka-Głowacka L., Zieliński A.

Oceanologia

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2004

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No. 46 (1)

65-83

EN

Quantitative expressions are presented describing the potential reproductive rate per individual female of Pseudocalanus spp. in several different waters (not reduced by food limitation) as a function of both temperature and cephalothorax length of females (one equation for each studied region). The calculations were made for some geographically separate populations of Pseudocalanus spp. from southwest Baffin Island, Nova Scotia, Long Island Sound, Scotland, as well as the southern North Sea and its adjacent waters (e.g. the English Channel). On the basis of the findings presented in this work and from other studies, the reproductive rate was computed as the mean number of eggs per sac divided by 1.25 times the embryonic duration at the given temperature. Also computed was the amount of egg matter produced per day as a percentage of body carbon (and dry weight) of female weight for all localities. The relationships for females from the southern North Sea were obtained for "viable eggs", but they should be treated with reserve. A more suitable expression describing egg production in the southern North Sea is the equation for females from the English Channel obtained here. Our assumptions and approximations appear to predict quite well the temperature-length of female dependent daily rates of egg production of well-fed females of Pseudocalanus spp. for the above waters, and we suggest that they can be used to test the hypothesis more thoroughly.

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Growth rate of Pseudocalanus spp. as a function of food concentration, body weight and temperature

Dzierzbicka-Głowacka L., Zieliński A.

Oceanological and Hydrobiological Studies

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2003

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Vol. 32, No. 4

171-197

EN

This paper does not report the results of original research; it is an analysis of data from the literature. The aim of this project was to develop quantitative expressions to describe the effects of food concentration, temperature and body weight on the growth rate of copepodid stages of Pseudocalanus spp. Calculations were done for two geographically separate populations of Pseudocalanus – one from Puget Sound (Washington, USA) and the other from the southern North Sea- based on experimental data from the literature (see Vidal 1980, Thompson 1982). The relationships between the growth rate of Pseudocalanus from Puget Sound and temperatures in the range of 8o-15.5oC, food concentration and body weights ranging from 1.5 to 10 ěgd.w. (case 1) and 0.51 to 3.7 ěgC (case 2) were determined, as were those for Pseudocalanus from the southern North Sea at a high food concentration and at temperatures ranging from 4o to 15oC. The results demonstrate that the maximum growth rate decreased as temperature fell and that it become less dependent on temperature at higher body weights. The critical food concentration for growth increased with body size proportionally more at high than at low temperatures. Slight differences in growth rate were also detected between the two species of Pseudocalanus.