Environmental cues and constraints affecting the seasonality of dominant calanoid copepods in brackish, coastal waters: a case study ofAcartia,TemoraandEurytemoraspecies in the south-west Baltic
Information on physiological rates and tolerances helps one gain a cause-and-effect understanding of the role that some environmental (bottomup) factors play in regulating the seasonality and productivity of key species. We combined the results of laboratory experiments on reproductive success and field time series data on adult abundance to explore factors controlling the seasonality of Acartia spp., Eurytemora affinis and Temora longicornis, key copepods of brackish, coastal and temperate environments. Patterns in laboratory and field data were discussed using a metabolic framework that included the effects of controlling, masking and directive environmental factors. Over a 5-year period, changes in adult abundance within two south-west Baltic field sites (Kiel Fjord Pier, 54 19 0 89N, 10 09 0 06E, 1221 psu, and North/Baltic Sea Canal NOK, 54 20 0 45N, 9 57 0 02E, 410 psu) were evaluated with respect to changes in temperature, salinity, day length and chlorophyll a concentration. Acartia spp. dominated the copepod assemblage at both sites (up to 16,764 and 21,771 females m-3 at NOK and Pier) and was 4 to 10 times more abundant than E. affinis (to 2,939 m-3 at NOK) and T. longicornis (to 1,959 m-3 at Pier), respectively. Species-specific salinity tolerance explains differences in adult abundance between sampling sites whereas phenological differences among species are best explained by the influence of species-specific thermal windows and prey requirements supporting survival and egg production. Multiple intrinsic and extrinsic (environmental) factors influence the production of different egg types (normal and resting), regulate life-history strategies and influence matchmismatch dynamics.
Diekmann, A. Berenike S. / Clemmesen, Catriona / St. John, Michael / et al: Environmental cues and constraints affecting the seasonality of dominant calanoid copepods in brackish, coastal waters: a case study ofAcartia,TemoraandEurytemoraspecies in the south-west Baltic. 2012.
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