The spring development of calanoid copepod populations in the Dutch coastal waters as related to primary production
Fransz, H.G. (1976). The spring development of calanoid copepod populations in the Dutch coastal waters as related to primary production, in: Persoone, G. et al. (Ed.) Proceedings of the 10th European Symposium on Marine Biology, Ostend, Belgium, Sept. 17-23, 1975: 2. Population dynamics of marine organisms in relation with nutrient cycling in shallow waters. pp. 247-269 In: Persoone, G.; Jaspers, E. (Ed.) (1976). Proceedings of the 10th European Symposium on Marine Biology, Ostend, Belgium, Sept. 17-23, 1975: 2. Population dynamics of marine organisms in relation with nutrient cycling in shallow waters. European Marine Biology Symposia, 10(2). IZWO/Universa Press: Wetteren. ISBN 90-6281-002-0. 712 pp., more In: European Marine Biology Symposia., more |
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| Abstract | The development of calanoid copepod populations in the period February 18- April 11, 1974 has been compared for three areas of the North Sea off the Dutch coast with different phytoplankton development. The onset and the culmination of the phytoplankton spring bloom occurred during this period. Due to differences in turbidity, the phytoplankton bloom culminated in March offshore but was retarded in a zone adjacent to the coast. Six developmental classes of the copepods were distinguished: small and large nauplii and copepodites, adult females, and males. Per developmental class and date the number per m³, the developmental and mortality rate level as determined by multiple regression, and production of the four most abundant species Temora longicornis, Pseudocalanus elongatus, Acartia clausi and Centropages hamatus are given. The results indicate that at the end of the winter all developmental stages are present with a homogeneous distribution. The species Temora and Acartia started to increase their number and production in March, but there was an apparent lack of positive correlation between the phytoplankton production and the development of the copepod populations. No significant difference in level of developmental or mortality rate could be detected between species, developmental classes and areas. In most species, the adult males were more abundant than the females. Some conclusions are inferred. The contribution of the younger developmental stages to production puts emphasis on the relative importance of the food relationships and requirements of the nauplii and young copepodites. The daily secundary production by the calanoids amounted to approximately 10 % of the primary production at the end of the period observed. The development of calanoid populations seems to be induced by abiotic factors like temperature increase and day length. Early phytoplankton spring blooms as observed in one of the areas may have negative effects on the zooplankton development, when the zooplankton is metabolically inactive. By depletion of essential nutrients, such as silicate, such blooms may endanger the nutrition of zooplankton when food is required. The significance of the phenological coincidence of phytoplankton and zooplankton is discussed. |
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