Inter-Research
Marine Ecology Progress Series

ABSTRACT: The effect of the chemical composition of seston on the egg-production rates (E_r: eggs female^-1 d^-1) of the copepods Acartia hudsonica Pinhey and Temora longicornis (Müller) was studied in Long Island Sound, USA, (41* 00' N, 73* 05' W) during spring 1990. The seston was analyzed for carbon, nitrogen, protein, carbohydrate (CHO) and fatty acid content as well as chlorophyll (chl) and ciliate concentrations. Principal component analysis (PCA) revealed significant correlations [score >0.7 on a same principal component (PC)] between in situE_r of the 2 copepod species and the chemical composition of the seston. Protein, CHO and specific fatty acids correlated strongly with E_r of A. hudsonica (CHO negatively). The same components were moderately correlated (score >0.6 on a same PC) with the E_r of T. longicornis. The fatty acid requirements of A. hudsonica and T. longicornis were for high omega3:omega6 ratios and low 20:5 to 22:6 ratios. The fatty acid 22:6omega3 was also correlated with E_r of both species. The concentration of ciliates and the C:N ratio of seston did not affect E_r of any of the species under any condition. Path analysis models were composed to evaluate the important mechanisms controlling the E_r observed in this study. The analysis demonstrated the strength and importance of indirect relationships that were not apparent from conventional correlation statistics. The results from 4 path analysis models showed that chl and ciliates exert an important control on natural egg production rates, through their chemical composition, despite the fact that linear correlations between phytoplankton and ciliates and E_r were not significant.

KEY WORDS: Acartia . Temora . Egg production . Food quality . Spring bloom . Path analysis

Published in MEPS Vol. 119 (1995) on March 23
Print ISSN: 0171-8630; Online ISSN: 1616-1599. Copyright © Inter-Research, Oldendorf/Luhe, 1995