Egg production, population structure and biochemical composition of the subantarctic copepod Paraeuchaeta antarctica in the Kerguelen Archipelago
Résumé
The population structure and reproductive biology of the predatory calanoid copepod Paraeuchaeta antarctica (Giesbrecht, 1902) were investigated in the Kerguelen Archipelago over 1 yr. The seasonal frequencies of the various developmental and adult stages showed that the population produces 1 generation per year, with recruitment taking place during the austral spring. Occurrence of females with spermatophores indicated that mating occurred in winter. Counts of egg-bearing females and of number of eggs per sac confirmed that the peak of reproduction was from winter to late spring. Seasonal variations in body dry weight, lipid and protein contents of the various developmental and adult stages reflected changes in food availability and the reproduction cycle. P. antarctica increased lipid and protein content during spring and summer when prey organisms were abundant. The subsequent loss in winter was associated with the production of eggs. A study of lipid classes showed that lipid accumulations were essentially composed of wax esters, which permitted production of eggs when food conditions were unfavorable. The population dynamics and reproductive biology of P. antarctica from Kerguelen are discussed in comparison with the antarctic populations described at South Georgia and off the Antarctic Peninsula, as well as with the northern euchaetiid Euchaeta norvegica.