Reproductive activity of two dominant Antarctic copepod species, Metridia gerlachei and Ctenocalanus citer, in late autumn in the eastern Bellingshausen Sea


Contact
bniehoff [ at ] awi-bremerhaven.de

Abstract

AbstractThe main reproductive period of herbivorous Antarctic copepods is coupled to the phytoplankton bloom in spring, while omnivorous or carnivorous species apparently reproduce year round. However, our knowledge of the reproduction during autumn and winter is limited. Therefore this study during a cruise with RV `PolarsternŽ aimed to measure reproductive activity in two dominant copepod species Metridia gerlachei and Ctenocalanus citer in late autumn (April/May). For this purpose, gonad development stages of both species were determined from species taken with Bongo net in the eastern Bellingshausen Sea (Antarctic Peninsula region), and related to the ambient feeding conditions represented as chlorophyll a concentration. In addition, experiments were conducted with M. gerlachei to estimate in-situ egg production rates and to study the influence of feeding and starvation on gonad development. Gonad maturity of M. gerlachei differed considerably between stations and decreased over time. The correlation of chlorophyll a and the proportion of mature females, though significant, was weak and highly variable. In experiments, the gonads of feeding females were in better condition than those of their starving counterparts, showing that reproductive activity in M. gerlachei is related to ambient feeding conditions. The in-situ egg production rates measured during 24h incubations were low, ranging from 0 to 1.9 eggs female-1 d-1. Calculated egg production rates based on preserved samples, however, were considerably higher with a maximum of 9.1 eggs female-1 d-1 suggesting that the incubation method might not be applicable in M. gerlachei. Mature females of C. citer were found at each station (20 to 60%). The gonad stage composition was rather similar at all stations showing no clear temporal and spatial trend. In this species, the proportion of mature females was not related to the chlorophyll a concentration, indicating either that the ambient phytoplankton stock was sufficient to fuel maturation or that other food sources were used. Our study shows that both species are producing during the austral autumn, indicating that their reproduction is partially decoupled from the spring phytoplankton bloom.Key words: austral autumn, copepods, reproduction, Metridia gerlachei, Ctenocalanus citer



Item Type
Article
Authors
Divisions
Programs
Peer revision
ISI/Scopus peer-reviewed
Publication Status
Published
Eprint ID
5411
DOI 10.1007/s00300-002-0378-7

Cite as
Niehoff, B. , Schiel, S. , Cornils, A. and Brichta, M. (2002): Reproductive activity of two dominant Antarctic copepod species, Metridia gerlachei and Ctenocalanus citer, in late autumn in the eastern Bellingshausen Sea , Polar biology, 25 , pp. 583-590 . doi: 10.1007/s00300-002-0378-7


Share


Citation

Research Platforms

Campaigns


Actions
Edit Item Edit Item