Sustained fecundity when phytoplankton resources are in short supply: Omnivory by Calanus finmarchicus
Despite low ambient concentrations of phytoplankton, Calanusjkzmarchicus sustained relatively high rates of egg production (1 l-45 eggs female 1 d-l) in the open waters of the Gulf of St. Lawrence in late June-early July. These rates were comparable to egg production rates observed in high-chlorophy...
| Main Authors: | , |
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| Other Authors: | |
| Format: | Text |
| Language: | English |
| Published: |
1994
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| Online Access: | http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.503.8661 http://www.aslo.org/lo/toc/vol_39/issue_1/0021.pdf |
| Summary: | Despite low ambient concentrations of phytoplankton, Calanusjkzmarchicus sustained relatively high rates of egg production (1 l-45 eggs female 1 d-l) in the open waters of the Gulf of St. Lawrence in late June-early July. These rates were comparable to egg production rates observed in high-chlorophyll waters of the lower St. Lawrence estuary. Contrary to classical, linear food-chain models, variations in egg production of C. jinmarchicus were therefore not prcdictablc from variations in standing stocks of auto-trophic cells. Egg production rates wcrc independent of the concentration of chlorophyll in situ, the abundance of autotrophic microplankton cells, in situ gut fluorescence, and the rate of ingestion of autotrophic particles. Hctcrotrophic microplankton- including ciliates and dinoflagellates presumed to bc heterotrophic-constituted a disproportionate fraction of the ration of C. finmarchicus in the open Gulf of St. Lawrence, despite their relatively low cell densities. Evidence suggests that heterotrophic microplankton frequently provided a prey resource sufflcicnt for net lipid synthesis as well as for egg production. For several decades the dominant view in marine zooplankton ecology has been that |
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