Abstract
We investigated physiological traits associated with a reproductive-resting stage in adult female harpacticoid copepods, Coullana canadensis (Willey). Our hypothesis was this stage represents a life-history strategy that could increase fitness by improving winter survivorship and future reproductive success in spring. To test if physiological rates are suppressed in this stage, we compared gut-cell morphology, nitrogen excretion rates, enzyme activities, and phytoplankton grazing rates of reproductive-resting and reproductive females reared in the laboratory under high food conditions. Copepods came from laboratory cultures originating from individuals collected in Maine and Maryland, USA in 1990. Reproductive-resting females had lower physiological rates, and the surface area of gut-cells was reduced compared to reproductive females. Distinct morphological differences in the distribution of lipids between reproductive and reproductive-resting females were observed under light and electron microscopy, the latter having a diffuse accumulation of lipid in the area normally occupied by the ovaries. Differences in lipid composition were also found. Reproductive copepods had a significantly higher ratio (%) of polar lipids to total lipid, and a lower proportion of triacylglycerols compared to reproductive-resting copepods. These laboratory findings are consistent with the hypothesis that the reproductive-resting stage in C. canadensis is an adaptive response to increase winter survival.
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Received: 29 May 1996 / Accepted: 3 December 1997
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Lonsdale, D., Hassett, R., Dobbs, F. et al. Physiological traits associated with a reproductive-resting stage in Coullana canadensis (Copepoda: Harpacticoida). Marine Biology 131, 123–131 (1998). https://doi.org/10.1007/s002270050303
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DOI: https://doi.org/10.1007/s002270050303