Reproduction rates and secondary production of three species of the rotifer genus Synchaeta in the estuarine Potomac River |
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Authors: | Heinbokel John F; Coats DWayne; Henderson Kelly W; Tyler Mary A |
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Institution: | Chesapeake Bay Institute, The Johns Hopkins University Shady Side, MD 20764
1Present address: Department of Biology, Washington College Chestertown, MD 21620, USA
2College of Marine Studies, University of Delaware Lewes, DE 19958, USA
2Present address: Versar, Inc. 9200 Rumsey Rd, Columbia, MD 21045, USA |
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Abstract: | Rotifers are a relatively well-studied component of lacustrinesystems but their role is only poorly understood in estuaries.Three species of the genus SynchaetaS. baltica, S. triophthalmaand S.ceciliadominate the cold-water assemblage of rotifersin Chesapeake Bay. Laboratory experiments were conducted todetermine the temperature dependence of egg development time(EDT) for each species; EDT varied over an approximate rangeof 909 h as temperature (T) varied from 2 to 22°C.The EDT/temperature relationships could be closely fitted bya simple polynomial equation of the form log(EDT) = a + b(logT) + c(log T)2 for each species. Natural populations of thesethree rotifers were sampled during a cruise in the Potomac River(711 March 1983). Estimates of specific reproductiverates (b) were calculated based on the previously defined EDT/temperaturerelationship and the observed ratio of eggs/rotifers for eachspecies. The two most abundant species, S.triophthalma and S.cecilia,showed a clear dependence of b on the observed chlorophyll aconcentrations. Maximum reproductive rates ({small tilde}0.015h1) were attained only at relatively high phytoplanktondensities within a bloom of Heterocapsa triquetra where thechlorophyll a concentrations exceeded 10 µg l1.Estimates of secondary production suggest that Synchaeta spp.may contribute to the trophic flow of carbon in this systemwith a significance at least similar to that of the planktoniccopepods. |
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