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Food-Limited Growth And Condition Index In The Eastern Oyster, Crassostrea Virginica (Gmelin, 1791), And The Bay Scallop, Argopecten Irradians Irradians (Lamarck, 1819), Michael A. Rice, Robert B. Rheault Jr.
Food-Limited Growth And Condition Index In The Eastern Oyster, Crassostrea Virginica (Gmelin, 1791), And The Bay Scallop, Argopecten Irradians Irradians (Lamarck, 1819), Michael A. Rice, Robert B. Rheault Jr.
Michael A Rice
The growth response of the eastern oyster, Crassostrea virginica, and the bay scallop, Argopecten irradians irradians, to varying degrees of food limitation was evaluated. Under conditions of low current speed, dense assemblages of shellfish can rapidly deplete ambient food concentrations, resulting in measurable effects on growth and condition index. A flume study demonstrated significant growth and condition index responses to resource competition after reductions as small as 27% in relatively high ambient food concentrations (—4.6 u.g/1 chlorophyll). Growth rates and condition index are linearly correlated with the average chlorophyll ration consumed. A field study demonstrated similar growth responses when the …
The Potential For Ontogenetic Vertical Migration By Larvae Of Bathyal Echinoderms, William Jaeckle, Craig M. Young, Michael G. Devin, Suki U.K. Ekaratne, Sophie B. George
The Potential For Ontogenetic Vertical Migration By Larvae Of Bathyal Echinoderms, William Jaeckle, Craig M. Young, Michael G. Devin, Suki U.K. Ekaratne, Sophie B. George
William Jaeckle
Planktotrophy is a relatively common developmental mode among bathyal and abyssal echinoderms, but the sources of food used by deep-sea planktotrophic larvae remain generally unknown. Very few deep-sea echinoderm larvae have been collected in plankton samples, so we do not know whether larvae migrate to the euphotic zone to feed or if they rely on bacteria or detritus at greater depths. We approached this question indirectly by investigating whether larvae of bathyal echinoids can tolerate the temperatures they would encounter in the euphotic zone and whether they possess sufficient energy stores to migrate to the euphotic zone without feeding. Twenty-four …