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Abstract

Ozbay, G. and L.M. Brown. 2006. An examination of comparative size class feeding in eastern oyster (Crassostrea virginica): implications for habitat restoration and conservation. JEMREST 2:51-72.

Historically, many eastern oyster (Crassostrea virginica) restoration activities have not accounted for differences in size-specific feeding patterns. The stocking of an area with a particular size class may lead to depletion of preferred algal food sources. In natural oyster reefs, size-specific differences in feeding exist and may ultimately lead to depletion of specific algae. In this study, we quantified particle filtration, retention, and bio-deposition differences from the individual oysters fed with Tetraselmis chui (strain PLY-429) over 4 h using flow cytometry. Oysters kept 24 h until algal food was completely depleted in the feeding chamber were then examined for feces and pseudofeces production. We obtained significant differences (P < 0.05) in clearance rates between the different size classes and between sampling intervals. Clearance rates of large size oysters significantly (P < 0.05) varied between oysters. The average clearance rate decreased as oysters size increased in this study. Oysters with high clearance rates produced more feces and pseudofeces (P < 0.05). As a result, the smaller size groups filtered greater quantities of T. chui and appeared to be more efficient in their filtration, resulting in particle-size dependable feeding responses, perhaps their less selectivity for particles in water. Considering this difference in particle filtration of oysters of various sizes, restoration efforts may increase the probability of success via decreased competition for preferred algal resources among cohorts. These differences in response of feeding and bio-deposition rates are important to our knowledge of phytoplankton dynamics. Scientists and managers should consider size and age of oysters in restoration efforts of sensitive habitats susceptible to eutrophication and algal bloom events.