Matthew Raps, Stockton University

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Abstract:

Eastern oyster (Crassostrea virginica) larvae exhibit several types of migratory and swimming behavior that has been well observed in nature and studied in laboratory settings, but less is known about larvae behavior within oyster hatcheries. Water conditions and larvae are assumed to be uniform in larval tanks, but this assumption doesn’t consider evolved behaviors. We used a Sequoia LISST-100X particle-size analyzer (LISST) to detect oyster larvae behavior within hatchery rearing tanks. The LISST was verified with a comparison to a hand count using 2-day-old larvae. Larvae profiles were taken from five mass larval tanks (MLTs) at the Horn Point Laboratory Oyster Hatchery (HPLOH). Additionally, a conductivity, temperature, and depth logger (CTD) was used to profile the water conditions of seven MLTs. Results were inconclusive for detecting larvae behavior because linear regression models showed that larval density was a function of depth for only two out of the five tanks. CTD data suggested that conditions within and among tanks were not homogeneous. Overall, the larvae profiles created using the LISST was a proof of concept for easily detecting oyster larvae, and results from this study point to new avenues of research to help hatchery managers improve larvae production.