A New Behavioral Phenotyping Strategy for Pacific Oyster (Crassostrea gigas) Larvae Reveals Cohort-Level Effects on Copper Toxicity Swimming Response - Abstract
Copper is among the most studied marine metallotoxins. It is both heavily utilized in commercial applications (e.g. industrial discharges and antifouling hull coatings) and
readily bioavailable in the water column. In bivalve mollusks, common responses to coppertoxicity include increased mortality rates and disruption of normal development,
especially during early life history stages. Bivalve studies, however, focus primarily on physiological and morphological changes in conditional or field experiments, while behavior remains relatively unexplored. This study profiles the larval movement characteristics of 48 hour old larval Pacific oysters Crassostrea gigas (C. gigas) under increasing concentrations of Cu2+. C. gigas full sibling families were subjected to a series of increasing Cu2+ concentrations in Filtered Sea Water (FSW), from 0 ppb to 36 ppb, for n=10 conditions. Across all trials, a negative correlation was observed with increasing Cu2+ loads and percent survival, normal morphological development, and average width. MovTrack, in-house developed tracking software, was used to quantitatively show that Cu2+ concentration and total movement of larvae are not dependently linked. A familial component of Cu2+ stress reaction was potentially observed, with some genetic lines showing significant differences in movement metrics, supporting the hypothesis that Cu2+ toxicity response may have a heritable component. This study provides evidence that previously documented physiological responses to Cu2+ toxicity are fundamentally a cellular response, rather than a synergistic effect of altered behavior and cell-level disruption. Finally, this work provides a proof of concept for MovTrack software as a reliable phenotyping strategy for quantitative measurement of marine larvae behavior.