MEPS 367:261-269 (2008)  -  DOI: https://doi.org/10.3354/meps07576

ABSTRACT: Vertical distributions of marine fish larvae are of central importance to their ecology, because feeding, predation, and larval transport vary considerably with depth. While numerous studies have characterized vertical distributions of larvae, vertical swimming behavior of individual larvae is poorly understood. In this study, the role of hydrostatic pressure in vertical swimming behavior of pelagic coral reef fish larvae was examined. Larval angelfishes (Pomacanthidae), triggerfishes (Balistidae), surgeonfishes (Acanthuridae), and filefishes (Monacanthidae) were collected in plankton net tows in the Straits of Florida. Tows were vertically stratified with 5 different nets sampling discrete depths up to 100 m. Larvae were individually placed in a hyperbaric chamber and subjected to a sequence of pressure levels simulating depths of up to 66 m seawater. Larvae from all 4 families showed significant responses, swimming up in response to high pressure and down in response to low pressure. In situ, this barokinetic behavior would cause depth regulation by larvae actively swimming towards ‘preferred’ pressure levels. Individual pressure preferences were calculated from experimental data and compared to capture depths of the same larvae. Among angelfishes and triggerfishes there was significant correlation between in situ capture depths and experimentally derived pressure preferences, suggesting that the experimental observations resembled natural in situ behavior.

KEY WORDS: Fish larvae · Vertical distribution · Behavior · Depth regulation · Barokinesis · Hydrostatic pressure · Coral reef