Diversity and spatiotemporal variation of an Eastern Tropical Pacific pelagic vertebrate community assessed with drifting pelagic BRUVS

Information about the composition of pelagic communities generally lags far behind that of coastal communities, and largely derives from fisheries data that do not reflect small and non-target species. Spatiotemporal vertebrate diversity and variability associated with environmental drivers across a 3,486 km(2) area of a highly productive pelagic marine ecosystem off Pacific Panama (7.583 degrees N, 78.200 degrees W) were described between August 2019 and March 2020 using drifting pelagic baited remote underwater video stations (BRUVS), a non-invasive fishery-independent sampling technique. From similar to 240 h of footage, we observed 26 taxa from 17 families, including 1 mammal, 3 reptile, 5 elasmobranch, and 17 teleost species. Community composition varied spatiotemporally with higher taxa richness and total abundance during the wet (April-December) than dry season (January-March). Total abundance also increased with increasing distance from shore/seafloor depth. Spatiotemporal assemblage differences were largely driven by the relative abundance of the small zooplanktivorous fishes: Psenes cyanophrys, Caranx caballus, and Decapterus spp. Psenes cyanophrys and juvenile C. caballus were commonly observed during the wet season and their abundances increased with distance from shore/seafloor depth. Decapterus spp. were observed year-round but were observed more often and in greater numbers with increasing with distance from shore/seafloor depth. This study demonstrates the practical application of drifting pelagic BRUVS to detect a diverse range of pelagic vertebrates and environmentally driven changes in pelagic communities to fill knowledge gaps in data-limited species and regions.

Automated summary

This study used drifting pelagic baited remote underwater video stations to describe the vertebrate diversity and variability in a highly productive pelagic ecosystem off Pacific Panama. The results showed that community composition varied spatiotemporally, with higher richness and abundance during the wet season and with increasing distance from shore/seafloor depth. The study highlights the importance of using non-invasive sampling techniques to fill knowledge gaps in data-limited species and regions.