Small-Scale Spatial Variability in Coral Reef Fish Settlement
Abstract:
Larval fish dispersal and recruitment processes play a crucial role in determining the overall health, persistence and resilience of coral reef ecosystems. Yet, the degree and importance of small-scale spatial variability in larval fish settlement to reef habitats is still poorly understood. This work seeks to identify the small-scale (1-10km) spatial variations present in settlement, as well as the key biological and physical drivers of any such variation. Larval settlement was investigated across ten different sites within a ten kilometer stretch on the south coast of St. John, USVI. Sites comprised mostly high- and low-quality reefs, but also one sandy bottom habitat. Larvae were collected in light traps deployed between March and November throughout 2016 and 2017. Associated biological data (e.g. adult fish abundance, coral cover, habitat integrity, diversity of resident taxa) and physical measurements (e.g. near-shore currents) were also collected and used to investigate correlations with settlement. Multivariate analyses revealed significant among-site differences in reef fish settlement and high inter-taxon variability in settlement patterns. With coral reefs experiencing an unprecedented rate of decline, understanding the mechanisms behind reef fish settlement on a small scale can give us insight into how coral reef ecosystems may respond in the face of continuing global change, thereby informing future conservation management efforts.