MEPS prepress abstract   -  DOI: https://doi.org/10.3354/meps14733

ABSTRACT: Seasonal upwelling in tropical coastal regions can create dynamic oceanographic conditions similar to temperate systems, which are known to influence the distribution and movement of marine species. Mobile marine species may seek for warmer environments (behavioral thermoregulation) in response to stronger winds during the upwelling season, which cause cold, nutrient-rich waters to rise and cool shallower environments. Pacific nurse sharks (Ginglymostoma unami) are present in the upwelling regions of the Eastern Tropical Pacific (ETP) coastline, serving as an ideal model species to study the effects of changing water temperatures on movement behavior. In this study, we analyze four years of passive acoustic telemetry data to quantify the movement, residency, and habitat use of G. unami in Santa Elena Bay, north Pacific coast of Costa Rica, located within the Papagayo upwelling system. A total of 28 sharks (15 males and 13 females) ranging from 85-256 cm total length (TL) were monitored inside the Bay. The mean (± SD) residency index (i.e. number of days detected relative to the number of days monitored) of individual sharks was 37 ± 28%. Generalized additive mixed models (GAMMs) revealed seasonal and diel patterns of G. unami use of Santa Elena Bay which were associated with water temperature and wind speed changes during upwelling season. G. unami likely uses the warmer waters of Santa Elena Bay as thermal refuge during the upwelling season to avoid colder adjacent waters. This research will serve as a baseline to understand movement behavior of this species as climate change alters upwelling patterns.