Extreme events provide a unique opportunity to understand how sudden changes in the environment can impact species and ecosystem processes. Hurricanes can cause drastic changes to aquatic ecosystems, with possible short-term changes to salinity, hypoxia, mangrove and seagrass loss, for example. In addition to the immediate changes to the environment, hurricanes can leave lasting demographic effects on coastal populations. Studies in the coastal waters of the Gulf of Mexico and the Bahamas have shown that hurricane events caused changes in social structure, demography, and reproductive success of coastal bottlenose dolphins (Tursiops truncatus). There are, however, few studies that have investigated how behavior and habitat use might change immediately before and after a storm. In September 2017, Hurricane Irma, a category 4 storm, made landfall in South Florida, USA. Our study site, the Florida Coastal Everglades (FCE), recorded a storm surge of over 10ft at the mouth of the Shark River Estuary. Five CPOD (Chelonia Ltd., Cornwall, U.K.) passive acoustic monitors have been deployed as part of a Long-Term Ecological Research (FCE-LTER), since May 2017, to investigate the habitat use of bottlenose dolphins. CPODS were deployed across the Shark River estuary, from the mouth to upstream brackish waters, and were used to investigate how environmental conditions (pressure levels, wind speed, temperature, salinity, water levels) correlated with detections of dolphins at a fine scale (hourly) throughout the Shark River Estuary.
Results/Conclusions
Dolphin detections per minute (DPM) increased up to 4-fold in the upstream locations, starting two days following the hurricane landfall, and continuing up to two weeks. DPMs in downstream stations showed the opposite pattern with decreased detections compared to prior months. Investigating the immediate effects of hurricanes on habitat use of coastal species may provide insight on the magnitude of disturbance.