Abstract
In this study we investigate the impact of severe weather on marine animals, specifically fish and sea turtles, in Canaveral, Florida. There is a lack of studies that examine potential impacts of multiple species to the same weather events, and for several events across years in the same study area. Extreme weather has potential to create major disturbances to the physical environment and associated disruption to species behavior. The ecology, metabolic requirements, and duration of each storm are also very important considerations. In this study, tagging technology (acoustic and satellite) is utilized to monitor movements of animals before, during, and after storm events, and these data are compiled and analyzed via a combination of traditional residency and unique statistical and movement modeling approaches. The study focuses on determining species‐specific behavior and how they may be impacted by severe weather; developing, fitting, and tuning a Bayesian state‐space movement model; characterizing acoustic background noise, sounds, and array performance; and examining the behavioral response of tagged animals to tropical cyclones. The findings indicate that different species exhibit varied responses to severe weather events, some that were correlated with changing environmental conditions, and others that were a clear direct result of a major hurricane (blacknose sharks and individual green turtles). Key outcomes for fish show that red drum and sharks may be subject to short‐term changes in core preferred areas, movements, and even displacement. Overall, these species were found to have different responses major storm events. For example, Tropical Depression (TD) Ana in 2015 likely resulted in moderate impacts to foraging conditions for red drum, that were correlated with movements of matched individuals (i.e. same individual pre/post) to deeper water further from shore. These types of movements were not observed for red drum in response to TD Emily in 2017, while Atlantic sharpnose sharks had a lack of detections after this storm that was likely associated with offshore movements, and blacknose showed an increase in speed and distance from shore after the storm. In more moderate intensity storms without a large drop in barometric pressure, sharks appeared to mostly stick with preferred habitats. However, a flight response was documented for all tagged blacknose sharks in response to Hurricane Matthew and a large change in pressure and local environmental conditions, taking more than a week to return to the study area. Short‐term displacement from the study area was also documented for a subset of blacknose sharks in response to Hurricane Irma, and also for Hurricane Dorian where significant changes to currents and pressure were recorded. Overall, blacknose sharks appeared to show less resilience to impacts or displacement as compared with the sharpnose shark, a species that is wide‐ranging and has an affinity for offshore waters. The study also revealed that fish chorusing may be impacted by severe weather events during particular times of the year. Hurricane Dorian showed a clear impact on mixed species fish chorusing for the days surrounding the storm, although this appears to be limited in duration to just a few days in comparison with apparent impacts to suspected Atlantic midshipman chorusing. The availability of satellite data for sea turtles facilitated the examination of the response to TD Emily and Hurricane Irma near Canaveral. Notably, there was increased dispersion in longitude for green turtles after the storm, and one individual also exhibited a highly directed movement south the day of the storm, moving 45 miles and returning 11 days later. In response to this storm, loggerhead turtles decreased their speed and distance from shore but did not show a directed flight response. Finally, all 3 matched individual green turtles (pre/post) displayed increased speed and move persistence in response to Hurricane Irma. One individual green turtle also exhibited a highly directed movement and flight response to the north associated with this storm, during an important period of post‐nesting. The approach in this study provides a mechanism to synthesize acoustic telemetry or satellite data and fit Bayesian state‐space movement models based on prior knowledge, and utilize this information to examine important questions on potential response to extreme weather events. Connecting these movement metrics with more traditional indices on residency, occurrence, and displacement helps to create a more comprehensive assessment of how tropical cyclones may impact finfish, sharks, and sea turtles differently. This broader knowledge is important in the ecological context of potential movements out of preferred foraging areas, vast movements outside the study area, and increased energy expenditure, particularly for important periods of reproduction such as post‐nesting sea turtles with lower metabolism. These findings are also important to understanding important stressors for small coastal sharks, particularly Carcharinids such as the blacknose that have demonstrated flight responses for multiple species, and for this group of coastal sharks that has one species ESA protected (Oceanic Whitetip) and another under consideration (smalltail). The ability of sharks to seek refuge and foraging opportunities elsewhere may mitigate the potential impacts of extreme weather, but increased activity due to a behavioral response could temporarily disrupt metabolic functioning.