Movements of Juvenile Bull Sharks in Response to a Major Hurricane Within a Tropical Estuarine Nursery Area
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Predicting the responses of animals to environmental changes is a fundamental goal of ecology and is necessary for conservation and management of species. While most studies focus on relatively gradual changes, extreme events may have lasting impacts on populations. Animals respond to major disturbances such as hurricanes by seeking shelter, migrating, or they may fail to respond appropriately. We assessed the effects of Hurricane Irma in 2017 on the behavior and survival of juvenile bull sharks (Carcharhinus leucas) within a nursery of the Florida coastal Everglades using long-term acoustic telemetry monitoring. Most of our tagged sharks (n = 14) attempted to leave the shallow waters of the Shark River Estuary before the hurricane strike, but individuals varied in the timing and success of their movements. Eight bull sharks left within hours or days before the hurricane, but three left more than a week in advance. Nine of 11 bull sharks (~ 82%) eventually returned to the array within weeks or months of the storm. Six of these returning individuals were detected in a different coastal array in nearshore waters ca. 80 km away from the mouth of the estuary during their absence. The remaining three bull sharks moved downstream relatively late (after the hurricane) and may have died. We used binomial generalized linear mixed models to estimate the probability of presence within the array as a function of several environmental variables. Departure from the array was predicted by declining barometric pressure, increasing rate of change in pressure, and potentially fluctuations in river stage. Juvenile bull sharks may weigh multiple environmental cues, perceived predation risk, their own physical size, and shifting prey resources when making decisions during and after hurricanes.
KeywordsAnimal movement Estuaries Extreme events Hurricane Juvenile bull sharks Nursery habitat Carcharhinus leucas
We are grateful to many field and lab volunteers that assisted with capture and sample processing. This is a contribution from the Center for Coastal Oceans Research in the Institute for Water and Environment at Florida International University. B. Strickland was supported by University Graduate School and Department of Biological Sciences assistantships at Florida International University as well as an Everglades Foundation fellowship. We would like to thank Yannis Papastamatiou and two anonymous reviewers for their comments and suggestions to improve the manuscript. In addition, we would like to acknowledge Javiera Hernandez, Hugh Willoughby, and Robert Burgman for their insights on hurricanes.
This work was supported by the National Science Foundation through the Florida Coastal Everglades Long-Term Ecological Research program under Grant DEB-1237517 and in collaboration with the RECOVER program of the Comprehensive Everglades Restoration Plan. Dissolved oxygen measurements were made as part of a project supported by the National Science Foundation through the Water Sustainability and Climate solicitation (EAR 1204572) and the National Aeronautics and Space Administration (NNX14AJ92G) under the Carbon Cycle Science Program.
Research and animal procedures were conducted under the auspices of protocol no. IACUC-16-022 from the Institutional Animal Care and Use Committee of Florida International University and in accordance with sampling permit no. EVER-2017-SCI-0031 granted by Everglades National Park.
- Bailey, H., and D.H. Secor. 2016. Coastal evacuations by fish during extreme weather events. Nature 6: 30280.Google Scholar
- Burnham, K.P., and D.R. Anderson. 2002. Model Selection and Multimodel Inference: A Practical Information-theoretic Approach. 2nd ed. New York: Springer-Verlag.Google Scholar
- Cangialosi, J. P., A. S. Latto, R. J. Berg. 2018. Hurricane Irma (AL112017). Tropical Cyclone Report: National Hurricane Center. https://www.nhc.noaa.gov/data/tcr/AL112017_Irma.pdf. Accessed 13 September 2018.
- Castro, J.I. 2011. The sharks of North America. New York: Oxford University Press.Google Scholar
- Lowe, C.G. 1996. Kinematics and critical swimming speed of juvenile scalloped hammerhead sharks. The Journal of Experimental Biology 199 (Pt 12): 2605–2610.Google Scholar
- Matich, P., and M.R. Heithaus. 2014. Multi-tissue stable isotope analysis and acoustic telemetry reveal seasonal variability in the trophic interactions of juvenile bull sharks in a coastal estuary. Journal of Animal Ecology 83 (1): 199–213. https://doi.org/10.1111/1365-2656.12106.CrossRefGoogle Scholar
- National Oceanic and Atmospheric Administration. 2018. Automated Surface Observing System: Miami International Airport Station Data. https://www.ncdc.noaa.gov/data-access/land-based-station-data/land-based-datasets/automated-surface-observing-system-asos. Accessed 13 September 2018.
- Southeast Regional Climate Center. 2019. Royal Palm Ranger Station Data, Florida (1949–2012). https://sercc.com/cgi-bin/sercc/cliMAIN.pl?fl7760. Accessed 13 June 2019.
- United States Geological Survey. 2018. Everglades Depth Estimation Network database. https://sofia.usgs.gov/eden/. Accessed 13 September 2018.
- Van de Pol, M.S. Jenouvrier, J.H.C. Cornelissen, and M.E. Visser. 2017. Behavioral, ecological, and evolutionary responses to extreme climactic events: challenges and directions. Philosophical Transactions of the Royal Society B 372 (1723).Google Scholar
- Wiley, T.R., and C.A. Simpfendorfer. 2007. The ecology of elasmobranches occurring in the Everglades National Park, Florida: implications for conservation and management. Bulletin of Marine Science 80: 171–189.Google Scholar