Wednesday, September 4, 2013
Phil Matich: overview of "seasonal variability in the trophic interactions of juvenile bull sharks in a coastal estuary" paper
Hey everyone. Our manuscript, “Multi-tissue stable isotope analysis and acoustic telemetry reveal seasonal variability in the trophic interactions of juvenile bull sharks in a coastal estuary” has just been published in Journal of Animal Ecology (http://onlinelibrary.wiley.com/doi/10.1111/1365-2656.12106/abstract). The manuscript details our investigation of bull sharks’ use of freshwater prey from adjacent marsh habitats that migrate into the Shark River Estuary seeking refuge during the dry season when marsh water levels drop and the marsh dries up. Tracking data show that during the late dry season, sharks significantly increase their use of areas where prey enter the estuary, and stable isotope data reveal that sharks increase the proportion of freshwater taxa in their diets at this time. These findings are really exciting, because other predators, like snook, also show similar changes in their behavior in response to this event, and data suggest it’s an important component to their annual energy budget. If this is also true for bull sharks, then annual variability in the magnitude and timing of this pulse of freshwater prey could affect survival and growth rates of bull sharks within the nursery. Thus, if marsh water levels are affected by restoration efforts and/or climate change (precipitation), then the availability of food for bull sharks during the dry season may change, and in turn affect their behavior and ecological role within the ecosystem.
To see a video summary of our work, go to: http://vimeo.com/69532148