2018 ESA Annual Meeting (August 5 -- 10)

COS 72-10 - Effects of vegetation type on Callinectes sapidus predation success and predator behavior

Wednesday, August 8, 2018: 4:40 PM
355, New Orleans Ernest N. Morial Convention Center
Rachael M. Glazner, Ecology and Evolutionary Biology, Texas A&M University, Galveston, TX, Jade T. Blennau, Stony Brook University, NY and Anna Armitage, Department of Marine Biology, Texas A&M University at Galveston, Galveston, TX
Background/Question/Methods

Climate change is predicted to induce sea level rise and reduce the severity of freezing events on the Texas Gulf Coast; these changes are likely to lead to increased mangrove cover within the marsh-mangrove ecotone. The blue crab Callinectes sapidus is a commercially and ecologically important species within estuarine ecosystems along the Texas coast. It is a mobile invertebrate that feeds on a variety of organisms, and as an adult can be found foraging in both marsh and mangrove environments. Therefore, the aim of this study was to determine if vegetation type had a significant impact on the amount and rate of prey capture by Callinectes, as well as crab movement. Two vegetation matrices were created within 20-gallon tanks: simulated mangrove pneumatophores were constructed from rigid plastic rods, and plastic aquarium plants simulated flexible marsh grasses; these matrices were compared to nonvegetated control tanks. One crab and five penaeid shrimp were placed in each treatment for a total of three hours. A GoPro Hero+ was mounted above each habitat to record predation. The total number of shrimp consumed and rate of shrimp capture were recorded. Predator movement (velocity and time spent moving) was quantified using the software Ethovision.

Results/Conclusions

In the mangrove pneumatophore treatment, 64% fewer shrimp were captured compared to the marsh and nonvegetated treatments. It took crabs 3.4 times longer to capture the first shrimp in the mangrove treatment compared to the marsh and the nonvegetated treatments. There were no significant differences in mean predator velocity or time spent moving among treatments. Within a matrix of mangrove pneumatophores, crabs spent the same amount of foraging effort but captured fewer prey, suggesting that there may be an energetic cost to crabs foraging in mangrove-dominated coastal wetland habitats.