Science Serving Maryland's Coasts
Denise Breitburg, Ph.D.
Smithsonian Environmental Research Center
The Effect of Submerged Aquatic Vegetation on Callinectes sapidus Predation of Mya arenaria
The rate of predation and feeding behavior of the blue crab Callinectes sapidus on the soft-shelled clam Mya arenaria, in relation to the presence of artificial submerged aquatic vegetation (SAV) was examined in 1 m2 raceway tanks at the Academy of Natural Sciences Estuarine Research Center in St. Leonard, Maryland. Two types of experiments were conducted. The first experiment tested whether individual crabs would exhibit different rates of predation in single habitat tanks, where the habitat is defined by zero, low, medium, and high SAV density. The second experiment gave each individual crab a choice of three habitats: zero, medium, and high density SAV. Crabs participating in this experiment were video monitored to observe their feeding efficiency by quantifying the proportion of time each crab spent in each habitat compared to the amount of clams consumed in each habitat. The results of the first experiment showed that when not given a choice of habitat, crabs do not display significantly different predation rates between habitats, indicating that clams were not benefiting from the potential refuge created by higher densities of SAV. However, when given a choice of habitat, the crabs showed preference for feeding where SAV was absent over medium and high SAV habitats, but did not display significant differences of predation between the medium and high-density habitats. This suggests that the clams are getting protection from the presence of SAV, but may not get enhanced protection as the density of SAV increases. The results of the video monitoring showed highly variable feeding efficiency and behavior between individuals.
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