Experiments on Competition and Predation Among Shrimps of Seagrass Meadows

A series of experiments was conducted to evaluate the distribution and abundance patterns of two species of macrophyte—inhabiting caridean shrimps found in Apalachee Bay, Florida, USA. Experiments using Palaemonetes vulgaris and Palaemon floridanus included microhabitat association and behavioral interactions. Predator—prey relationships, as they apply to habitat complexity and interspecifc interactions, were also examined using the pinfish, Lagodon rhomboides, a natural predator. Pt. vulgaris individuals were excluded from the experimental habitats by P. floridanus over a range of densities. We conclude that their nonoverlapping microgeographical distribution is primarily a consequence of interspecific competition rather than just microhabitat selection. Predation success on single species was inversely related to the physical complexity of the experimental habitat. However, when placed together, a significantly greater proportion of Pt. vulgaris is consumed than P. floridanus. We posit that the displacement of Pt. vulgaris from cover by P. floridanus significantly increases the former's risk of detection and capture. The importance of refuges in regard to: (1) seagrass predator strategies; (2) prey tactics, and (3) species abundance and richness patterns in macrophyte—dominated communities are discussed.