Seasonality and Spatial Patterns of Seagrass-Associated Amphipods of the Indian River Lagoon, Florida

Amphipods of Halodule wrightii seagrass beds in the Indian River, Florida, showed variable seasonal patterns of abundance and diversity, but were generally more abundant in November-May than in June-October. These seasonal patterns of abundance and diversity are largely attributed to seasonality of fish and decapod predation, and are not attributable to seasonality of seagrass biomass. Spatially, amphipod densities were generally (1) lower near ocean inlets, and (2) lower at the southern versus northern sample locations within the Indian River. In both cases, these patterns are attributable to greater abundance of predators at sites where amphipod density was low. A total of only 15 species was collected from five sites over 4 years with overall mean density at these sites only 807 individuals per m2.