LANDSCAPE ECOLOGY AND THE MARINE-ENVIRONMENT - HOW SPATIAL CONFIGURATION OF SEAGRASS HABITAT INFLUENCES GROWTH AND SURVIVAL OF THE BAY SCALLOP

Landscape ecology includes the study of the effects of spatial pattern ing of habitats on biotic and abiotic processes. Seagrass beds occur i n a variety of spatial configurations providing a model system to test how spatial patterning of habitats influences ecological processes. W e established four replicate plots over very patchy (22% cover),patchy (70% cover), and continuous (97% cover) seagrass beds so that each pl ot contained approximately 100 m(2) of vegetated bottom. Fifty individ ually marked scallops were placed within the seagrass in each plot and their survivorship monitored over three replicate 24-h periods, and g rowth and survival monitored over an additional four-week period. Ther e was no pattern in survivorship with differences in habitat configura tion over the first three 24-h of the experiment. By four weeks, more scallops were lost to predation in the very patchy seagrass beds than in the patchy or continuous beds. There was a non-significant trend fo r increased growth of juvenile scallops with increased patchiness of t he seagrass habitat. Vegetation characteristics such as shoot density, biomass, and blade length, which have been shown to affect survival o f seagrass-associated invertebrates, were not significantly different among seagrass beds with different spatial configurations. Our results demonstrate that spatial patterning of the habitat, independent of st ructural characteristics of the seagrass, can alter rates of predation on seagrass inhabitants. This implies that habitat utilization and/or foraging strategies of predators change with the spatial patterning o f the vegetation and that very patchy seagrass beds may provide habita ts where transfer of secondary production to higher trophic levels is great.