COMPOSITION, ABUNDANCE, BIOMASS, AND PRODUCTION OF MACROFAUNA IN A NEW-ENGLAND ESTUARY - COMPARISONS AMONG EELGRASS MEADOWS AND OTHER NURSERY HABITATS

Quantitative suction sampling was used to characterize and compare the species composition, abundance, biomass, and secondary production of macrofauna inhabiting intertidal mud-flat and sand-flat, eelgrass mead ow, and salt-marsh-pool habitats in the Nauset Marsh complex, Cape God , Massachusetts (USA). Species richness and abundance were often great est in eelgrass habitat, as was macroinvertebrate biomass and producti on. Most striking was the five to fifteen times greater rate of annual macrofaunal production in eelgrass habitat than elsewhere, with value s ranging from approximately 23-139 g AFDW m(2) yr(-1). The marsh pool containing widgeon grass (Ruppia maritima) supported surprisingly low numbers of macroinvertebrates, probably due to stressfully low dissol ved oxygen levels at night during the summer. Two species of macroinve rtebrates, blue mussels (Mytilus edulis) and to a lesser extent bay sc allops (Argopecten irradians), used eelgrass as ''nursery habitat.'' C alculations showed that macroinvertebrate production is proportionally much greater than the amount of primary production attributable to ee lgrass in the Nauset Marsh system, and that dramatic changes at all tr ophic levels could be expected if large changes in seagrass abundance should occur. This work further underscores the extraordinarily large impact that seagrass can have on both the structure and function of es tuarine ecosystems.