Primary Production of the Sand Microflora in Seagrass Beds of Mississippi Sound

The sandy sediments beneath beds of the seagrass Halodule wrightii Ascherson in Mississippi Sound support a diverse and productive benthic microalgal assemblage. Over an annual cycle (June 1989-June 1990), virtually all algal cells comprising the sand microflora were small araphid, monoraphid, and biraphid pennate diatoms <15 μm in length. Chlorophyll a concentrations in the sediments beneath Halodule ranged from 14 to 125 mg m −2 for individual beds with an annual mean of 44 mg m −2 . Stepwise multiple regression indentified water temperature and the density of Halodule blades as the best predictors of chl a concentration; however, R 2 was only 0.38