Benthic community dynamics in Galveston Bay, Texas

Abstract

Sediment oxygen consumption and inorganic nutrient production have been measured in situ benthic incubation chambers across a representative range of environmental conditions in Galveston Bay. Estimates of community biomass (macrofauna, meiofauna and bacteria) were made at the same time using conventional grab or core sampling followed by laboratory sorting and biomass determinations. The mean of the community heterotrophic metabolism was high, but the mean total community biomass was relatively low indicating that the total biota, including bacteria, are characterized by a rapid mean turnover time (ca.11.4 days). The net flux of regenerated inorganic nitrogen, mostly in the form of NH4+, had a mean value of 4.9 mmol N m-2 d-1, which is believed to be a significant source of nitrogen for photosynthetic organisms. Photosynthesis by pennate diatoms on the sediment surface can be exceptional when light conditions permit, and this is believed to contribute to the bay's high biological activity. It is hypothesized that the low biomass of the macrofauna may be a result of top down predation.