Microbiology of a high energy beach sediment: evidence for an active and growing community

Abstract

Microbial biomass, heterotrophic activity, and growth rates were measured in sandy sedirnents from 2 very different beaches in Nova Scotia, Canada: a protected beach inside Halifax Harbor (HH), and an exposed, high energy beach along the coast (LT). SEM of sand grains revealed that the microbial cells from HH were predominantly cocci whereas the cells from LT were mostly rods. HH sand contained 3.8 times as many cells (direct count) and 6.9 times as much biomass (ATP) as did LT sand. Likewise, the heterotrophic uptake, rates of nucleic acid synthesis, and the rate of carbon production were all several times higher in HH sand than in LT sand. However, on a biomass-specific basis, both sediments had similar activity. Moreover, specific growth rates (5.18 d-') were identical. The data indicate that size and total activity of the microbial population depend on the location of the sediment but that growth rate and per cell activity are apparently not affected by abrasion and shear stress.