Bacterial abundance, biomass, and secondary production along a forest-to-ocean landscape gradient

Abstract

Bacterial abundance, biomass, and rates of secondary production were measured at three locations along a transect extending from stream-input areas to near-ocean areas at the North Inlet salt-marsh ecosystem. Bacterial abundances, biomass, and growth rates were low in stream areas compared to abundances, biomass, and growth rates in high-marsh and near-ocean marsh. This general pattern was influenced by tidal events. Bacteria were more abundant and had higher growth rates during low tides than during high tides at high-marsh and near-ocean marsh sites. This pattern was reserved in stream input areas where bacterial abundance and growth rates were higher during high tides than during low tides. Estimates of bacterial secondary production ranged between 1.8 × 10 7 and 4.5 × 10 7 cells·1 −1·h −1 and significantly covaried with salinity. Covariance of growth rates and salinity suggested that bacterial growth rates were more closely associated with a given water mass than with a particular landscape segment or the characteristics of that landscape segment.