Variability in total microbial biomass measurements made in cross-sections of salt-marsh creeks

Abstract

The temporal fluctuation and distribution of microbial biomass were studied at two salt-marsh creeks having different salinities and hydrographic features. One creek, North Jones Creek, is adjacent to the marsh inlet, while the second creek, South Jones Creek, interfaces with a brackish-water embayment. Samples for analysis of microbial biomass, measured as adenosine 5′-triphosphate (ATP), were collected synoptically for 25 h from three depths at each of three sites within each creek cross-section. The temporal fluctuation pattern of ATP at North Jones Creek followed a tidal rhythm with maximum concentrations occurring at high tide. The temporal fluctuation pattern at South Jones Creek was somewhat erratic with highest concentrations of ATP recovered from samples collected during flooding tides. The distribution of mean ATP densities as well as net flux through each interface proved to be complex which suggests that sampling depth and station placement are critical in determining net fluxes through marsh creeks.