Aquatic Sciences Meeting, Albuquerque 2001

CS20 Microbial Dynamics

Date: Friday, February 16, 2001, Time: 9:15:00 AM

Location: Ruidoso/Pecos

Maranger, R, , Institute of Ecosystem Studies, Millbrook, USA, MarangerR@ecostudies.org

Pace, M, L, Institute of Ecosystem Studies, Millbrook, USA, PaceM@ecostudies.org

Caraco, N, , Institute of Ecosystem Studies, Millbrook, USA, CaracoN@ecostudies.org

Cole, J, J, Institute of Ecosystem Studies, Millbrook, USA, ColeJ@ecostudies.org

del Giorgio, P, A, Horn Point Laboratory, Cambridge, USA, delgior@hpl.umces.edu

CONSISTENT SPATIAL PATTERNS IN BACTERIAL PRODUCTION AND GROWTH EFFICIENCY IN THE TIDAL HUDSON RIVER

The amount of C cycling through a planktonic bacterial community is a function of bacterial production and respiration and both are required to capture the role of bacteria in ecosystem level C dynamics. We measured bacterial C production (BP) at 40 stations and bacterial respiration (BR) at 12 stations monthly from April until October along a 200 km reach of the tidally influenced Hudson River. A strong repeatable spatial pattern was observed whereby BP was significantly higher in the northern reaches of the river. BR showed no clear spatial pattern. However bacterial carbon assimilation rates were considerably higher (2 fold) in the northern reaches of the river. Because of the spatial heterogeneity of this C assimilation, calculated river wide bacterial C demand could be under or overestimated 60% or 160% respectively depending on scale of study. The bacterial growth efficiency (BGE) ranged from 5-30% and was related hyperbolically to BP (r2=0.45). Nutrients are abundant and their availability likely does not explain the variation in BGE observed. We predict that C quality accounts for this range in BGE.

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Aquatic Sciences Meeting, Albuquerque 2001

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