Distribution and dynamics of bacterial production in relation to wind perturbations in a Mediterranean lagoon

Abstract

We examine the relationship between spatial and temporal variations of bacterial production (3H‐thymidine incorporation into DNA) and wind‐induced physical perturbations in a marine coastal ecosystem. Spatial and temporal patterns of bacterial production are described on different scales in Thau Lagoon (France). The spatial patterns generally consist of gradients whose highest values are located in areas of permanent input from a watershed. On the seasonal scale, these patterns are relatively constant, and only the mean values of thymidine incorporation change. On the daily scale, the spatial patterns can be less constant. The variability arises from the intensity of wind forces acting on the surface, which produce hydrodynamic changes. A strong relationship (r = 0.91, P ≤ 0.0001) is demonstrated between windspeed and the spatial variance of bacterioplankton production. The frequency of windspeed > 5 m s−1 also affects daily change in thymidine incorporation into DNA. Physical processes must be taken into account to explain spatial and temporal patterns of bacterial variables in marine coastal environments.