Contribution of particle-bound bacteria to total microheterotrophic activity in five ponds and two marshes

We examined the abundance and heterotrophic uptake of bacteria attached to particulate matter suspended in five coastal ponds and two marshes near Woods Hole, Mass. Although the number of particle-bound bacteria was low (<10%), these bacteria incorporated a large proportion (>40%) of [C]glucose and [C]glutamate in selected aquatic systems. The uptake per cell was significantly higher for epibacteria than for unattached bacteria in all systems. Two groups of the aquatic environments sampled were statistically different in the contribution made by particle-bound bacteria to total bacterial abundance and to total assimilation of [C]glucose and [C]glutamate. Particle-bound bacteria were more important in those waters with a high particle concentration and not flushed regularly by tides than in waters with a low particle concentration and flushed regularly.