Effects of tidal currents on meiofauna densities in vegetated salt marsh sediments

Abstract

The effect of tidal currents on densities of mud-dwelling meiofauna in natural vegetated sediments is unknown. To test for an effect, replicate core samples were collected at low (air exposed), flood, slack high and ebb tide from an intertidal Spartina alterniflora marsh. Emergence traps were set to determine if benthic species occur in suspension. Meiofauna were present but not abundant in all emergence traps. For most taxa, highest sediment densities were at low tide and lowest densities were on the ebbing tide when current velocities were highest. Densities were significantly lower on the ebbing tide compared to low tide for nematodes, copepod nauplii and for 3 of the 6 most abundant copepod species. Total currents passing among S. alterniflora culms are sufficient to affect meiofauna densities by suspending individuals above vegetated sediments. Behavior and life-style of individual copepod species must determine which species will be affected.