The effects of depositing dredged material from offshore on benthic macroinvertebrates inhabiting the swash zone and the first sandbar at Panama City Beach, Florida, are discussed. The dredged material was similar to existing beach material at most sites. The turbidity was relatively low, except near the area of deposition, because alongshore currents dispersed the turbid water. The numbers of individuals at treated stations in the swash zone were reduced after deposition, and five to six weeks later, populations assumed levels comparable to untreated stations. No notable effects of deposition were observed on fauna inhabiting the sandbar. The significant differences in the number of species and individuals between treated and untreated stations both before and after deposition indicated that community compo- sition, distribution, and abundance of macroinvertebrate fauna at similar stations (swash zone and sandbar) may differ naturally, even when the stations are located along the same beach.

Technical Memorandum