Influence of salinity on the distribution and abundance of larvae ofdominant oyster-reef decapods in southwest Florida

摘要

Spatial and temporal variability in recruitment of associated organisms to oyster reefs is dependent upon a number of factors including larval supply, which, in turn, is influenced by freshwater inflow and salinity. Distribution and abundance of larvae of the three dominant decapod crustaceans found on oyster reefs in Es-tero Bay, Florida (Petrolisthes armatus, Eurypanopeus depressus and Rhithropanopeus harrisii) were quantified using monthly plankton tows. Sampling included stations near passes connecting to the Gulf of Mexico, in the open waters of the bay, and in association with tidal tributaries. Larval densities of the marine stenohaline P. armatus were greater in bay waters and near passes. Larvae of the euryhaline E. depressus occurred abundantly throughout the bay and in association with tidal tributaries. Larvae of R. harrisii, a species known to favor reduced salinities, were most abundant near tidal tributaries. Densities of P. armatus and E. depressus peaked at the end of the dry season (May) and were depressed with the onset of seasonal rains (June). In contrast, R. harrisii larvae were in short supply during dry months but were abundant during the wet season. Weighted mean salinity of capture was higher for P. armatus (29.72) and E. depressus (29.88) than for R. harrisii (6.72), and larval density was positively correlated with salinity of capture for P. armatus and E. depressus and negatively correlated for R. harrisii. These results suggest the importance of considering the effects of salinity on spatial and seasonal variation in larval supply in understanding recruitment dynamics of oyster-reef associates.