Comparison of the decapod communities in an anthropogenic impacted lagoon and its adjacent coastal waters

In this study, benthic decapods were sampled approximately for every three months between September 2000 and June 2002 in a heavily used subtropical lagoon and its vicinity waters in southwestern Taiwan. Seventeen shrimp species (dominated by Metapenaeus ensis and Penaeus semisulcatus) and 19 crab species (dominated by Thalamita crenata) were recorded within the lagoon, whereas a combined total of 32 shrimp species (mainly Metapenaeopsis barbata and M. palmensis) and 50 crab species (dominated by Portunus hastatoides) were recorded at 10, 20, 30, and 40-m depths outside the inlet-outlet of the lagoon. The decapod community in the lagoon varied little temporally, and was significantly different from those in the nearby waters. The results of this study document a decapod fauna in a lagoon subjected to decades of aquaculture activities and revealed that these activities benefited a distinct decapod assemblage, yet may have prevented the potential use of the lagoon by other species as a nursery or refuge. Aquaculture activities have since been prevented and dredging of the benthic sediments in the lagoon has been underway; thus the results of present study will provide a valuable and rare baseline data set to be used for future studies to determine how decapod communities shift in response to habitat change.