The effects of Cyclina sinensis bioturbation on alkaline phosphatase and total microbial hydrolytic activities in marine clam-shrimp integrated ponds.

This study investigated the influence of Venus clam Cyclina sinensis bioturbation activities on the total benthic microbial and phosphatase activities and selected sediment properties: total phosphorus (TP), total organic nitrogen (TON), and total organic carbon (TOC) in aquaculture ponds. Sediments samples from clam-shrimp integrated pond and non-clam integrated pond were sampled for the study, in which sediment microbial activity (MBA) and alkaline phosphatase activity (APA), sediment organic contents (TP, TON, TOC, TOM) and water quality parameter (dissolved oxygen, temperature, pH, and moisture content) were analyzed. The p-nitrophenyl phosphate disodium (p-NPP) and fluorescein diacetate (FDA) were adopted to measure APA and MBA, respectively. Results indicated that MBA and alkaline phosphatase activity (APA) in sediments significantly increased in the pond cultured with clam/shrimp compared to a non-clam cultured pond. Phosphorus concentration increased significantly and varied among months (P < 0.05), implying an increased phosphate mineralization in the sediments. The concentrations of TON and TOC did not differ significantly among months and with the treatments (P > 0.05), implying increased TON mineralization. Correlation analyses showed that there was a positive correlation with the total MBA, APA, phosphorus concentration, and organic matter content within the sediments bioturbated by the Venus clam. The results suggest that, the Venus clam sediment reworking mechanisms influenced the sediment-microbial and APA activities and mineralization, thereby affecting the pond alkaline phosphatase enzyme-related activities.