The water samples, collected from two abalone culture ponds and two raft-culture areas in the Dongshan District of Fujian, were filtered using 0.45 m filter membranes, and were used for the
extraction of mixed microorganisms’ DNA (Water DNA kit, Omega,Norcross, GA, USA). The DNA of Drosophila simulans and Caenorhabditis elegans was extracted with a Wizard Genomic DNA Purification Kit (Promega).