Laboratory evidence suggests glochidia metamorphosis in Sinanodonta japonica (Bivalvia: Unionidae) is supported by gills,but no other tissues of the host Gymnogobius urotaenia (Perciformes: Gobiidae)

We quantitatively assessed the ability of the gills, caudal fin and scales of the floating goby Gymnogobius urotaenia (Hilgendorf, 1879) (Perciformes: Gobiidae) to serve as substrates for the larvae (glochidia) of the freshwater mussel Sinanodonta japonica (Clessin, 1874) (Unionida: Unionidae) by comparing parasitism success and metamorphosis success. We established three experimental treatments with 10 fish per treatment. Twenty glochidia were introduced onto one of the three body parts of each test fish by direct pipette infestation. Glochidia in the gill group had higher parasitism success than those in the fin and scale groups. Juvenile mussels were obtained only in the gill group. We quantitatively assessed the appropriateness of the three body parts as substrates for glochidia on the basis of three indicators: parasitism success; metamorphosis success; and parasitism and metamorphosis success. We conclude from our laboratory experiment that the artificial introduction of S. japonica glochidia onto G. urotaenia gills is a better procedure for obtaining juvenile mussels than the introduction onto fin or scales.