Testing the repellent effects of construction materials on the attachment of the invasive golden mussel, Limnoperna fortunei, in a Japanese urban tidal river

The golden mussel, Limnoperna fortunei, is native to South China but has spread to Japanese freshwater environments as a nuisance invasive species. The golden mussel colonizes hard manmade substrates and its attachment can cause economic losses at water intake facilities. To evaluate the repellent effects of the high alkalinity (pH 12–13) of freshly prepared cement mortar on golden mussels, test pieces made of cement were immersed in a Japanese urban tidal river. Compared with coated mortar, and wood and limestone test pieces, the cement mortar did not show significant repellent effects on golden mussel attachment. Therefore, concrete constructions on riverbanks may be a preferred substrate for golden mussel colonization. A 4-year immersion experiment showed that copper substrate had a strong repellent effect on biofouling, while cement mortar, aluminum, and stainless steel did not have any adverse effects on golden mussel attachment. This experiment also revealed the settlement of invasive golden mussel in an urban tidal area where the salinity fluctuated up to 20.0‰.