Cu, Zn, Fe AND Mn CONCENTRATIONS OF SOME GASTROPODS IN THE WAKAGAWA ESTUARY TIDAL FLAT

Abstract

The Wakagawa estuary tidal flat was heavily polluted by industrial wastewater in the past. Since then, organic pollution has decreased due to inflow regulations, etc., and it is now an important wetland with rich biota. However, it is expected that metallic elements remain in the tidal flat and affect benthic organisms. Therefore, some benthic animals, mainly sediment feeders, which are expected to be strongly affected by the sediment, were collected in 2016. Then the concentrations of some metallic elements in their bodies were measured. In this paper, copper, zinc, iron, and manganese concentrations in the soft bodies of six benthic gastropod species are reported. It was suggested that soil zinc concentration was not uniform and some areas were high in this tidal flat, especially in places where water flow is obstructed topographically and mud tends to accumulate. Some degree of partial accumulation in the sediment within this tidal flat was suggested for copper, iron and manganese. Exclusive or partial detritus feeders showed higher metal concentrations than microalgae feeders. Among gastropods, three species of genus Batillaria (B. attramentaria, B. multiformis and B. zonalis) for copper; Batillaria multiformis, B. zonalis and Pirenella nipponica for zinc; Batillaria zonalis and Pirenella nipponica for iron and manganese, are considered useful as an indicator species.