Antioxidant Responses of a Brackish Water Clam to Sediment Composition and Water Quality: a Field Experiment

Abstract

Field experiments were conducted at brackish-water sites (Lake Hinuma, Hinuma River, and Naka River) to investigate oxidative stress responses of a brackish-water clam, Corbicula japonica, to sediment composition and water quality. To ascertain the influence of the sediment composition, clams were subjected to three test sediments with different contents of clay/silt and organic matter from the same site. Sediment with ~33% of clay/silt content and ~10% of ignition loss exhibited decreased oxygen radical absorbance capacity (ORAC) within two weeks (p 0.05). To ascertain the influence of the water quality, clams were placed in baskets without sediment at four brackish-water sites. Significant differences in ORAC were observed in response to salinity and chlorophyll a (Chl a) (p < 0.05). Multiple regression analysis indicated that the levels of salinity and water temperature as well as variations in Chl a, dissolved oxygen, and turbidity for 1 d prior to the sampling date affected ORAC. We concluded that natural influencing factors need to be considered in ORAC assays for C. japonica, when anthropogenic impacts are assessed.

Keywords

• corbicula japonica
• oxygen radical absorbance capacity
• sediment
• salinity
• chlorophyll a