Integrated Biomarker Responses of a Brackish Water Clam to Global Warming Conditions

Abstract

To analyze physiological and biochemical marker responses of brackish water clam Corbicula japonica under global warming conditions, different water temperatures (20°C and 25°C), salinity (5 and 20 psu), and food availability (0.5 and 2.0 mg SS ind⁻¹ d⁻¹) levels were tested. Appropriate biomarkers were selected based on the sensitivity of biomarker responses, condition index (CI), energy reserves, superoxide dismutase (SOD), catalase, oxyradical-absorbance capacity, and lipid peroxidation (LPO) (p < 0.05), and five methods of integrated biomarker response index (IBR) were calculated. CI, SOD, and LPO were employed for IBR_I, although four biochemical biomarkers were generally employed for IBR. At high water temperature (HT), all biomarkers were deleteriously affected. HT significantly affected all the IBR methods (p < 0.05), and the highest correlation was discovered in IBR_I (r = 0.92, p < 0.01). The lowest and highest IBRs were observed at natural (control = 1.14) and global warming (HT = 2.43) conditions, respectively. The contribution of LPO scores was higher under HT, demonstrating poor organism health. Based on our estimates, three sensitive biomarkers could detect stress in C. japonica under global warming conditions. We conclude that the IBR method based on sensitive biomarkers should be used to quantify anthropogenic impacts on aquatic organisms, especially C. japonica.