Juvenile Paralichthys olivaceus were exposed to waterborne hexavalent chromium at various concentrations (0, 0.5, 1.0, and 2.0 mg/L) for 10 days. After chromium exposure, the activities of superoxide dismutase and glutathione S-transferase, which are oxidative stress indicators, were significantly increased; however, the glutathione level was significantly reduced. Acetylcholinesterase activity as a neurotoxicity marker was significantly inhibited upon chromium exposure. Other stress indicators, including plasma cortisol and heat shock protein 70, were significantly increased. The immune response markers (lysozyme and immunoglobulin M) were significantly decreased after chromium exposure. These results suggest that exposure to environmental toxicity in the form of waterborne chromium at concentrations higher than 1.0 mg/L causes significant alterations in antioxidant responses, neurotransmitters, stress, and immune responses in juvenile olive flounders. This study will provide a basis for an accurate assessment of the toxic effects of hexavalent chromium on aquatic organisms.

This study investigated the genetic diversity and structure of thirteen wild populations of Crassostrea gigas in Korea. The purpose of this investigation was to provide foundational data for selecting reference populations to enhance genetic diversity. Overall, the genetic diversity of Korean C. gigas was relatively low. Analysis using AMOVA, genetic differentiation, and DAPC revealed a genetic structure that was consistent with one group. This study identified reference populations to be used for selective breeding to increase the genetic diversity of Korean C. gigas and provided essential data on genetic diversity and structure for future selective breeding efforts in C. gigas.

Fisheries and Aquatic Sciences