Search

Juvenile Epinephelus coioides were exposed to three nominal concentrations (8, 32, 128 mg wet sediments L−1) of suspended sediments ( SS) from Port Shelter ( PS), Mirs Bay ( MB) and Victoria Harbour ( VH) for 10 and 30 days using semi-static system. Sediments from VH contained higher concentrations of Cu and polycyclic aromatic hydrocarbons ( PAHs) than sediments from PS and MB. Gill damages including lamellar blood sinus dilation and vascular congestion were prevalent after just 10 days of exposure to SS. Fish exposed to SS at the highest concentration of 128 mg L−1 showed higher incidence of lamellar aneurism. Hyperplasia in the base of lamellae was recorded in fish that had been exposed to contaminated SS from VH. Significant increases in the density of chloride cells and mucous cells were found on the gills of fish that had been exposed to 128 mg L−1 of SS from PS. Clogging of gills by SS produced hypoxic-like responses in fish. Polluted sediments from VH produced addictive or synergistic effects between SS and chemical contaminants on fish. [ABSTRACT FROM AUTHOR]

The present study was conducted to investigate the effect of dietary cadmium (Cd) level on the growth, body composition and several enzymatic activities of juvenile yellow catfish, Pelteobagrus fulvidraco. The experimental diets were formulated with CdCl2·2.5H2O at levels of 0, 0.01, 0.1 and 1.0 g kg−1 diet, resulting in four dietary Cd levels of 0.25 (control), 4.92, 48.57 and 474.7 mg Cd kg−1 diet respectively. They were fed to juvenile yellow catfish (mean initial weight: 3.26±0.07 g, mean±SD) for 4 weeks. Weight gain, specific growth rate, feed intake and protein efficiency ratio tended to decline with increasing dietary Cd levels ( P<0.05). In contrast, the feed conversion ratio was the lowest when the dietary Cd level was 0.25 mg Cd kg−1 diet. Dietary Cd levels significantly influenced body composition and Cd accumulation. Whole body and vertebrae Cd content generally increased as the dietary Cd levels increased ( P<0.05). However, muscle Cd content was detected only in fish fed the diets containing the highest Cd level of the diet ( P>0.05). Hepatic alkaline phosphatase, glutathione peroxidase and lactate dehydrogenase activities increased ( P<0.05) with increasing dietary Cd level. Succinate dehydrogenase was very variant and not related to dietary treatments. Malic dehydrogenase activity showed no significant differences among the treatments ( P>0.05). The present study provided for the first time the toxic assessment of dietborne Cd in yellow catfish, based on growth performance and the changes in hepatic enzymatic activities for the fish species. [ABSTRACT FROM AUTHOR]