Histological effects of contaminated sediments in Mae Klong river tributaries, Thailand, on Nile tilapia, Oreochromis niloticus

Abstract

Histopathological biomarkers of toxicity in fish organs are a useful indicator of environmental pollution. Nile tilapia, Oreochromis niloticus exposed for one month to sediments from the Mae Klong River, Samutsongkram province, South West Thailand, which contained elevated levels of heavy metals (lead and chromium), developed abnormalities of the gills, liver and kidney. In the gill filaments, cell proliferation, lamellar cell hyperplasia, and lamellar fusion were observed. In the liver, there was vacuolation of hepatocytes and nuclear pyknosis. Kidney lesions consisted of dilation of Bowman's space and accumulation of hyaline droplets in the tubular epithelial cell. No recognizable changes were observed in muscle tissue. Despite these histopathological changes, no firm correlation between levels of heavy metals in sediments and those in fish tissues could be established.