Bioaccumulation of heavy metal lead (Pb) in different tissues of brackish water fish Mugil cephalus (Linnaeus, 1758)

This study was performed to determine the heavy metal accumulation concentrations in different tissues ofthe selected brackish water fish Mugil cephalus. The fishes were exposed to sub-lethal concentrations of leadacetate (Pb (C2H3O2)2) for 96 hour, and LC50 value was found to be 18.7 ppm. The one-tenth of (1/10) LC50(1.89 ppm) value was selected as a lower sub-lethal concentration for the exposure period of 30 days. Theorgans of fish, namely, gills, liver, and muscle were carefully separated through the dissection from fish forthe determination of heavy metal using Absorption Spectrophotometer (Perkin Elmer Analyst-400, USA). Theresults reveal that the low concentration of lead (1.89 ppm) exhibits a maximum level of accumulation in theliver (0.746 ± 0.0033 μg/g), gills (0.672 ± 0.0069 μg/g), and muscle (0.254 ± 0.0052 μg/g) tissues of 30 daysexposed. The result of the present investigation also reveals that the time-dependent lead accumulation indifferent tissues of fish M. cephalus exposed to different sub-lethal concentration of the lead. These findingsextend for future studies on the evaluation of lead accumulation tendency in relation to the eco-toxicologicalobservations for heavy metals risk assessment.

Morphologic and Genetic Evidence for Mixed Infection with Two Myxobolus Species (Myxozoa: Myxobolidae) in Gray Mullets, Mugil cephalus, from Korean Waters

The present study was performed to trace the decisive evidence for mixed infection of 2 Myxobolus species, M. episquamalis and Myxobolus sp., in the gray mullet, Mugil cephalus, from Korean waters. Mullets with whitish cyst-like plasmodia on their scales were collected near a sewage plant in Yeosu, southern part of Korea, in 2009. The cysts were mainly located on scales and also found in the intestine. The spores from scales were oval in a frontal view, tapering anteriorly to a blunt apex, and measured 7.2 microm (5.8-8.0) in length and 5.3 microm (4.7-6.1) in width. Two polar capsules were pyriform and extended over the anterior half of the spore, measuring 3.5 microm (2.3-4.8) in length and 2.0 microm (1.5-2.2) in width. In contrast, the spores from the intestine were ellipsoidal, 10.4 microm (9.0-11.9) in length and 8.4 microm (7.3-10.1) in width. The polar capsules were pyriform but did not extend over the anterior half of the spore, 3.7 microm (2.5-4.5) in length and 2.2 microm (1.8-2.9) in width. The nucleotide sequences of the 18S rDNA gene of the 2 myxosporean spores from scales and intestine showed 88.1% identity to each other and 100% identity with M. episquamalis and 94.5% identity with M. spinacurvatura from mullet, respectively. By the above findings, it is first confirmed that mullets from the Korean water are infected with 2 myxosporean species, M. episquamalis and Myxobolus sp.