Abstract:
In response to growing worldwide market demand, intensive shrimp farming, particularly of whiteleg shrimp Litopenaeus vannamei, has expanded tremendously. The present study investigated induced DNA damage in gill (GL), haemolymph (HL) and muscle (ML) cells in juveniles of L. vannamei (length: 52.2 plus-minus 6.4 mm; weight: 1.78 plus-minus 0.5 g; mean plus-minus SD) exposed to 2 sublethal (SL) concentrations, SL1 (0.36 Micro-g l sup(-1)) and SL2 (0.18 Micro-g l sup(-1)), of the organophosphorus pesticide chlorpyrifos (CPF) during 21 d of exposure (DoE). The magnitude of DNA damage (percent tail DNA) as measured by the comet assay at specified intervals (3, 7, 14 and 21 DoE) was found to be tissue specific and time and dose dependent (p less than 0.05). At the end of the experiment, at 21 DoE, percent tail DNA damage was relatively higher at SL1 (53.61 plus-minus 8.71, 49.36 plus-minus 3.42 and 32.40 plus-minus 4.97 percent) compared to SL2 (39.25 plus-minus 3.90, 32.22 plus-minus 4.21 and 22.66 plus-minus 2.85 percent) in GL, HL and ML cells, respectively. No significant differences in water quality parameters were found among treated and control aquaria. The significant reduction in specific growth rates (percent growth d sup(-1)) observed in exposed shrimps indicated that SL concentrations of CPF negatively impacted growth in L. vannamei juveniles. A very low 96 h median lethal concentration (1.44 micro-g l sup(-1)) indicated sensitivity of L. vannamei juveniles to CPF, suggesting that the species could be used as a bioindicator for assessing pesticide pollution. The study results highlight the implications of extending the farming of L. vannamei to low-salinity inland areas adjacent to traditional agricultural fields.
