Trace Metal Concentrations in Mesopodopsis orientalis (Crustacea: Mysidae) with Regard to Its Life Stages and Sex in the Cochin Estuary, India

Trace metal concentrations with regard to certain life stages and sex of mysid species, Mesopodopsis orientalis, from the Cochin estuary were studied during monsoon and pre-monsoon seasons. Spatially varying heterogeneous patterns of trace metal loads were apparent within the mature males, immature males, spent females, brooding females, immature females and juveniles of M. orientalis for the region. The concentration ranges of trace metals like Fe, Mn, Zn, Pb, Cu, Cd, Ni, Cr and Co in M. orientalis were: 590.5 to 1554.9 mg/kg, 4.1 to 15.1 mg/kg, 42.0 to 126.5 mg/kg, 2.5 to 17.0 mg/kg, 12.8 to 61.9 mg/kg, 0.2 to 2.3 mg/kg, 7.6 to 25.5 mg/kg, 8.8 to 33.4 mg/kg and 0.2 to 2.2 mg/kg, respectively. Higher metal concentrations were noted for the life stages of M. orientalis during the monsoon season than in the pre-monsoon season. Mature males, immature males, spent females, brooding females, immature females and juveniles of M. orientalis showed large variability in bioaccumulation for specific metals probably associated with distinct physiological processes. Juveniles and immature stages of M. orientalis showed higher metal concentrations than adult organisms. High metal bioaccumulation and its spatial and seasonal variability with regard to animal life stages and sex suggest the importance of M. orientalis as a biomonitor for tracing metal contamination in estuarine environments.