Regulation of essential heavy metals (Cu, Cr, and Zn) by the freshwater prawn Macrobrachium malcolmsonii (Milne Edwards).
Despite the low concentrations of heavy metals in the surrounding medium, aquatic organisms take them up and accumulate them in their soft tissues to concentrations several fold higher than those of ambient levels (Bryan 1979; Rainbow et al. 1990). Knowledge of accumulation patterns of a particular trace metal is a prerequisite for understanding the significance of an observed metal concentration in a particular animal, especially from the aspect of biomonitoring. Many marine invertebrates accumulate heavy metals without any regulation and the accumulation necessarily being associated with mechanisms to store the metals in a detoxified form. Two detoxification mechanisms have been described, both of which may occur in one specimen. Heavy metals can either be bound up in insoluble metalliferous 'granules' (Mason and Nott 1981), or are bound to soluble metal-binding ligands, such as metallothioneins (Roesijadi 1992). Some marine decapod crustaceans have an innate ability to regulate the internal concentrations of essential but potentially toxic metals within a constant level, presumably to meet their metabolic demands (Rainbow 1985, 1992). However, at present, there is no such information relating to freshwater decapod crustaceans, especially shrimps which occupy a totally different environment. Macrobrachium malcolmsonii (Milne Edwards), a potential aquaculture species for freshwater is found in abundance in one of the major Indian rivers, the Cauvery. In the present study, an attempt was made to determine whether the freshwater prawn, M. malcolmsonii, is able to regulate the three essential elements, copper, chromium and zinc, over a wide range of dissolved concentrations. These three metals were chosen because the Cauvery River receives pollutants containing these metals (Vijayram et al. 1990).
Vijayram
K
K
Research Department of Zoology, Periyar E.V.R. College, Tiruchirappalli, India.
Geraldine
P
P
D000818:Animals; D002857:Chromium / Q000493:pharmacokinetics*; D003300:Copper / Q000493:pharmacokinetics*; D033541:Palaemonidae / Q000378:metabolism*; D014874:Water Pollutants, Chemical / Q000493:pharmacokinetics*; D015032:Zinc / Q000493:pharmacokinetics*
D014874:Water Pollutants, Chemical; D002857:Chromium; D003300:Copper; D015032:Zinc