STUDIES ON BIOACCUMULATION OF HEAVY METALS IN SELECTED CRABS OFF MANGALURU COAST
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Date
2022
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KARNATAKA VETERINARY, ANIMAL AND FISHERIES SCIENCES UNIVERSITY, BIDAR – 585 401
Abstract
Heavy metal contamination is hazardous and a severe problem in the marine
environment because it is long-lasting and difficult to oxidise, degrade, remove or convert
to less dangerous components by biological or chemical processes. The inshore waters off
Mangaluru receive a substantial amount of pollution from nearby industries and companies,
including wastes from oil refineries, fertilisers, pesticides and other contaminants.
Decapods have been extensively researched as bioindicators of metal concentrations.
The crab fishery is primarily supported by Portunus pelagicus and P. sanguinolentus, both
of which have high export demand and are important component of the country's small-scale
coastal fisheries. Commercially important crab populations are found in coastal areas with
high levels of heavy metals.
Considering the polluted state of marine ecosystem, an attempt has been made to
know the concentrations of five heavy metals concentration in water, plankton, sediment and
different organs of P. pelagicus and P. sanguinolentus. The order of heavy metal
concentration in different organs of P. pelagicus was Cu>Zn>Ni>Pb>Cd in gills; Zn>Cu>
Ni>Pb>Cd in muscles and Zn>Cu>Cd>Ni>Pb in hepatopancreas. However, in P.
sanguinolentus, the heavy metal concentration was in the order of Cu>Zn>Ni>Cd>Pb in
gills; Zn>Cu>Ni>Pb>Cd in muscles and Zn> Cu > Cd > Ni>Pb in hepatopancreas. Whereas
abundance of heavy metal concentrations in the waters of study area was
Ni>Zn>Pb>Cu>Cd. The abundance of heavy metal concentrations in the plankton of study
area were in the sequence of Cu>Zn>Ni>Pb>Cd. While abundance of heavy metal
concentrations in the sediment of study area was in the sequence of Zn>Cu>Ni>Pb>Cd.