Lactate dehydrogenase in guppy fish (Poedlia reticulata) as a biomarker for heavy-metal pollution in freshwater ecosystems

Heavy-metal concentrations and allozyme variations were determined in females of guppy fish {poedlia reticulata) populations collected from polluted and unpolluted sites. the concentrations of cu and fe were significantly (p< 0.05) higher in guppies collected from polluted drainage compared to the unpolluted population. higher concentrations of cu,fe and zn (p< 0.05) were found in the surface sediment,indicating contamination by the three metals in the polluted drainage. the insignificant difference (p> 0.05) in the zn concentrations between the polluted and the unpolluted populations indicated that zn,as a major essential metal,was regulated in this freshwater fish. seven enzyme systems est,g6pdh,ldh,mdh,pgi,pgm and sdh were tested. only ldh (lactate dehydrogenase) was found to be a good biomarker for the contamination of cu and fe in p. reticulata. the zymogram of the unpolluted wild population showed the same monomorphic allele as the unpolluted domesticated guppies from a pet shop,thus,further confirming ldh in p. reticulata as a good biomarker of contamination by cu. © universiti malaysia terengganu publisher.