Impact of heavy metal bioaccumulation on antioxidant activities and DNA profile in two earthworm species and freshwater prawn from Ogun River
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The use of freshwater invertebrates as bioindicator of heavy metal pollution is an important tool for environmental
biomonitoring. This study investigated antioxidant activities and DNA profile in two limicolous earthworms
(Almamillsoni and Libyodrilus violaceus) and freshwater prawns (Macrobrachiumvollenhovenii) at selected points
ofOgun River, Abeokuta.Heavymetal concentrations and DNA profile in the earthworms and prawn tissueswere
measured using standard procedures. Zn concentrationwas higher than other heavy metals in A. millsoni (685.83
±114.42mg/kg), L. violaceus (1913.3±1098.7 mg/kg) andM. vollenhovenii (134.7±13.61 mg/kg). Superoxide
dismutase activity ranged from62.44±7.16–79.82±11.18 U/g tissues, 60.26±11.18–71.07±7.54 U/g tissues
and 74.07 ± 16.69–87.79 ± 8.50 U/g tissues in A. millsoni, L. violaceus and M. vollenhovenii respectively. RAPDPCR
revealed varying DNA profile among the earthworms samples; the UPGMA dendrogram formed two distinct
clusters at genetic similarity coefficient of 0.15–0.2 with one cluster consisting of Alma millsoni and Libyodrilus
violaceus from Sokori, Enugada and Iberekodo sampling points and the second cluster forming two distinct sub-clusters comprising Arakanga and Ago-ika's L. violaceus in one and A. millsoni in the other. High genetic variability
was recorded among the earthworm species while the freshwater prawn showed no variability. Antioxidant
activities and genetic variability in earthworms could serve as biomarkers of heavy metal pollution in
freshwater environment.
Keywords
QL Zoology