Abstract:
Nuclear abnormalities in the peripheral erythrocytes of fishes inhabiting contaminant waters
are useful biomarkers for assessing genotoxic potential of surface waters impacted by
anthropogenic contaminants. Kelani river which receives a wide variety of contaminants from
multiple sources including industrial effluents and domestic waste, is ranked as the most
polluted river in Sri Lanka. However, scientifically based evidences on biological impacts of
Kelani river pollution on its resident fauna are meagre. In the present study, frequencies of
erythrocytic nuclear abnormalities in the two fish species inhabiting Kelani river viz.
Etroplus suratensis and Dawkinsia singhala were evaluated in order to assess the potential
genotoxic impacts. E. suratensis were sampled from Ruwanwella (upstream) and
Mattakkuliya (seaward site) sites, whereas D. singhala were sampled from the sites located in
Ruwanwella and Kaduwela (between upstream and seaward site) during the years 2013-2015
covering dry and wet periods. Erythrocytic nuclear abnormalities in the blood of sampled
fishes were evaluated using standard procedures. In addition, surface waters of the fish
sampling sites were physico-chemically characterized using standard analytical procedures.
Water quality parameters indicated high levels of chemical oxygen demand and heavy metal
levels in Mattakkuliya and Kaduwela sites in comparison to Ruwanwella site. Despite
temporal variations, frequencies of total erythrocytic nuclear abnormalities were significantly
higher in the E. suratensis sampled from Mattakkuliya site than those from Ruwanwella site
(P <0.05). In addition, D. singhala sampled from Kaduwela site had significant total
erythrocytic nuclear abnormalities than the fish from Ruwanwella site. Of the four types of
nuclear abnormalities detected, blebbed and noched nuclei contributed mainly to the
induction of total erythrocytic nuclear abnormalities than binuclei and nuclear buds.
Comparison of erythrocytic nuclear abnormalities of the two feral fish species inhabiting
Kelani river together with physico-chemical analysis revealed that Mattakkuliya and
Kaduwela sites of the Kelani river are polluted with genotoxic contaminations which can
induce harmful impacts on indigenous fauna.
This study was funded by the National Research Council research grant 11-11 and National
Science Foundation equipment grant RG/2011/EQ/16.
