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Effects of contaminated harbour sediment on the growth and histopathology of Nile tilapia (Oreochromis niloticus): A long-term study

Authors:

SHNP Gunawickrama ,

No. 75, Sri Subadrarama Mawatha, Galle, LK
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DD Hettiarachchi,

Department of Zoology, Faculty of Science, University of Ruhuna, Matara 81000, LK
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KBS Gunawickrama

Department of Zoology, Faculty of Science, University of Ruhuna, Matara 81000, LK
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Abstract

Growth and histopathology of juvenile Oreochromis niloticus (L.) was studied upon continuous exposure to contaminated sediments from the maritime fisheries harbour of Galle, Sri Lanka. Sixteen week long experiment comprised of four duplicated groups of fish in freshwater (NC: negative control without sediment, C: control with unit-dose of pristine sediment, T1 with unit-dose of contaminated sediment, T2 with three unit-doses of contaminated sediment) with total renewal of water and sediment on each fourth day serially. Unit-dose of sub-lethal wet sediment was arbitrarily decided as 38ml through a series of tolerance tests. Total length and weight of fish were recorded (n=20x4 per group) initially and on completion of weeks 4, 10 and 16. Gill and liver histology was qualitatively examined using four sacrificed fish per group at termination. Results showed that harbour sediment in water significantly (p<0.05) decreased cumulative growth rates of T1 and T2 fish in terms of absolute growth rate (0.58-0.59 mm/day and 0.17g/day), relative growth rate (1.52-1.56% length gain day-1 and 0.73% weight gain day-1) and specific growth rate (0.89-0.91% day-1 in length, 2.60-2.61% day-1 in weight) as compared to C and NC groups. T1 and T2 juveniles developed toxicopathic signs in gill (lamellae-fusion, decreased inter-lamellar space) and in liver (extensive necrosis, hydropic vacuolation). Growth parameters remained similar between C and NC groups throughout the study with no histological alterations suggesting that sediment borne salinity had no differential effect across groups. This study shows that exposure to contaminated sediment from Galle fisheries harbour causes growth reduction and pathologic lesions in gills and liver of O. niloticus juveniles.

DOI: http://dx.doi.org/10.4038/jur.v2i1-2.7850

J. Univ. Ruhuna 2014 2:14-23

DOI: http://doi.org/10.4038/jur.v2i1-2.7850
How to Cite: Gunawickrama, S., Hettiarachchi, D. & Gunawickrama, K., (2014). Effects of contaminated harbour sediment on the growth and histopathology of Nile tilapia (Oreochromis niloticus): A long-term study. Journal of the University of Ruhuna. 2(1-2), pp.14–23. DOI: http://doi.org/10.4038/jur.v2i1-2.7850
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Published on 24 Dec 2014.
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