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IJWESC Abstract

Influence of agricultural runoff on the spatial distribution and abundance of benthic macro invertebrates in the Runde River, Zimbabwe

Tafangenyasha Clifford, Marshall Brian and Naik Yogishkumar

Scientific Services, ZIMPARKS, P O Box CY 140, Causeway, Harare, Zimbabwe.

Accepted February 11, 2016

The water quality of the Runde River in southeast Zimbabwe was studied using physico-chemico-characteristics and biological monitoring parameters. Water and sampling points were obtained from 20 sampling stations to establish the variation in the physico-chemico characteristics and the integrity of the benthic macro invertebrates. The study recorded variations in the physico-chemical characteristics. A total of 12 orders, 26 families and 33 genera of macro invertebrates were observed. No significant (p>0.05) differences were found in Shannon index for benthic macro invertebrates between control and test sites. The Margalef index for benthic macro invertebrates for the control sites was lower than the test sites suggesting differences in nutrient levels and sources. Using Multiple Correspondence Analysis, Principle Component Analysis, Factor Analysis, majority of the sites were centrally clustered suggesting a failure in diagnostic characteristics to distinguish impaired sites from unimpaired sites and indication that the Runde River water quality was not different in the upstream and downstream of commercial agriculture. The hypothesis was that agricultural development is a key determinant of variability in benthic macro invertebrate distribution and abundance may not hold. The findings in the study are surprising considering the known impacts of commercial agriculture on river water quality thus, the need for a long time study on the same river. Physico-chemical and biodiversity of a river fluctuate seasonally.

Key words: Agricultural runoff, benthic macro invertebrates, Runde River, spatial distribution.

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