Fish Productivity Response to Water Quality Variations: A Case Study of Nyumba ya Mungu Dam, in Pangani Water Basin, Tanzania
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Date
2023
Authors
Mangi, Halima O.
Onywere, Simon M.
Kitur, Esther C.
Journal Title
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Publisher
ije
Abstract
Fish habitat degradation, such as water pollution due to the rapid expansion of incompatible land uses, is one of the noteworthy
challenges to freshwater ecosystems. Elevated contents of nutrients and contaminants in water are some of the imperative
challenges. *is research was conducted to investigate the link between water qualities and 3sh productivity in the Nyumba ya
Mungu Dam, whose 3shery potential had decreased by 95% between 1972 and 2018. Physicochemical characteristics, namely,
temperature, pH, dissolved oxygen (DO), turbidity, total nitrogen, total phosphorus, chlorophyll a, and the water depth of 3shing
net location, were assessed following standard procedure. Fish catches per unit e;ort representing 3sh biomass/productivity were
monitored for twelve months from January to December 2019. Pearson’s correlation analysis indicated that 3sh catch per unit
e;ort was positively and signi3cantly correlated with turbidity (r = 0.461, P < 0.01) and TP (r = 0.405, P < 0.01). Stepwise multiple
regression model results indicated that turbidity, dissolved oxygen, and the depth of the 3shing net location are the statistically
signi3cant predictors of 3sh catch per unit e;ort which represented 3sh biomass. Findings further indicated that the model
combining turbidity and dissolved oxygen predicted a 24% change in 3sh catch per unit e;ort, whereas turbidity, dissolved
oxygen, and the depth of 3shing net location contributed a 28.9% change in 3sh catch per unit e;ort. In conclusion, 3sh
productivity in the NMD is limited by organic matter availability and nutrient levels that cause algae bloom occurrence. Turbidity
is an indicator of organic matter availability and the e;ect of algae bloom on 3sh productivity. InCow of nutrients to the dam
nourishes the algae biomass, thus creating vicious cycles on 3sh productivity as 3sh species in the dam failed to take advantage of
high primary production by algae.
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Citation
Mangi, H. O., Onywere, S. M., & Kitur, E. C. (2023). Fish productivity response to water quality variations: A case study of nyumba ya mungu dam, in pangani water basin, Tanzania. International Journal of Ecology, 2023.