Toxicity Assessment of Bindare Stream Sediment on Chironomid Nutrient Composition and Growth Using Sediment Contact Bioassay: Zaria, Nigeria

Adakole, J. A.; Dauda, M. Z.; Muhammad, A. A.
Toxicity of four polluted sites and a reference site in the Bindare stream basin were investigated by a 10-day sediment contact bioassay. The test organism, the fourth instar of Chironomus spp (midge larvae) weighed 60.00 ± 13.00µg. Chironomid growth, crude proteins, and carbohydrate content were determined by conventional methods, as well as sediment metals and water physiochemical parameters. The stream water physicochemical parameters varied with the exception of dissolved oxygen concentration at sites 3 (1.25 ± 2.10mg/L) and 4 (3.20 ± 2.30mg/L), which were within the range suitable for survival of aquatic life. Site 4 sediment demonstrated the highest concentration levels of Zn (4.47 ± 0.11mg/kg), Cu (5.34 ± 0.61mg/kg) and Pb (4.32 ± 0.26mg/kg) while the highest levels of Cd (0.04 ± 0.01 mg/kg) and Fe (26.41 ± 0.81 mg/kg) were obtained at sites 3 and 1, respectively. Chironomid least mean weight gain (12.40 ± 5.46µg) was obtained at site 4, while the highest (22.00 ± 4.47µg) was obtained at site 5. Specific growth rate among the sites were as follows: site 5 > site 2 > site 3 > site 1 > site 4. Chironomids exposed to site 2 sediment had the least carbohydrate content (7.50 ± 1.20 %). Those exposed to site 1 were the most proteinous (19.60 ± 1.10%) while those at site 4 were the least (14.18 ± 1.25%). The measured end points/effects were compared to sediment contaminations and discussed. The results demonstrate differences in sensitivity of Chironomus species and the need for a sediment contact bioassay, when estimating effects of aquatic sediment pollution on benthic communities.
Contaminated Sediment; Bioassay; Chironomid Sp; Toxicity; Nutrient Composition; Growth
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