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The effects of chlorfenapyr pesticide were investigated on juvenile of Clarias gariepinus. Sub-lethal test was carried out using 5, 7, 9, 11 and 15 mgL-1 of chlorfenapyr pesticide for 96 hours, and peripheral blood was collected through the caudal vein and examined for haematological changes. There was significant reduction (P0.05) in WBC when compared to the control. RBC increase was directly proportional to increase in chlorfenapyr dose and significantly differed from control (p0.05). HGB increased in a dose-dependent manner. MCV values of all treatment groups, except 15 mgL-1, were higher when compared to control. MCH was not significantly different from control. PLT decreased with increase in concentration and was lower for all treatment when compared with control. Results obtained in this study suggest that exposure to sub-lethal concentrations of chlorfenapyr can alter the haematological indices of non-target organisms.

Benthic aquatic insects receive the most direct impact when surface waters are perturbed. However, scarce data and understanding about activities’ effects on surface water ecosystems remain a critical challenge for water resource managers and policymakers in tropical regions. In this study, we surveyed the implications of deteriorating physical and chemical parameters on aquatic insects’ structural assemblage to ascertain the ecological health of River Hadejia in North-Western Nigerian. We sampled aquatic insects and physicochemical parameters in three stations influenced by various land-use activities such as informal settlements and agricultural activities for six months. The two-way analysis of variance (ANOVA) revealed physicochemical parameters such as transparency, depth, and nitrate were not significantly affected by sites’ land-use activities (p > .05) in the six months sampled. However, mean electrical conductivity was lowest in Station 3 (104.3 ± 8.04 µS/cm). Dissolved oxygen (DO), five days biochemical oxygen demand (BOD5) values recorded portray a relatively perturbed water system. We recorded four aquatic insects orders belonging to 11 families and taxa. Dytiscus sp. was the most abundant taxon in the study area. A total of 44, 37, and 35 individuals of aquatic insects were recorded in stations 1, 2, and 3 in the river. The Post hoc test performed for all the diversity indices were not significantly different between the studied stations (p > .05). Canonical correspondence analysis (CCA) revealed poor relationship between the physicochemical parameters and the aquatic insects. However, Gyrinus sp. was positively affected by increased water depth, showing a strong negative association with depth. Cluster analysis revealed that aquatic insects’ assemblage structures were mainly grouped by temporal factors (months) rather than spatial differences between the sites. Overall, this study provides further insights and understanding regarding land-use impacts on the ecological health of the River Hadejia, and we recommend more stringent regulations to control human pressure on the river systems within the studied area to enable surface waters in the area to sustain the provision of desired and valued ecosystem services.

Trait-based approach (TBA) in recent time has received tremendous attention as complementary tool over taxonomic-based approach in assessing ecological health of riverine systems in developed countries, but in the Afrotropical region the trait-based approach is still in its infancy. No trait-based approach has been developed for riverine systems draining forested catchment in the Afrotropical region. Hence, this study was conducted to explore and apply macroinvertebrates traits as potential biomonitoring tools in assessing ecological health of riverine systems draining forested catchments in the Niger Delta area of Nigeria. Selected physico-chemical variables were sampled together with macroinvertebrates in 18 stations of 10 riverine systems from 2008 to 2012. The 18 stations were classified into three ecological classes namely near natural stations (NNS), slightly disturbed stations (SDS), and moderately disturbed stations (MDS) using physico-chemical-based classification with the aid of principal component analysis (PCA). The results revealed traits such as possessions of hardshell body armouring, preferences for clear and transparent water and opaque water, climbing and crawling mobility mechanisms, large (>20–40 mm) body size, preferences for scrapping, shredding, and grazing feeding habits to be associated with NNS and SDS based on RLQ (R, physico-chemical variables; L, taxa; Q, traits) analysis performed. Thus, these traits were deemed to be sensitive to human impact in forested systems. Also, traits such as tegument/cutaneous respiration, soft and exposed body armouring, burrowing mobility mechanism, spherical body shape, preference for detritus [fine particulate organic materials (FPOM)] food materials, small (>5–10 mm) body size and preference for filter feeding mechanism were associated with MDS. Hence, they were deemed tolerant of human impact in forested systems. A fourth-corner test performed revealed tegumental/cutaneous respiration preference, soft and exposed body armouring and burrowing mobility mode, which were associated with the MDS on the RLQ ordination were also positively correlated to 5 day biochemical oxygen demand (BOD5); while preference for clear and transparent water, which were positively associated with MDS, were also positively correlated with pH and negatively correlated to dissolved oxygen (DO). Overall, this study affirmed that the TBA can be explored in biomonitoring riverine systems draining forested catchments. Nevertheless, we suggest the trait-based approach to be further explored, with a view to developing trait-informed indices for biomonitoring Afrotropical riverine systems.