Parasite prevalence and bioaccumulation of polycyclic aromatic hydrocarbons as stressors in the silver catfish, chrysichthys nigrodigitatus (Siluriformes: Claroteidae)

The experiment explored the impacts of polycyclic aromatic hydrocarbons (PAHs) and the prevalence of Aspidogastrea africanus (endoparasite) in Chrysichthys nigrodigitatus (host) in Lekki lagoon, Lagos State, Nigeria. Host-parasite allotment of PAHs, histopathological analysis, and the oxidative status of parasite and host were investigated. Oxidative status of fish and endoparasites were determined by assessing the levels of reduced glutathion (GST), superoxide dismutase (SOD), catalase (CAT) and malondialdehyde (MDA). PAH concentrations were determined in the tissues of the host and parasite using gas chromatograph coupled to flame ionization detector (GC-FID). Physico-chemical parameters of water and sediment were assessed using a handheld multi-parameter probe (Horiba Water Checker Model U-10). The parasitic prevalence in the examined fish was proportional to length and weight of fish individuals. The parasites were more predominant among the length and weight cohorts of the female fishes than the males. Higher induction of oxidative stress enzymes in the intestine of the male C. nigrodigitatus than in the female, and the parasite can be attributed to the higher levels PAH and partly absence of parasites to depurate the toxicant in the fish. A. africanus shared the toxic burdens of chrysene, benzo(b)fluoranthene, dibenz(a,h)anthracene, benzo(g,h,i)perylene, dibenzo(a,l)pyrene, dibenzo(a,i)pyrene and particularly indo(1.2,3-cd)pyrene from the intestine of both sexes. In return, the endoparasite contributed to the oxidative stress in the intestine of the fish. Synergistic and antagonistic interactions between PAH congeners and A. africanus on silver catfish, C.nigrodigitatus is evident in the current study. We suggest mitigation of PAH-releasing anthropogenic activities around Lekki lagoon for the protection of C. nigrodigitatus.