Condition factor, hydrocarbons and bacterial burdens of shellfishes from mudflats in the Qua Iboe Estuary, Nigeria

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In this article, the condition factor (CF; health status), bacterial burdens and total petroleum hydrocarbons (TPH) accumulating potential of shellfishes harvested from tidal mudflats in the Qua Iboe Estuary mangrove ecosystem, Nigeria, were investigated. The results revealed that most species of shellfishes from the estuary were not healthy. Tympanotonus fuscatus had a healthy status (CF) of 54.6%, while Mytilis edulis, Thais haemostoma and Callinectes latimanus from hydrocarbon-impacted mudflats exhibited poor health statuses with CF values less than 40%. Though unhealthy, they exhibited great propensity to bioaccumulate hydrocarbons and bacteria including hydrocarbonoclastic bacteria from the environment. The mean levels of TPH in the shellfishes were 4.68 mg/g, 7.92 mg/g, 4.86 mg/g and 3.97 mg/g dry weight of T. fuscatus, M. edulis, Th. haemostoma and C. latimanus, respectively, as against 30.36 mg/g dry weight detected in the intertidal sediment. Correlation between levels of TPH accumulated and CF of the shellfishes (at p < 0.05) revealed weak and not definite relationships in T. fuscatus (r = 0.080), M. edulis (r = 0.102) and Th. haemostoma (r = 0.214), while a positive significant relationship was observed for C. latimanus (r = 0.583). The bacteria densities of freshly collected samples varied between the diverse species of shellfish. The relationship between bacterial load and CF was negative and insignificant in C. latimanus (r = − 0.123) but insignificantly positive in M. edulis (r = 0.011), Th. haemostoma (r = 0.347) and T. fuscatus (r = 0.347). These findings have shown that shellfishes from mudflats in the Qua Iboe Estuary are not healthy but have great capability to bioaccumulate hydrocarbons and bacteria. Their bioaccumulating potential is not definitive and health (CF) dependent, but plausibly determined by the availability and nature of contaminants and their feeding mode. Though the role of oil-degrading bacteria within the viscera of shellfishes is uncertain, it is obvious that the commercially valid species investigated could serve as possible bio-indicators of hydrocarbon and bacterial contaminants in the fishing waters.