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Heavy metal bioconcentration in crabs from an estuarine creek in the Niger Delta was examined using atomic absorption spectrophotometry. Health risk via human exposure to metal toxicity was evaluated. Mean metal levels (µg/g) were Cr 2.32 ± 0.71, Ni 2.76 ± 0.48, Cu 12.94 ± 3.53, Pb 5.67 ± 1.03, Ag 1.83 ± 0.71 and Cd 0.73 ± 0.14 with significant difference (p < 0.001) between periods. Ni, Pb and Cd had values above FAO/WHO recommended limits. Estimated daily intake values were below the reference oral doses and the target hazard quotient was <1 for each metal examined while hazard index for all metals was also <1. The target carcinogenic risk value for Ni was 3.4 × 10. Based on the evaluations, the study concluded that consumers of crabs from the study area had minimal/moderate metal toxicity exposures of no significant health concern but recommended continuous monitoring to detect anomalies.

The aim of this study was to assess the length-weight relationship (LWR) and condition factor (K) of Mugil cephalus and Oreochromis niloticus obtained from a tidal creek in the Niger Delta Nigeria. Six samples of each species were randomly collected monthly (January-December 2015) from fisher men making a total of 144 samples. Samples were immediately taken to the laboratory in ice pack coolers for analysis. The b-values ranged from 0.913-3.172 and 1.624-3.484 while K-values ranged from 0.79-1.07 and 1.01-1.08 for M. cephalus and O. niloticus respectively. The results indicated positive and negative allometric growth patterns (b>3 & b<3) for the two fish species, a departure from the cub law, but M. cephalus exhibited isometric growth pattern (b=3.003) during just one month of the study period, a compliance with the cube law. Growth coefficient also had obvious inter and intra specific variation while condition factor did not but indicated wellbeing of fish samples examined. The weight of both fish showed significant difference (P<0.01/ P<0.05) with respect to time while R 2 values indicated strong linear relationship between length and weight. The study concluded that allometric growth pattern observed for the two fish species had both inter and intra specific variation along temporal lines. However, inter and intra specific condition of fish examined was relatively stable across study period suggesting the two different species could have responded to ecological and environmental variables similarly.

Seafood and other environmental matrices are major entry route of harmful pollutants into humans due to constant contamination of the aquatic environment hence requires monitoring. This study scientifically explored the hypothesis that benthic gastropods bioaccumulate harmful pollutants that pose health risk to consumers of the sea food. Fifty samples of Thais coronata were collected per site from major regional fish landings. Two hundred samples were collected monthly for eight months to determine the concentrations of polycyclic aromatic hydrocarbon-PAH and possible health risks due to consumption using regulatory limits for guidance. Total PAH concentrations (μg/kg) varied between 65.68–173.52 suggesting differences in consumed concentrations at different times. The concentration of individual PAH congeners (1.376 ± 0.07-40.356±2.21 μg/kg) and PAH4 were below the European Union maximum limits. The Daily Dietary Intake values ranged from 0.075-2.212 μg/kg for individual PAH congeners while that of PAH4 was 1.359 μg/kg and were all below their respective reference oral doses. The carcinogenic potencies of the PAH congeners ranged from 0.001-143.389, the carcinogenic toxic equivalents (TEQs) of all PAH congeners was 0.1522 while that of PAH4 was 0.0044. The Excess cancer risk (ECR) value (10-8–10-5) was within USEPA guideline of 10-6 while the margin of exposure (MOE) of individual PAHs and PAH4 were higher than critical border line of 10,000 given by European Food Safety Authority but diagnostic ratio suggested PAH sources of pyrogenic origin in samples monitored. The study concluded low health risk for consumers of the shellfish (Thais coronata) in the study region but with recommendation advisory for regular monitoring to observe changes.