Biometric and gonadosomatic indices and chemical constituents of edible tissues and exoskeletons of Callinectes amnicola and their potential for reuse in the circular economy paradigm

Occurrence, distribution, source apportionment, ecological and health risk assessment of heavy metals in water, sediment, fish and prawn from Ojo River in Lagos, Nigeria

The study investigates the occurrence and bioaccumulation of heavy metals in water, sediment, fish, and prawn from the Ojo River with a view to identify the source of origin and the associated ecological and human health risks. The result shows that heavy metal concentrations in water [As = 0.010, Cd = 0.001, Cr = 0.041, Cu = 0.019, Co = 0.050, Fe = 0.099, Pb = 0.006, Ni = 0.003, and Zn = 0.452(mg/L)] were within the acceptable limits. The heavy metals in the sediment [As = 0.050, Cd = 0.287, Cr = 0.509, Cu = 0.207, Co = 0.086, Fe = 33.093, Pb = 0.548, Ni = 0.153 and Zn = 4.249 (mg/kg)] were within their respective background levels or earth's crust and the TEL and PEL standard limits. The bioaccumulation of heavy metals in fish and prawn tissues are in this hierarchical form: Fe > Zn > Cu > Cr > Ni > Co > Pb > Ar > Cd and Fe > Zn > Cu > Cr > Pb > Ar > Ni > Co > Cd, respectively. The bioaccumulation factors of heavy metals in fish ranged from 0.893 - 16.611 and 1.056 - 49.204 in prawn, which were higher than the biota-sedimentation factors (BSAF) values, inferring that the fish and prawns of this study ingested heavy metals highly from water column. The aggregated BSAF scores (fish = 5.584 and prawn = 9.137) showed that these organisms are good concentrators of heavy metals in sediments. The water quality index and other pollution indices (Single pollution index, Heavy metal assessment index, and Heavy metal pollution index) demonstrates slightly clean water, with a moderate level of contamination. The HI values of heavy metals in water, fish, and prawn were lower than 1, implying non-carcinogenic risk in children or adults. The ADD and EDI values of the metals were within their respective oral reference doses (RfD). The TCR values showed that exposure to water, either by ingestion or dermal absorption and the consumption of P. obscura and M. vollenhovenii from the Ojo River would not induce cancer risks in people, though As, Cr, Cd, and Pb showed carcinogenic potentials. The sediment contamination indices such as CF, mCd, EF, and Igeo showed a moderate level of pollution. The ecological risk values (NMPI, mCd = 0.068, PLI = 0.016, and R.I = 86.651) of heavy metals implies "no-moderate risk" except for Cd, which showed high risk. The ecotoxicological parameters,  m-PEL-Q (0.024) and m-ERM-Q (0.016) denotes low contamination and no probability of acute toxicity. The CV analysis showed high dispersions and variabilities in the distributions of the heavy metals in water. Other source analyses (Pearson's correlation matrix, PCA, and HCA) showed that both natural processes and anthropogenic activities are responsible for the occurrence of heavy metals in water and sediment from the Ojo River.

Proximate, minerals, carotenoid and trypsin inhibitor composition in the exoskeletons of seafood gastropods and their potentials for sustainable circular utilisation

Periwinkle shells of Tympanotonus fuscatus, Pachymelania aurita, and Thais coronata were analyzed for their proximate composition, nutritionally significant minerals, trypsin inhibitors, and carotenoids. The mean values obtained were compared using an ANOVA test. The results showed that T. fuscatus had the highest mean moisture content of 0.96 ± 0.14% and a mean value of 0.49 ± 0.13% for crude fibre but was not significantly different (P > 0.05) from P. auritus. The crude protein and fibre content of T. fuscatus was significantly higher (P < 0.05) than other periwinkle samples. T. coronata had the highest mean total ash content and was significantly different (p < 0.05) from other periwinkle samples. T. fuscatus had the highest mean value for Mg (0.32 ± 0.03 mg/kg) and differed significantly (P < 0.05). The mean Ca content of P. aurita was not significantly different (P > 0.05) from that of T. coronata. The mean values of CaCO3 in T. fuscatus, P. aurita, and T. coronata were 57.20 ± 2.46, 59.50 ± 3.23, and 62.36 ± 1.56 (mg/kg), respectively. T. coronata was significantly different (P < 0.05) from other periwinkle samples. The mean values of carotenoids in T. fuscatus, P. aurita, and T. coronata were 7.17 ± 2.14, 18.00 ± 5.27, and 11.20 ± 3.60 (mg/kg), respectively, and P. aurita was significantly different (P < 0.05) from other periwinkle samples. T. fuscatus and P. aurita had shells with significant amounts of trypsin inhibitor (23.30 ± 4.50 mg/kg and 22.90 ± 14.10 mg/kg, respectively), making them less suitable for livestock feed. In contrast, T. coronata had a lower mean value of 11.80 ± 7.19 mg/kg for trypsin inhibitor, making it an excellent addition to livestock feed. The low crude fibre and fat contents of the periwinkle samples in this study make them suitable for processing complementary foods, especially for hypertensive patients. The high percentage of CaCO3 in periwinkle shells makes them a probable source used in the production of slurry for chromatography. The findings suggest that periwinkle shells contain specific minerals that can be applied in numerous industries. Increased use of these gastropod shells will result in successful application in product creation and a sustainable bio-circular economy.