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This study identifies and quantifies the spatial variations of metal contamination in water, sediment and biota: the common cockle (Cerastoderma edule) and the Mermaid's glove sponge (Haliclona oculata), within a heavily anthropogenically impacted semi-enclosed estuarine-coastal area with a low ability to disperse and flush contaminants (Poole Harbour, UK). The results showed that metal contamination was detected in all environmental compartments. Water was polluted with As, and Hg sediment metals were mostly within "the possible effect range" in which adverse effects occasionally occurs. Cockles had considerable concentrations of Ni, Ag and Hg in areas close to pollution sources, and sponges accumulate Cu and Zn with very high magnitude. A systematic monitoring approach that includes biological monitoring techniques, which covers all embayments, is needed, and an integrated management of the semi-enclosed coastal zones should be based on the overall hydrological characteristics of these sensitive areas and their ability to self-restore which is different than open coastal zones.

This study was carried out in 2016 to investigate the feeding on phytoplankton profile of the Nile tilapia (Oreochromis niloticus) and mango tilapia (Sarotherodon galilaeus) inhabiting Lake Nasser, and its relation to their fisheries biological parameters. Phytoplankton Preference index (PPI), Index of Relative Importance (IRI), and Straus Linear index were used to investigate the feeding patterns of the two species in the lake. Moreover, some fish biological parameters of the two species were determined in the lake different areas. The results showed that O. niloticus and S. galilaeus feed mainly on the same phytoplankton items. Bacillariophyceae was identified as the most desired phytoplankton item to O. niloticus (IRI = 12.53) and S. galilaeus (IRI=18.28). Both fish species were more selective to five species from Bacillariophyceae and five species from Chlorophyceae, while they were more avoidant to four species from Cyanophyceae at all lake's areas. The results also showed that the main fisheries biological parameters are varied significantly between the two species and through lake different areas. This study concluded that the variation in fisheries biological parameters in Lake Nasser is not related to the pattern of feeding on phytoplankton but is led by other factors (e.g. fishing practices).

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Recently, tilapia have become increasingly important in aquaculture and fisheries worldwide. They are one of the major protein sources in many African countries and are helping to combat malnutrition. Therefore, maintenance and conservation genetics of wild populations of tilapia are of great significance. In this study, we report the population genetic structure and genetic diversity of the redbelly tilapia (Coptodon zillii) in three different Egyptian aquatic environments: brackish (Lake Idku), marine (Al‐Max Bay), and freshwater (Lake Nasser). The habitat differences, environmental factors, and harvesting pressures are the main characteristics of the sampling sites. Three mitochondrial DNA markers (COI: cytochrome oxidase subunit I; the D‐loop; CYTB: cytochrome b) were used to assess population structure differences among the three populations. The population at Lake Nasser presented the highest genetic diversity (H d = 0.8116, H = 6), and the marine population of Al‐Max Bay the lowest (H d = 0.2391, H = 4) of the combined sequences. In addition, the phylogenetic haplotype network showed private haplotypes in each environmental habitat. Results presented here will be useful in aquaculture to introduce the appropriate broodstock for future aquaculture strategies of C. zillii. In addition, evidence of population structure may contribute to the management of tilapia fisheries in Egyptian waters.

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