Natural hybridization between immigrant narrow–barred Spanish mackerel Scomberomorus commerson (Lacepède, 1800) and endemic West African Spanish mackerel Scomberomorus tritor (Cuvier, 1832) in the Egyptian Mediterranean coast

Immigrant narrow–barred Spanish mackerel, West African Spanish mackerel and specimens with an external appearance somewhere between these putative parents were collected from Abu Qir Bay, East Alexandria, Egypt. The hybrid index results and univariate and multivariate analysis indicated a natural hybridization between these two species. The discriminant function analysis successfully classified individual fish in the data to one of the three fish groups. Squared Mahalanobis distances extracted from the groups indicated the three groups were clearly distinct from each other. Moreover, distances between the hybrid and Scomberomorus tritor were longer than those of the hybrid and S. commerson. The mean values of the condition factor for the hybri were significantly higher than those of S. commerson. Natural mortality of the hybrid was significantly lower than that of the exotic parent (S. commerson), indicating that the environmental conditions in the examined region are more suitable for the hybrid type species than for the invasive parental species.

Metallothionein and Glutathione Content as Biomarkers of Metal Pollution in Mussels and Local Fishermen in Abu Qir Bay, Egypt

Background. When heavy metals accumulate in air, soil, and water, the risk of human exposure increases among industrial workers, as well as in people living near polluted areas. Heavy metals adversely affect a variety of bodily systems such as the cardiovascular, respiratory, endocrine, immune, and reproductive systems. In addition, long-term exposure and accumulation of heavy metals in the body may disturb oxidative stress genes and thus increase the susceptibility to various diseases. Objectives. The aim of this study is to estimate the metallothionein concentration in both mussel samples from Abu Qir Bay, Egypt and the blood of local fishermen as a biomarker of exposure to metal pollution. Methods. Levels of metallothionein and heavy metals were measured in mussels. Blood levels of metallothionein and heavy metals of local fishermen were measured and compared with a control group. The effect of heavy metal exposure on oxidative stress status was investigated through the determination of malondialdehyde (MDA), catalase and glutathione content. Results. The results of this study showed high concentrations of metallothionein in mussels and in fishermen's blood, accompanied by high concentrations of metals such as cadmium (Cd), copper (Cu), lead (Pb), chromium (Cr), and zinc (Zn). At the same time, a significant decrease in glutathione content and catalase enzyme activity was associated with a significant increase in the malondialdehyde concentrations in sera of fishermen. Conclusions. The present study found that the El Maadiya region is polluted with heavy metals, inducing oxidative stress in fishermen in the vicinity. These results reveal the necessity of further environmental monitoring in the study area in order to evaluate other types of pollutants and their effects on human health.