Invasioni biologiche nella Sicilia orientale: effetti dell’inquinamento su Callinectes sapidus Rathbun, 1896

Anthropic activities have huge impacts on marine ecosystems and for many aquatic animal species. Some human activities, in fact, are responsible for environmental contamination by heavy metals, which are considered serious pollutants in the marine environment because they are very persistent, toxic, non-biodegradable and organisms have a high inclination to bioaccumulate them. The effects of increasing metal concentrations in the environment could involve marine organisms, damaging them and causing their death. Some species instead benefit from pollution, these are certainly alien species, which are often able to adapt very quickly to impacted environments and compete with native species. In this work, a comparison is made between a polluted area (Augusta) and an Oriented Nature Reserve (Vendicari), both in Sicily, to study the effects of metal pollution on the size of the blue crab Callinectes sapidus Rathbun, 1896. Comparing the carapace width, carapace length and wet mass of the crabs, indeed the size of the crabs sampled in Augusta is larger than that of the crabs sampled in Vendicari. This suggests that the metal pollution caused a destabilization of the benthic community in the polluted site, which would have induced the blue crab to change its diet; having a more diversified diet results in enhanced crab fitness, causing them to increase in size. Moreover, other aspects such as reduced fishing effort or reduced cannibalism may have influenced the increased growth of crabs present at the polluted site. However, increasing the size of the blue crab could have profound effects on the local community; being C. sapidus an alien species, in fact, its increase can cause critical changes in ecological systems, profoundly altering host communities and ecosystems. Therefore, heavy metal pollution not only brings about highly impactful environmental damage but, by promoting the establishment and growth of alien species, also becomes responsible for biological pollution.