Although the effects of the anthropic impact are visible in many kinds of habitats, continental aquatic ecosystems are particularly affected. A good example are Mediterranean rivers, where many endemic species live, some of which are close to extinction. Anthropic pressure in the Mediterranean area comes from a long time ago, when the first human settlements were established along the main river corridors, in order to take advantage of the water and the riverbank soil fertility, and this pressure was intensified with the arrival of modern civilizations, which diversified even more the kind of the impacts, including the emerging pollutants and the massive entry of exotic species.

Fishes are a good indicator of the ecological consequences of anthropic impacts on aquatic systems. Placed in a high position of the food chain, they reflect the changes in the inner trophic levels. It is known that exotic fishes can have negative consequences on native species, such as hybridization, predation, pathogen introduction, trophic competition and agonistic interaction. However, it is a scarcely studied topic in the Mediterranean area, including Catalonia. So far, no studies have examined the relative influence of pollution and the presence of exotic fishes, on the health of the fishes. This study aims to cover this lack of knowledge.

The main goal of this project is to use a pioneering methodology to evaluate the effects of pollution and the presence of exotic fish, on the health of two native species of southern barbels: the Mediterranean barbel (Barbus meridionalis) and Catalonian barbel (Barbus haasi). The traditional ecotoxicology studies on fishes have been based on destructive methodologies such as histopathology, to evaluate the effects of pollution on the health. This project will contribute to the improvement of non-lethal diagnostic techniques, by exploring the usefulness of a nondestructive highly innovative methodology, based on the bacterial composition of fish epidermis.