Indagini preliminari riguardanti gli effetti delle malattie infettive emergenti sulla riproduzione di Tursiops truncatus (Montagu, 1821) e Stenella coeruleoalba (Meyen, 1833) spiaggiati lungo la costa del Mar Adriatico Centrale

Tursiops truncatus (Montagu, 1821) and Stenella coeruleoalba (Meyen, 1833) are the two most widespread cetacean species in the Mediterranean Sea and they are currently assessed as "vulnerable" in the Red list of the International Union for Conservation of Nature (IUCN); considering their life-history and ecological traits, marine mammals are particularly vulnerable to a wide range of threats. Nowadays, these two species are suggested as useful bioindicators of the potential effects of anthropogenic impacts, such as emerging infectious diseases (EIDs) and environmental contaminants like persistent organic pollutants (POPs) and heavy metals, in order to manage and conserve wild populations. As well as all cetaceans in general, T. truncatus and S. coeruleoalba play key roles within the marine ecosystem. Indeed, they influence the structure and the function of several aquatic communities, the recycling of nutrients and have a “top-down” effect on predation. To prevent this delicate equilibria from being compromised, it is fundamental to obtain a deeper knowledge of the reproductive biology and health status of wild populations. For this reason, the aim of this thesis is to present a general overview on the trend of stranded T. truncatus and S. coeruleoalba specimens registered during the last seven years (from May 2016 to November 2022), with a special focus on animals found along the Central Adriatic coasts (Abruzzo and Molise, Italy). First of all, these animals were analyzed by necropsies carried out by the Istituto Zooprofilattico Sperimentale dell'Abruzzo e Molise "G. Caporale" (Teramo, Italy). Afterward, through microbiological and parasitological analyses, the presence of emerging infectious diseases (EIDs) such as Brucella spp, Dolphins MorbilliVirus (DMV) and Toxoplasma spp was evaluated. The presence of this pathogen agents on T. truncatus and S. coeruleoalba was correlated with the sexual maturity, the hepatic health status and the reproductive capacity of organisms histologically evaluated. Furthermore, to determine a possible correlation of EIDs occurrence with pollutants, CYP-450 and metallothioneins levels were evaluated as biomarkers for exposure to persistent organic pollutants (POPs) and heavy metals, respectively. Histological analysis reported histopathological alterations on male and female reproductive system such as vacuolization, infiltration of white blood cells, necrosis, abnormalities in the morphology of germ cells and gas embolism. In the liver, the most common impairments were necrosis, hemolysis, gas embolism and thickened blood vessels and macrophage infiltration. Immunohistochemical analysis showed exposure to environmental contaminants in almost all the specimens analyzed but from correlation between response’s biomarkers and emerging infectious diseases with alteration associated and no significant value emerges. To date, to our knowledge, this is the first study performed on the central Adriatic coasts assessing the correlation between the presence of EIDs with the indirect responses of environmental pollutants biomarkers and the health status of these marine organisms. More studies should be performed to understand direct effects of these pathologies on the reproduction and the survival of these species, especially in this area of the Mediterranean sea.