Top-down cascading effects driven by the odontocetes in the Gulf of Taranto (Northern Ionian Sea, Central Mediterranean Sea)

An investigation of the marine food web in the Gulf of Taranto (Northern Ionian Sea, Central Mediterranean Sea) was carried out to explore the top-down cascading effects driven by the Odontocetes. The food web was analysed by a mass-balance model using 51 functional groups and detailing the trophic impacts of the striped and common bottlenose dolphins, the Risso's dolphin and the sperm whale during the period 2010-2014. Odontocetes resulted top-predators with the highest TL estimated for the Risso's dolphin (TL=5.40) and the lowest for the common bottlenose dolphin (TL=4.47). The striped dolphin played the highest top-down control, showing cascading effects up to the 3rd TL. The Risso's dolphin and the sperm whale played similar cascading effects, but weaker than the striped dolphin. Understanding pattern and strengthen of trophic controls played by the Odontocetes within the food web could contribute to identify the basal mechanisms involved in the ecosystem functioning.