Mesopelagic organisms play an important role in the marine ecosystems as they transfer energy and organic matter between the surface layers and the deep sea via the regular mechanism called diel vertical migration (DVM). One of the key components of the community of this zone is mesopelagic fishes due to their worldwide and abundant distribution in the world oceans. Moreover, having a high lipid content (e.g. wax esters) make them a significant source of energy intake for many marine predators such as cephalopods, fish, sea birds and marine mammals.

The Mediterranean Sea is one of the less productive seas of the world and the Northeastern Mediterranean is the most oligotrophic part of the Mediterranean. On the other hand, the very same area surprisingly serves as one of the important fishing grounds in the Mediterranean for a high trophic level fish such as such Atlantic Blue Fin Tuna (ABFT). Why such a high trophic level and highly migratory fish prefers such an extremely oligotrophic sea during the most food demanding spawning period is not fully understood yet. However, a limited number of studies conducted in the Eastern Mediterranean Sea on ABFT diet suggested that mesopelagic can be one of the major reasons!

Within the framework of SUMMER Project, along with the partners, METU aims to contribute the better understanding of the mesopelagic community, its structure, key players and their quantity, trophic interactions, specifically in the highly oligotrophic NE Mediterranean Sea by using the standard tools and approaches such as acoustic techniques, scientific trawl sampling and isotopic and stomach content analyses and ecosystem modelling.

Text and pictures provided by Middle East Technical University (METU)