The Middle Trophic Level of the Ross Sea is still not well known but it mainly characterized by two species of Krill: Euphausia superba, Euphausia Crystallorophias. These species are a key food source for a wide variety of marine birds and mammals in the Ross Sea. For this reason, it's necessary to improve the knowledge on abundance and spatial distribution of MTL species, and their interconnection with environmental parameters to understand the main drivers of the reproductive success and migrations of these species. In this project, an acoustic survey, a synoptic net sampling and a CTD/XBT samplings were carried out following the standard protocols indicated by CCAMLR. Acoustic monitoring was performed at five frequencies: 38, 70, 120, 200 and 333 kHz. Targeted net samplings were performed to validate the preliminary species allocation of the aggregations observed on the echosounder screen. Biometric measures of krill samples was made on board and samples were taken for further analysis. CTD and XBT data was collected and elaborated to characterize water masses and to study the possible influences of the distribution of the main oceanographic parameters on MTL species.

Anthropogenic microparticles (AMs) were found for the first time in specimens of Trematomus bernacchii collected in 1998 in the Ross Sea (Antarctica) and stored in the Antarctic Environmental Specimen Bank. Most of the identified AMs were fibers of natural and synthetic origin. The natural AMs were cellulosic, the synthetic ones were polyester, polypropylene, polypropylene/polyester, and cellulose acetate. The presence of dyes in the natural AMs indicates their anthropogenic origin. Five industrial dyes were identified by Raman spectroscopy with Indigo occurring in most of them (55%). Our research not only adds further data to the ongoing knowledge of pollution levels in the Antarctic ecosystem, it provides an interesting snapshot of the past, highlighting that microplastics and anthropogenic fiber pollution had already entered the Antarctic marine food web at the end of the ‘90 s. These findings therefore establish the foundations for understand the changes in marine litter pollution over time.