Micronekton, taxonomically diverse pelagic organisms ranging from 0.2 to 20 mm in size, serve as vital links within the Southern Ocean food web. They connect primary and secondary production, facilitating the transfer of energy to higher trophic levels including fish, marine mammals, and seabirds. Additionally, through their diel vertical migration, micronekton contribute to the downward export of carbon from the sea surface to the deeper layers of the ocean, termed the mesopelagic-migrant pump. Despite their importance, the extent of the role that micronekton play in biogeochemical cycling in the Southern Ocean remains unclear, partly due to a lack of observations and gaps in our understanding of food web dynamics in the Southern Ocean.
In this study, we present findings from a community-level analysis of carbon and nitrogen stable isotopes conducted at one subantarctic and two polar sites south of Tasmania, sampled during the SOLACE voyage in the summer of 2020/2021. Our analysis aims to compare isotopic niches and trophic positions to understand how carbon is transferred between depth strata across the three sites. Finally, we will discuss how these datasets can be used to inform models of downward carbon export through the mesopelagic-migrant pump in the Southern Ocean.