INSIGHTS INTO YEAR-ROUND MERCURY CONCENTRATIONS IN ANTARCTIC KRILL AND ITS RELATIONSHIP WITH BIOLOGICAL AND ENVIRONMENTAL PARAMETERS

Long-range atmospheric transport and deposition processes have resulted in mercury (Hg) being widely available in the oceans, even in areas away from major urban settlements, such as Antarctica. In polar zones, Hg can be deposited onto sea-ice and snow and potentially transferred to the ocean upon thawing. Phytoplankton take up Hg within the photic zone from the surrounding water, which can then bioaccumulate through the food web. Antarctic krill (Euphausia superba) are an important link in the Antarctic food web, as they transfer energy generated by primary producers to higher trophic levels. They can, however, also transfer contaminants. Evaluating the impacts and associated risks of Hg to top predators in Southern Ocean food webs is of high ecological and economic importance, especially under the context of climate change. To do so, it is crucial to first understand how Hg concentration in lower trophic levels (in this case, krill) varies spatially and temporally. In this presentation, we provide a baseline of total Hg concentrations in sexed krill individuals obtained fortnightly from December 2013 until August 2019 (except for the October and November months) from a commercial fishing vessel that operates in three Southern Ocean locations: South Georgia, the South Orkney Islands, and the West Antarctic Peninsula. We also present and discuss the results of generalised linear models which tested the importance of biotic (length, dry mass, sex, and stage) and abiotic (location and time of sampling) parameters in explaining Hg concentrations in krill.

Presentation Preference: Oral

Primary Presenter: Rita Franco-Santos, CSIRO (rita.franco-santos@outlook.com)

Authors:

Rita Franco-Santos, CSIRO Environment  (rita.franco-santos@outlook.com)

Sam Eggins, Research School of Earth Sciences, Australian National University  (sam.eggins@anu.edu.au)

Michael Ellwood, Australian Centre for Excellence in Antarctic Science, Research School of Earth Sciences, Australian National University  (michael.ellwood@anu.edu.au)

Nils Hoem, Aker BioMarine, Universitetet i Oslo Det Matematisk-naturvitenskapelige Fakultet  (nils.hoem@akerbiomarine.com)

William Maher, Research School of Earth Sciences, Australian National University  (maher.canberra@gmail.com)

Peter Nichols, CSIRO Environment  (peter.nichols@csiro.au)

Patti Virtue, Institute for Marine and Antarctic Studies, University of Tasmania  (p.virtue@utas.edu.au)