Ecological Niche Interaction Between Co-Existing Antarctic Krill (Euphausia superba) and the Pelagic Tunicate (Salpa thompsoni) in the Northern Antarctic Peninsula

Antarctic krill (Euphausia superba; krill) and the pelagic tunicate (Salpa thompsoni; salps) are crucial to the Southern Ocean ecosystem, and krill supports the largest fishery in the Southern Ocean in term of catch. Given recent climatic changes in the northern Antarctic Peninsula (NAP), the distribution of krill and salps are shifting poleward. Unlike krill, salps thrive in warmer water temperatures and can form large blooms under favorable conditions, potentially outcompeting krill for resources. However, krill are ecologically more important, serving as a primary food source for higher trophic levels. The interspecific interactions, including hotspots and ecological niches, of krill and salps in the NAP were therefore investigated using historical datasets and species distribution models. We found that both spatial separation and overlap occurred between krill and salps hotspots, with the primary overlap occurring around Elephant Island. Furthermore, there was a significant overlap in their ecological niches, suggesting that they may have similar ecological requirements. This study emphasized the importance of krill and salps interactions in the Southern Ocean ecosystem. The krill habitat and therefore food web of the Southern Ocean could be influenced significantly if salps continue to shift poleward in the future. The information provided in this study aids in the conservation and management of the Southern Ocean ecosystem.