A Southern Ocean archipelago enhances feeding opportunities for a krill predator

• Published in: Marine Mammal Science
• Main Authors: Harrison, Lisa‐Marie K., Goetz, Kimberly, Cox, Martin J., Harcourt, Robert
• Other Authors: Antarctica New Zealand, Australian Antarctic Division, Australian Research Council, Macquarie University, National Institute of Water and Atmospheric Research
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley 2019
• Subjects: Aquatic Science; Ecology, Evolution, Behavior and Systematics; Antarc*; Antarctic; Antarctic Krill; Balleny Islands; Euphausia superba; Megaptera novaeangliae; Southern Ocean
• Online Access: http://dx.doi.org/10.1111/mms.12645; https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1111%2Fmms.12645; https://onlinelibrary.wiley.com/doi/pdf/10.1111/mms.12645; https://onlinelibrary.wiley.com/doi/full-xml/10.1111/mms.12645; https://onlinelibrary.wiley.com/doi/am-pdf/10.1111/mms.12645

Abstract Productivity in the oceans is heightened around oceanographic and bathymetric features such as fronts and islands. This can have a flow‐on effect, providing increased food availability for higher trophic level species. Using data from a 5‐day combined visual and acoustic survey, we examined the hypothesis that higher Antarctic krill ( Euphausia superba ) density provides a lucrative resource for humpback whales ( Megaptera novaeangliae ) at a remote Antarctic feeding area, the Balleny Islands (67 o S, 164°E). We assessed whale presence at the feeding area in relation to prey (krill), productivity and environmental variables using density surface modeling. We found stark differences between krill swarms near the islands and those in adjacent open water. Swarms were twice as dense and three times more numerous near the Balleny Islands compared to an open water pelagic environment, suggesting that the islands offered a profitable feeding opportunity. At the feeding area, whales were found in deeper and more productive waters with medium krill densities. These relationships, along with the high krill availability around the islands, may be the result of the Island Mass Effect.