A research expedition is underway to study the distribution of Antarctic krill between Heard Island and Antarctica in the Southern Indian Ocean in an area known as the Kerguelen Axis.

The ecosystem in Antarctica is based on a tiny creature, krill. All animals either feed on krill directly or on other animals that feed on krill. Understanding what determines krill distributions is essential to understand the Antarctic food web. A team of Australian and international marine scientists departed Hobart in the beginning of January for the Southern Ocean to investigate the impact of climate change on the Kerguelen Axis, a biological hotspot where swarms of krill sustain iconic Antarctic wildlife, including fish, seals, penguins and whales.

A team of 44 scientists and support staff will spend the next eight weeks on board the Australian icebreaker investigating the Kerguelen Axis in the Southern Ocean. Photo: Jessica Fitzpatrick
A team of 44 scientists and support staff will spend the next eight weeks on board the Australian icebreaker investigating the Kerguelen Axis in the Southern Ocean. Photo: Jessica Fitzpatrick

Chief Investigator Dr Andrew Constable, said the voyage would study the factors controlling the distribution of Antarctic krill located between Heard Island and Antarctica in the Southern Indian Ocean and more than 4000 km from Western Australia; an area known as the Kerguelen Axis. “The Kerguelen Axis is a biological hotspot where abundant swarms of krill sustain an enormous diversity of species including fish, seals, penguins and whales,” Dr Constable said.

Antarctic krill (Euphausia superba) is the most important food source in the Southern Ocean. Its abundance is related to various factors and determines the hotspots in the Southern Ocean. Photo: Uwe Kils, Wikipedia
Antarctic krill (Euphausia superba) is the most important food source in the Southern Ocean. Its abundance is related to various factors and determines the hotspots in the Southern Ocean. Photo: Uwe Kils, Wikipedia

“The most basic question we hope to answer is where the northernmost boundary for krill currently lies, and from that we hope to determine which factors control the location of the boundary. “It’s important to understand what will happen to the distribution of krill during this century, as the ocean continues to warm and become more acidic. Krill are a cold-loving species, and our current view is that their northern boundary will gradually move southward toward Antarctica as the ocean warms. However, we lack the data to make any firm conclusions. Our hope is that over the long-term this research will enable the development of more effective measures for conservation and fisheries management in the Southern Ocean, which is a critical region for Australia.”

A CTD (pictured) is an oceanography instrument used to determine the conductivity, temperature, and depth of the ocean Photo: Rose Croasdale
A CTD (pictured) is an oceanography instrument used to determine the conductivity, temperature, and depth of the ocean Photo: Rose Croasdale

The Australian Antarctic Division Chief Scientist, Dr Gwen Fenton, said the data collected will provided the most detailed biological, physical and chemical snapshot of the area ever recorded. “If you draw a line from the South Pole, through the Amery Ice Shelf on the East Antarctic coast, and out into the Southern Ocean, between Heard Island and Kerguelen Island, you have an axis that intersects three key habitat areas,” Dr Fenton said. “The Kerguelen Axis habitats and biology make it an excellent place to identify physical, chemical and biological drivers of the various food web structures in the Southern Ocean and to measure ecosystem change.“

The Aurora Australis will be joined by five vessels as part of a multi-ship collaboration, each of which will take samples and measurements in multiple locations around the Kerguelen Axis over the next eight weeks. They will work together with the French ship Marion Dufresne, the Japanese vessels Umitaka Maru and Hakuho Maru, and the Australian Marine National Facility research vessel Investigator to collect a range of data, while the US vessel Roger Revelle will provide oceanographic input.

The Aurora Australis departed Hobart with 44 scientists and support staff on board, including marine scientists from China and the UK. The scientists will also make measurements to determine the chemical and physical factors controlling the growth of marine phytoplankton and zooplankton, the tiny marine organisms that sustain the growth of all ocean life.

Source: Australian Antarctic Division