Southern elephant seal with a satellite tracking device, Marion Island. Photo: Nico de Bruyn

In a rapidly changing world, we need to know which areas of our planet warrant protection from existing, developing and forthcoming threats. This is hard to do objectively in the vast realm of the oceans, and particularly so in the most remote parts, the Southern Ocean. A paper published this week in the journal Nature (together with a companion data paper in the journal Scientific Data) describes a novel solution to this problem, using electronic tracking data from birds and marine mammals.

The solution relies on a simple principle: animals go to places where they find food. So, identifying areas of the Southern Ocean where predators most commonly go also tells us where their prey can be found. For example, humpback whales and penguins will go to places where they can feed on krill, whereas elephant seals and albatrosses go where they can find fish, squid, or other prey. If all these predators and their diverse prey are found in the same place then this area has both high diversity and abundance of species, indicating that it is of high ecological significance.

Hindell et al 2020. https://www.nature.com/articles/s41586-020-2126-y

The project was conducted by the Scientific Committee for Antarctic Research (SCAR), with support from the Centre de Synthèse et d'Analyse sur la Biodiversité, France, and the WWF-UK.

SCAR engaged its extensive network of Antarctic researchers to assemble existing Southern Ocean predator tracking data. After careful validation, the result was an enormous database of over 4000 individual animal tracks from 17 species, collected by more than 70 scientists (including Nico de Bruyn and Marthan Bester) across 12 national Antarctic programs. MIMMP research associate and past student, Ryan Reisinger, was one of the joint lead authors on this study. This database is now available for public download.

Even this impressive database does not directly represent all Southern Ocean predator activity, because it is impossible to track every species from all their breeding colonies. Simple mapping would therefore provide a biased representation of animal distribution. To overcome this, sophisticated statistical models were used to predict the at-sea movements for all known colonies of each predator species across the entire Southern Ocean. These predictions were combined across the 17 predator species to provide an integrated map of those areas used by many different predators with diverse prey requirements.

The most important of these areas - areas of ecological significance - are scattered around the Antarctic continental shelf and in two wider oceanic regions, one projecting from the Antarctic Peninsula engulfing the Scotia Arc, and another surrounding the sub-Antarctic islands in the Indian sector of the Southern Ocean.

Marine Protected Areas (MPAs) are a crucial tool in the conservation management toolbox. Existing and proposed MPAs are mostly found within the areas of ecological significance, suggesting that they are currently in the right places. Yet when using climate model projections to account for how areas of important habitat may shift by 2100, the existing MPAs with their fixed boundaries may not remain aligned with future important habitats. Dynamic management of MPAs, updated over time in response to ongoing change, are therefore needed to ensure continued protection of Southern Ocean ecosystems and their resources in the face of growing resource demand by the current and future generations.

Read the article here: https://www.nature.com/articles/s41586-020-2126-y

And the associated Scientific Data paper here: https://www.nature.com/articles/s41597-020-0406-x