A first-of-its-kind study has mapped the global movements of a range of marine animals around the world, including whales, sharks, sea birds and polar bears, to understand how they travel the ocean.
The analysis revealed that despite significant differences in body size, shape and mode of movement, marine animals move through the ocean in similar ways.
The study published today in the journal PNAS was led by researchers from The University of Western Australia and the Australian Institute of Marine Science. It was the result of a worldwide collaborative effort from researchers involved in the Marine Megafauna Movement Analytical Program (MMMAP).
The researchers analyzed the satellite tracking data of more than 2,500 tagged marine animals from 50 species, looking at their speed and movement patterns. Some of the tracks extended back to 1985.
Unlike terrestrial species, where movement is commonly associated with body size, the team was surprised to find that unrelated marine species displayed similar movement patterns. For example, one-ton whales display comparable movement patterns to seabirds weighing a few hundred grams. "Tracking the movements of marine animals poses several unique challenges compared with working in the terrestrial environment," notes Prof. Michael Berumen of the King Abdullah University of Science and Technology (KAUST), one of the study co-authors. "It is uncommon for a single study to include so many marine animal tracks from so many different types of animals, allowing us to ask questions that transcend patterns of individual species."
The differences found across all species were associated with where these species were moving and is potentially linked with the way they use different marine habitats. The study also revealed that movement in oceanic habitats was more directed (straight towards a key location) while in coastal environments movement was more complex, suggesting animals adapt their behavior when closer to shore, potentially in search of food or for protection.
The ability of marine animals to adapt their behaviour to their habitat provides hope of these animals' resilience to a rapidly changing, coastal marine environment.
Lead author Dr. Ana Sequeira from the UWA Oceans Institute said it was important to understand how animals adapt their movement patterns to different environments, particularly as rapid changes are taking place in the ocean with potentially profound effects on the conservation of these species. "Understanding drivers of animal movement is crucial to assist mitigating adverse impacts of anthropogenic activities on marine megafauna," Dr. Sequeira says.
Prof. Carlos M. Duarte, Director of the Red Sea Research Center at KAUST, adds "Understanding the basic rules of individual animal movement, such as those reported in this work, are an important first step toward understanding how animals may co-ordinate their movement and adjust their behavior in response to environmental clues and human impacts; it is this information that will allow us to best conserve marine animals". Duarte is a cofounder of MMMAP.
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A. M. M. Sequeira el al., "Convergence of marine megafauna movement patterns in coastal and open oceans," PNAS (2018). www.pnas.org/cgi/doi/10.1073/pnas.1716137115