Focus on marine barriers

EARTH’S oceans may seem interconnected there are many marine barriers preventing the movements and exchange of genetic information for certain marine animals, local researchers say.

Lead by James Cook University PHD candidate Maximilian Hirschfeld, a new study of 1000 elasmobranch (shark, ray and skate) species found they were impacted by the ocean’s patchwork of diverse aquatic environments.

“We found 45 unique marine barriers. For example, deep ocean trenches, drastic changes in temperature and salinity, ocean currents, and even large river deltas, can limit genetic connectivity in sharks and rays at large to surprisingly small spatial scales,” he said. “These subdivisions can pose barriers to the movements of marine animals that are adapted to very specific environments, which reduces the exchange of genetic information among populations.

“The impact of barriers on connectivity also depends on the ecology of individual species. We found that ecological factors, including the habitat a species lives in, how deep it can dive, and its body size, are good indicators for its capacity to move across potential barriers.”