Climate change: A new dimension to marine climate change

Marine organisms may be able to migrate to greater depths as well as towards the poles in response to climate change, but they will experience a compressed three-dimensional habitat, according to a paper published in Nature Ecology & Evolution.

If marine species are to survive rising temperatures, they may move poleward to maintain the same environmental temperature, or they may adapt to the higher temperatures in their original location. However, marine life might also migrate vertically to greater depths, although less is known about this possibility.

Gabriel Jorda and colleagues calculate the vertical movements required of marine species across the global oceans for maintaining a constant temperature until 2100. The authors find considerable local variation, but all locations studied show a deepening by an average of 18.7 m of suitable thermal habitat under a moderate emissions scenario and 32.3 m under a business-as-usual scenario. However, temperature is not the only determinant of suitable habitat. Deeper waters do not provide enough light for some species, and the actual maximum depth might be a limiting factor in some places. Bearing this in mind, the authors show that both phytoplankton, and shallow bottom-dwelling species such as corals, kelps and seagrasses will experience a vertical compression of their suitable habitat as temperatures increase. The full combined effects of thermal adaptation with horizontal and vertical migration are likely to be complex and vary considerably between species and locations.

These analyses represent a first global estimate of the potential for vertical migration in response to climate change.