Not even those who dwell at the bottom of the sea can escape global warming. An international research team from Australia, Canada, France and the U.K. have found that those who live far below the surface of the ocean will not go unscathed due to climate change. Specifically, two very important and currently abundant types of ocean plankton, a key component of many aquatic animals’ diets, will be adversely affected as marine ecosystems change.
As scientists from the U.K.’s National Oceanography Center report in Global Change Biology, over the next century, the number of organisms that live on the sea floor will fall by more than 5 percent globally and by 38 percent in the North Atlantic.
These deep-sea communities (which live at depths of four kilometers or 2.5 miles) are bottom-feeders who rely on plants and animals that live at the ocean surface and sink bottomwards after they die for their food. Organisms that live at or near the surface will themselves be in decline as their ocean habitat is altered. Warmer, rainier weather resulting from climate change will, it is predicted, cause a slowing down of the circulation of the oceans worldwide and also lead to stratification, an increased separation between layers of water.
Comments Daniel Jones, the study’s lead author,
“There has been some speculation about climate change impacts on the seafloor, but we wanted to try and make numerical projections for these changes and estimate specifically where they would occur.
“We were expecting some negative changes around the world, but the extent of changes, particularly in the North Atlantic, was staggering. Globally we are talking about losses of marine life weighing more than every person on the planet put together.”
Jones and other scientists used computer models to predict how the food supply in the world’s oceans will be affected in the upcoming decades. Drawing on a huge global database of marine life, they looked at the relationship between the food supply in the ocean and biomass (biological material derived from living organisms or those that were recently alive). Most deep sea habitats including cold-water coral reefs, seamounts (a mountain rising from the ocean floor that does not reach its surface) and canyons are predicted to experience a loss of total biomass.
Even more, the food supply for bottom-dwelling creatures will decline because the organisms that do subsist will be smaller and less efficient users of energy. One example of megafauna (large animals) that will likely decline in numbers is the hydroid Corymorpha glacial.
The loss of plankton that nourishes bottom-dwellers is also of concern as they help to regulate the amount of carbon in the atmosphere. For all that these animals live at depths that we can only begin to imagine, they are as much affected by global warming as we are. If you’re starting this new year by working on cutting down on the amount of plastics you use and otherwise reducing your carbon footprint, remember that your doing so helps not only yourself and those in your community, but organisms living deep under the sea.
Photo via Wikimedia Commons