Tropical seas too hot for critters


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Marine species increasingly can’t live at equator due to global heating

Study suggests it is already too warm in tropics for some species to survive

Global heating has made the ocean around the equator less rich in wildlife, with conditions likely already too hot for some species to survive, according to a new study.

Analysis of the changing locations of almost 50,000 marine species between 1955 and 2015 found a predicted impact of global heating – species moving away from the equator – can now be observed at a global scale.

It said further global heating, which is now unavoidable, would cut the richness of species in the ocean in tropical regions even further.

Scientists said the consequences of the shift could be profound and would be challenging to predict.

Species attached to the ocean floor had not declined, but the diversity of free-swimming species such as fish had dropped significantly between 1965 and 2010, said Prof David Schoeman, a co-author of the study.

Schoeman, of the University of the Sunshine Coast, said the drop in the richness of species would likely affect communities that relied on the ocean for food in areas where the fish they used to find were no longer there.

“These species haven’t disappeared, they’ve just gone from the tropics.

“There’s not only a gradual warming happening, but also superimposed on top of that are marine heatwaves that are becoming more frequent and more severe. They are partly responsible for the rapid movement of tropical species.”

To be expected, the oceans store 90% of the excess heat from global warming. Apart from that, rates of change are a problem and plants and critters can only cope by migrating. Critters can move, plants can only move by seeds or parts of stems reaching areas not too hot for those plants. None of this is unexpected with the remarkable shrinking of Arctic sea ice, the disappearance of ice shelves in Arctic and Antarctic circles.

A lot of people rely on seafood, fish for their protein. This is going to be a problem soon!