Chip-shop fish key to seabed health, study finds

The Atlantic cod jointly topped the list of these important "ecosystem engineers"

Many of the fish we eat play a key role in maintaining the seabed and therefore our climate, according to new research by the University of Exeter.

Scientists working on the Convex Seascape Survey focussed on the role of fish in bioturbation, the process of churning the seabed to keep it healthy and fertile, in shallow UK seas.

The Atlantic cod, a staple in chip shops, jointly topped the list of these important "ecosystem engineers", along with Atlantic hagfish and European eel.

In total, 185 fish species were found to play a role in bioturbation, and 120 of these are targeted by commercial fishing.

The survey found that cod is one of several "powerful diggers" of the seabed which has been overfished

"Ocean sediments are the world's largest reservoir of organic carbon, so what happens on the seabed matters for our climate," said Mara Fisher, a University of Exeter PhD student, who led the study.

"Bioturbation is very important for how the seabed takes up and stores organic carbon, so the process is vital to our understanding of how the ocean absorbs greenhouse gases to slow the rate of climate change.

"Our study is the first to attempt to quantify the bioturbation impact of fish, and it shows they play a significant, widespread role."

Prof Callum Roberts, from the Centre for Ecology and Conservation at Exeter's Penryn Campus in Cornwall, said: "We found that species with the highest bioturbation impacts are among the most vulnerable to threats like commercial fishing.

"Many of the largest and most powerful diggers and disturbers of seabed sediments, like giant skates, halibut and cod, have been so overfished they have all but vanished from our seas.

"These losses translate into big, but still uncertain, changes in the way seabed ecosystems work."

The Convex Seascape Survey is a five-year partnership between Blue Marine Foundation, the University of Exeter and Convex Group Limited, and aims to build a greater understanding of the ocean in attempts to slow climate change.