Trawlers causing carnage among health-giving wonders of the deep

Deep-sea trawling is damaging the UK's sponge beds and threatening a potential source of medical cures, scientists have warned.

Researchers in Edinburgh say deep-water sponges are "treasure chests" of future discoveries but are being worn away by fishing and engineering works.

Ocean sponges from shallower waters have already been the sources of new drugs, and experts believe the deep-water variety will be equally valuable, if not more so.

A study led by a team from Heriot-Watt University shows that sponge grounds dating back up to 9,000 years are being destroyed.

Murray Roberts, from the university's Centre for Marine Biodiversity and Biotechnology, said: "People might think of natural sponges as just a bit of a bath- time luxury, but they are potentially vitally important to future medical developments.

"We already know that some sponges contain substances which are being used to treat cancers, but there are so many other species in our own UK and Scottish deep waters that we simply don't know about.

"We found 100 sponge species at Scotland's only inshore, cold-water coral reef near Mingulay (south of Barra in the Outer Hebrides], and over the next few years, we will be investigating other sites around Scotland, where we hope to find many more.

"But, meanwhile, we have also shown that deep-water bottom trawling is causing carnage among these slow-growing but potentially invaluable colonies."

Mr Roberts explained that sponges grew fixed in place and had to compete for space with many neighbouring sea creatures.

This means that, over millions of years, they have evolved to include many powerful chemicals - known as secondary metabolites - to defend themselves.

It is these complex chemicals that are showing promise as a new generation of drugs, Mr Roberts said.

He went on: To make sure that this potential isn't lost to us, we need to take steps to protect deep-water sponges on our doorstep and further afield.

Sponges form structurally complex habitats on the seabed, supporting locally rich biodiversity.

A growing and significant biotechnological industry has developed and a number of drugs have now been discovered from sponges and taken through clinical trials.

The team's report, Deep Sea Sponge Grounds: Reservoirs of Biodiversity, is being unveiled today at the European Marine Biology Symposium at Heriot-Watt University.

Mr Roberts said: "Appreciation of deep-sea sponge grounds and consideration of them in conservation and management decision-making is only just beginning, and the report launched today provides an excellent foundation upon which to build this work."