An international report is set to reveal how much damage we have done to the oceans — and how little we know about them.

Deep trouble

By Helen Massy-Beresford

‘I frequently hear people say that we know less about the oceans than about the surface of the moon,’ says Alex Rogers, a professor in conservation biology at the Department of Zoology and fellow of Somerville College. ‘I don’t think that’s a very useful comparison but it’s true that our knowledge decreases the deeper you go and the further away from the coast you go.

‘For some parts of the ocean our knowledge is incredibly flimsy. The deep-water column in particular is something we just don’t really understand,’ Professor Rogers says, explaining that this part of the marine environment is important for the understanding of the biological carbon pump – the process by which carbon dioxide is dragged down from the atmosphere into the deep sea by biological activity.

Researchers have investigated only about 0.0001 per cent of some deep-sea ecosystems including areas known as the abyssal plains and the deep pelagic zones, with that figure rising to around 10 per cent for mid-ocean ridges, says Professor Rogers. His current research projects include the ecology and evolution of Southern Ocean chemosynthetic ecosystems, the ecology of the seamounts of the South West Indian Ocean Ridge and the ecology of cold-water coral ecosystems.

In what he describes as the twilight zone, at depths of between 200 and 1,000 metres, fish are adept at avoiding nets and the myriad gelatinous creatures simply disintegrate when caught, making analysing what is there a challenge.

‘Although our knowledge is reasonable in many parts of the shallow oceans, that knowledge declines rapidly with increasing depth and there are many things that are potentially important in terms of managing human impacts on the oceans that we just don’t understand at the moment,’ Professor Rogers says.

Measuring that human impact is a vital part of marine researchers’ work and Professor Rogers is one of the authors of the forthcoming United Nations World Ocean Assessment, a snapshot of the state of the oceans that will help reveal how the human impact on the oceans is evolving and what can be done to protect marine ecosystems.

Deep trouble

Ocean covers seven-tenths of our planet, and we have been using the sea for millennia, but it is only now that we have the first global integrated assessment of the marine environment.  In 2002, the World Summit on Sustainable Development eventually recommended that the UN should set up a regular process for the global reporting and assessment of the marine environment, including socio-economic aspects. 

‘It took nearly ten years to get agreement on how such a major and novel task should be carried out,’ says Alan Simcock (Exeter, 1961), who, as one of two coordinators of the ‘group of experts’, has played in a key role in developing the assessment. The 22 experts, drawn from as many countries from all around the world, have worked with more than 400 other independent specialists. Professor Rogers has contributed a chapter on seamounts and one on deep-sea hydrothermal vents.

‘We are interested in the level of human impact in marine ecosystems and the resilience of those ecosystems to those impacts. We want to work with policy makers to change systems of ocean governance to the point where those harmful impacts are avoided or at least minimised,’ he says.

‘For the seamounts chapter, the major problem is deep-sea fishing using bottom-trawling equipment which is tremendously damaging to these ecosystems.’

The authors have reported some progress towards a more responsible relationship with the oceans, including the establishment of regional fisheries management organisations to protect marine ecosystems from deep-sea fishing techniques. However, they have concluded that it is yet to be seen whether these measures will be effective in large parts of the world’s oceans.

Additional material courtesy of Alan Simcock. Waterline © Willyam Bradberry, via Shutterstock. Waves crashing onto a coral reef, Raja Ampat, Indonesia © Fiona Ayerst, also via Shutterstock.