Published: 22.04.2021 Updated: 03.05.2021
“95 percent of the deep ocean is still not described by science. That means we don’t know about all of the species that live there. Meanwhile, human impacts on the sea floor are increasing. We therefore expect various unknown species to become extinct before we discover them.”
That is the view of Lis Lindal Jørgensen, a researcher at the Institute of Marine Research (IMR) and one of the co-authors of the report, which was launched on Wednesday.
The Second World Ocean Assessment, which builds on the first assessment from 2015, provides an updated picture of ocean health.
The report points out that on the one hand we are learning more and more about the ocean, including how to combine sustainable use with conservation. On the other hand, the ocean environment is changing rapidly, mainly as a result of human activities.
One impact of that is that species in the deep ocean are disappearing. According to the report, the reasons for this include the ocean becoming warmer and more acidic, emissions and pollution, bottom trawling and overfishing.
Plans to extract minerals from the seabed for use in green technology create another challenge with potential for major consequences.
The report states that we currently know about more than 150,000 species of benthic fauna. Over 10,000 new species have been described since 2012. But there are still gaps in our knowledge, which moreover is unevenly distributed.
“We know most about shallow waters managed by rich countries, and least about deep waters and marine areas managed by developing countries”, says Lis Lindal Jørgensen, who had overall responsibility for the report’s chapter on benthic fauna.
In Norway, we are mapping the seabed and the species that live there through initiatives such as the Mareano programme. In our ecosystem surveys of the Barents Sea we monitor the progress of species. This kind of mapping and monitoring is in short supply in other parts of the world, and particularly in poorer countries.
“It is difficult to assess the current status of these seas, and how they are changing, when the data available varies greatly or is completely lacking”, says Jørgensen.
Our lack of knowledge makes it difficult to protect life in the deep ocean effectively. When species disappear, it can affect other species as well.
“The benthic fauna is important to the ocean, and to us as humans. We eat shrimps, crabs and bivalves, and in places like China they also eat sea cucumbers and many other species. In addition, bioprospecting, in other words looking for natural substances than can be used in medicines or industrial products, has had great success with marine species”, says Jørgensen.
She also points out the importance of benthic fauna as a “home” for other species:
“A coral reef or sponge forest can be home to large numbers of other species that eat, live and shelter there. They provide somewhere for juvenile fish to grow up safe from their enemies. So by conserving life on the seabed, we are also protecting our fish stocks.”
Another scientist at the IMR, Mette Skern-Mauritzen, has contributed to the new report’s chapter on sea mammals.
“We have documented that several species of sea mammal remain critically endangered. However, many other species are doing well – for example the baleen whales, which were heavily hunted in the past. Their populations are now recovering”, says Mauritzen.
Today, Norway is one of the few countries that hunts whales. The annual catches are small, and within what are considered the sustainable limits.
“The species that are critically endangered now are generally not the ones that are hunted, but rather species with limited habitats that are heavily impacted by human activities. These include the vaquita porpoise in Baja California, which often becomes entangled in fishing nets”, says Mauritzen.
There may be fewer than 20 individuals left of this species, putting it at extremely high risk of extinction.
One important topic covered by the report is the link between ocean health and human health.
Bjørn Einar Grøsvik was responsible for part of the chapter on toxins and discharge from oil and gas installations. He points out that metals and persistent organic pollutants can accumulate in the food chain, creating a health risk to both animals and humans.
“In the Barents Sea, we have observed that toxin levels have fallen and then levelled off. Now we are wondering whether that is ‘good enough’”, says Grøsvik.
“In the Mediterranean and many other seas further south, toxin levels are so high that some of the top predators – like dolphins and orcas – are struggling to reproduce”, he adds.
Oil and gas production results in the release of produced water, which may contain oil residues, amongst other things. These can form so-called DNA adducts when they attach themselves to DNA, causing mutations.
“We still know too little about the long-term impacts of these emissions. However, from an environmental point of view it is a concern that we are finding DNA adducts in benthic fish in the North Sea year after year”, says Grøsvik.
Grøsvik, Mauritzen and Jørgensen are three of over 300 researchers from all over the world who have contributed to the ocean assessment, which is over 900 pages long.
The importance the UN places on this work can be seen from the fact that Secretary-General Antonio Guterres participated in its launch on Wednesday, as well as writing the foreword to the report.
At the launch, Guterres emphasised that the number of “dead zones” in the ocean almost doubled from 400 in 2008 to 700 in 2019, and that a number of species and habitats are threatened.
“The World Ocean Assessment shows that the many benefits that the ocean provides are at risk. I urge leaders and all stakeholders to heed the warnings in the Assessment as we work to conserve and sustainably manage our planet’s marine environment”, says Guterres in the foreword.
Bjørn Einar Grøsvik considers the ambitions behind the report to be both very big and very important.
“The aim was to build up an overall picture of the current state of the ocean’s health, look at how it influences human health and find out what we need to study in order to improve our understanding in the future. It will inform the UN Decade of Ocean Science and support our efforts to achieve the Sustainable Development Goals by 2030”, he says.