Ocean conservation: How do we look after the largest environment on Earth?

For millennia, people have pondered the depths of the deep blue sea.

The oceans cover more than 70% of Earth’s surface, and are staggering in their diversity. Just beneath the waves in shallow coastal waters lie coral reefs, whose dazzling array of colourful creatures make up a third of all marine life.

Head out into the open water and there’s a world with no such thing as ground. Countless species from minute plankton to enormous whales will float for their entire lives – being born, feeding, reproducing and dying without ever touching a solid surface.

Deeper still are the midnight zone and the abyss, whose inhabitants will never see the Sun. Their lives are occasionally punctuated by the bright lights of bioluminescence before being plunged once again into total darkness.

Eventually, over four kilometres beneath the waves is the abyssal plain. While it may not look like anything lives in these vast, often featureless tracts of land, scientists studying this habitat are discovering new species every year.

“The abyssal plain covers 54% of our planet, and is the largest habitat on Earth,” explains Dr Adrian Glover, who leads our deep sea research. “It’s on a vast scale. So vast that you could continue in one direction for thousands of kilometres and only see the same kind of seafloor.”

“In some regions of the deep sea, we have calculated that over 80% of the species we bring up in samples are new to science. We have described at least 50 species in the past 15 years and there are probably hundreds more just in the area we’re investigating, let alone the wider ocean.”

The sheer diversity of habitats, and the marine life that lives in them, are vital for the health of our planet.

Why is ocean conservation important?

Ocean conservation is important because the seas act as Earth’s regulatory system. They influence the weather, the temperature and even the spin of the planet.

Some of the most important contributors to this system are some of the smallest. Prochlorococcus, for example, may just look like a green blob under the microscope, but it’s actually one of the world’s biggest producers of oxygen. In fact, almost 5% of all photosynthesis is carried out by these microbes alone.

While most of the oxygen they make is used by other marine life, this process also locks away enormous amounts of carbon. Along with other photosynthesisers, this means the ocean acts as a huge carbon sink.

Seagrasses, for example, suck in carbon from the atmosphere up to 35 times faster than rainforests can. This carbon is then buried beneath the waves, buffering the world from the impacts of climate change.

Marine life also protects us in other ways. Globally, coral reefs are estimated to save communities around £3 billion every year by breaking up waves and storms before they can cause damaging floods.

Mangroves, meanwhile, provide nurseries for young fish that drive fisheries around the world. Over 3.3 billion people depend on fish for at least 20% of their animal protein intake, not to mention the consumption of shellfish, crustaceans and other marine life.

But while the bounty of the sea was once thought to be endless, our overreliance on the ocean is now pushing it beyond its limits.

Overfishing has brought fish populations to the brink of collapse – in turn starving the predators which depend on these animals. Levels of chemical pollution are still concerningly high, while rising levels of plastic are not just entangling animals but also affecting how their bodies function.

As if that wasn’t enough, the impacts of climate change are also being felt around the world. Coral reefs are bleaching with alarming regularity, while the oceans are becoming more acidic as they absorb ever more carbon emissions.

Turning this around will require a sea change in our understanding of the oceans and our relationship with the natural world. Scientists at the Natural History Museum are beginning this process at home.

Discovering the secrets of the sea

While the UK may only cover about 250,000 square kilometres of land, it’s the custodian of almost six million square kilometres of ocean. Most of this is found around British Overseas Territories, which are being investigated as part of the Blue Belt Programme.

The programme aims to study these waters so that they can be sustainably managed and cared for. This survey work is mostly carried out by scientists onboard research vessels. One such scientist is James Maclaine, our Senior Curator of Fishes.

“I first went on a Blue Belt cruise in 2019 to help sort and identify the fish being brought up,” James explains. “These cruises aim to record as many species as possible, whether they’re swimming in the open water or living down on the seabed, as well as mapping the area and measuring the water conditions.”

“This can turn up unexpected ecosystems, like large deep-sea coral beds around St Helena and Tristan de Cunha in the South Atlantic. These take hundreds of years to grow in the cold water, showing just how pristine these areas are.”

Once these cruises are over, the long process of sorting begins. The samples and specimens that have been collected are given to natural history museums, where they provide a wealth of information to researchers.

“The specimens and samples from modern and historic expeditions preserved in museums provide a snapshot of what the oceans were like when they were collected,” James says. “Sediment samples, preserved fish and nannofossils can come together to provide a baseline for what a region was like at a particular time: the temperature, the conditions and the species that lived there.”

This information is crucial for highlighting where biodiversity hotspots are and how they’re changing.

How do natural history museums conserve the ocean?

The research carried out with the collections of natural history museums helps to build up an evidence base about the oceans. This record is continually being updated, allowing scientists to track how the oceans are changing.

“By comparing older and newer specimens in the collections, we can identify clear trends such as rising levels of marine plastic,” James says. “One study that came out of our work on the Blue Belt Programme revealed that microfibres are even getting into the stomachs of deep sea fish.”

This research supports policymakers, conservationists and local communities to make decisions about how to conserve vulnerable species and ecosystems based on the best available evidence.

Once these rules are in place, data from collections can ensure that they are followed. Natural history museums are regularly asked to compare seized plants and animals using their collections, which can help identify whether endangered species are being exploited.

These collections can also help to steer potential future industries far below the ocean’s surface. Down on the expansive abyssal plains, research is contributing to the debate over what these unique environments should be used for, if anything.

This is because these plains are covered with polymetallic nodules, which are potato-sized lump of minerals that contain elements such as cobalt and nickel. While these mineral resources could help the planet transition to greener energy, the impact deep sea mining might have is not well understood.

“While the abyssal plains might appear flat and empty, there’s plenty of life beneath the surface,” Adrian explains. “Most of this diversity is in the mud and dominated by millimetre-sized animals like polychaete worms and small crustaceans.”

“We’re still discovering new species and features of this environment, which is gradually giving us a broader understanding of the deep sea’s ecology. It’s vital that we continue this research so that we can provide the best evidence to inform policy choices.”

The future of marine conservation

One of the most prominent policies being discussed at the moment is 30 by 30. This is an initiative in which many nations have pledged to conserve 30% of their oceans and lands by 2030.

Hitting this target is a difficult task, as less than 10% of the ocean is currently protected. As such, deciding which areas should be preserved and how they should be managed is a subject of intense debate.

In the UK, the work of scientists as part of the Blue Belt Programme has helped to introduce one of the largest marine protected areas (MPAs) in the world around Ascension Island in the South Atlantic. This means that an incredible 445,000 square kilometres, an area the size of Sweden, is now off limits to commercial fishing and mineral extraction.

The scientists’ research has also helped to develop policies that more sustainably manage other MPAs, from new rules managing fishing around St Helena to having a better understanding of the species that live around Ducie Island in the Pacific.

While this research helps in national waters, these cover just a fraction of the overall ocean. Most of the ocean lies in what is termed the ‘high sea’, the vast stretches of water outside of national jurisdiction that belong to both everyone and no one.

This may be about to change following the agreement of a High Seas Treaty by the United Nations. When it comes into force, it would allow international waters to become protected ocean areas for the first time.

“National reserves are important, but it would also be good to see the idea of 30 by 30 applied to the wider ocean,” James says. “It’s long been known that features such as seamounts and undersea ridges are biodiversity hotspots, attracting vast populations of fish and invertebrates.”

“Many of these undersea landscapes are currently unprotected as they sit beyond the borders of countries, making them vulnerable to overfishing, oil and gas extraction and other threats. High seas marine protected areas would give them security for the first time.”

The work of researchers in museums and out in the field will continue to feed into this debate, so that the decisions about the future of oceans can benefit both the humans and wildlife that call Earth home.