The Brilliant Abyss is a book by marine biologist, author and broadcaster Helen Scales, first published in 2021. Much of the book explores the fascinating forms of life found in the deepest parts of the ocean, the vast majority of which will be unknown to a general audience. However, in the later chapters, the book examines the threats to the deep sea environment such as commercial fishing, plastic pollution and deep sea mining.
At the outset of the book, Scales tells us that this is a golden age for deep-sea exploration. New species are being discovered on a regular basis and our understanding of deep-sea ecosystems is constantly increasing. We are told that the deep sea is likely to be the place where all life on earth began, and deep sea organisms could provide cures to many diseases and may even be able to solve the climate crisis through their ability to absorb carbon. But we are also warned that the deep sea is no longer an untouched wilderness which is immune to human activities. Through deep-sea commercial fishing and seabed mining, humans can easily degrade and destroy much of the deep sea before it is even explored and understood by science.
The book briefly covers the history of deep-sea exploration. We find out that in the mid-1800s the belief persisted that life could not exist below 500 metres, but the evidence that creatures could live and thrive at depths of many thousand metres slowly grew. The following chapters cover fascinating creatures such as deep-diving sperm whales and how they, as air-breathing mammals, are adapted to catch prey at immense depths. Another covers “zombie worms”, a newly discovered deep-sea species of worm which feed on the bones of whales. It is not currently known how the worms find whale skeletons, or even how they move through the sea to get to the skeletons. How little we know about the deep sea is a recurring theme. For example, many deep sea creatures are bioluminescent, meaning they are able to produce light through chemical reactions which take place within their bodies, but it remains unknown why most bioluminescent species do this. It may be to entice prey, repel or confuse predators, attract a mate or for a combination of all three reasons. Furthermore, it is almost impossible for scientists to study this, as most bioluminescent creatures either cannot be kept in captivity or do not display bioluminescence when they are.
These chapters are extremely detailed and interesting, although a general audience may be somewhat confused by some of the scientific language Scales uses as terms such as phylum, class and genera are used with little background explanation as to what they mean. But this does little to detract from the overall enjoyment of these chapters and in the vast majority of this book Scales is very good at making the life cycles of the strange and unusual organisms she describes understandable and accessible to a non-scientific, non-expert audience.
The later sections of the book look at the impact that human activities have on the deep sea. The story of orange roughy – a deep sea species previously known as slimehead – is recounted, although Scales brings a lot of detail to the explanation of how the species has been almost fished out along much of its range. The damage that deep sea commercial trawls do to seamounts, and how they may be able to at least partially recover if fishing ceases is also discussed. Scales also discusses the madness of the economics of deep-sea fishing. This form of commercial fishing destroys fragile marine environments and wipes out populations of slow-growing and late-maturing fish which cannot recover, all to provide less than half of one per cent of the fish people eat. Deep sea fishing does this while running at a massive financial loss and is only propped up by the overgenerous subsidies for fuel, tax exemptions and boat buyback schemes offered by European nations. Further issues covered include the MSC (Marine Stewardship Council) ecolabels and how they are often given to deep-sea fisheries which are far from sustainable, and the issue of plastic pollution in the deep sea.
The most detail is given to deep-sea seabed mining, possibly because this is a huge threat to the deep sea and one which could still be stopped. Scales explains how the deep sea holds reserves of rare earth metals and other elements such as nickel and cobalt which are now in high demand for batteries for electric cars and electronic devices. Countries which have such metals within their exclusive economic zones are campaigning to be allowed to mine them, often making the misleading claim that this will cause little harm to the deep sea environment and will prevent damaging land mining of rare earth metals in poor and politically unstable counties such as the Congo. Scales rebuts these arguments, stating that we have no idea of the long-term impacts of deep-sea mining and that allowing such activity could cause serious damage to the entire marine environment which will not become apparent for years.
The Brilliant Abyss is a highly interesting book. The chapters on deep-sea life are fascinating and the move into more political and environment-focussed topics in the later chapters is well-judged and expands the scope of the book, making the reader aware that many of the weird and wonderful creatures we have learned about may not be there if human activities such as deep sea mining are allowed to commence. The Brilliant Abyss is recommended to anyone who wishes to expand their knowledge of the world’s seas and oceans beyond the shallow waters and marine species which anglers and beach-goers are already familiar with, and also understand the political tensions caused by the growing demand to exploit the deep sea.