The Ocean of Life

by Callum Roberts

  Plastics came into widespread use after World War II, so pretty much all of the plastic at-large on the high seas got there after 1945. Since then the tide of plastic pollution has grown relentlessly, and it is fragmenting into ever-smaller pieces. It is often said that plastics take hundreds or even thousands of years to degrade. Japanese researchers found that plastics floating in the North Pacific for decades were degrading much faster than expected.29 This apparently good news story has a poisonous twist. These particles are not just harmless roughage. They concentrate toxic compounds on their surfaces, sometimes to levels a million times or more above concentrations in the seawater around them.30 Recall from the last chapter that the surface microlayer of the sea, in which many plastics can be found, concentrates toxins. They attach to plastics. In one Japanese experiment, polystyrene beads soaked in seawater for several days picked up PCBs. When they break down, plastic particles release toxic compounds like flame retardants, styrene, phthalates, and bisphenol A into the sea. These toxins exert their insidious effects on wildlife, and us, at minute concentrations.

  Bisphenol A and phthalates are ingredients of a large variety of plastics. Phthalates are added to increase flexibility and transparency, but they don’t bond with the plastic and so are easily leached out. Bisphenol A is added to the resins that coat the inside of food tins, among many other products. Both have become highly controversial in recent years because of health concerns about their endocrine-disrupting properties, and both have been banned or restricted in a number of countries, including Canada, Australia, the United States, Japan, and those in the European Union. Some organizations, like the UK’s Food Standards Agency, insist that such substances are safe, but research is ongoing, and many subtle developmental effects have been detected in lab studies. Phthalates are attracted to fats like those they would contact in the surface microlayer. Given the ubiquity of these compounds in plastics, the possibility of harm to marine life (and us) must be taken seriously.

  We have only recently been confronted with the plastic confetti that is the legacy of decades of pollution. In the late 1990s Hawaiian beaches were inundated with a multicolored snowstorm of plastic fragments. People there were used to bits of plastic bobbing around but had seen nothing like this before. Periodically loops of water twist off the vast ocean currents that circle our oceans to escape from the pool trapped inside the gyre. In some cases this might happen but once in half a century. It seemed that the ocean gyre near Hawaii had belched a gutful of plastic that had been building within it since plastic came into widespread use.31

  An alarming new twist is that most cosmetics manufacturers now add submillimeter-sized plastic granules to hand lotions and face creams as exfoliants. They are too small to be filtered out by sewage works, and most of the particles are washed to sea, where they can be ingested by tiny plankton that mistake them for food such as copepods or fish eggs. Like other plastic fragments, these granules have a high surface area with which to attract and concentrate poisons like PCBs and mercury. Since plankton are the foundation of almost all ocean food webs, the problems this could create are clear. It is nearly impossible to buy an exfoliating face or hand cream today that doesn’t include plastics. Take a look at the labels on yours. If you find polyethylene in the list of ingredients, you are washing yourself with plastic.

  Many of the particles at-large in the oceans range from a few hundredths to a few thousandths of an inch in size. They now fall into the size range of planktonic food for a huge variety of life at the bottom of the food web. A third of plankton-feeding fish sampled in the North Pacific Central Gyre had plastics in their guts.32 Experiments with captive animals show that microplastic particles are eaten by almost any species that filters water, picks drifting particles of food, or slurps deposits from the seabed. Few people have looked, but in places where they have, beach and bottom sediments are stuffed full of microplastic particles.

  These microplastics have concentrated chemicals that could pass into animals that eat them, providing a fast track for the accumulation of toxins all the way up to top predators that we like to eat. Scarcely any research has been done on the transfer of chemicals from plastic fragments to animals that eat them, but this is certain to change in the next few years, because the world’s attention has turned to plastics at sea. What we do know at this point is that plastic particles fed to mussels end up in their circulation system and stay there for long periods. Chicks of a scavenging seabird, the great shearwater, that carried higher loads of ingested plastic had higher concentrations of PCBs in their tissues.33

  Remote regions of the ocean, like the Sargasso Sea and Northeast Pacific, have become slowly rotating graveyards of plastic junk, some of it decades old. The tangled remains of lost and abandoned fishing nets drift past golf balls, toothbrushes, gas lighters, and plastic bags. For how many hundreds or thousands of years will they continue their aimless voyages? In one telling incident, a dead albatross chick from Midway Island in the North Pacific had been fed a piece of plastic engraved with a serial number. It was traced to a U.S. bomber that crashed into the sea in 1944.34 The amount of plastic at-large is still growing exponentially year by year. You come face-to-face with this truth on virtually any beach in the world. In South Africa, for instance, bottle lids on beaches, used as an indicator of the prevalence of smaller plastic rubbish, increased by over fifty times between 1984 and 2005.35 That is not 50 percent, but 5,000 percent. The genie is already out of its plastic bottle. The oceans are choking on plastics and will continue to do so for hundreds of years, even if we were to stop dumping plastics today. But it is never too late to start the cleanup.

  Problems from plastics, sewage, oil, and toxic chemicals are all too familiar, but there are some things we don’t normally think of as pollution, at least in the sea. Noise and “biological” pollution—that is, the spread of species beyond their native haunts—are growing concerns, and I turn to them in the next two chapters.

  CHAPTER 11

  The Not So Silent World

  When I was a graduate student I spent three unforgettable summers exploring Saudi Arabia’s coral reefs. I was part of a team sent there to map its biological riches for the first time, and we were allowed to visit places long closed to foreigners. I remember well the keen thrill of slipping into the water, knowing that I was the first person ever to scuba dive there and wondering what I might discover. In 1984, we reached Tiran Island by sailboat after days beating up the Red Sea against bone-jarring waves raised by powerful northerlies. It was bliss when at last we found shelter in the lee of Tiran’s mountainous flank. We had hardly seen a soul for weeks, and Tiran felt like the end of the world. That night, far across the sea, a few lights from the Egyptian coast suggested we were not alone. But the peace was palpable.

  The next day I dived one of the coral reefs that defend the entrance to the Gulf of Aqaba. Below water the bottom was hard to make out at first through a blizzard of plankton-feeding damselfish, basslets, and glassfish that swayed to the silent pulse of unseen currents. Purple sea fans and chocolate sea whips bent and wafted on the liquid breeze amid a tapestry of corals of marvelous shapes and colors. Surrounded by such tranquil beauty, I lost all sense of time.

  A little more than a decade later I returned to dive the same spot, this time setting forth by day boat from the Egyptian resort of Sharm-el-Sheikh with fifteen other divers. We charged north with ten other boats, all hoping to be the first to tie up to one of the moorings that marked a string of dive sites. The Egyptian coast behind me had been utterly transformed. Whereas before there had been only a few dwellings, now resorts and hotels studded the clifftops, coves, and beachfronts. At the dive site I had to pick my moment carefully to leap into the sea to avoid the propeller blades of two latecomers jostling for space.

  I expected to find immediate relief from the confusion and fumes above water, but even thirty feet below the surface I was overwhelmed by the engine roar from boats overhead and others coming and going from more dist
ant sites. The near-constant bombardment made this dive feel like the underwater equivalent of standing in the middle of a multilane highway. I tried to find a quiet corner to while away the dive, but the noise was everywhere. From a rocky ledge a stonefish looked at me with an unblinking scowl. It seemed an appropriate expression. I wondered whether the fish on this reef were relieved when the last boats left in the evening and a semblance of peace was restored.

  Jacques Cousteau published his first book in 1953. He called it The Silent World but his title was misleading. As well as the timeless notes of whale song, Cousteau’s seas were filled with the scratch and rasp of foraging animals, the whistles and clicks of dolphins, the low groans of whales, and the rumble of breaking waves. By that time the thump and growl of boat engines had also invaded the oceans. Noise levels have grown to a roar since the 1950s as the world’s globalized economy has launched tens of thousands of new merchant ships. The sound of a supertanker is ear-splitting, and because sound goes further underwater than in air, it can be heard by a whale a day before the ship arrives. Background noise levels in the sea have not been measured systematically, but in the few places we know about, they have increased by about three decibels per decade since the 1950s.1 The loudness of sounds underwater doubles for every six decibels. So today’s seas could be over eight times noisier than those that Cousteau taught us to love in the early 1950s, and in some hot spots are over one hundred times as loud.

  A few years ago I had a haunting experience off the tiny volcanic island of Saba in the eastern Caribbean. I had begun a dive to count fish when I heard a loud drawn-out rumbling growl, or rather I felt it as it thrummed through me. I spun around, expecting to see a leviathan bearing down, but none was there. Then came the unmistakable melodious moan of a humpback whale. For the rest of the dive I listened to a song as beautiful as any by Verdi. I never saw whales on this or many subsequent whale-song dives in Saba. They were probably far away, perhaps many miles, for their songs have evolved to carry enormous distances in the sea.

  The much greater density of seawater carries sounds farther and faster than air. Noise travels about five times more quickly in the sea, reaching five thousand feet per second in temperate waters. It drops off less quickly in water than in air, so noises can be heard at far greater distances.2 High frequencies attenuate more quickly than low frequencies, so deep notes go farther. Some of the great whales communicate over hundreds or even thousands of miles using the kind of low frequency rumbles I heard in Saba. Sounds go farthest of all if animals take advantage of a strange property of the sea. Between the warm lighter layer at the surface and the cool dense water below there is a narrow region where sounds travel in a similar way to light in a fiber-optic cable. Differences in density across this boundary—the thermocline, we have come across it before—keep soundwaves produced there in a narrow channel, where they lose little energy as they travel. Before the days of satellite beacons the U.S. Navy issued pilots with an explosive charge. If they had to ditch in the sea, they were to lower the charge on a string and explode it in this acoustic pipeline. The sound would carry to sensors perhaps thousands of miles away in places like California, Hawaii, and Panama that could then work out where the pilot was by triangulation.

  Several species of whales are thought to use this aquatic telephone to broadcast calls over hundreds of thousands of square miles of ocean. Their voices are well adapted to be heard from far away. Blue whales are the largest and loudest animals on the planet, and they can bellow at over 190 decibels. Sperm whales are also very loud. Doug Anderson, a cameraman on the BBC’s Planet Earth series, once came across a newborn sperm whale calf in the Azores that he began to film while the mother hung around below with an older calf. The baby played with him for a while before the camera housing caught in one of its fetal folds. This obviously hurt, because it gave out a stream of clicks and blew hard. Anderson turned to find the mother’s head filling his entire field of vision. He thought she would charge, but instead there was a crack like the splintering of a falling tree, so loud it shook his body and left him stunned.3

  The peace and quiet of the oceans is today broken by far more energetic sounds than ships. All over the world, seismic bangs from oil and gas exploration race through the sea to probe the rock beneath. Survey ships have air guns that produce pulses of sound above 200 decibels to send shockwaves through the seabed. The boom of military sonars used to track submarines can reach 235 decibels. Things sound about 61.5 decibels quieter in the sea compared to air.4 Sonar noises and seismic blasts therefore come in at an above-water equivalent of around 150 decibels to 175 decibels. For comparison, a rock concert can reach 110 decibels, and people feel pain from 120 decibels, or about the noise of a big chain saw close up. The sound of a seismic gun is over thirty times louder still, and the sound of the most powerful military sonar more than a thousand times louder.

  It isn’t quite this simple, and I must admit to shameless anthropomorphism in my description of the disgruntled Red Sea stonefish in the chapter opening. There is a second and equally important dimension to sound, which is frequency. High-pitched noises have a high frequency, whereas low-pitched sounds have a low frequency. Most animals can only hear over a limited frequency range. Bats hear higher frequencies than we can. My stonefish would have been stone deaf to many of the sounds that you and I hear, since its hearing range is set lower than ours (although boats produce loud noise at low frequencies, so the reef would probably have been as noisy for the fish as it seemed to me). What would constitute a gut-churning blast of sound for a human might register as only a whisper or not be heard at all by some other creature.

  Beaked whales are especially susceptible to sudden loud noises in the sea. These odd animals look like a whale crossed with a porpoise or dolphin. Some have blunt foreheads and thick fleshy lips, while others have drawn-out snouts, like bottlenose dolphins. They are shy, can dive for more than an hour, and rarely spend more than a few moments at the surface, so they are hardly ever seen. We think there are twenty-one species, but there could be more. These whales are so enigmatic they have been called “the least understood group of large animals on Earth.”5 Some species have never been seen alive and are known only from their dead bodies when they washed ashore. They range in size from thirteen feet long and a ton in weight to forty feet and sixteen tons. It is hard to imagine that we could overlook animals the size of elephants or bigger so easily, but it is their lifestyle that makes them elusive.

  Peter Tyack from Woods Hole Oceanographic Institution in the United States has devoted his life to understanding how whales use sound to communicate. I once spent a lively bus journey with him crossing Santa Cruz Island in the Galápagos. He completely turned around my notion of what it means to be a whale—in just an hour. Until that time I had thought of whales as animals that lived at or near the surface but dove into the deep blue to find food. Peter said that we should think of beaked whales as deep-living animals that occasionally pop to the surface for breath. The abyss is their home. It is this deep lifestyle that makes intense sonar noise a real problem for them.

  In 1996 there was an unusual mass stranding of a species called Cuvier’s beaked whale in Greece’s Kyparissiakos Gulf. When whales strand together they usually all come ashore at once in the same place. This time the whales came ashore separately along twenty-five miles of coast. No wounds or other signs of harm were found on the bodies. Most of the whales’ stomachs were full of squid, which suggested they had fed just before their deaths. For Alexandros Frantzis, then a young biologist at the University of Athens, the smoking gun was a NATO research vessel that had been in the Gulf to test a naval sonar system at exactly the time the whales died.6 The system used extremely loud sounds at low frequencies—some well within the range of whale hearing—to detect ultraquiet submarines. He became convinced that the sounds had somehow either injured the whales directly or disoriented them so badly that they beached themselves inadvertently.

  Beaked whales of many di
fferent species have since stranded in similar ways, and almost always the military are in the vicinity testing some extreme noise-making device.7 Closer scrutiny reveals these victims to have suffered serious internal injury. Some even come ashore bleeding from the ears. Like human divers who have spent too long underwater, many whales had suffered decompression sickness.8 When divers breathe at depth, nitrogen gas dissolves in their blood. As any diver knows, spend too long too deep or ascend too quickly and the nitrogen will fizz out into your blood, causing the bends. Severe cases can kill you. As the whales surfaced, bubbles of nitrogen formed in their blood, fat, and organs, literally tearing them apart internally and blocking their circulation. How these whales get decompression sickness is still a bit of a mystery. Initially people thought it was because they had been frightened to the surface too quickly. But Peter Tyack doesn’t think this would cause injuries of the kind he saw.9 Instead, he believes that when sonars scare whales they spend too much time bounce diving between 100 feet and 250 feet deep, snatching short breaths at the surface, and so they accumulate dangerous amounts of nitrogen in their blood.