The Next Species: The Future of Evolution in the Aftermath of Man (24 page)

Increased CO
₂
in the bloodstream can reduce an organism’s ability to bind and transport oxygen, which is perhaps one of the reasons for the appearance of PETM dwarfs.

Such a high CO
₂
scenario would have enormous effects on our present-day coral reefs. Coral reefs are breeding grounds for fish, but with acidification, corals don’t aggregate or form stony structures for other marine creatures to cling to or crevices in which to hide. Coral reefs are natural breakwaters for many South Sea islands. But acidification and sea level rise are threatening these places.

Maria Cristina Gambi, of the Stazione Zoologica Anton Dohrn, in Naples, Italy, studies natural volcanic CO
₂
vents off the island of Ischia in the Gulf of Naples. She and her colleagues have found fewer animal groups and lower biomass in the extreme low-pH areas near the vents. Instead, a few small acidification-resilient species have filled the gap with population booms, which decreases the number of species.

During the Permian, ocean acidification left a unique legacy in its sedimentary layers, the “Lazarus taxa”—“taxa” meaning biological groups. Certain species seem to disappear at the end of the Permian but then resurface millions of years later, apparently coming back from the dead, as Lazarus did in the Bible.

The resurrection of these creatures may be due to ocean acidification. Without a shell or an exoskeleton, many creatures would leave no fossil or other evidence of their existence. It could be that many of these creatures survived “in the nude” for a while and came back when the oceans were less acidic and more hospitable to building shells.

Mary L. Droser, a paleontologist at the University of California, Riverside, believes Lazarus taxa may actually represent not a resurrection of old species but the convergent evolution of other animals. In other words, they are different species evolving to fill the same ecological niche. Such is the case when a number of different animals evolved to have crocodile-like jawbones and bodily features. They weren’t all crocodiles, it’s just that the crocodile had for some reason proved evolutionarily successful at that time, and evolution loves a winner. Droser likes to refer to them not as Lazarus taxa but as
“Elvis taxa” in that most forms were primarily imitations. But there were a lot of them. About 30 percent of all such groups were Lazarus taxa during some point between the mid-Permian and the mid-Triassic.

One of the most crucial problems with acidification is
the loss of coral. Coral reefs build up over time and offer shelter for smaller fish and other organisms. The coral reefs of the world are home to 25 percent of all marine species, yet they occupy a total area about half the size of France. Global warming and acidification have already led to increased levels of coral bleaching, which eliminates algae in reefs. Coral have a symbiotic relationship with various species of algae. They provide algae a place to live, and algae provide coral with vital nutrients. But coral bleaching eliminates the algae, and as a result coral starve.

About two-thirds of coral species live in deep, cold reefs, far outnumbering the more famous shallow, near-shore habitats of the Indian and Pacific Oceans and the Caribbean Sea, which are better known to vacationing snorkelers. Like shallow reefs, deep coral reefs provide shelter to an enormous and colorful bouquet of sea life. Fish that live in both deep, cold coral reefs and shallow, warm reefs represent a quarter of the annual marine catch in Asia, and feed about a
billion people.

There are effects in the Southern Ocean encircling Antarctica as well.
Acidification there dissolves the shells of sea snails. Geraint Tarling with the British Antarctic Survey in Cambridge captured free-swimming sea snails called pteropods and found that under an electron microscope they showed signs of strong corrosion. Experiments have shown that coral and mollusks use calcium carbonate in the water to make their shells. But increasing levels of ocean acidification means there is more carbonic acid in the water and this attacks shell building.

Certain types of phytoplankton, which have calcium carbonate shells, may be devastated by acidification in our oceans. Plankton that live in reef communities will suffer a double whammy, since acidification will destroy corals and raise temperatures above reef animal tolerances.

What happens then? Well, considering that atmospheric oxygen comes from two major sources—the tropical rain forests and marine plants such as kelp, algal plankton, and phytoplankton—deforestation and acidification may literally be attacking the air we breathe.

With ocean acidification, we may be harming the environment less purposefully than by overfishing, but the two combined are a bombshell to our present-day marine environments. It’s amazing to consider, but it hasn’t been that long since we started taking fish from the ocean. Archaeologists studying fish bones at 127 archaeological sites across England found a remarkable change in catches starting around 1050. According to Callum Roberts, a professor of marine conservation at the University of York, England, and author of
The Unnatural History of the Sea
, it was only in the beginning of the last millennium that people who were used to eating freshwater fish and freshwater/ocean migrants (such as salmon) began eating fish primarily from the sea.

Fish from rivers and ponds, such as pike, trout, and perch, as well as migratory fish like salmon, smelt, and sea trout dominated archaeological sites from the seventh to the tenth centuries, but from the
eleventh century onward the fish bones in English digs changed to mostly herring, cod, whiting, and haddock—all sea-based creatures. New fishing technologies as well as bigger boats stoked the fishing fires, but the truth was there simply weren’t enough inland fish left to feed the growing British population.

Trawling, the dragging of nets across the seafloor, goes back to the late fourteenth century. It’s a destructive type of fishing that indiscriminately catches fish both big and small. Trawling nets are, however, a boon to ocean fishing.

Hook-and-line fishing enjoyed a boost in the eighteenth century when long lines with hundreds of thousands of hooks replaced hand lines with much fewer. But the true dawn of industrial fishing began in the mid-1870s when the steam trawler appeared. The fishing power of sailing trawlers had been limited by tides and wind, but the steam trawlers were forever freed from the constraints of weather. Steam trawlers quickly replaced sail power for bottom trawling.
The development of the frozen food industry during the 1920s provided the next big boost.

Even so, coming out of World War II in the 1940s and 1950s, such environmentalists as Rachel Carson, author of
Silent Spring
, couldn’t fathom a future without fish. Most marine experts thought the oceans were inexhaustible. They were wrong.

In the decades that followed, intensive fishing became an enormous worldwide industry. Bigger boats, longer lines, and ever-larger trawls worked the sea with an efficiency not previously possible. Doctors started talking about how fish was much better than beef for one’s health, providing another big boost for the fishing industry. Global fish catches reached a peak at about 85 million metric tons a year in the 1980s. Large catches were maintained by a growing fleet with more advanced equipment.

Peter Ward, a paleontologist at the University of Washington, claims that by some estimates every square mile of the world’s continental shelves is trawled every two years. But as the continental shelves have begun to diminish, fishermen have entered the last great
wilderness: the deep sea. Muddy bottoms cover much of the deep-sea floor. But here and there seamounts (underwater mountains) thrust their peaks up just shy of the surface and allow for pockets of enormous fish diversity. Giant circular currents move up and down, bathing the tops of the seamounts in phytoplankton.

In the late 1960s, Soviet fishermen discovered plentiful schools of
armorhead fish around seamounts off Hawaii and began to harvest them. Fish around seamounts had to contend with stronger open-ocean currents, so they were more muscular and tastier than coastal fishes. Other countries followed the Russian lead, and seamounts off Hawaii were fished intensively. But the run didn’t last. Around 1976, catches collapsed from 30,000 tons to just 3,500 tons. If the Hawaiian fish bonanza had proved to be short-lived, no matter: there were plenty of seamounts left in the sea.

The next jackpot came from Soviet ships fishing at depths of 2,600 to 3,300 feet (800 to 1,000 meters) over the Chatham Rise off New Zealand in the early 1980s. Here, fishermen ran into plentiful populations of a bright-orange fish—what scientists referred to as
Hoplostethus atlanticus
, a relatively large deep-sea fish and a member of the slimehead family. But “slimehead” didn’t sound like something housewives would want to unload their wallets for, so they changed the name to “orange roughy.” It is still used worldwide for breaded fillets, fish cakes, and fish sticks, along with other white fish.

Fishermen in New Zealand and Australia quickly joined the Russians in
a full-scale assault on the fishery. One Australian fisherman, Allan Barnett, struck it rich at St. Helen’s Hill off the edge of the Tasmanian island shelf in 1989. In the first year, the hunt brought in a whopping seventeen thousand tons of orange roughy. But catches soon began to plummet as fishermen worked one seamount after another. Orange roughy are a very long-lived fish that do not reach reproductive maturity for over twenty years, making them extremely susceptible to overfishing and very slow to recover.

But that’s not the end. I visited Craig R. McClain, assistant director of science at the National Evolutionary Synthesis Center, in
Durham, North Carolina. He is a husky, young, friendly evolutionary marine biologist whose specialties are deep-sea species and very large marine animals like giant squid.

According to McClain, “We have overfished the shallow seas and are now moving into the deeper waters and doing the same.” He claimed the next big pressure in the deep sea is going to come from industrial mining companies that want to harvest the rare minerals in the bottom of the ocean. Mining companies off Papua New Guinea are starting to explore deep-sea vents, as they are made of a lot of precious minerals needed to make things like computers and, ironically, Toyota Prius hybrids. China is now considering
harvesting deep-sea sediments for their rare earth metals.

The runoff of nitrogen and phosphorus fertilizers from inland farms that travels downriver to the oceans is another part of our marine problems. During my visit McClain told me, “We are doing the equivalent of fertilizing a forest and that completely changes the makeup of sea plants and animals. And we are warming the oceans as we are acidifying the waters. This is all radically altering the temperature and chemistry of the sea.” He claimed we are suffering from severe reductions of shark species, some migrating species, and all the top predators. McClain sees the problem as reaching beyond just the loss of the deep sea, and said: “We are in danger of losing the entire ocean.”

This is changing the way biologists approach the ocean. In late summer, while visiting Frank Hurd, the science director of Olazul in La Paz, Mexico, I noticed all the divers were wearing long-sleeve T-shirts and long tights, what they called full-body exposure suits, though the waters were quite warm. I kidded him about finding the waters off Baja cold. “I don’t wear these things to keep warm,” said Hurd. “I wear them to protect myself from the jellyfish.”

According to Hurd, there have been massive jellyfish blooms along the coastlines of the US and Mexico in recent years. One of the hot spots for jellyfish is Monterey Canyon, in the center of Monterey Bay, the largest submarine canyon along the coast of North America.
The National Science Foundation, in a special report titled
“Jellyfish Gone Wild,” claims that one-third of the total weight of all life in Monterey Bay consists of jellyfish and similar gelatinous creatures. This is also a prime area for Humboldt squid.

Jellyfish move in as fish move out. They are tolerant of both low-oxygen environments and ocean acidification. A look into the future of the ocean could take us to the Republic of Palau, a group of islands about 550 miles east of the Philippines. About ninety thousand tourists visit Palau annually and
one of their favorite haunts is Jellyfish Lake (Ongem’l Tketau to the locals), which is easily accessible by boat from Koror, Palau’s capital. There are five landlocked marine lakes on Palau and each has different species of jellyfish. Scientists at the Coral Reef Research Foundation on Palau believe that the spotted jellyfish was the original ancestor of all Palau’s landlocked jellyfish, but they followed the rules of evolution and morphed over time into unique species for each of the five lakes, much like Darwin’s finches did in the Galápagos.

Jellyfish Lake’s jellies range from the size of a blueberry to the size of a cantaloupe. Tourist snorkelers love to swim through the millions of jellies as they pulse in and out. These jellies migrate across the lake each day. They go eastward in the morning to the edge of the shadow cast by the mangrove trees that surround the lake and then reverse their course, congregating by the western shadow line by midafternoon. Though these jellies have stingers, they target crustaceans about the size of a bee in the lake. Your skin might tingle if you touched one, but it wouldn’t sting.

However, the sting of a box jellyfish, found off Indonesia and Australia, can kill a man or a woman in just three minutes. Jellyfish sting about 500,000 people each year in the Chesapeake Bay, the largest estuary in the United States, on the Atlantic Coast, surrounded by Maryland and Virginia, but the US has nothing as lethal as a box jellyfish. Box jellyfish kill twenty to forty people each year.

During jellyfish blooms, about 500 million
refrigerator-sized Nomura’s jellyfish float in the Sea of Japan. They can grow up to 6.5 feet
(2 meters) wide and weigh 450 pounds (220 kilograms). Though normally more common off China or Korea, they have been showing up in Japanese waters, where they clog fishing lines and can poison fish catches with their toxic stingers.