The Next Species: The Future of Evolution in the Aftermath of Man (15 page)

In rare instances where bird flu has spread from poultry to people, it’s been one of the deadliest viruses ever described. About 600 people have been infected with bird flu and 350 have died, about 60 percent. “But what if the virus were to mutate into easy human-to-human transmissibility?” asked Greger in a televised interview with Thom Hartmann about his book
Bird Flu: A Virus of Our Own Hatching
. “It would be like crossing one of the most deadly diseases, Ebola, with the most contagious disease ever known, influenza.”

In 1900, the leading causes of death were tuberculosis, pneumonia, and enteritis. Today, more than a century later, the chief causes of death are heart disease, cancer, and stroke.
These chronic diseases have overtaken infectious diseases as our number one killers. This is not a bad thing, since chronic diseases generally affect older populations. Thus the abatement of infectious disease in just the last century has increased average life spans by thirty years or more. The decrease in the role of infectious killers is largely due to inoculations and antibiotics. Some of the greatest recipients of these benefits have
been the young, who are disproportionately affected by infectious disease.

But the balance is changing. Recently, Dr. Margaret Chan, director general of the World Health Organization, addressed a group of experts gathered in Geneva, Switzerland, to tackle antibiotic resistance.
“Some microorganisms are resistant to nearly everything we can offer to save the lives of infected patients,” Chan said in a speech to the convention. “And few new antimicrobials are in the R&D pipeline. Medicines lost because of microbial resistance are not being replaced. We are moving towards a post-antibiotic era where common infections will once again kill. If we lose our most effective antimicrobials [antibiotics, antifungals, antivirals, and antiparasitics], we lose modern medicine as we know it.”

Disease is not likely to take man out, any more than the plague, World World II, or AIDS has. But if you take new diseases, couple them with antibiotic resistance, add some rising populations, and mix in a lack of food and proper nutrition, then we might have the recipe
for our own extinction.

U
NLIKE THE EMERGING THREAT
of new diseases and the resistance to antibiotics, one doesn’t have to wait to see how man’s interference is changing the marine environment. Many of those changes are already here. One shining example is the Gulf of California between mainland Mexico and the Baja California peninsula, what was once lovingly referred to as the “Baja Fish Trap” for its abundance of marine life. Overfishing, acidification, and warming waters have altered the ecology of these famous marine waters. The marlin, swordfish, and sharks that anglers once came here for have dramatically dwindled and a new ecology made up of Humboldt squid and sperm whales has taken over.

It is still a pristine environment. A drive south of the US border down Mexico’s Highway 1 takes you past volcanoes, mountains, and sculpted red rock through a series of valleys populated with whiplike boojum trees and giant cardon cacti. About five hundred miles south of the border it summits the coastal mountains and descends rapidly onto the Gulf of California just above the historic French mining town of Santa Rosalía. The Gulf of California, in Mexico, was created six to ten million years ago when Baja California began to separate
from mainland Mexico, producing the geologically diverse peninsula and the biologically diverse waters of the Gulf.

On a recent visit, the moist evening breeze brought in the briny smell of marine life to cool the town of Santa Rosalía as the fishermen headed toward the dock and the boats for the nighttime catch. Biologist William Gilly, from Stanford University’s Hopkins Marine Station—a big, friendly academic with lots of interesting stories—and his group of student researchers joined the fishermen as they motored out to sea. It was September on the Baja Peninsula, where open-ocean schools of tuna, swordfish, and sharks were once an annual gift of the Gulf, but have diminished in recent years.

Now
Santa Rosalía fishermen pursue Humboldt squid (also known as jumbo squid), which appear to have replaced many of the finfish in the Gulf of California. They still fish as before, only they go out in the late evening, not at dawn. At sunset, I watched the local fishermen join the parade of pangas, twenty-two-foot open skiffs with outboard motors that departed from the sandy shores. The Gulf waters turned from blue to black as the boats lined up about a mile offshore, their colored lights glistening in the evening shadows. The fishermen used hand lines baited with fluorescent jigs to catch the squid.

These boats represent a growing group of local small-scale fishermen who, but for their outboard motors, rely little on the hardware of the modern commercial fishing industry. Instead, they fish the waters off the Baja Peninsula from unregulated camps that line the shore using primitive gear. Over the last decade the Mexican Humboldt squid fishery has caught between 50,000 and 200,000 tons of squid annually, mostly from the Gulf of California, and sold it predominantly to markets in Korea and China.

The Humboldt squid was named for the Humboldt Current, an ocean current that flows north along the west coast of South America from the southern tip of Chile to northern Peru. It was thought that the Humboldt squid in Baja originated in Pacific waters off South America, though when, exactly, they arrived off Baja is a mystery.
There have been few historical sightings of the squid in marine records farther north than the Galápagos Islands off South America.

Humboldt squid (
Docidicus gigas
) have not only invaded the waters of the Gulf of California, they have expanded their domain northward along the Pacific coast as far as Alaska and westward along the equator toward the Hawaiian Islands.

Squid here seem to have filled a niche left vacant when finfish such as tuna, sharks, marlin, and swordfish began to disappear in the late twentieth century. Squid have a much shorter life span than other fish, rarely living over a year and a half. And they are highly productive, meaning they can bounce back from fishing pressure much faster than finfish, which are not as productive. But Gilly thought this factor was less important than the ability of squid to cope with the spread of low-oxygen waters, a new problem on the horizon that may be giving the squid their ticket to expand.

The increase in the biomass of Humboldt squid in the Gulf of California is promoted by the development of
low-oxygen zones in the water, a result of climate change and possibly decreased ocean circulation. These zones are different from the dead zones created by agricultural runoff, but the two could act in tandem to worsen the effects. Low-oxygen waters support fewer species but can support high quantities of those few species that are tolerant of it. Again, we are seeing the live-fast-die-young generation: a few species that are able to survive a toxic environment, which then take over the world—or the ocean in this case.

Santa Rosalía developed as a copper mining town in the late 1800s, and it was prosperous until the ore ran out in the 1920s. Still there are touches of prosperity from its mining days. Gustave Eiffel, of Eiffel Tower fame, built the church in the town center in France and then shipped it to this Baja town, where it was reassembled in 1897, an indication of the wealth mining generates. Still the town has none of the lights, bars, or tourist trappings you might find in Puerto Vallarta
or Acapulco farther south.

The Santa Rosalía copper mine has recently reemerged as newer techniques have made the mining of old ore deposits viable.
Gilly wonders what the long-term effects will be as the mine gears up for another run. Only, the proportions are much larger now than in the late 1900s, as miners will be using huge equipment to extract lower amounts of copper from already-mined soils.

Gilly has developed a program for monitoring intertidal shellfish communities, both near the new mine and in a more protected area about twenty miles north of town. “If the mine begins to disturb the marine environment off Santa Rosalía, the monitoring plan is designed to detect it. We’re lucky to be able to commence monitoring before major production commences,” said Gilly. He’s working with students from a local technology school that was established here in recent years.

Still his biggest concern is the changing face of oxygen in the deep ocean, here and in the oceans around the world. Gilly referred me to a paper by Lothar Stramma, a physical oceanographer at Kiel University in Germany, who led a study in 2008 that analyzed oxygen content at six different spots in the deep waters of the Pacific, Atlantic, and Indian Oceans. That study found significant increase in low-oxygen water in most spots, and these areas, known as oxygen minimum zones, were below the livable threshold of many marine animals. These low-oxygen zones are a natural phenomenon of the eastern Pacific Ocean and occur in the upper layers of the water, but they are expanding in all directions worldwide. Scientists link this change to global warming.

The oxygen minimum zone restricts the depth to which tropical open-ocean fishes, such as marlin, sailfish, and tuna, can go by compressing their habitat into a narrow surface layer, where they are more easily fished out. In general, the Pacific has lower oxygen minimum zones than the Atlantic. German oceanographer Stramma said that the lowest oxygen value in the Atlantic found in the 2008 study was 40 percent saturation (surface is 100 percent), whereas in the Pacific there were
oxygen minimum zones that reached almost zero percent.

This has serious consequences for marine organisms. According to Gilly, at 10 percent dissolved oxygen content in the water, microorganisms can no longer utilize oxygen and start metabolizing nitrogen compounds, releasing nitrates, which are strong greenhouse gases. “At zero percent, microorganisms start metabolizing sulfate ion compounds and releasing hydrogen sulfide, and that can be lethal,” said Gilly. During the Permian extinction the oceans went stagnant in places, caused by a loss of ocean currents. Douglas Erwin at the Smithsonian thinks that the emergence of this chemical compound into the atmosphere may have been one of the dominant killing forces at the time.

Humboldt squid feed on lantern fish in the Gulf of California but may prefer hake in Chile and Peru as well as off Northern California. “Hake” is a term that includes any of several large marine fishes of the cod family. South American authorities struggle with problems in their hake fishery, which is squeezed between overfishing and oxygen-starved waters.
Northern California’s hake fishery has not been affected by oxygen-starved waters, though bottom-dwelling creatures have.

Off the Oregon and California coasts, the oxygen minimum layer is rising up and moving nearer the shore. “It’s intersecting the continental shelf and moving rapidly inland like a river breaching its levees,” said Gilly. “And there are a lot of things that live at the bottom that can’t swim away.”

The presence of large numbers of Humboldt squid off the Pacific Northwest has impacted the valuable hake fishery there. For example, in 2009 there were so many squid present in the areas of hake schools that sonar estimates taken of hake numbers could not be used to set national quotas for the US and Canadian hake fisheries.

Few predators catch squid at these depths. Gilled finfish like tuna and shark can dive to the upper limits of the oxygen minimum zone and feed on squid there, but few can go into the zone and stay there for a significant length of time. Scientists at Stanford University have tracked great white sharks, which migrate annually toward Hawaii,
and have found that large numbers of these animals stop en route at a mid-ocean area called the
“White Shark Café,” where they repeatedly engage in dives above the oxygen minimum zones. Whether they are mating or feeding is not yet known, but Gilly thinks they could be diving for Humboldt squid or the purple-back flying squid that may also inhabit the area.

Fertilizer runoff from the mainland shores in the northeastern part of the Gulf may be enhancing the low oxygen effects here. Such runoff has created dead zones at the mouth of the Mississippi River in the US; the mouth of the Yangtze River in China; within the Black Sea Basin in eastern Europe; in the Skagerrak, the strait that separates Norway and Sweden from Denmark; and in the Cariaco Basin, near the coast of Venezuela. There are more than 150 such dead zones around the world.

The difference between dead zones and low-oxygen zones is that the latter involve an oxygen deficiency in the specific layer of water that forms beneath the maximum depth of daytime surface light in coastal and mid-ocean environments. Scientists measuring that layer of water, between 650 and 3,000 feet (200 and 700 meters), have found
a measurable decrease in oxygen and an expansion of the vertical and horizontal limits of the layer over the last fifty years.

This maximum depth of daylight surface light is also known as the deep-scattering layer, a name given to it by twentieth-century naval captains who found that sonar gave a false seafloor echo as it bounced off this zone because of the high density of marine life present. Plankton and zooplankton congregate in the deep-scattering layer primarily to avoid visual predators, and their feeding habits use up dissolved oxygen in the water, creating the oxygen minimum zones.

Few marine creatures have adapted to the oxygen minimum zones. But Humboldt squid are one of these low-oxygen-tolerant wonders. When they enter the zone, their metabolism slows and they consume less than 20 percent of the oxygen they need at the surface. Specialized gills allow them to scavenge oxygen from the water more efficiently. Their hearts don’t race wildly as they chase down their prey,
since their prey are slowed down by the lack of oxygen as much as the squid are. “It’s not like a lion chasing after a gazelle,” says Gilly. “They catch fish with little effort.”

What are known as “common market squid,” a smaller but important part of the California fishery, probably find such zones lethal. Gilly, who has studied both common market squid and Humboldt squid for decades, believes that increasing loss of oxygen in the seas will lead to the expansion of Humboldt squid from this point forward. This is bad for finfish, as the larger fish—already crowded into shallower oxygen-rich zones—will become more vulnerable to commercial fishing. Such a situation is happening now off the coast of Peru and Chile around the Humboldt Current, one of the richest fisheries on earth, where catches are high but the sustainability of these catch rates is in doubt.