Tag Archives: deep ocean pollution

The Impact of Oil Spills on the Deep Sea: the Deepwater Horizon Oil Spill

The Louisiana University Marine Consortium (LUMCON) published in September 2019 a study on the Deepwater Horizon Oil Spill in Royal Society Open Science.  The BP’s Deepwater Horizon oil rig exploded in April 2010, killing 11 workers.  The subsequent cleanup and restoration had cost nearly $65 billion..but while while we can burn off and disperse oil on the surface, but we don’t have the technology to get rid of oil on the seafloor. So approximately 10 million gallons of it settled there….In 2017 , the The LUMCON surveyed the site surrounding the wreck of the rig, and another one 1,640 feet north. There were no giant isopods, glass sponges, or whip corals that would have jumped (metaphorically) at the chance to colonize the hard substrate of the rig, such as discarded sections of pipe…..But]  crabs were just about everywhere. The researchers were shocked by the sheer number of crustaceans and other arthropods that had colonized the spill site. According to rough estimates, Atlantic deep sea red crabs, red shrimp, and white caridean shrimp were nearly eight times more populous at the Deepwater site than at other spots in the Gulf. “Everywhere there were crabs just kicking up black plumes of mud, laden with oil,” Nunnally says. But abundance does not mean the site was recovering, or even friendly to life. Particularly eerie was the crab’s achingly slow movement. “Normally, they scatter when they see the ROV lights,” he says. But these crabs seemed unbothered, or unaware of the robot’s presence.

Crabs on the seabed of the Deepwater Horizon oil spill

The researchers hypothesize that degrading hydrocarbons are what’s luring unwitting crabs from the surrounding seafloor to the deep-sea equivalent of a toxic dump. “The chemical makeup of oil is similar to the oils naturally present on crustaceans,” Nunnally says. “They’re attracted to the oil site, but everything goes downhill for them once they’re in the area.” A similar kind of chemical confusion occurred at an oil spill in Buzzards Bay in New England in 2003, which attracted hordes of American lobsters. The researchers liken the death trap to the La Brea Tar Pits: Once lured in, the crabs lose their ability to leave. With no other species able to thrive in the area, the crabs have no food source—except each other. And as one might imagine, consuming the flesh of a toxin-riddled crab or starving to death in a deep-sea tar pit is sort of a lose/lose situation.

The crabs also looked anything but normal: some claws shrunken, some swollen, shriveled legs, a dusting of parasites. “There were deformities, but mostly things were missing,” Nunnally says. “You come in with eight legs and try to get away on four or five.” The researchers have yet to ascertain what specific toxins led to these maladies. The shrimp looked just as awful as the crabs. “They didn’t look like shrimp from other sites,” Nunnally says, adding that many of the small crustaceans had humps in their backs—tumors, perhaps.

Excerpts from SABRINA IMBLERS, A Decade Later, the Deepwater Horizon Oil Spill Has Left an Abyssal Wasteland, Atlas Obscura, Sept. 18, 2019

Gummy Squirrels v. Cobalt: Mining the Seabed for Real


Sometimes the sailors’ myths aren’t far off: The deep ocean really is filled with treasure and creatures most strange. For decades, one treasure—potato-size nodules rich in valuable metals that sit on the dark abyssal floor—has lured big-thinking entrepreneurs, while defying their engineers. But that could change April 2019 with the first deep-sea test of a bus-size machine designed to vacuum up these nodules.

The trial, run by Global Sea Mineral Resources (GSR), a subsidiary of the Belgian dredging giant DEME Group, will take place in the international waters of the Clarion-Clipperton Zone (CCZ), a nodule-rich area the width of the continental United States between Mexico and Hawaii. The Patania II collector, tethered to a ship more than 4 kilometers overhead, will attempt to suck up these nodules through four vacuums as it mows back and forth along a 400-meter-long strip.

Patantia Vessel for Deep Sea Mining by DEME

Ecologists worried about the effect of the treasure hunt on the fragile deep-sea organisms living among and beyond the nodules should get some answers, too. An independent group of scientists on the German R/V Sonne will accompany GSR’s vessel to monitor the effect of the Patania II’s traverses. The European-funded effort, called MiningImpact2, will inform regulations under development for seafloor mining,…

The nodules are abundant, and they are rich in cobalt, a costly metal important for many electronics that is now mined in the forests of the Democratic Republic of the Congo, a conflict zone…Ideal for nodule formation, the CCZ is estimated to contain some 27 billion metric tons of the ore. But its abyssal plain is also a garden of exotic life forms. Craig Smith, a benthic ecologist at the University of Hawaii in Honolulu, has helped lead biological surveys in the CCZ that, in one case, revealed 330 species living in just 30 square kilometers, more than two-thirds of them new to science. The CCZ’s inhabitants include a giant squid worm,  green-yellow sea cucumbers that researchers called “gummy squirrels,” and a greater variety of bristle worms than ever reported before.

gummy squirrel on seabed

Mining could leave a lasting imprint on these ecosystems. In 2015, MiningImpact scientists visited the site of a 1980s experiment off Peru in which a small sledge was pulled along the bottom to simulate nodule harvesting. Three decades later, “It looked like the disturbance had taken place yesterday,” says Andrea Koschinsky… Many of the species in the deep seabed, such as corals and sponges, live right on the nodules. “They will be sucked up and are gone. You can’t go back.”Such concerns make many environmentalists wary of opening any of the deep sea to mining…

For one thing, the legal framework for mining in international waters is uncertain. Although the United Nations’s International Seabed Authority has granted contracts for exploration, it is still drafting rules that will govern commercial operations and set limits for environmental damage. The rules are unlikely to be final before 2021…

These sensors will focus on the plume of sediment the collector kicks up. The waters of the CCZ are some of the clearest in the world, and scientists have long feared that mining could spread a vast blanket of silt, hurting life far outside the mining area. Recent experiments, however, suggest most of the silt particles will clump together and fall out within a kilometer or two, Koschinsky says. But a film of finer nanoparticles might spread farther.

Excerpts from Scheme to Mine the Abyss Gets Sea Tria, Science,  Mar. 15, 2019

Turning Oceans into Muck

Oxygen is critical to the health of the planet. It affects the cycles of carbon, nitrogen and other key elements, and is a fundamental requirement for marine life from the seashore to the greatest depths of the ocean. Nevertheless, deoxygenation is worsening in the coastal and open ocean. This is mainly the result of human activities that are increasing global temperatures (CO2-induced warming) and increasing loads of nutrients from agriculture, sewage, and industrial waste, including pollution from power generation from fossil fuels and biomass.

Facts: During the past 50 years the area of low oxygen water in the open ocean has increased by 4.5 million km2. The world’ oceans are now losing approximately  1 gigaton of oxygen each year. The Millennium Ecosystem Assessment released by the UN in 2005 reported that nitrogen containing compounds (e.g. sewage, fertilizers) release into the oceans grew 80 percent from 1860 to 1990.  Increasing temperatures will reduce the capacity of the ocean to hold oxygen in the future. Oxygen deficiency is predicted to worsen in estuaries, coastal areas and oxygen minimum zones in the open ocean. The ocean’s capacity to produce oxygen will be reduced in the future.
Habitat loss is expected to worsen, leading to vertical and horizontal migration of species.

Oxygen deficiency will alter biogeochemical cycles and food webs. Lower oxygen concentrations are projected to result in a decrease in reproductive capacity and biodiversity loss. There are important local decreases of commercially important species and aquaculture production. Harmful Algal Blooms will be exacerbated from nutrients released in bottom waters due to hypoxia (e.g. in the Baltic Sea).Reduced ocean oxygen concentrations will lead to an increase in greenhouse gas emissions, thereby initiating feedbacks on climate change.

Excerpts from UNESCO, Jan. 2018

View Extensive Abstract

Background paper (pdf)

Global Ocean Oxygen Network: Through the participation of high level scientists from across the world, the IOC expert group, the Global Ocean Oxygen Network GO2NE, established in 2016, is committed to providing a global and multidisciplinary view of deoxygenation, with a focus on understanding its multiple aspects and impacts.

Pollution 10,994 Metres Below Sea Level

Not far off the coast of Guam lies the deepest point on Earth’s surface, the Mariana trench. Its floor is 10,994 metres below sea level. If Mount Everest were flipped upside down into it, there would still be more than 2km of clear water between the mountain’s base and the top of the ocean. Such isolation has led many to assume that it and similar seabed trenches will be among the few remaining pristine places on the planet. However, a study led by Alan Jamieson of Newcastle University, in England, has shown that nothing could be further from the truth. As Dr Jamieson and his colleagues report this week in Nature Ecology and Evolution, trenches are actually loaded with pollutants….

No vents are known to exist below 5,000 metres, though, and no sunlight penetrates a trench. The organisms found in them thus depend entirely on dead organic material raining down upon them from far above.  Since these nutrients, having once flowed into a trench, never make their way out again, Dr Jamieson found the notion that trenches have somehow remained untouched by human activities questionable. He suspected that long-lived pollutants such as polychlorinated biphenyls (which were once used widely in electrical equipment) and polybrominated diphenyl ethers (employed in the past as flame retardants) might have made their way into the bodies of organisms living in trenches.

To test this idea out, he and his colleagues sent an unmanned lander to the bottom of the Mariana trench and also to the bottom of the Kermadec trench, near New Zealand. This lander fell to the seabed and spent between eight and 12 hours there, capturing amphipods (a type of crustacean,) using funnel traps baited with mackerel. At the end of its mission it jettisoned some ballast and floated back to the surface with its prey.
When the team looked for pollutants in the captured amphipods, they found that polybrominated diphenyl ethers were indeed present, but at moderate concentrations. Levels of polychlorinated biphenyls, however, were almost off the scale.

Exceprts Oceanic pollution: Entrenched, Economist, Feb. 18, 2017, at 67