Scientists caution against exploitation of deep ocean

A new OSU study looks at how exploiting the ocean's vast resources have put it in peril. 
Credit: Image courtesy of Oregon State University

The world's oceans are vast and deep, yet rapidly advancing technology and the quest for extracting resources from previously unreachable depths is beginning to put the deep seas on the cusp of peril, an international team of scientists warned this week.

In an analysis in Biogeosciences, which is published by the European Geosciences Union, the researchers outline "services" or benefits provided by the deep ocean to society. Yet using these services, now and in the future, is likely to make a significant impact on that habitat and what it ultimately does for society, they point out in their analysis.

"The deep sea is the largest habitat on Earth, it is incredibly important to humans and it is facing a variety of stressors from increased human exploitation to impacts from climate change," said Andrew Thurber, an Oregon State University marine scientist and lead author on the study. "As we embark upon greater exploitation of this vast environment and start thinking about conserving its resources, it is imperative to know what this habitat already does for us."

"Our analysis is an effort to begin to summarize what the deep sea provides to humans because we take it for granted or simply do not know that the deep sea does anything to shape our daily lives," he added. "The truth is that the deep sea affects us, whether we live on the coast or far from the ocean -- and its impact on the globe is pervasive."

The deep sea is important to many critical processes that affect Earth's climate, including acting as a "sink" for greenhouse gases -- helping offset the growing amounts of carbon dioxide emitted into the atmosphere. It also regenerates nutrients through upwelling that fuel the marine food web in productive coastal systems such as the Pacific Northwest of the United States, Chile and others. Increasingly, fishing and mining industries are going deeper and deeper into the oceans to extract natural resources.

"One concern is that many of these areas are in international waters and outside of any national jurisdiction," noted Thurber, an assistant professor (senior research) in Oregon State's College of Earth, Ocean, and Atmospheric Sciences. "Yet the impacts are global, so we need a global effort to begin protecting and managing these key, albeit vast, habitats."

Fishing is an obvious concern, the scientists say. Advances in technology have enabled commercial fisheries to harvest fish at increasing depths -- an average of 62.5 meters deeper every decade, according to fisheries scientists. This raises a variety of potential issues.

"The ability to fish deeper is shifting some fisheries to deeper stocks, and opening up harvests of new species," Thurber said. "In some local cases, individual fisheries are managed aggressively, but due to how slow the majority of the fish grow in the deep, some fish populations are still in decline -- even with the best management practices."

The orange roughy off New Zealand, for instance, is both a model of effective and conservation-based management, yet its populations continue to decline, though at a slower rate than they would have experienced without careful management, Thurber noted.

"We also have to be concerned about pollution that makes its way from our continental shelves into the deep sea," he added. "Before it was 'out of sight, out of mind.' However, some of the pollution can either make it into the fish that we harvest, or harm the fishers that collect the fish for us. It is one of the reasons need to identify how uses of the deep sea in the short term can have long-term consequences. Few things happen fast down there."

Mining is a major threat to the deep sea, the researchers point out in their analysis. In particular, the quest for rare earth and metal resources, which began decades ago, has skyrocketed in recent years because of their increased use in electronics, and because of dwindling or limited distribution of supplies on land. Mining the deep ocean for manganese nodules, for example -- which are rich in nickel -- requires machines that may directly impact large swaths of the seafloor and send up a sediment plume that could potentially affect an even larger area, the scientists note.

These mining resources are not limited to muddy habitats, Thurber pointed out. Massive sulfides present at hydrothermal vents are another resource targeted by mining interests.

"The deep sea has been an active area for oil and gas harvesting for many years," he said, "yet large reservoirs of methane and other potential energy sources remain unexploited. In addition to new energy sources, the potential for novel pharmaceuticals is also vast.

"There are additional threats to these unique habitats, including ocean acidification, warming temperatures and possible changes to ocean circulation through climate change."

The next step, the researchers say, is to attach an economic value to both the services provided by the deep sea -- and the activities that may threaten those services.

"What became clear as we put together this synopsis is that there is vast potential for future resources but we already benefit greatly through this environment," Thurber said. ""What this means is that while the choices to harvest or mine will be decided over the coming decades, it is important to note that the stakeholders of this environment represent the entire world's population."

"The Bible, the Koran, the Torah, and early Greek texts all reference the deep sea," he added. "Maybe it's time for all of us to take a closer look at what it has to offer and decide if and how we protect it."

Source: Oregon State University

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Lead pollution beat explorers to South Pole, persists today

Composite ice core records of lead in Antarctica from 1600 to 2010. The areas shaded in blue and red indicate when lead values were below or above the 410-year average, respectively, highlighting the dramatic change before and after industrialization in the Southern Hemisphere. Credit: Desert Research Institute

Norwegian explorer Roald Amundsen became the first man to reach the South Pole in December 1911. More than 100 years later, an international team of scientists that includes a NASA researcher has proven that air pollution from industrial activities arrived to the planet's southern pole long before any human.

Using data from 16 ice cores collected from widely spaced locations around the Antarctic continent, including the South Pole, a group led by Joe McConnell of the Desert Research Institute (DRI) in Reno, Nevada, created the most accurate and precise reconstruction to date of lead pollution over Earth's southernmost continent. The new record, described in an article published today in the online edition of the Nature Publishing Group's journal Scientific Reports, spans a 410-year period from 1600 to 2010.

"Our new record shows the dramatic impact of industrial activities such as smelting, mining and fossil fuel burning on even the most remote parts of the world," McConnell said.

"It is very clear that industrial lead contamination was pervasive throughout Antarctica by the late 19th century, more than two decades before the first explorers made it to the South Pole," he added. "The idea that Amundsen and Scott were traveling over snow that clearly was contaminated by lead from smelting and mining in Australia, and that lead pollution at that time was nearly as high as any time ever since, is surprising to say the least."

This study included ice cores collected as part of projects funded by the National Science Foundation. Additional ice cores were contributed to the study by international collaborators including the British Antarctic Survey, the Australian Antarctic Division and the Alfred Wegener Institute in Germany.
"The ice cores obtained through international collaborations were critical to the success of this study in that they allowed us to develop records from parts of Antarctica not often visited by U.S.-based scientists," said co-author Tom Neumann of NASA's Goddard Space Flight Center in Greenbelt, Maryland, who participated in a Norway-U.S. traverse that collected several of the cores used in this study. "This included the Law Dome region of East Antarctica and a big section of East Antarctica visited by the Norwegian-United States Scientific Traverse of East Antarctica."

Composite ice core records of lead in Antarctica from 1600 to 2010. The areas shaded in blue and red indicate when lead values were below or above the 410-year average, respectively, highlighting the dramatic change before and after industrialization in the Southern Hemisphere.

All measurements of lead and other chemicals used in this study were made using DRI's continuous ice core analytical system. Low background atmospheric concentrations, together with well-known and often distinct isotopic characteristics (variants of lead with different atomic weights) of industrial sources make lead an ideal tracer of industrial pollution.

"Lead is a toxic heavy metal with strong potential to harm ecosystems," said co-author Paul Vallelonga of the University of Copenhagen. "While concentrations measured in Antarctic ice cores are very low, the records show that atmospheric concentrations and deposition rates increased approximately six-fold in the late 1880s, coincident with the start of mining at Broken Hill in southern Australia and smelting at nearby Port Pirie."

The similar timing and magnitude of changes in lead deposition across Antarctica, as well as the characteristic isotopic signature of Broken Hill lead found throughout the continent, suggest that this single emission source in southern Australia was responsible for the introduction of lead pollution into Antarctica at the end of the 19th century and remains a significant source today, the authors report.

Data from the new ice core array illustrates that Antarctic lead concentrations reached a peak in 1900 and remained high until the late 1920s, with brief declines during the Great Depression and the end of World War II. Concentrations then increased rapidly until 1975 and remained elevated until the 1990s.

Concentrations across the Antarctic continent have since declined, but still are about four-fold higher than before industrialization, despite the phase out of leaded gasoline and other mitigation efforts in many countries in the Southern Hemisphere, the report states.

"Our measurements indicate that approximately 660 tonnes [1.5 million pounds] of industrial lead have been deposited on the snow-covered surface of Antarctic during the past 130 years," McConnell said. "While recent contamination levels are lower, clearly detectable industrial contamination of the Antarctic continent persists today, so we still have a ways to go."

Source: NASA/Goddard Space Flight Center

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Leaf-mining insects destroyed with the dinosaurs, others quickly appeared

This is a mine produced by a micromoth larva on Platanus raynoldski, a sycamore. Credit: Michael Donovan, Penn State

After the asteroid impact at the end of the Cretaceous period that triggered the dinosaurs' extinction and ushered in the Paleocene, leaf-mining insects in the western United States completely disappeared. Only a million years later, at Mexican Hat, in southeastern Montana, fossil leaves show diverse leaf-mining traces from new insects that were not present during the Cretaceous, according to paleontologists.

"Our results indicate both that leaf-mining diversity at Mexican Hat is even higher than previously recognized, and equally importantly, that none of the Mexican Hat mines can be linked back to the local Cretaceous mining fauna," said Michael Donovan, graduate student in geosciences, Penn State.
Insects that eat leaves produce very specific types of damage. One type is from leaf miners -- insect larvae that live in the leaves and tunnel for food, leaving distinctive feeding paths and patterns of droppings.

Donovan, Peter Wilf, professor of geosciences, Penn State, and colleagues looked at 1,073 leaf fossils from Mexican Hat for mines. They compared these with more than 9,000 leaves from the end of the Cretaceous, 65 million years ago, from the Hell Creek Formation in southwestern North Dakota, and with more than 9,000 Paleocene leaves from the Fort Union Formation in North Dakota, Montana and Wyoming. The researchers present their results in today's (July 24) issue of PLOS ONE.

"We decided to focus on leaf miners because they are typically host specific, feeding on only a few plant species each," said Donovan. "Each miner also leaves an identifiable mining pattern."
The researchers found nine different mine-damage types at Mexican Hat attributable to the larvae of moths, wasps and flies, and six of these damage types were unique to the site.

The researchers were unsure whether the high diversity of leaf miners at Mexican Hat compared to other early Paleocene sites, where there is little or no leaf mining, was caused by insects that survived the extinction event in refugia -- areas where organisms persist during adverse conditions -- or were due to range expansions of insects from somewhere else during the early Paleocene.

However, with further study, the researchers found no evidence of the survival of any leaf miners over the Cretaceous-Paleocene boundary, suggesting an even more total collapse of terrestrial food webs than has been recognized previously.

"These results show that the high insect damage diversity at Mexican Hat represents an influx of novel insect herbivores during the early Paleocene and not a refugium for Cretaceous leaf miners," said Wilf. "The new herbivores included a startling diversity for any time period, and especially for the classic post-extinction disaster interval."

Insect extinction across the Cretaceous-Paleocene boundary may have been directly caused by catastrophic conditions after the asteroid impact and by the disappearance of host plant species. While insect herbivores constantly need leaves to survive, plants can remain dormant as seeds in the ground until more auspicious circumstances occur.

The low-diversity flora at Mexican Hat is typical for the area in the early Paleocene, so what caused the high insect damage diversity?

Insect outbreaks are associated with a rapid population increase of a single insect species, so the high diversity of mining damage seen in the Mexican Hat fossils makes the possibility of an outbreak improbable.

The researchers hypothesized that the leaf miners that are seen in the Mexican Hat fossils appeared in that area because of a transient warming event, a number of which occurred during the early Paleocene.

"Previous studies have shown a correlation between temperature and insect damage diversity in the fossil record, possibly caused by evolutionary radiations or range shifts in response to a warmer climate," said Donovan. "Current evidence suggests that insect herbivore extinction decreased with increasing distance from the asteroid impact site in Mexico, so pools of surviving insects would have existed elsewhere that could have provided a source for the insect influx that we observed at Mexican Hat."

Source: Penn State

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Deep sea fish remove one million tons of carbon dioxide every year from UK and Irish waters

This is a deep sea lizard fish (Bathysaurus ferox) from 2000m depth on the continental slope off the west coast of Scotland.
Credit: Dr. Clive Trueman

Deep sea fishes remove and store more than one million tonnes of CO2 from UK and Irish surface waters every year, according to a new study led by the University of Southampton.

This natural carbon capture and storage scheme could store carbon equivalent to £10 million per year in carbon credits.

Fish living in deep waters on the continental slope around the UK play an important role carrying carbon from the surface to the seafloor.

It is assumed that deep water fishes all depend on particles that fall from the surface for their energy. These bottom-living deep water fishes never come to the surface and the carbon in their bodies stays at the seafloor. However, at mid-slope depths there is an abundant and diverse ecosystem where a huge volume of animals make daily vertical migrations to feed at the surface during the night. The animals conducting this migration then transport nutrients from the surface back to the deep.

Researchers from the University of Southampton and Marine Institute, Ireland used novel biochemical tracers to piece together the diets of deep-water fish revealing their role in transferring carbon to the ocean depths.

They found that more than half of all the fishes living on the seafloor get their energy from animals that otherwise go back to the surface, and not from settling particles. These bottom-living fishes therefore become a carbon capture and storage facility. Global peaks in abundance and biomass of animals at mid slope depths occur because this is the depth range where the vertically migrating animals are most easily captured by fishes that live at or near the seafloor.

Lead author, Dr Clive Trueman from the University of Southampton, says: "As fishing, energy extraction and mining extend into deeper waters, these unfamiliar and seldom seen fishes in fact provide a valuable service to all of us. Recognising and valuing these ecosystem services is important when we make decisions about how to exploit deep water habitats for food, energy or mineral resources."

As it is difficult to study animals living under a kilometre or more of water, the researchers measured forms, or isotopes, of carbon and nitrogen, in the muscles of fish caught in deep-water research surveys on the continental slope west of Ireland, at water depths ranging from 500 to 1800m. These were collected on the RV Celtic Explorer, a multi-disciplinary research vessel operated by the Irish Marine Institute.

Small differences in the mass of these isotopes mean that they are processed at slightly different speeds in the body, leading to patterns which can show who eats who in the slope ecosystem. By measuring the isotopes in all of the most common species, the researchers were able to estimate how much carbon is captured and stored by these deep water fish.

The study, which is published in the journal Proceedings of the Royal Society B, was funded by the University of Southampton and the Marine Institute.

Source: University of Southampton.

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