New Insights Into Marine Ecosystems And Fisheries Production
Two of the four marine ecosystems studied in MENU are in the eastern Bering Sea and the coastal region of the northern Gulf of Alaska.
NOAA and Norwegian researchers recently completed a comparative analysis of marine ecosystems in the North Atlantic and North Pacific to see what factors support fisheries production, leading to new insights that could improve fishery management plans and the ecosystems.
Known as MENU, for Marine Ecosystems of Norway and the U.S., the collaborative project involved scientists at the NOAA Fisheries Service’s Northeast Fisheries Science Center and Alaska Fisheries Science Center and colleagues at the Institute of Marine Research in Norway. Results of their analyses, funded by the Norwegian Research Council, were recently published in a special issue of the journal Progress in Oceanography.
Researchers involved in MENU and in other comparative analyses found underlying patterns in the ecosystems that would not have been apparent had only one ecosystem been studied. For example, MENU results revealed that deeper eastern ocean boundary systems, like those off Alaska or in the eastern North Atlantic off Europe, are more strongly influenced by bottom-up mechanisms, known as forcing. These would include broad scale oceanographic systems like the Pacific Decadal Oscillation and the El Nino Southern Oscillation.
Shallower western boundary systems, mainly on continental shelves, like Georges Bank and other areas off the east coast of the U.S. and Canada, are more strongly influenced by top-down processes, such as fisheries exploitation. “Both top-down and bottom-up processes occur in all of these ecosystems, but being able to determine their relative importance is difficult.,” Link said.
The researchers compared marine ecosystems in the northern hemisphere and mostly in high latitudes, ranging from the eastern Bering Sea and Gulf of Alaska in the North Pacific to Georges Bank and the Gulf of Maine, North Sea and the Adriatic Sea off Italy. Other ecosystems studied included the Gulf of St. Lawrence, Scotian Shelf, Newfoundland Shelf, Southern New England, Gulf of Finland, and the Baltic Sea. All of these ecosystems support commercially important fisheries.
Fisheries landings in the ecosystems studied appear to have shifted from groundfish to invertebrates, such as squid, shrimp and scallops. In many, the fish community has changed from one dominated by demersal or bottom-dwelling species to one dominated by pelagic or upper water column species. The researchers note that it is unclear if their findings are true of all marine ecosystems, or just those studied. One of the many questions raised by the comparative analyses is whether similar species in different ecosystems react to environmental conditions in similar ways, or whether the local ecosystems override global factors.
Fisheries production varies widely among ecosystems, and is affected by changing natural and human-induced factors such as climate, pollution and fishing effort. With so many factors involved, Link said scientists need to understand the relative importance of each factor in each ecosystem, something that is difficult to achieve but important for an ecosystem approach to fisheries management and conservation.
Scientists are already undertaking more integrated ecosystem assessments like MENU in the U.S. to build on decades of smaller scale, more focused studies on individual ecosystems. Comparative Analysis of Marine Ecosystem Organization, or CAMEO, is a partnership between NOAA’s Fisheries Service and the National Science Foundation to advance understanding of marine ecological systems using a comparative approach.
Lasers From Space Show Thinning Of Greenland And Antarctic Ice Sheets
New comprehensive maps of Greenland and Antarctica show extent of glacier thinning. (Credit: ICESat, NASA)
The most comprehensive picture of the rapidly thinning glaciers along the coastline of both the Antarctic and Greenland ice sheets has been created using satellite lasers. The findings are an important step forward in the quest to make more accurate predictions for future sea level rise.
Reporting last week in the journal Nature, researchers from British Antarctic Survey and the University of Bristol describe how analysis of millions of NASA satellite measurements from both of these vast ice sheets shows that the most profound ice loss is a result of glaciers speeding up where they flow into the sea.
The authors conclude that this ‘dynamic thinning’ of glaciers now reaches all latitudes in Greenland, has intensified on key Antarctic coastlines, is penetrating far into the ice sheets’ interior and is spreading as ice shelves thin by ocean-driven melt. Ice shelf collapse has triggered particularly strong thinning that has endured for decades.
Lead author Dr Hamish Pritchard from British Antarctic Survey says, “We were surprised to see such a strong pattern of thinning glaciers across such large areas of coastline – it’s widespread and in some cases thinning extends hundreds of kilometres inland. We think that warm ocean currents reaching the coast and melting the glacier front is the most likely cause of faster glacier flow. This kind of ice loss is so poorly understood that it remains the most unpredictable part of future sea level rise.”
The scientists compared the rates of change in elevation of both fast-flowing and slow-flowing ice. In Greenland for example they studied 111 fast-moving glaciers and found 81 thinning at rates twice that of slow-flowing ice at the same altitude. They found that ice loss from many glaciers in both Antarctica and Greenland is greater than the rate of snowfall further inland.
In Antarctica some of the fastest thinning glaciers are in West Antarctica (Amundsen Sea Embayment) where Pine Island Glacier and neighbouring Smith and Thwaites Glacier are thinning by up to 9 metres per year.
Keeping An Eye On The Oceans
Jason 2 satellite, operated by EUMETSAT, whose onboard altimeter scans the world’s oceans, recording global sea level to the nearest cm. (Credit: Image courtesy of EUMETSAT)
During the last ten years, scientists have set up a global observing system to monitor the world’s oceans. The observation system works by combining satellite observations with data from in-water recording devices such as buoys, tide gauges and an array of more than 3000 Argo robots.
Scientists met last week at OceanObs’09 in Venice to see how they can expand the system and, perhaps most importantly, secure it for the long term. OceanObs ‘09 was organized by UNESCO’s Intergovernmental Oceanographic Commission and the European Space Agency (ESA) and was attended by EUMETSAT(European Organisation for the Exploitation of Meteorological Satellites) and over 580 participants from 36 countries. EUMETSAT’s role in ocean observations is to establish, maintain and use systems of operational meteorological satellites, contribute to the operational monitoring of the climate and the oceans – for instance monitoring sea level rise with the Jason 2 altimetry satellite – and establish new ocean-monitoring missions, such as Jason 3.
So how does the ocean observing system operate?
In the water, recording devices such as tide gauges, mooring buoys, and drifting buoys, monitor aspects of the sea such as tides, water temperature, and currents. Over the last 10 years, scientists have also dropped more than 3000 Argo robots into the sea, and these robots are now methodically rising and falling around the world’s oceans recording temperature and salinity profiles, and transmitting this data via satellite back to scientists every ten days. The Argo robots are also joined by pilot-less ocean gliders which bristle with recording instruments and soar and glide through the oceans – sometimes down to depths of 6 km – collecting data.
Joining the gliders, scientists have also sporadically enlisted the help of marine animals, such as elephant seals, by attaching miniature data loggers to record the temperature, salinity and depth conditions they experience on their daily travels. And even ships and ferries are playing a part in monitoring the ocean, as boats on regular passage around the world tow plankton recorders interfaced to sophisticated on-board systems, which are like mini oceanographic laboratories.
All this data from the in-water samplers – so called in situ data – provides the detail on conditions in specific locations, but for the big picture of what is happening in the oceans, scientists are relying on satellites. One of the key tools in understanding issues such as global sea level rise is the Jason 2 satellite, operated by EUMETSAT, whose onboard altimeter scans the world’s oceans, recording global sea level to the nearest cm. When this information is combined with information from satellite-based gravity measurements, tide gauges, Argo floats and other devices, it gives scientists the ability to precisely monitor global sea levels. Satellites are also monitoring a host of other ocean variables – from sea surface temperature, to wind, ocean colour and sea ice cover.
One of the most important features of any ocean observing system is that it must be a long-term system if changes are to be understood in the right context. As an example, satellite monitoring of sea levels began in 1992 with the launch of the TOPEX/Poseidon satellite, which was followed by Jason 1 (2001), Envisat (2002) and more recently Jason 2 (2008), which will be joined in 2012 by Sentinel-3, another satellite carrying altimetry equipment.
Dr Hans Bonekamp, Ocean Mission Scientist at EUMETSAT said: “The long-term datasets on sea levels that the satellite altimeters are collecting are enabling scientists to establish how sea levels have changed in the last two decades and understand the effects of global warming at regional and global levels.”
Making sure the existing ocean observation system, both satellite and in situ data, is sustainable in the long-term is one of the key aims of Oceanobs’09, where the ocean observing community will take stock of progress to date and map out the priorities for the next decade – a task that is unlikely to be easy in the current financial climate.
But the benefits that an operational ocean observing system will bring, are an extremely strong justification: the system is already providing data for the International Panel on Climate Change assessments, and it will also provide better data for maritime security, oil spill prevention, management of marine resources, marine meteorology, seasonal and long term weather forecasting, coastal activities, and monitoring of water quality.
New Robot Monitors Deep-sea Ecosystems
During July 2009, the Benthic Rover traveled across the seafloor while hooked up to the Monterey Accelerated Research System ocean observatory. This allowed researchers to control the vehiclein real time. (Credit:MBARI)
Like the robotic rovers Spirit and Opportunity, which wheeled tirelessly across the dusty surface of Mars, a new robot spent most of July traveling across the muddy ocean bottom, about 40 kilometres (25 miles) off the California coast. This robot, the Benthic Rover, has been providing scientists with an entirely new view of life on the deep seafloor. It will also give scientists a way to document the effects of climate change on the deep sea. The Rover is the result of four years of hard work by a team of engineers and scientists led by MBARI project engineer Alana Sherman and marine biologist Ken Smith.
About the size and weight of a small compact car, the Benthic Rover moves very slowly across the seafloor, taking photographs of the animals and sediment in its path. Every three to five meters (10 to 16 feet) the Rover stops and makes a series of measurements on the community of organisms living in the seafloor sediment. These measurements will help scientists understand one of the ongoing mysteries of the ocean—how animals on the deep seafloor find enough food to survive.
Most life in the deep sea feeds on particles of organic debris, known as “marine snow”, which drift slowly down from the sunlit surface layers of the ocean. But even after decades of research, marine biologists have not been able to figure out how the small amount of nutrition in marine snow can support the large numbers of organisms that live on and in seafloor sediment.
The Benthic Rover carries two experimental chambers called “benthic respirometers” that are inserted a few centimetres into the seafloor to measure how much oxygen is being consumed by the community of organisms within the sediment. This, in turn, allows scientists to calculate how much food the organisms are consuming. At the same time, optical sensors on the Rover scan the seafloor to measure how much food has arrived recently from the surface waters.
MBARI researchers have been working on the Benthic Rover since 2005, overcoming many challenges along the way. The most obvious challenge was designing the Rover to survive at depths where the pressure of seawater is about 420 kilograms per square meter (6,000 pounds per square inch). To withstand this pressure, the engineers had to shield the Rover’s electronics and batteries inside custom-made titanium pressure spheres.
To keep the Rover from sinking into the soft seafloor mud, the engineers outfitted the vehicle with large yellow blocks of buoyant foam that will not collapse under extreme pressure. This foam gives the Rover, which weighs about 1,400 kilograms (3,000 pounds) in air, a weight of only about 45 kilograms (100 pounds) in seawater.
Other engineering challenges required less high-tech solutions. In constructing the Rover’s tractor-like treads, the design team used a decidedly low-tech material—commercial conveyor belts. After watching the Benthic Rover on the seafloor using MBARI’s remotely operated vehicles (ROVs), however, the researchers discovered that the belts were picking up mud and depositing it in front of the vehicle, where it was contaminating the scientific measurements. In response, the team came up with a low-tech but effective solution: they removed the heads from two push brooms and bolted them onto the vehicle so that the stiff bristles would clean off the treads as they rotated.
The team also discovered that whenever the Rover moved, it stirred up a cloud of sediment like the cloud of dust that follows the character “Pig-Pen” in the Charlie Brown comic strip. This mud could have affected the Rover’s measurements. To reduce this risk, the engineers programmed the Rover to move very, very slowly—about one meter (3 feet) a minute. The Rover is also programmed to sense the direction of the prevailing current, and only move in an up-current direction, so that any stirred-up mud will be carried away from the front of the vehicle.
In its basic configuration, the Benthic Rover is designed to operate on batteries, without any human input. However, during its month-long journey this summer, the Rover was connected by a long extension cord to a newly-completed underwater observatory. This observatory, known as the Monterey Accelerated Research System (MARS), provided power for the robot, as well as a high-speed data link back to shore.
According to Sherman, “Hooking up the Rover to the observatory opened up a whole new world of interactivity. Usually when we deploy the Rover, we have little or no communication with the vehicle. We drop it overboard, cross our fingers, and hope that it works.” In this case, however, the observatory connection allowed MBARI researchers to fine tune the Rover’s performance and view its data, videos, and still images in real time. Sherman recalls, “One weekend I was at home, with my laptop on the kitchen table, controlling the vehicle and watching the live video from 900 meters below the surface of Monterey Bay. It was amazing!”
Later this fall, the Rover will be sent back down to the undersea observatory site in Monterey Bay for a two-month deployment. Next year the team hopes to take the Rover out to a site about 220 km (140 miles) offshore of Central California. They will let the Rover sink 4,000 meters down to the seafloor, where it will make measurements on its own for six months. The team would also like to take the Rover to Antarctica, to study the unique seafloor ecosystems there. The Rover may also be hooked up to a proposed deep-water observatory several hundred miles off the coast of Washington state.
In addition to answering some key questions of oceanography, the Benthic Rover will help researchers study the effects of climate change in the ocean. As the Earth’s atmosphere and oceans become warmer, even life in the deep sea will be affected. The Benthic Rover, and its possible successors, will help researchers understand how deep-sea communities are changing over time.
Just as the rovers Spirit and Opportunity gave us dramatic new perspectives on the planet Mars, so the Benthic Rover is giving researchers new perspectives of a dark world that is in some ways more mysterious than the surface of the distant red planet.
Satellites And Submarines Give The Skinny On Sea Ice Thickness
Patterns of average winter ice thickness from February to March show thicker ice in 1988 (above), compared to thinner ice averaged from 2003-2008 (below). (Credit: Ronald Kwok/NASA)
This summer, a group of scientists and students — as well as a Canadian senator, a writer, and a filmmaker — set out from Resolute Bay, Canada, on the icebreaker Louis S. St-Laurent. They were headed through the Northwest Passage, but instead of opening shipping lanes in the ice, they had gathered to open up new lines of thinking on Arctic science.Among the participants in the shipboard workshop (hosted by Fisheries and Oceans Canada) was Ron Kwok of NASA’s Jet Propulsion Laboratory in Pasadena, Calif. Kwok has long provided checkups on the health of Arctic sea ice — the frozen sea water floating within the Arctic Ocean basin. He also knows that some important clues about ice changes can’t be seen from a ship.
Extending the Record
While satellites provide accurate and expansive coverage of ice in the Arctic Ocean, the records are relatively new. Satellites have only monitored sea ice extent since 1973. NASA’s Ice, Cloud, and land Elevation Satellite (ICESat) has been on the task since 2003, allowing researchers to estimate ice thickness as well. To extend the record, Kwok and Drew Rothrock of the University of Washington, Seattle, recently combined the high spatial coverage from satellites with a longer record from Cold War submarines to piece together a history of ice thickness that spans close to 50 years.
Analysis of the new record shows that since a peak in 1980, sea ice thickness has declined 53 percent. “It’s an astonishing number,” Kwok said. The study, published online in Geophysical Research Letters, shows that the current thinning of Arctic sea ice has actually been going on for quite some time.
“A fantastic change is happening on Earth — it’s truly one of the biggest changes in environmental conditions on Earth since the end of the ice age,” said Tom Wagner, cryosphere program manager at NASA Headquarters. “It’s not an easy thing to observe, let alone predict, what might happen next.”
Sea ice influences the Arctic’s local weather, climate, and ecosystems. It also affects global climate. As sea ice melts, there is less white surface area to reflect sunlight into space. Sunlight is instead absorbed by the ocean and land, raising the overall temperature and fueling further melting. Ice loss puts a damper on the Arctic air conditioner, disrupting global atmospheric and ocean circulation.
To better identify what these changes mean for the future, scientists need a long-term look at past ice behavior. Each year, Arctic ice undergoes changes brought about by the seasons, melting in the summer warmth and refreezing in the cold, dark winter. A single extreme melt or freeze season may be the result of any number of seasonal factors, from storminess to the Arctic Oscillation (variations in atmospheric circulation over the polar regions that occur on time scales from weeks to decades).
But climate is not the same as weather. Climate fluctuates subtly over decades and centuries, while weather changes from day to day and by greater extremes.
“We need to understand the long-term trends, rather than the short-term trends that could be easily biased by short-term changes,” Kwok said. “Long-term trends are more reliable indicators of how sea ice is changing with the global and regional climate.” That’s why a long-term series of data was necessary. “Even decadal changes can be cyclical, but this decline for more than three decades does not appear to be cyclical,” Rothrock said.
All the Ice Counts
Arctic sea ice records have become increasingly comprehensive since the latter half of the 20th century, with records of sea ice anomalies viewed from satellites, ships, and ice charts collected by various countries. Most of that record, kept in the United States by the National Snow and Ice Data Center at the University of Colorado, Boulder, describes the areal extent of sea ice.
But a complete picture of sea ice requires an additional, vertical measurement: thickness. Melting affects more than just ice area; it can also impact ice above and below the waterline. By combining thickness and extent measurements, scientists can better understand how the Arctic ice cover is changing.
Kwok and other researchers used ICESat’s Geoscience Laser Altimeter System to estimate the height of sea ice above the ocean surface. Knowing the height, scientists can estimate how much ice is below the surface.
Buoyancy causes a fraction (about 10 percent) of sea ice to stick out above the sea surface. By knowing the density of the ice and applying “Archimedes’ Principle” — an object immersed in a fluid is buoyed by a force equal to the weight of the fluid displaced by the object — and accounting for the accumulation of snowfall, the total thickness of the ice can be calculated.
In 2008, Kwok and colleagues used ICESat to produce an ice thickness map over the entire Arctic basin. Then in July 2009, Kwok and colleagues reported that multiyear ‘permanent’ ice in the Arctic Ocean has thinned by more than 40 percent since 2004. For the first time, thin seasonal ice has overtaken thick older ice as the dominant type.
Submarines and Satellites
To put the recent decline in context, Kwok and Rothrock examined the recent five-year record from ICESat in the context of the longer history of ice thickness observed by U.S. Navy submarines. During the Cold War, the submarines collected upward-looking sonar profiles, for navigation and defense, and converted the information into an estimate of ice thickness. Scientists also gathered profiles during a five-year collaboration between the Navy and academic researchers called the Scientific Ice Expeditions, or “SCICEX,” of which Rothrock was a participant. In total, declassified submarine data span nearly five decades—from 1958 to 2000—and cover a study area of more than 1 million square miles, or close to 40 percent of the Arctic Ocean.
Kwok and Rothrock compared the submarine data with the newer ICESat data from the same study area and spanning 2003 to 2007. The combined record shows that ice thickness in winter of 1980 averaged 3.64 meters. By the end of 2007, the average was 1.89 meters.
“The dramatic decrease in multiyear ice coverage is quite remarkable and explains to a large degree the decrease in total ice area and volume,” Kwok said.
Rothrock, who has worked extensively with the submarine data, agrees. “This paper shows one of the most compelling signals of global warming with one of the greatest and fastest regional environmental impacts.”
Ice Through Human Eyes
While it is critical to keep monitoring the Arctic with satellites and aircraft, Kwok believes there is also a benefit in physically standing in a place and seeing the changes through human eyes—particularly for non-scientists, who do not keep a close watch on sea ice.
The August 2009 workshop in the Northwest Passage brought together an eclectic group of politicians, artists, and scientists to see the ice firsthand. The challenge was to see the problem of a changing Arctic environment from a variety of scientific, political, cultural and human perspectives and to discuss the future of collaborative study in the Arctic. The science of sea ice has implications for people’s livelihoods, for long-established ecosystems, and for opening a new part of the world to exploration and exploitation.
The workshop participants now take their experiences and observations back to warmer climates, where there is sometimes less urgency about ice retreat.
“Sea ice is about more than just hard science; it’s a geopolitical and human issue,” Kwok noted. “There is a big personal impact when you get away from your desk and see it in person.”
Warming Of Arctic Current Over 30 Years Triggers Release Of Methane Gas
Researchers in Germany have found that more than 250 plumes of bubbles of methane gas are rising from the seabed of the West Spitsbergen continental margin in the Arctic, in a depth range of 150 to 400 metres. (Credit: Image courtesy of National Oceanography Centre, Southampton)
The warming of an Arctic current over the last 30 years has triggered the release of methane, a potent greenhouse gas, from methane hydrate stored in the sediment beneath the seabed.
Scientists at the National Oceanography Centre Southampton working in collaboration with researchers from the University of Birmingham, Royal Holloway London and IFM-Geomar in Germany have found that more than 250 plumes of bubbles of methane gas are rising from the seabed of the West Spitsbergen continental margin in the Arctic, in a depth range of 150 to 400 metres.
Methane released from gas hydrate in submarine sediments has been identified in the past as an agent of climate change. The likelihood of methane being released in this way has been widely predicted.
The data were collected from the royal research ship RRS James Clark Ross, as part of the Natural Environment Research Council’s International Polar Year Initiative. The bubble plumes were detected using sonar and then sampled with a water-bottle sampling system over a range of depths.
The results indicate that the warming of the northward-flowing West Spitsbergen current by 1° over the last thirty years has caused the release of methane by breaking down methane hydrate in the sediment beneath the seabed. Professor Tim Minshull, Head of the University of Southampton’s School of Ocean and Earth Science based at that the National Oceanography Centre, says: “Our survey was designed to work out how much methane might be released by future ocean warming; we did not expect to discover such strong evidence that this process has already started.”
Methane hydrate is an ice-like substance composed of water and methane which is stable in conditions of high pressure and low temperature. At present, methane hydrate is stable at water depths greater than 400 metres in the ocean off Spitsbergen. However, thirty years ago it was stable at water depths as shallow as 360 metres.
This is the first time that such behaviour in response to climate change has been observed in the modern period.
While most of the methane currently released from the seabed is dissolved in the seawater before it reaches the atmosphere, methane seeps are episodic and unpredictable and periods of more vigorous outflow of methane into the atmosphere are possible. Furthermore, methane dissolved in the seawater contributes to ocean acidification.
Graham Westbrook Professor of Geophysics at the University of Birmingham, warns: “If this process becomes widespread along Arctic continental margins, tens of megatonnes of methane per year – equivalent to 5-10% of the total amount released globally by natural sources, could be released into the ocean.”
The team is carrying out further investigations of the plumes; in particular they are keen to observe the behaviour of these gas seeps over time.
Scientists Discover Bioluminescent ‘Green Bombers’ From The Deep Sea
In the latest proof that the oceans continue to offer remarkable findings and much of their vastness remains to be explored, scientists at Scripps Institution of Oceanography at UC San Diego and their colleagues have discovered a unique group of worms that live in the depths of the ocean.
The discoveries feature worms—nicknamed “green bombers”—that can release body parts that produce a brilliant green bioluminescent display. The discovery is described in the August 21 issue of the journal Science and is led by Karen Osborn of Scripps Oceanography.
The researchers introduce seven previously unknown species of swimming worms in the annelid phylum ranging from 18 to 93 millimeters (.7 to 3.6 inches) in length. They were discovered by the scientists using remotely operated vehicles at depths between 1,800 and 3,700 meters (5,900 and 12,140 feet). The first species described in the paper has been given the scientific name Swima bombiviridis, referring to its swimming ability and the green bombs.
Osborn says one key aspect of the discoveries is that the newly found worms are not rare. Opportunities to witness such animals and collect and study them, however, have been extremely rare.
“We found a whole new group of fairly large, extraordinary animals that we never knew anything about before,” said Osborn, a post-doctoral researcher in the Marine Biology Research Division at Scripps. “These are not rare animals. Often when we see them they number in the hundreds. What’s unique is that their habitat is really hard to sample.”
Largely transparent except for the gut area, the worms propel themselves with fans of long bristles that form swimming paddles.
“The depths between 1,000 and 4,000 meters (3,280 and 13,120 feet) form the biggest habitat on Earth and also the least explored,” said Scripps Professor Greg Rouse, a coauthor of the paper and curator of Scripps Benthic Invertebrate Collection. “With fairly limited time on submersible vehicles, mainly off California, we’ve picked up seven new species. It goes to show that we have much more exploration ahead and who knows what else we’ll discover?”
Each of the species features a variety of elaborate head appendages. Five of them are equipped with luminescent structures, the “bombs,” that are fluid-filled spheres that suddenly burst into light when released by the animal, glowing intensely for several seconds before slowly fading.
Due to the bright lights of the submersible, scientists were not able to witness bomb-casting in the worm’s natural habitat, but rather on ships after the animals were captured. While the scientists speculate that the bombs are used as a defensive mechanism against potential predators, more studies are needed to fully understand the process.
Rouse says the green bombers in the newly discovered clade, (a common ancestor and all its descendant organisms), are fascinating from an evolutionary standpoint. Looking closely at their relatives that live on the seafloor, it appears the bombs were once gills that evolutionarily transformed over time.
“The relatives have gills that appear to be in exactly the same places as the bombs,” said Rouse. “The gills can fall off very easily so there’s a similarity of being detachable, but for some reason the gills have transformed to become these glowing little detachable spheres.”
Osborn continues to probe many of the various adaptations the worms have made since evolving into swimming species. The challenges faced by animals living in a three-dimensional open water habitat above the seafloor are very different than those faced by animals living on the seafloor. These include locating new food sources, finding ways to maintain optimal depth and grappling with predators that come from various directions.
“I’m interested in how animals have evolved in the water column,” said Osborn. “These worms are great examples. How does a worm transform into a wonderful glowing animal?”
In addition to Osborn and Rouse, coauthors of the Science paper include Steven Haddock of the Monterey Bay Aquarium Research Institute, Fredrik Pleijel of the University of Göteborg in Sweden and Laurence Madin of the Woods Hole Oceanographic Institution (WHOI).
The research was supported by Scripps Institution of Oceanography, a University of California President’s Postdoctoral Fellowship, the David and Lucile Packard Foundation, NOAA, WHOI and the National Geographic Society.
Humans Damaging The Oceans In Profound Ways
There is mounting evidence that human activity is changing the world’s oceans in profound and damaging ways.
Man-made carbon emissions “are affecting marine biological processes from genes to ecosystems over scales from rock pools to ocean basins, impacting ecosystem services and threatening human food security,” the study by Professor Mike Kingsford of the ARC Centre of Excellence for Coral Reef Studies and James Cook University and colleague Dr Andrew Brierley of St Andrews University, Scotland, warns.
A new review, published in the latest issue of the journal Current Biology, says that rates of physical change in the oceans are unprecedented in some cases, and change in ocean life is likely to be equally quick.
These include changes in the areas fish and other sea species can inhabit, invasions, extinctions and major shifts in marine ecosystems. “In the past, the boundaries between geological ages are marked by sudden losses of species. We may now be entering a new age in which climate change and other human-caused factors are the major threats for the oceans and their life,” Andrew and Mike say.
“Given how essential the oceans are to how our entire planet functions it is vital that we intervene before more tipping points are passed and the oceans go down the sort of spiral of decline we have seen in the world’s tropical forests and rangelands, for example.”
Man-made carbon emissions are now above the ‘worst case’ scenario envisioned by the Intergovernmental Panel on Climate Change (IPCC), causing the most rapid global warming seen since the peak of the last Ice Age. At the same time the carbon is acidifying the oceans, with harmful consequences for certain plankton and shellfish.
“At current emission rates it is possible we will pass the critical level of 450 parts per million CO2 in the atmosphere by 2040. That’s the level when, it is generally agreed, global climate change may become catastrophic and irreversible,” they add. “At that point we can expect to see the loss of most of our coral reefs and the arctic seas.”
“The climate is currently warming faster than the worst case known from the fossil record, about 56 million years ago, when temperatures rose about 6 degrees over 1000 years. If emissions continue it is not unreasonable to expect warming of 5.5 degrees by the end of this century.”
Scientists expect ocean oxygen levels to decline by about six per cent for every one degree increase in temperature and areas in the sea which are low in oxygen to grow by at least 50 per cent. This has major implications for the world’s most productive fishing waters in the cool temperate regions. The seas provide a major source of humanity’s protein food – and any loss in fisheries production will have a direct impact on us, he adds.
Besides the changes induced by carbon emissions, the oceans are also under assault from increased UV exposure, toxic pollution, alien species and disease. The combined effect is to weaken the ability of many species to withstand these multiple stresses. Another risk is that warming will unlock vast reserves of frozen methane in the seabed, triggering uncontrollable, runaway global warming.
“In the face of such terrifying changes even large scale interventions such as establishment of very large networks of Marine Protected Areas are unlikely to be effective,” Mike cautions. “On a global scale, an immediate reduction in CO2 emissions is essential to minimize future human-induced climate change.”
The oceans can also play a role in the proposed solution of eliminating carbon emissions, by producing clean energy from wind, wave and tide, by triggering phytoplankton blooms with fertilisers to absorb more carbon from the atmosphere, or using the seabed to store CO2.
New Hull Coatings for Ships Cut Fuel Use, Protect Environment
New hull coatings being developed by the United States Office of Naval Research (ONR) are showing promise in reducing the build-up of marine crustaceans – namely barnacles – on ships´ hulls, optimizing vessel performance and dramatically reducing fuel costs.
The Naval Surface Warfare Center estimates that biofouling reduces vessel speed by up to 10 percent. Vessels can require as much as a 40 percent increase in fuel consumption to counter the added drag. For the Navy, that translates into roughly $1 billion dollars annually in extra fuel costs and maintenance to keep its ships free of barnacles, algae and other debris.
For the coating, researchers are currently looking at two non-toxic substances. The first one combines texture and antimicrobial properties to repel microorganisms. The other, a mixed-charge compound, would prohibit proteins and cells from binding to a ship’s exterior.
Marine growth adds weight and increases drag reducing a vessel´s fuel efficiency – not good in an era of soaring fuel costs. This increases fuel consumption and green house gas emissions. ONR-sponsored biofouling prevention coatings provide an environmentally safe alternative for protecting naval ship hulls, which could also benefit the commercial shipping industry.
High-performance naval warships and submarines rely on critical design factors such as top speed, acceleration and hydroacoustic stealth. Previous biofouling prevention methods used toxic coatings, or biocides, to clear barnacle colonies from the ship exteriors. Although effective in the short-term, biocides exact a heavy environmental burden.
By studying the environment, researchers are learning from nature how it beats the “crusty fouler” naturally.
Woods Hole Oceanographic Institution Vehicle “Nereus” Reaches Deepest Part of the Ocean
Nereus was tested in the waters off the WHOI dock in April before being sent to the Challenger Deep in the Pacific's Mariana Trench. At 11,000 meters — more than a mile deeper than Mount Everest is high — Challenger Deep is arguably one of the most remote locations on Earth. (Photo by: Tom Kleindinst, Woods Hole Oceanographic Institution )
Nereus was tested in the waters off the WHOI dock in April before being sent to the Challenger Deep in the Pacific’s Mariana Trench.
At 11,000 meters — more than a mile deeper than Mount Everest is high — Challenger Deep is arguably one of the most remote locations on Earth.
(Photo by: Tom Kleindinst, Woods Hole Oceanographic Institution )
A new type of deep-sea robotic vehicle called Nereus has successfully reached the deepest part of the world’s ocean. The dive to 10,902 meters (6.8 miles) occurred on May 31, 2009, at the Challenger Deep in the Mariana Trench in the western Pacific Ocean. The dive makes Nereus the world’s deepest-diving vehicle and the first vehicle to explore the Mariana Trench since 1998.
Nereus’s unique hybrid-vehicle design makes it ideally suited to explore the ocean’s last frontiers. The unmanned vehicle is remotely operated by pilots aboard a surface ship via a lightweight, micro-thin, fiber-optic tether that allows Nereus to dive deep and be highly manoeuvrable. Nereus can also be switched into a free-swimming, autonomous vehicle.
“The Mariana Trench is the deepest known part of the ocean. Reaching such extreme depths represents the pinnacle of technical challenges and the team is very pleased Nereus has been successful in reaching the very bottom to return imagery and samples from such a hostile world. With a robot like Nereus we can now explore virtually anywhere in the ocean,” said Andy Bowen, the project manager and principal developer of Nereus at the Woods Hole Oceanographic Institution (WHOI). “The trenches are virtually unexplored, and I am absolutely certain Nereus will enable new discoveries. I believe it marks the start of a new era in ocean exploration.”
“Much of the ocean’s depth remains unexplored. Ocean scientists now have a unique tool to gather images, data, and samples from everywhere in the oceans,” said Julie Morris, director of the National Science Foundation (NSF) Ocean Sciences Division, the principal sponsor of the $8 million project. “With its innovative technology, Nereus allows us to study and understand the ocean’s deepest regions, previously inaccessible. We’re very pleased with the success of these sea trials.” Aside from NSF, funds for Nereus have been provided by the Office of Naval Research, the National Oceanic and Atmospheric Administration, the Russell Family Foundation, and WHOI.
The Mariana Trench forms the boundary between two tectonic plates, where the Pacific Plate is subducted beneath the small Mariana Plate. It is part of the Pacific Ring of Fire, a 40,000-kilometer (25,000-mile) area where most of the world’s volcanic eruptions and earthquakes occur. At 11,000 meters, its depth is approximately the same as the cruising altitude of a commercial airliner.
To reach the trench, Nereus dove nearly twice as deep as research submarines are capable of and had to withstand pressures 1,000 times that at Earth’s surface—crushing forces similar to those on the surface of Venus. Only two other vehicles have succeeded in reaching the trench: the U.S. Navy-built bathyscaphe Trieste, which carried Jacques Piccard and Don Walsh there in 1960, and the Japanese-built robot Kaiko, which made three unmanned expeditions to the trench between 1995 and 1998. Neither of these is presently available to the scientific community. Trieste was retired in 1966, and Kaiko was lost at sea in 2003.
The Nereus engineering team knew that, to reach these depths, a tethered robot using traditional technologies would be prohibitively expensive to build and operate. So they used unique technologies and innovative methods to strike a balance between size, weight, materials cost, and functionality.
Building on previous experience developing tethered robots and autonomous underwater vehicles (AUVs) at WHOI and elsewhere, the team fused the two approaches together to develop a hybrid vehicle that could fly like an aircraft to survey and map broad areas and then be converted at sea into a tethered, remotely operated vehicle (ROV) that can hover like a helicopter near the seafloor to conduct experiments or to collect biological or rock samples under real-time human control. The present trials of Nereus are being conducted in this tethered, ROV mode of operation.
The tethering system presented one of the greatest challenges in developing a cost-effective ROV capable of reaching these depths. Traditional robotic systems use a steel-reinforced cables containing copper wires to power the vehicle and optical fibers to enable information to be passed between the ship and the vehicle. If such a cable were used to reach the seafloor in the Mariana Trench, it would snap under its own weight.
To solve this challenge, the Nereus team adapted fiber-optic technology developed by the Navy’s Space and Naval Warfare Systems Center Pacific (SSC Pacific) to carry real-time video and other data between the Nereus and the surface crew. Similar in diameter to a human hair and with a breaking strength of only 4 kilograms (8.8 pounds), the tether is composed of glass fiber core with a very thin protective jacket of plastic. Nereus brings approximately 40 kilometers (25 miles) of cable in two canisters the size of large coffee cans that spool out the fiber as needed. By using this very slender tether instead of a large cable, the team was able to decrease the size, weight, complexity, and cost of the vehicle.
On its dive to the Challenger Deep, Nereus spent over 10 hours on the bottom, sending live video back to the ship through its fiber-optic tether and collecting geological and biological samples with its manipulator arm, and placed a marker on the seafloor signed by those onboard the surface ship. “The samples collected by the vehicle include sediment from the subducting and overriding tectonic plates that meet at the trench and, for the first time, rocks from deep exposures of the Earth’s crust close to mantle depths south of the Challenger Deep,” said Fryer. “We will know the full story once the shore-based analyses are completed back the laboratory this summer and integrate them with the new mapping data to tell a story of plate collision in greater detail than ever before accomplished in the worlds oceans.”
“These and future discoveries by Nereus will be the result of its versatility and agility – it’s like no other deep submergence vehicle,” said Shank. “It allows vast areas to be explored with great effectiveness. Our true achievement is not just getting to the deepest point in our ocean, but unleashing a capability that now enables deep exploration, unencumbered by a heavy tether and surface ship, to scientifically investigate some of the most dynamically-rich geological and biological systems on Earth.”
The Woods Hole Oceanographic Institution is a private, independent organization in Falmouth, Mass., dedicated to marine research, engineering, and higher education. Established in 1930 on a recommendation from the National Academy of Sciences, its primary mission is to understand the oceans and their interaction with the Earth as a whole, and to communicate a basic understanding of the oceans’ role in the changing global environment.
