Tag Archives: deep sea

Deep Sea fish

Deep sea fish remove a million tonnes of CO2 every year from UK and Irish waters

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 has been 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 (between 500 and 1800 m) 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.”

The study is published in the journal Proceedings of the Royal Society B.

Further Reading:
Proc. R. Soc. B 22 July 2014 vol. 281 no. 1787 20140669

Photo credit: Citron, CC BY-SA 3.0

Deep-Sea Study reveals cause of 2011 Tsunami

Scientists shake hands  when they  found the ocean-floor fault in the drill core when investigating the cause of the 2011 tsunamiThe devastating tsunami that struck Japan’s Tohoku region in March 2011 was touched off by a submarine earthquake far more massive than anything geologists had expected in that zone.

Now, a team of scientists has published a set of studies in the journal Science that shed light on what caused the dramatic displacement of the seafloor off the northeastern coast of Japan. The findings also suggest that other zones in the northwest Pacific may be at risk of similar huge earthquakes.

The fault is very thin – just 5 m thick – and filled with extremely slippery clay which can act as a lubricant.

The tsunami caused devastation in Japan and resulted in nuclear meltdown at Fukushima. Some 19,300 people died in the tragedy.

Professor Christie Rowe, of McGill’s Department of Earth & Planetary Sciences, was one of 27 scientists from 10 countries who participated in a 50-day expedition in 2012 on the Japanese drilling vessel Chikyu, to find why the earthquake was so extreme. The team drilled three holes in the Japan Trench area to study the rupture zone of the earthquake, a fault in the ocean floor where two of the Earth’s major tectonic plates meet, deep beneath the surface of the Pacific Ocean.

The joint where the Pacific and North American plates meet forms what is known as a “subduction” zone, with the North American plate riding over the edge of the Pacific plate. The latter plate bends and plunges deep into the earth, forming the Japan Trench.

The conventional view among geologists has been that deep beneath the seafloor, where rocks are strong, movements of the plates can generate a lot of elastic rebound. Closer to the surface of the seafloor, where rocks are softer and less compressed, this rebound effect was thought to taper off.

Until 2011, the largest displacement of plates ever recorded along a fault occurred in 1960 off the coast of Chile, where a powerful earthquake displaced the seafloor plates by an average of 20 metres. In the Tohoku earthquake, the slip amounted to 30 to 50 metres – and the slip actually grew bigger as the subterranean rupture approached the seafloor. This runaway rupture thrust up the seafloor, touching off the horrifying tsunami.

The results of last year’s drilling by the Chikyu expedition, outlined in the Science papers published Dec. 6, reveal several factors that help account for this unexpectedly violent slip between the two tectonic plates.

For one thing, the fault, itself, is very thin – less than five metres thick in the area sampled. “To our knowledge, it’s the thinnest plate boundary on Earth,” Rowe says. By contrast, California’s San Andreas fault is several kilometres thick in places.

The scientists also discovered that the clay deposits that fill the narrow fault are made of extremely fine sediment. “It’s the slipperiest clay you can imagine,” says Rowe. “If you rub it between your fingers, it feels like a lubricant.”

The discovery of this unusual clay in the Tohoku slip zone suggests that other subduction zones in the northwest Pacific where this type of clay is present – from Russia’s Kamchatka peninsula to the Aleutian Islands – may be capable of generating similar, huge earthquakes, Rowe adds.

To conduct the studies, the scientists used specially designed deep-water drilling equipment that enabled them to drill more than 800 metres beneath the sea floor, in an area where the water is around 6,900 metres deep. No hole had ever before been drilled that deep in an area of similar water depth. At those extraordinary depths, it took six hours from the time the drill pulled core samples from the fault until it reached the ship.

During night shifts on deck, Rowe was in charge of deciding which sections of drill core would go to geochemists for water sampling, and which would go to geologists for studies of the sediment and deformation structures. “We X-rayed the core as soon as it came on board, so the geochemists could get their water sample before oxygen was able to penetrate inside the pores of the sediment.”

Further Reading:
Japan Trench Fast Drilling Project

Scientists unveil first maps of deep sea corals

deep sea coralsScientists have unveiled the first-ever set of maps detailing where vulnerable deep-sea habitats, including cold water coral reefs and sponge fields, are likely to be found in the North East Atlantic.

The Bristish team used complex modelling techniques to chart a surface area more than three times the size of the UK’s terrestrial boundaries. Importantly, the maps let researchers determine the proportion of coral reefs and sponge beds that would be covered by the proposed network of Marine Protected Areas (MPAs). The maps show that if all of the current proposed Marine Protected Areas are put in place, 30% of the UK’s deep sea coral reefs will be protected – but just 3% of the sponge fields.

At the World Summit on Sustainable Development in 2002 world leaders committed themselves to creating representative networks of MPAs by 2012.

Dr Kerry Howell, project lead and member of the Plymouth University Marine Institute, says the maps are important evidence with which to present to present to policy-makers. She said: “Many people think of the deep-sea as the last great wilderness on earth, but we are increasingly relying on it for food from fishing, energy from oil and gas, and now we are even mining it for precious metals like gold, copper and zinc.

Dr Howell continued: “We have better maps of the surface of Mars than some parts of our deep-sea – but this marks the dawning of a new era in deep-sea mapping, and our first steps into understanding the deep-sea realm as never before.”

Cold-water coral reefs, like their shallow water relatives, provide a source of food and shelter to many species – but unlike them, do not require light in order to grow. The UK has extensive cold-water coral reefs in its waters, and all but one are found in the deep-sea, below 200m in depth.

Deep-sea sponge fields are similarly important in the role they play in the ecosystem. They live on soft, sandy or muddy sediments at a depth of around 1,300m, in total darkness, extreme cold and under crushing pressures. Individual sponges are about the size of a tennis ball, but they live at such densities that they form a unique habitat.

Rebecca Ross, a researcher at Plymouth University who produced the maps, said “Although the mathematical process is complicated, the principle of the technique is quite straightforward: we know the conditions that we find a reef under, so we can use mathematical models to find other places that have the right combinations of conditions for reefs to grow.

“The use of predictive modelling is an important step forward in deep-sea exploration because the deep-sea is so vast and so expensive to visit that we cannot possibly hope to survey it all.”

The study is published in the scientific journal Diversity and Distributions.

What are Marine Protected Areas?

Marine protected areas describes a wide range of marine areas which have some level of restriction to protect living, non-living, cultural, and/or historic resources. The UK has signed up to international agreements such as the Convention on Biological Diversity and the OSPAR Convention, that aim to establish an ‘ecologically coherent network of Marine Protected Areas (MPAs)’ by 2012.

Further Reading

Ross, R. E. and Howell, K. L. (2012), Use of predictive habitat modelling to assess the distribution and extent of the current protection of ‘listed’ deep-sea habitats. Diversity and Distributions. doi: 10.1111/ddi.12010
So what is a representative network of MPAs?, WWF
University of Plymouth

Live fast and die young: same-sex sexual behaviour in a deep-sea squid

Little is known about the reproductive habits of deep-living squids. Using remotely operated vehicles in the deep waters of the Monterey Submarine Canyon, scientists from the Monterey Bay Aquarium Research Institute and University of Rhode Island have found evidence of mating on similar body locations in males and females of the rarely seen mesopelagic squid Octopoteuthis deletron.

In a study published today in Biology Letters, male squid were found to routinely and indiscriminately mate with both males and females.

Most squid species are short-lived and promiscuous, with a single, brief reproductive period. In the deep, dark habitat where O. deletron lives, potential mates are few and far between. The researchers suggest that same-sex mating behaviour by O. deletron is part of a reproductive strategy that maximizes success by inducing males to indiscriminately and swiftly inseminate every same species squid that they encounter.

Direct observations of mating behaviour of deep-sea squid are restricted to a single observation of a possible mating event. Using remotely operated vehicles (ROVs) for exploration and research, has shed new light on our knowledge of deep-sea squid behaviour.

Males of the genus Octopoteuthis deposit spermatophores, complex structures containing millions of sperm, on the female. Here they discharge sperm-containing sacs called spermatangia that implant into the female’s tissue. Empty spermatangia remain attached to a female’s body and provide evidence of recent mating.

Same sex mating behaviour in marine invertebrates is very poorly known, although it has been reported before in cephalopods.

Mating in O. deletron, as in many other squids, is probably rapid, as spermatophores are quickly passed between partners and spermatangia release follows soon thereafter. Mature males and maturing mated females of O. deletron are of the same size, solitary and have only minor morphological differences. The combination of a solitary life, poor sex differentiation, the difficulty of locating a squid of the same species and the rapidity of the sexual encounter probably results in the observed high frequency of spermatangia-bearing males in this species. Apparently, the costs involved in losing sperm to another male are smaller than the costs of developing sex discrimination and courtship, or of not mating at all. This behaviour further exemplifies the ‘live fast and die young’ life strategy of many cephalopods

Further Reading:
Hendrik J. T. Hoving, Stephanie L. Bush, and Bruce H. Robison
A shot in the dark: same-sex sexual behaviour in a deep-sea squid
Biol Lett 2011 : rsbl.2011.0680v1-rsbl20110680.

Scientists call for end to Deep Sea Fishing

A team of leading marine scientists from around the world is recommending an end to most commercial fishing in the deep sea. Instead, they recommend fishing in more productive waters nearer to consumers.

In a comprehensive analysis published online this week in the journal Marine Policy, marine ecologists, fisheries biologists, economists, mathematicians and international policy experts show that, with rare exceptions, deep-sea fisheries are unsustainable. The “Sustainability of deep-sea fisheries” study, funded mainly by the Lenfest Ocean Program, comes just before the UN decides whether to continue allowing deep-sea fishing in international waters, which the UN calls “high seas.”

According to the Marine Conservation Institute, food is scarce in the Deep Sea and life processes happen at a slower pace than near the sea surface. Some deep-sea fishes live more than a century; some deep-sea corals can live more than 4,000 years. When bottom trawlers rip life from the depths, animals adapted to life in deep-sea time can’t repopulate on human time scales. Powerful fishing technologies are overwhelming them.

The deep sea provides less than 1% of the world’s seafood. But fishing there, especially bottom trawling, causes profound, lasting damage to fishes and life on the seafloor, such as deep-sea corals, experts say.

Since the 1970s, when coastal fisheries were overexploited, commercial fishing fleets have moved further offshore and into deeper waters. Some now fish more than a mile deep.

“Because these fish grow slowly and live a long time, they can only sustain a very low rate of fishing,” says author Dr. Selina Heppell, a marine fisheries ecologist at Oregon State University. “On the high seas, it is impossible to control or even monitor the amount of fishing that is occurring. The effects on local populations can be devastating.”

The authors document the collapse of many deep-sea fishes around the world, including sharks and orange roughy. Other commercially caught deep-sea fishes include grenadiers (rattails) and blue ling.

“Fifty years ago no one ate orange roughy,” said author Dr. Daniel Pauly, a fisheries biologist with the University of British Columbia (UBC). “In fact, it used to be called slimehead, indicating no one ever thought we would eat it. But as we’ve overfished our coastal species, that changed and so did the name.”

Orange roughy take 30 years to reach sexual maturity and can live 125 years. Compared with most coastal fishes, they live in slow-motion. Unfortunately for them and the deep-sea corals they live among, they can no longer hide from industrial fishing.

There are very few exceptions to unsustainable deep-sea fisheries around the world. One is the Azores fishery for black scabbardfish. There the Portuguese government has banned bottom trawling, which overfished black scabbardfish elsewhere. Azores fish are caught sustainably with hook and line gear from small boats. In most deep sea-fisheries, however, trawlers fish outside of nations’ 200-mile Exclusive Economic Zones, outside of effective government control.

High seas trawlers receive some $162 million each year in government handouts, which amounts to 25% the value of the fleet’s catch, according to Dr. Rashid Sumaila, an author and fisheries economist at UBC.

The authors of this Marine Policy paper say that the best policy would be to end economically wasteful deep-sea fisheries, redirect subsidies to help displaced fishermen and rebuild fish populations in productive waters closer to ports and markets, places far more conducive to sustainable fisheries.

“Instead of overfishing the Earth’s biggest but most vulnerable ecosystem, nations should recover fish populations and fish in more productive coastal waters,” says Dr. Norse. “Deep-sea fishes are in deep trouble almost everywhere we look. Governments shouldn’t be wasting taxpayers’ money by keeping unsustainable fisheries afloat.”

Further Reading:
Marine Conservation Institute: Are Deep Sea Fisheries Sustainable

Scientists discover new deep sea species

Census of Marine Life scientists have inventoried an astonishing abundance, diversity and distribution of deep sea species that live down to 5,000 meters (around 3 miles) below the ocean waves.

Revealed via deep-towed cameras, sonar and other technologies, animals known to thrive in an eternal watery darkness now number 17,650, a diverse collection of species ranging from crabs to shrimp to worms. Most have adapted to diets based on meager droppings from the sunlit layer above, others to diets of bacteria that break down oil, sulphur and methane, the sunken bones of dead whales and other implausible foods.

Edward Vanden Berghe, who manages the Census’ inventory of marine life observations, notes that the number of species recorded falls off dramatically at deeper depths – a function of the dearth of sampling in the deep sea.

While the collective findings are still being analysed for release as part of the final Census report to be released in London on 4 October 2010, scientists say patterns of the abundance, distribution and diversity of deep-sea life around the world are already apparent.

“Abundance is mostly a function of available food and decreases rapidly with depth,”
says Robert S. Carney of Louisiana State University, co-leader of the Census project
studying life along the world’s continental margins. “The continental margins are where we find the transition from abundant food made by photosynthesis to darkened poverty. The transitions display the intriguing adaptations and survival strategies of amazing species,” says Dr. Carney.

Abundance in the deep sea requires one or more of the following:
* Swift current, which increases an animal’s chance of encountering food;
* Long-lived animals, populations of which grow numerous even on a meager diet;
* Abundant food in higher layers that either settles to the depths or to which deep animals can migrate;
* An alternative to photosynthesis of food, such as chemosynthetic production.

At 1,000 to 3,000 meters (~.6-1.9 miles): NOAA researchers led by Mike Vecchione of
the Smithsonian Institution collected a very large specimen of a rare, primitive animal known as cirrate or finned octopod, commonly called “Dumbos” because they flap a pair of large ear-like fins to swim, akin to the cartoon flying elephant.

The jumbo Dumbo netted by Census explorers was estimated to be nearly two meters (~6 feet) long and, at 6 kg (~13 pounds), the largest of only a few specimens of the species ever obtained.

Altogether, nine species of gelatinous “Dumbos” were collected on the Mid-Atlantic
Ridge, including one that may be new to science. Scientists were surprised to find such a plentiful and diverse assemblage of these animals, which rank among the largest in the deep sea.

Further Reading:
Census of Marine Life

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IUCN to unveil mysteries of the deep

The International Union for Conservation of Nature (IUCN) hopes that its new project will reveal the mysteries of southern Indian Ocean seamounts and help improve conservation and management of resources.

Two research expeditions will survey seamounts. These underwater mountains are magnets for marine life. The aim is to determine priority areas for the establishment of future marine Protected Areas, and improve the management and conservation of the ocean’s species.

“It is critical that we get more information on the impact of climate change on these deep-water species, in order to help set up protective measures. Deep-sea species are particularly vulnerable to climate change” said Dr Alex David Rogers, Principal Scientist and Marine Biologist at the Zoological Society of London.

You can read about the expedition’s progress on their blog at http://seamounts2009.blogspot.com/

IUCN is the world’s largest global environmental network – a union with more than 1000 government and NGO member organisations, and almost 11000 volunteer scientists in more than 160 countries.

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Deep-sea corals live thousands of years

Gerardia coral. Credit: OAR/National Undersea Research Program (NURP) Deep-sea corals are found on hard substrates on seamounts and continental margins worldwide at depths of 300 to around 3000 m. Deep-sea coral communities are hotspots of living things, both in terms of numbers and diversity of species. They provide critical habitat for fish and invertebrates.

According to research published this week in the Proceedings of the National Academy of Sciences, newly applied radiocarbon dating of the deep water corals Gerardia and Leiopathes species show that their growth rates are extremely low, and that individual colonies live for thousands of years. The longest-lived specimens were Leiopathes species (black corals) at 4265 years old.

The coral specimens were collected with submersibles off the coast of Hawaii. The authors measured the age of the corals’ proteinaceous skeleton and found that the corals grew much more slowly than previous dating techniques had shown.

The management and conservation of deep-sea coral communities is challenged by their commercial harvest for the jewellery trade and damage caused by deep-water fishing practices.

The scientists conclude that in light of the corals’ unusual longevity, we need to better understand their ecology and relationship with other bottom-dwelling creatures before forming a coherent international conservation strategy for these important deep-sea habitat-forming species.

Black Corals
Leiopathes black corals have a dark skeleton, after which they are named. The black skeleton forms irregularly branching, tree-like structures. Gorgonian-like, the skeleton is covered with polyps. Leiopathes corals are listed on Appendix II of the Convention on International Trade in Endangered Species (CITES), which means that they are not necessarily now threatened with extinction now but that may become so unless trade is closely controlled. Gerardia species are sometimes known as False Black Corals. Not all of these are deep sea: colonies are found in the Mediterranean between 50 and 80 m.

Journal References:
E. Brendan Roark, Thomas P. Guilderson, Robert B. Dunbar, Stewart J. Fallon, and David A. Mucciarone. Extreme longevity in proteinaceous deep-sea corals. PNAS 2009 : 0810875106v1-pnas.0810875106.

E. Brendan Roark, Thomas P. Guilderson, Robert B. Dunbar and B. Lynn Ingram. Radiocarbon-based ages and growth rates of
Hawaiian deep-sea corals. MARINE ECOLOGY PROGRESS SERIES, Vol. 327: 1–14, 2006
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Robot Vehicle Surveys Deep Sea Off Pacific Northwest

The first scientific mission with Sentry, a newly developed robot capable of diving as deep as 5,000 meters (3.1 miles) into the ocean, has been successfully completed by scientists and engineers from the Woods Hole Oceanographic Institution (WHOI) and the University of Washington (UW).

The vehicle surveyed and helped pinpoint several proposed deep-water sites for seafloor instruments that will be deployed in the National Science Foundation (NSF)’s planned Ocean Observatories Initiative (OOI).

Sentry is a state-of-the-art, free-swimming underwater robot that can operate independently, without tethers or other connections to a research ship.

The autonomous underwater vehicle, or AUV, is pre-programmed with guidance for deep-water surveying, but it can also make its own decisions about navigation on the terrain of the seafloor.

“This investment into emerging technologies is paying off in delivering state-of-the-art science support,” said Julie Morris, director of NSF’s Division of Ocean Sciences. “In the near future, Sentry will conduct high-resolution oceanographic surveys that would be otherwise impossible.”

Working in tandem with sonar instruments on the UW-operated research vessel Thomas G. Thompson and with photo-mapping by WHOI’s TowCam seafloor imaging system, Sentry gathered the most precise maps to date of seafloor features known as Hydrate Ridge and Axial Volcano off the coast of Oregon and Washington.

The AUV can collect the data needed to make seafloor maps at a resolution of less than one meter. On this first cruise, Sentry collected as many as 60 million individual soundings of seafloor depth in a single dive.

Powered by more than 1,000 lithium-ion batteries-similar to those used in laptop computers, though adapted for extreme pressures, Sentry dove for as long as 18 hours and 58 kilometers, with the potential for longer trips in the future.

Sentry is designed to swim like a fish or fly like a helicopter through the water. The sleek hydrodynamic design allows the vehicle to descend quickly from the sea surface to the depths (about 3,500 meters per hour). The novel shape also gives the vehicle tremendous stability and balance while cruising through bottom currents.

The vehicle has thrusters built into its foils, or wings. Like an airplane, the foils allow the vehicle to gain lift or drag or directional momentum, as needed.

When necessary, the AUV also can hover over the bottom for close-up inspections, navigational decision-making, and for rising up and down over rugged seafloor terrain. The design allows the vehicle to start, stop, and change directions, whereas many AUVs tend to travel in one direction.

The AUV steers itself with a magnetic compass; long-baseline (LBL) navigation triangulated from underwater beacons; a sophisticated inertial guidance system (INS); and, when within 200 meters of the bottom, an acoustic sensor that can track the vehicles’ direction and speed with incredible precision.

“Sentry is a true robot, functioning on its own in the deep water,” said Rod Catanach, a WHOI engineer who works with Sentry. “The vehicle is completely on its own from the time it is unplugged on the deck and cut loose in the water.”

Eventually, vehicles like Sentry and its successors will plug into and interact with the ocean observatory system, using the power charging systems and high speed communications delivered by the submarine networks.

Further Reading: National Science Foundation

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Countries urged to protect coldwater corals

WWF-Canada have released a new study that identifies three coldwater coral “hotspots” off Newfoundland and Labrador and assesses the impact of fishing on these fragile organisms. The study provides the scientific basis for Canadian and European governments to protect sensitive coral habitat in the Northwest Atlantic.

Coldwater corals are long-lived animals that live along continental slopes, seamounts, and mid-ocean ridges. These corals are important parts of deep-sea ecosystems and provide habitat for other invertebrates and fishes. Coldwater corals can be damaged by fishing or other seafloor directed activities and may take centuries to grow back, if at all.
Copyright WWF-Canada
“Canada, Spain, Portugal and Russia are the countries that have the greatest potential to damage these globally important concentrations of corals,” said Dr. Robert Rangeley, Vice President, Atlantic, WWF-Canada. “Their fleets are among the largest operating off Newfoundland and fish in and around the areas identified as hotspots. This also means they have the greatest opportunity to protect them.”

“Our study mapped where corals are found, and identified areas where coral bycatch is highest for a variety of fisheries and gear types,” said lead author of the study Dr. Evan Edinger. “Our research demonstrates that no matter what type of fishing gear is used, bottom-contact fishing in coral habitat damages corals. Therefore, it is very important that any areas established to protect corals exclude all bottom directed fishing activities.” This research builds on a growing global movement to protect coldwater corals and seamounts. In 2006, the United Nations General Assembly called on fisheries management agencies like the Northwest Atlantic Fisheries Organization (NAFO) to implement vulnerable habitat protection measures by December 2008. In response, last year NAFO signalled their intent to protect seamount habitats.

The Report, Coldwater Corals off Newfoundland and Labrador: Distribution and Fisheries Impacts may be downloaded at: http://wwf.ca/coral

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