Tuesday, November 29, 2011

Hagfish Anti-Shark Slime Weapon

The hagfish found in New Zealand’s deepest waters is grotesque enough, thanks to its scary protruding teeth straight from a horror film. Now, scientists have witnessed the full power of its other gruesome feature – a built-in slime weapon to deter predators such as sharks, making it one of the planet’s ultimate survivors.

Researchers from Massey University and Te Papa have just released graphic underwater footage showing for the first time how the primitive hagfish – also known as the snot-eel – defends itself by emitting a choking, gill-clogging slime that might be the envy of any surfer under attack from a shark.

The footage, part of a study of New Zealand’s deep-sea animal diversity, is from special cameras that captured images of various fish attacking hagfish off Three Kings and Great Barrier Islands as they feed on bait attached to the camera. As soon as it is attacked, the hagfish releases a gooey mucus-like substance from its battery of slime glands and up to 200 slime pores, causing predators to gag before hastily retreating.

The video footage in New Zealand waters has proven that hagfish secrete slime at an incredibly fast speed when under attack by predators such as large sharks or bony fishes.

A paper on the findings just published online in Scientific Reports (Nature Publishing Group) titled Hagfish predatory behaviour and slime defence mechanism describes the effectiveness of the “copious slime” in choking would-be predators without apparently poisoning or killing them. This in turn allows the hagfish to carry on feeding or to make an escape, clearly a success as an evolutionary strategy.

Other new findings include the discovery that the hagfish is not only an ocean scavenger but is also a predator – with a twist. Footage reveals its bizarre method of burrowing into sand in pursuit of a red bandfish by knotting its tail for additional leverage as it grabs its hidden prey before unknotting and emerging from the sand.

Since 2009, the scientists have deployed cameras at depths ranging from 50 to 1500 metres around New Zealand. So far, over 1000 hours of footage has been collected off the Kermadec Islands, Three Kings Islands, Great Barrier Island, White Island and Kaikoura, with surveys to extend in 2012 to the sea off the Otago Peninsula and down as far as the Auckland Islands.

This research was funded by a Royal Society of New Zealand Marsden Fund Grant to Dr Roberts and Professor Anderson, a Te Papa Collection Development Grant as well as support by the Ministry of Science and Innovation via NIWA and the University of Western Australia.

Watch a video of the hagfish in action: http://www.youtube.com/watch?v=Bta18FdkVcA&feature=player_embedded

Source: Massey University

Wednesday, November 16, 2011

Swim Little Fishes, Swim if You Can

Fish and other sea creatures will have to travel large distances to survive climate change, international marine scientists have warned.

Sea life, particularly in the Indian Ocean, the Western and Eastern Pacific and the subarctic oceans will face growing pressures to adapt or relocate to escape extinction, according to a new study by an international team of scientists published in the journal Science.

The current research shows that species which cannot adapt to the increasingly warm waters they will encounter under climate change will have to swim farther and faster to find a new home.

Using 50 years’ data of global temperature changes since the 1960s, the researchers analysed the shifting climates and seasonal patterns on land and in the oceans to understand how this will affect life in both over the coming century.

The velocity of climate change (the geographic shifts of temperature bands over time) and the shift in seasonal temperatures for both land and sea found both measures were higher for the ocean at certain latitudes than on land, despite the fact that the oceans tend to warm more slowly than air over the land.

The findings have serious implications especially for marine biodiversity hotspots – such as the famous Coral Triangle and reefs that flourish in equatorial seas, and for life in polar seas, which will come under rising pressure from other species moving in.

Unlike land-dwelling animals, which can just move up a mountain to find a cooler place to live, a sea creature may have to migrate several hundred kilometres to find a new home where the water temperature, seasonal conditions and food supply all suit it.

Under current global warming, land animals and plants are migrating polewards at a rate of about 6 kilometres a decade – but sea creatures may have to move several times faster to keep in touch with the water temperature and conditions that best suit them.

There  are also a complex mosaic of responses globally, related to local warming and cooling. For example, analysis suggests that life in many areas in the Southern Ocean could move northward, however, as a rule, they are likely to be as great or greater in the sea than on land, as a result of its more uniform temperature distribution.

The migration is likely to be particularly pronounced among marine species living at or near the sea surface, or subsisting on marine plants and plankton that require sunlight – and less so in the deep oceans.

At the same time, sea life living close to the poles could find itself overwhelmed by marine migrants moving in from warmer regions, in search of cool water.

Future research will focus on how different ocean species respond to climate change and they are compiling a database on this for the Intergovernmental Panel on Climate Change (IPCC).

The paper “The Pace of Shifting Climate in Marine and Terrestrial Ecosystems” by Michael T. Burrows, David S. Schoeman, Lauren B. Buckley, Pippa Moore, Elvira S.Poloczanska, Keith M. Brander, Chris Brown, John F. Bruno, Carlos M. Duarte, Benjamin S. Halpern, Johnna Holding, Carrie V. Kappel, Wolfgang Kiessling, Mary I.O’Connor, John M. Pandolfi, Camille Parmesan, Franklin B. Schwing, William J. Sydeman and Anthony J. Richardson, appears in today’s issue of Science.

Source: The ARC Centre of Excellence for Coral Reef Studies

Wednesday, October 12, 2011

Will Extinction Predictor Help Protect Coral Reefs?

More than a third of coral reef fish species are in jeopardy of local extinction from the impacts of climate change on coral reefs.

A new predictive method developed by an international team of marine scientists has found that a third of reef fishes studied across the Indian Ocean are potentially vulnerable to increasing stresses on the reefs due to climate change.

The method also gives coral reef managers vital insights to better protect and manage the world’s coral reefs, by showing that local and regional commitment to conservation and sustainable fisheries management improves prospects for coral recovery and persistence between storms and bleaching events.

The team applied their ‘extinction risk index’ to determine both local and global vulnerability to climate change and human impacts. They tested the method by comparing fish populations before and after the major 1998 El Nino climate event which caused massive coral death and disruption across the Indian Ocean.

In all, 56 of the 134 coral fish species studied were found to be at risk from loss of their habitat, shelter and food sources caused by climate change. Those most in jeopardy were the smaller fishes with specialised eating and sheltering habits. Because most of these species have wide geographic ranges and often quite large local populations, few were at particular risk of global extinction.

The loss of particular species can have a critical effect on the stability of an entire ecosystem – and our ability to look after coral reefs depends on being able to predict which species or groups of fish are most at risk.

For example, we know that the loss of seaweed-eating grazing fishes can lead to coral reefs which have suffered some other form of disturbance being replaced by weeds. Protecting these fish, on the other hand, gives the corals a much better chance to recover.

Where there is a widespread death of corals from a climate-driven event such as bleaching, the fish most affected are the ones that feed or shelter almost exclusively on coral. However when corals die off and the reef structure collapses, small reef fish generally are much more exposed to predators.

By understanding which species and groups of fish are most at risk, we can better manage coral reefs and fish populations to ensure their survival in times of increasing human and climate pressure.

The study does, however, offer encouragement by showing that the fish most at risk from climate change are seldom those most at risk from overfishing or other direct human impacts, pointing to scope to manage reef systems and fishing effort in ways that will protect a desirable mix of fish species that promote ecosystem stability.

Critically, the species of fish that are important in controlling seaweeds and outbreaks of deleterious invertebrate species are more vulnerable to fishing than they are to climate change disturbances on coral reefs. This is encouraging, since local and regional commitment to fisheries management action can promote coral recovery between disturbances such as storms and coral bleaching events.

They conclude that identifying the fish species most at risk and most important to ecosystem stability and then managing coral reefs to maintain their populations will help ‘buy time’ while the world grapples with the challenge of limiting carbon emissions and the resulting climate change.
The team adds that their novel approach to calculating extinction risk has wider application to conservation management beyond coral reef ecosystems and can readily apply to other living organisms and sources of stress.

Their paper “Extinction vulnerability of coral reef fishes” by Nicholas A. J. Graham, Pascale Chabanet, Richard D. Evans, Simon Jennings , Yves Letourneur, M. Aaron MacNeil, Tim R. McClanahan, Marcus C. Öhman, Nicholas V. C. Polunin and Shaun K. Wilson appears in the latest issue of the journal Ecology Letters.

Source: ARC Centre of Excellence in Coral Reef Studies

Tuesday, April 5, 2011

Older Reserves Protect Fish Better

A new Simon Fraser University study warns that marine reserves globally may require up to 15 years of protection before the reserves significantly benefit their fish inhabitants, especially large locally fished species.
SFU biologist Isabelle Côté and scientists Phil Molloy and Ian McLean wanted to investigate widespread discrepancies in the reported effectiveness of marine reserves as fish management and conservation tools.

“As the time required for reserves to ‘start producing’ is critical to the development of management plans and community support, resolving this age effect on a global scale is an important task,” the authors write.

However, their key conclusion that the overall effectiveness of marine reserves in enhancing fish densities improves over time is footnoted by several surprising findings that don’t observe this rule.

The authors add, “The magnitude and speed of responses to protection vary with the extent of fishing pressure nearby as well as with various species attributes. Reserve stakeholders therefore need to have realistic expectations and management plans need to incorporate short-term uncertainty and long-term perspective.”

Through statistical analysis, Côté, Molloy—a former SFU postdoctoral fellow—and McLean—a former student of Côté—distilled the results of 33 studies evaluating marine reserve effectiveness. The previous studies had compared fish populations inside and outside of 32 marine reserves worldwide, aged one to 26 years old. The reserves are off Europe, the western United States and Australia, in the Mediterranean and along the Eastern African and Indo-Pacific coastlines.

The trio’s paper— Effects of marine reserve age on fish populations: a global meta-analysis—reports the results of their broad-scale analysis in a new issue of the Journal of Applied Ecology.

As well as being published in this British-based ecological science journal, the paper is covered in an issue of Science for Environment Policy, a publication of the European Commission’s news alert service.

The Science for Environmental Policy, explains Molloy, “is circulated to thousands of environmental policy makers and resource managers throughout Europe. As a result, this research will likely have a direct impact on future marine policy in Europe.”

The SFU-generated study Effects of marine reserve age on fish populations: a global meta-analysis doesn’t include any evaluations of Canadian marine reserves. But John Reynolds, an SFU biologist and the Tom Buell B.C. Leadership Chair in Salmon Conservation, predicts Canada will take note of its global significance.

Source: Simon Fraser University

Wednesday, March 30, 2011

A Motley Collection of Boneworms

It sounds like a classic horror story—eyeless, mouthless worms lurk in the dark, settling onto dead animals and sending out green "roots" to devour their bones. In fact, such worms do exist in the deep sea. They were first discovered in 2002 by researchers at the Monterey Bay Aquarium Research Institute (MBARI), who were using a robot submarine to explore Monterey Canyon. But that wasn't the end of the story. After "planting" several dead whales on the seafloor, a team of biologists recently announced that as many as 15 different species of boneworms may live in Monterey Bay alone.

After years of study, the researchers have begun to piece together the bizarre story of the boneworms, all of which are in the genus Osedax. The worms start out as microscopic larvae, drifting through the darkness of the deep sea. At some point they encounter a large dead animal on the seafloor. It may be a whale, an elephant seal, or even the carcass of a cow that washed out to sea during a storm. Following chemical cues, the tiny larvae settle down onto the bones of the dead animal.

osedax with orange collar
Most female boneworms have long, graceful palps
that wave in the ocean currents.
Image: © 2008 Greg Rouse

Once settled, the boneworms grow quickly, like weeds after a rain. One end of each worm develops feathery palps, which extract oxygen from seawater. The other end of the worm develops root-like appendages that grow down into the bone. Bacteria within these roots are believed to digest proteins and perhaps lipids within the bones, providing nutrition for the worms.
Soon the worms become sexually mature. Strangely enough, they all become females. Additional microscopic larvae continue to settle in the area. Some of these larvae land on the palps of the female worms. These develop into male worms. But they never grow large enough to be seen by the naked eye. Somehow these microscopic male worms find their way into the tube that surrounds the female's body. Dozens of them share this space, not eating at all, but releasing sperm that fertilize the female's eggs. Eventually the female worm sends thousands of fertilized eggs out into the surrounding water, and the cycle begins again.

Dr. Robert Vrijenhoek, an evolutionary biologist at MBARI, has been fascinated with these worms ever since he and his colleagues first discovered their unusual lifestyles and bizarre reproductive habits. Vrijenhoek has been trying to find out how widespread and genetically diverse these worms are. He would also like to know how they manage to find and colonize the bones of dead whales in the vast, pitch-black expanse of the deep seafloor.

osedax with orange collar
This photo shows the skull of a dead whale on
the seafloor—the preferred habitat for boneworms.
Image: © 2006 MBARI

Between 2004 and 2008, Vrijenhoek's research team towed five dead whales off of Monterey Bay beaches and sank them at different depths within Monterey Canyon. Every few months, coauthor Shannon Johnson and others on the team would send one of MBARI's remotely operated vehicles (ROVs) down to study the worms and other animals that had colonized the whale carcasses.

To their surprise, the different whale carcasses yielded different types of boneworms. One whale carcass hosted three or four different types of worms. After examining all of the worms, coauthor Greg Rouse concluded that most of them were entirely new to science. The researchers also discovered that the worms would colonize cow-bones placed on the seafloor, which showed that the worms were not limited to feeding on dead whales.

In their recent paper in the journal BMC Biology, Vrijenhoek and his coauthors describe the results of extensive DNA analyses on all the different types of Osedax worms that have been discovered so far (including two species found off Sweden and Japan). This work suggests that these worms could belong to as many as 17 different species, most of which have yet to be named. None of the worms appear to interbreed, despite the fact that some of them grow side by side.

osedax with spiral tip
These unusual boneworms live in seafloor
sediment and send roots into the sediment,
presumably to digest fragments of bone.
Image: © 2005 MBARI

Based on their appearance and similarities in their DNA, the researchers divided the boneworms into several groups. Some of the worms have feathery palps, which may be red, pink, striped, or even greenish in color. Others have bare palps. One type of boneworm has no palps at all. Its body forms a single, long, tapering tube, which curls at the end like a pig's tail. This worm has evolved to live in the seafloor sediment near a dead whale. It sends long, fibrous "roots" into the mud, presumably in search of fragments of bone on which to feed.

Knowing how fast the DNA of these worms changes (mutates) over time, the researchers can calculate how long it has been since worms in the genus Osedax first evolved as a distinct group. Using one possible estimate of mutation rates, the researchers hypothesized that this group could have evolved about 45 million years ago—about the time the first large open-ocean whales show up in the fossil record. Alternatively, the worms may have evolved more slowly, which would suggest that the genus is much older, and first evolved about 130 million years ago. If this second estimate is correct, the worms could have feasted on the bones of immense sea-going reptiles during the age of the dinosaurs.

osedax with green palps
This photograph shows a female of an as yet un-named
boneworm in the genus
, which has been carefully
removed from the whale bone in which it was growing. This
worm has green, feathery palps, which extract oxygen from
seawater. At its lower end are an ovisac and bulbous "roots"
which would normally be embedded in the whale bone.
Image: © 2009 Greg Rouse

Eventually the researchers will give all these new worms their own species names. First, however, they must collect enough samples of each possible species for additional laboratory analysis and distribution to type-specimen collections. Like a classic horror story, the macabre saga of the boneworms will continue to thrill marine biologists for years to come.

This research was sponsored by the David and Lucile Packard Foundation.

Journal article:A remarkable diversity of bone-eating worms (Osedax; Siboglinidae; Annelida). Robert C Vrijenhoek, Shannon B Johnson and Greg W Rouse BMC Biology.

Source: Monterey Bay Aquarium Research Institute (MBARI)

Saturday, February 12, 2011

Marine Reserves Mend Food Chains, Link By Link

Conservation managers need to take a long-term view when assessing the value of marine protected areas, according to a paper in today’s Proceedings of the National Academy of Sciences of the United States of America.

The paper, ‘Decadal trends in marine reserves reveal differential rates of change in direct and indirect effects’, was written by an international team of authors led by Russ Babcock of the CSIRO Wealth from Oceans Flagship. It is the first paper to summarise the results from the most significant published long-term studies of temperate and tropical marine reserves.

The team examined ecological data from coastal marine reserves in New Zealand, Australia, California, the Philippines and Kenya that had been in place for 10 years or more and were monitored before and after protection.

As marine reserves gain favour worldwide, stakeholders want to know how rapidly changes will occur after protection, but the changes are sometimes surprising and difficult to predict, Dr Babcock says.

Our study suggests it will take decades to observe, predict, and validate the full implications of marine reserves because many of the processes we need to understand operate on these timescales.
Dr Babcock says most studies to date have focused on the restoration of fished species (higher predators) without considering the cascading effects on prey such as small fish, invertebrates, algae and corals.

We found that while the direct effects of protection on fished species are rapid, initially occurring within five years, it takes 13 years on average to detect the indirect effects on the broader ecosystem.
For example, in temperate reef systems, the recovery of lobsters and large fish can increase predation on sea urchins, causing reduced grazing and recovery of kelp forests.

A co-author of the paper, Neville Barrett of the Tasmanian Aquaculture and Fisheries Institute, says marine reserves show different timeframes for different types of recovery.
“It takes a while for primary, secondary and tertiary effects to occur,” Dr Barrett says. "In some areas we are still seeing changes 20, 30, and 40 years post-protection.

For a large predatory fish such as the blue groper which lives 70–80 years and grows to 1.5 metres, five years of protection is hardly anything. It’s only grown 30–40 centimetres in that time. Then it can take another 20 or 30 years for the effects of protection to occur at the next level of the food chain.

A conservation manager may expect ecosystem recovery in five years, but in many places this won’t be the case. It’s not an inappropriate management plan; you might need to wait 20 years to see the full range of positive effects.”

Dr Babcock says long-term monitoring of marine reserves shows that populations of fished species are more stable in reserves than in fished areas. This makes them an important tool for conservation and restoration.

Protected areas also offer a valuable research tool, providing unique insights into the function of marine ecosystems and the effects of human activities.

Source: Commonwealth Scientific and Industrial Research Organisation (CSIRO)

Thursday, January 27, 2011

Finding New Ways to Protect Both Fish and Fishers

In pioneering research carried out in Fiji in collaboration with the Wildlife Conservation Society (WCS), the CoECRS team has reported a new approach that enables communities to balance the need to protect the environment with the need to maintain local food supplies and incomes.
Concern over the worldwide decline of coral reefs has prompted many countries and local communities to impose marine reserves to protect dwindling fish stocks. However these can adversely affect the incomes and welfare of fishers and their communities.

For a marine protected area to work, the people living around it have to trust it to deliver both the conservation goals and the needs of the community. They have to be comfortable with it - otherwise they won’t comply with it.

While the research was carried out in Fiji, it could equally apply to the protection of coral reef resources across the six nations of the Coral Triangle, to Australia’s north, and to Australia’s own Great Barrier Reef and other coral regions.

Designing a protected area so that it meets both conservation and community goals is a complicated affair. It requires strong community involvement and a lot of dialogue.

Essentially we modeled the highest value fishing grounds, both now, and into the future assuming the introduction of new kinds of fishing gear. Then investigate how  to reposition the fishing closures to reduce conflict and ensure that fishermen would not lose too much income in the process.
The success of the project was founded on two elements - the first being that many coral-dependent communities across the Pacific and Coral Triangle want to establish marine protected areas to protect their sea areas from incursions by large industrial fishing vessels.

In Fiji, they have long had areas which are tabu, where fishing is forbidden on traditional grounds, so the concept of a protected area is part of their culture.

It was also noted that fishermen were well aware that protected areas help to restock the surrounding waters with fish, and can see the benefits from practical experience.

The paper "Improving social acceptability of marine protected area networks: A method for estimating opportunity costs to multiple gear types in both fished and currently unfished areas" by Vanessa M. Adams, Morena Mills, Stacy D. Jupiter and Robert L. Pressey appears in the journal Biological Conservation 144 (2011).