Into the Blue Serengeti

November 24, 2012 by  
Filed under Secrets of the Ocean

Blue whales are among the Pacific predators whose large-scale movements have been tracked. They dine on small crustaceans called krill, and, like some “nomadic” African lions, migrate to where their prey is seasonally abundant.

The dugout canoe does not know the depth of the water” (Umubindi ushira uvimye). So say the Hangaza, a group of more than 150,000 people who live along Lake Victoria, west of Tanzania’s Serengeti National Park. The proverb rings true: floating on the water won’t tell you what is going on below. Half a world away from Tanzania, along the United States West Coast, oceanographers are finding new ways of looking beneath research vessels that ply the Pacific. They’re getting a fish’s eye view of the deep by placing electronic tags on predators such as blue whales and California sea lions, yellowfin tuna and white sharks. As the data come in, their thoughts turn to the Serengeti.

Their project is called Tagging of Pacific Ocean Predators (TOPP). It focuses on certain areas of the Pacific, among them the California Current, an undersea river of water that flows south along the western coast of North America, beginning off British Columbia and ending near Baja California. The current supports large populations of whales and seabirds, and fuels important fisheries. Its productivity comes from an upwelling of cold subsurface waters, caused by prevailing northeasterly winds. The chilly waters ferry a steady supply of nutrients to the surface. The scientists are also studying an area called the North Pacific Transition Zone, the boundary between cold subarctic water and warm subtropical water, about halfway between Hawaii and Alaska. It’s a major trans-Pacific corridor for the movements of predators and prey.

Combined map shows movement patterns of twenty-two species documented by scientists collaborating in the TOPP (Tagging of Pacific Ocean Predators) project.

“These are the oceanic areas where food is most abundant,” says marine scientist Barbara A. Block of Stanford University’s Hopkins Marine Station in Pacific Grove, California. “They’re the savanna grasslands of the sea.” Knowing where and when species migrate is critical information for managing and protecting ecosystems, says biologist Daniel P. Costa of the University of California, Santa Cruz. TOPP was launched in 2000 by Block and Costa along with Steven J. Bograd of the National Oceanic and Atmospheric Administration’s Southwest Fisheries Science Center in La Jolla, Randall E. Kochevar of Stanford, and others. The project was part of the Census of Marine Life, a ten-year-long investigation of the diversity, distribution, and abundance of ocean species. TOPP became the world’s largest “biologging” (electronic tagging) study, involving more than seventy-five biologists, oceanographers, engineers, and computer scientists in eight countries. A decade of findings were reported in the journal Nature in June 2011. They reveal that the migrations of twenty-two marine species overlap.

“It’s been like looking across the entire African savanna,” says Block, “and trying to figure out: Where are the watering holes a zebra or a cheetah might frequent? Where are the fertile valleys? Where are the deserts that animals might avoid, and the migratory corridors species such as wildebeest use to travel from place to place?”

Block, Costa, and their colleagues use an array of technologies to track species and to record such environmental variables as water temperature, salinity, and depth. The TOPP project alone deployed 4,306 satellite-monitored tags, yielding a massive amount of data. Scientists spent two years synthesizing data sets. They discovered intersecting ocean hotspots and highways of life—and learned much about how marine conditions influence where animals hang out.

The results show that many migratory marine species, like animals on the Serengeti grasslands, return to the same regions each year, homing in with astonishing fidelity to the places where they were first tagged. “It’s akin to a student from London studying in far-off Rome and coming home each summer at the same moment—but doing it all in the dark without a map or compass, using only his or her internal sense of position and direction,” says Costa.

Leatherback sea turtle: Two populations have been observed, one whose females travel to lay eggs along beaches in the eastern Pacific, another that prefers western Pacific beaches.

Leatherback sea turtles, for example, travel huge distances between their nesting and feeding sites. In the Pacific Ocean, contingents from two populations of leatherbacks make their way each year to beaches along the eastern and western Pacific, respectively, to lay eggs. (An individual female will nest once every two or three years.) Helen Bailey of the University of Maryland Center for Environmental Science placed tracking devices on 135 leatherbacks’ shells. Leatherback turtles in the eastern Pacific were tagged at their nesting sites in Costa Rica and Mexico; western Pacific turtles were tagged at nesting sites in Indonesia and on their foraging grounds off the coast of California. The instruments transmitted satellite signals each time the turtles surfaced.

The results of Bailey’s study were published in the April 2012 issue of Ecological Applications. The western Pacific turtles traveled to feeding sites in the South China Sea, Indonesian seas, southeastern Australia, and the U.S. West Coast. “This wide dispersal,” says Bailey, “allows for a greater likelihood of finding food. It also means that the turtles are more vulnerable to being snagged unintentionally in fishing gear.”

The eastern Pacific leatherbacks have a different migration pattern, traveling south from nesting sites in Mexico and Costa Rica to the southeast Pacific. The turtles feed in offshore upwelling areas where their meals, almost exclusively jellyfish, are easy catches. “The limited feeding grounds of the east Pacific turtles make them vulnerable to changes that might occur in the abundance of jellyfish,” says Bailey. “Being caught in fishing gear also poses a greater risk to this population because it has a smaller range than western Pacific leatherbacks.” Entanglement in fishing gear is believed to be a major cause of death in leatherback sea turtles. James R. Spotila of Drexel University, a coauthor of the paper, notes that leatherback turtles are long-lived animals that take a long time to reach maturity. Because the species’ numbers are declining very fast, he considers it critical to take measures so they don’t go extinct. In the past thirty years, leatherback numbers in the eastern Pacific have dropped by 90 percent. Information on the turtles’ movements will help scientists determine where fishing should be limited at certain times of the year, says Bailey. A good precedent is a decision made in 2010 to close a swordfish and thresher shark fishery off California from mid-August to mid-November. That may have dramatically reduced incidental leatherback catches.

Water temperature is key to the seasonal migrations of many North Pacific Ocean species. That’s especially true in the marine ecosystem defined by the California Current, where whales, sharks, tuna, seals, seabirds, and turtles migrate each year. Like the African savanna, says Costa, the Pacific Ocean has a “Big Five”: he compares great white sharks to lions, bluefin tuna to leopards, blue whales to African elephants, leatherback sea turtles to black rhinos, and elephant seals to Cape buffaloes.

Scientists see parallels between migration patterns of prey, predators, and scavengers in East Africa’s Serengeti region and movements of species in the Pacific. Mapped here are (top left and right) zebra and wildebeest, (middle left and right) nomadic lion and hyena, and (bottom) vultures. Most lion prides occupy defended territories; nomadic lions, usually single males, tend to follow migrating herds while trying to avoid detection by resident males.

“The Serengeti is an ecosystem that’s synonymous with animal movements,” says ecologist Grant Hopcraft of the Frankfurt Zoological Society–Africa, headquartered in the Serengeti. “Each year more than one and a half million ungulates cross its plains.” Their seasonal migrations follow cyclic rains that lead to the growth of savanna grasses. Where grasses sprout up, ungulates such as wildebeest follow. Predators such as nomadic lions trail closely behind. (Although most lion prides occupy defended territories, nomadic lions, usually single males, tend to follow migrating herds while trying to avoid detection by resident males.) “The movements of marine species in the California Current are similar to those in the Serengeti,” says Hopcraft, “which raises the question: Why? Research at the population level suggests that it’s a changing food supply that drives animal migrations. But recent animal collaring [tracking] projects in the Serengeti show a huge amount of variation in individual species’ responses.”

There’s a lot more going on, Hopcraft believes, beneath the surface. “For the Serengeti—and the California Current—does an animal’s internal condition determine how it responds? Is it remembering previous routes and responding to the same cues? How will environmental change affect these great migrations of the land and the sea?”

Some predators spend their lives in the California Current, but others migrate long distances across the Pacific Ocean to reach the current’s abundant prey, including krill, sardines, anchovies, and squid. “Why a young bluefin tuna less than two years old wakes up in the light of the Japan Sea and decides to swim to Baja is unknown,” Block says. “But once it arrives, tagging data indicate that it lives there for years, taking advantage of the rich ‘forage’ along the coast.” Many species—including black-footed albatrosses, sooty shearwaters, bluefin tuna, and salmon sharks—migrate more than 1,200 miles from the western, central, or southern Pacific Ocean to reach the California Current’s rich food resources.

Farther off shore is the mysterious White Shark Café, as it’s known, an open-ocean winter and spring habitat for otherwise coastal great whites. The area, halfway between Baja California and Hawaii, hadn’t been a suspected shark hangout. But when scientists mapped data from satellite tags placed on 179 great white sharks between 2000 and 2008, they discovered that the sharks frequently travel to and loiter there. While at the café, they dive to depths of 1,000 feet as often as once every ten minutes, according to Salvador J. Jorgensen of Stanford’s Hopkins Marine Station. He and colleagues published their results online in November 2009 in Proceedings of the Royal Society B.

Coming mostly from rookeries along the Pacific coast, the great whites take up to 100 days to arrive, traveling at about two knots. The study showed that the sharks adhere to a rigid route of migration across the sea, returning to exactly the same spot. Since both male and female sharks have been tracked to the café, an early hypothesis was that it could be the undersea equivalent of a trendy pickup bar. Further studies, however, revealed that juvenile sharks also make their way there.

The purpose of the deep dives is not yet known, with the great whites lingering, often for months, in what seems to be an oceanic “desert” where food is scarce. Michael L. Domeier of the Marine Conservation Science Institute in Fallbrook, California, hypothesizes that the predators are feeding not on fish but on giant squid. Sperm whales, which feed on giant squid, are sighted in that area. Tracking other species, such as tuna, may help explain how the shark café came to be. “We’re only beginning to understand what it means to have the equivalent of lions in the ocean wilderness off California,” says Block.

Tuna, sharks, and blue whales may be cued to seasonal changes in chlorophyll concentrations,” says Bograd. Chlorophyll indicates the presence of phytoplankton, the grasslands of the sea.

Marine scientists work with a lightly anesthetized male northern elephant seal. After using fast-acting epoxy to glue a telemetry tag to the hair on the animal’s head, they measure blubber thickness with an ultrasound device and collect blood samples.

Elephant seals, for example, are drawn to a particular oceanographic feature—a boundary zone between two large rotating currents, or gyres. Along this boundary, the cold nutrient-rich waters of the subpolar gyre in the north mix with the warmer waters of the subtropical gyre to the south, driving the growth of phytoplankton and supporting a veritable feast of marine life.

An oceanic surface feature linked with the boundary zone and caused by blooms of phytoplankton is visible on satellite images. It moves seasonally by as much as 600 miles, however. Some elephant seals don’t follow; they continue to target the deep boundary zone between the two gyres.

Using data from nearly 300 tagged animals, Costa showed that the elephant seals travel throughout the northeast Pacific Ocean on foraging trips in search of prey such as fish and squid. “For the first time, we can truly say that we know what elephant seals as a population are doing,” he says. The results were published in May 2012 in the journal PLoS ONE.

A small number of elephant seals search for food in coastal regions, pursuing bottom-dwelling prey along the continental shelf. Among these is a female that feeds near Vancouver Island. She holds the record for deepest recorded dive by an elephant seal: 5,765 feet, more than a mile down.

The scientists have also looked at the partitioning of habitats by closely related species. Certain species, for example, are attracted to particular water temperatures; these preferences correlate with physiological adaptations. “We can now predict when and where individual species are likely to be in a given ocean region, and begin to understand the factors that control where they go next,” says Costa. “It’s the basis of ecosystem-based management.”

Following on the heels of TOPP, the scientists have spawned a new effort to study the blue Serengeti. “Where are the hotspots needing immediate protection?” Block asks. “We’re conducting the ecosystem science that reveals who’s at watering holes like White Shark Café and, most importantly, why.”

The ocean sunfish, or common mola, is known to dine on jellyfish, but its diet may be far broader.

One new project, called WhaleWatch, is looking at how to reduce the number of whales entangled in fishing gear, by identifying the areas whales are most likely to visit. Satellite tags have been attached to gray whales and to three other whale species—blue, fin, and humpback—off the U.S. West Coast. WhaleWatch scientists such as Bailey are using satellite data and migration models of gray whales to identify high-risk areas for the whales, and to develop conservation policies for reducing ship strikes and entanglements.

Among whales, the gray is the West Coast species most often hit by ships and caught up in fishing gear. Gray whales are known for long migrations of more than 10,000 miles from their feeding grounds in the Bering Sea to breeding areas along the coast of Baja California, Mexico. WhaleWatch researchers are analyzing gray whale satellite tracks to determine where the hotspots are for these whales.

This June, no one needed satellite tracking to find whales in Monterey Bay, California. As many as 100 blue whales splashed around in plain sight there. Upwelling led to a bumper crop of krill, the whales’ favorite food, and attracted countless other marine species. “It’s been one of the best ‘lunch stops’ in the Pacific,” says Block. “We need to protect these areas, places where large pelagic predators—the cheetahs and lions of the sea—gather.”

There’s an Africa-like game park in the waters off the West Coast, she says. “It will take enormous vision to preserve this wild place. Without conservation of such ocean realms, the bluefin tunas and blue whales, whale sharks and great whites might not be there in future generations.”

Along the U.S. East Coast, humpback whales, also long-distance migrators, are frequently ensnared in fishing gear. This July, scientists at the Provincetown Center for Coastal Studies in Massachusetts freed a whale caught in fishing line wrapped around its mouth and head. The researchers are part of a team following satellite-tagged humpbacks in the Gulf of Maine.

The snagged whale is one often seen in local waters. A mark on its tail fluke is shaped like a giraffe, giving the humpback its name: Serengeti.

Article source: http://www.naturalhistorymag.com/features/242338/into-the-blue-serengeti

New carnivorous harp sponge discovered in deep sea

November 20, 2012 by  
Filed under Secrets of the Ocean

A blog by Scientific American.

You may remember the Monterey Bay Aquarium Research Institute (MBARI) from such discoveries as the Yeti crab, the squid with elbows and my personal favourite, the pigbutt worm, and now they’re back with footage of a new species of carnivorous sponge.

Seventeen years ago, Jean Vacelet and Nicole Boury-Esnault from the Centre of Oceanology at France’s Aix-Marseille University provided the first real evidence that a sponge could be more than, well, a sponge. They had discovered a new species of deep-sea sponge living in the unusual setting of a shallow Mediterranean sea cave, the inside of which mimicked the conditions of its usual habitat more than a kilometre below the surface. This allowed the researchers an unprecedented view of the sponge’s eating habits, and they watched as it snared its prey of small fish and crustaceans instead of absorbing bacteria and organic particles through their bodies, like most other sponge species do – including ones living in the very same cave.

Vacelet and Boury-Esnault’s sponges were of the Asbestopluma genus and belonged to the Cladorhizidae family of carnivorous demosponges – the class that contains over 90% of the world’s sponges. Since reporting their discovery in a 1995 issue of Nature, 24 new species of cladorhizid sponges, including the incredible ping-pong tree sponge (see below), have also been discovered. Yet due to the difficulty of studying their behaviour at such incredible depths, researchers have had little opportunity to describe essential aspects of their lives, particularly how they reproduce.

Chondrocladia, or ping-pong, sponge.  MBARI

Chondrocladia, or ping-pong, sponge. MBARI

Which is where MBARI’s remotely operated vehicles (ROVs) Tiburon and Doc Ricketts, come in. Using these deep-diving vessels, a team of researcher s led by Senior Research Technician Lonny Lundsten discovered a species of harp sponge called Chondrocladia lyra off the coast of California, at depths of 3316–3399m.

As Mr_Skeleton pointed out on Reddit this week, this sponge doesn’t look like it could clean anything. But it can catch prey, envelope it in membrane and digest it whole, so it certainly has other priorities. Based on footage of several individuals and two large, fragmentary specimens brought up by the ROVs, Lundsten’s team described how the vertical branches and horizontal stolons that make up the sponge’s basic harp-like structure, called a vane, are covered in barbed hooks and spines. They found that a number of crustacean prey were passively ensnared on these branches thanks to the Velcro-like hooks and then aggressively enclosed in a cavity to be dismembered into small, digestible particles, which provided direct evidence of the species’ carnivorous appetites.

The vertical branches of the harp sponge are tipped by swollen terminal balls containing packets of sperm.

The vertical branches of the harp sponge are tipped by swollen terminal balls containing packets of sperm.  MBARI

The vertical branches of the harp sponge are tipped by swollen terminal balls containing packets of sperm. MBARI

C. lyra can grow up to 37cm long – impressive for a sponge – and are anchored to the sea-floor by a structure called a rhizoid, which looks like a root system. They can have 1-6 vanes, each supporting a number of equidistant vertical branches, and each of these end in swollen terminal balls. According to the researchers, these terminal balls produce condensed packets of sperm called spermatophores, which are released into the surrounding water in the hopes of fertilising other harp sponges in the area. Each C lyra sponge also has an egg development area around the mid-point of the branches, and when the spermatophores make contact, these areas swell up as the eggs are fertilised and begin to mature.

The team suggests that the structure of the harp sponge is designed to ensure that they catch the most prey possible, and also maximise their chances of catching spermatophores from other harp sponges.

“Video footage taken as the ROVs approached specimens of C. lyra provided information about the biological diversity of the areas in which the sponges live,” the researchers added in their report in the current issue of Invertebrate Biology. “Among the coexisting invertebrates were unidentified sea anemones; the soft coral Anthomastus robustus, members of several species of sea pens; and the sea cucumber Paelopadites confundens, as well as another sea cucumber in the family Elipidiidae.”

Article source: http://www.nature.com/news/new-carnivorous-harp-sponge-discovered-in-deep-sea-1.11789

Creatures of deep new to scientists

November 20, 2012 by  
Filed under Secrets of the Ocean

Weird underwater discoveries such as an egg-eating Australian sea serpent and a strikingly coloured worm named after Star Wars‘ Yoda could carry on for decades to come, with new research estimating that up to one third of species remain undiscovered.

A study co-led by a University of Auckland expert and published today in international journal Current Biology calculated there were fewer than one million marine species on the planet, lower than some previous estimates. The number undiscovered likely amounts to a third of all species.

Hot spots for new finds included deep sea ecosystems and those in tropical areas, said Associate Professor Mark Costello from the University of Auckland, who co-led the research with Ward Appeltans of Flanders Marine Institute and the Intergovernmental Oceanographic Commission of Unesco.

“If we look at the number of undescribed species and samples from around the world, especially deep sea and tropical areas, the average over 100 studies was that about 30 per cent of those new species were new to science,” he told the Herald.

Easier identification, better technology and more scientists would boost the rate of discovery.

“It’s likely it will get harder and harder to find the rarer things, but it also gets more exciting.”

Bizarre species discovered within the past year included Yoda purpurata, which had features resembling the Jedi master’s large sagging ears, a crimson shrimp found at a depth of 2600m beneath the Norwegian Sea, and an odd-looking bristle worm discovered 1600m below the northeast Pacific.

“Knowing how many species there are in our oceans, and describing them, is vital for science and conservation for several reasons,” Professor Costello said.

“Species are the most practical measure for distinguishing habitats and tracking progress in exploring the earth’s biodiversity.

“They are as fundamental to biology as elements are to chemistry and particles to physics.

“So failure to consider all species in an ecosystem is analogous to an accountant ignoring items of inventory in a company’s stock.”

Better understanding of what species exist enabled more accurate estimates of extinction rates through habitat loss, while having a “master list” of species’ names was essential for quality assurance.

Research efforts have been boosted by the World Register of Marine Species – an open-access, online database that has received contributions from almost 300 scientists from 32 countries.

The study supports previous research by Professor Costello and colleagues, which used statistical modelling and an earlier version of the register to reach a similar estimate of the number of species on earth and in the oceans. It is also the culmination of 14 years’ work for Professor Costello, who began a European register of marine species in 1997 that expanded until the world register was initiated in 2006.

OCEANS STILL TO GIVE UP THEIR INHABITANTS

Around 226,000 species have been described by science and as many as 72,000 more are in collections awaiting description – yet hundreds of thousands more may still be waiting for discovery in our oceans.

The rate of discovery is, however, increasing, with an unprecedented 20,000 new marine species described in the past decade alone, suggesting that most marine species will be discovered this century.

Earlier estimates of ocean diversity had relied on expert polls based on extrapolations from past rates of species descriptions and other measures.

Those estimates varied widely, suffering because there was no global catalogue of marine species, and a new study gauging a more accurate figure canvassed 120 of the world’s top experts on the taxonomy, or classification, of marine species.

Mammals, birds, reptiles, insects and larger plants were some of the best-described groups of marine species to date.

Many of the species yet to be discovered will come from among the smaller crustaceans, molluscs, algae, worms, and sponges.

By Jamie Morton Jamienzherald Email Jamie

Article source: http://www.nzherald.co.nz/nz/news/article.cfm?c_id=1&objectid=10847735

Oil Platform Fire Sends Shockwaves Through Gulf On Heels of Record BP Fines

November 20, 2012 by  
Filed under Toxic Spills

An oil platform explosion and fire today near the site of the nation’s greatest offshore oil spill in history—BP’s Deepwater Horizon—sent shivers up the spines of many Gulf residents as the U.S. Coast Guard reported that 11 crewmembers were flown to area hospitals and two crewmembers were still missing as of Friday evening. News reports said four workers were critically injured with burns.

A Coast Guard spokesman said the oil and gas platform was 20 miles southeast of Grand Isle, LA, and was owned by Black Elk Energy, a fast-growing oil and gas drilling operation based in Houston. News reports stated the oil platform was not actively producing oil and that a welder involved in a maintenance operation may have caused the accident. Although there were reports of an oil sheen near the platform, there were no reports of a major oil leak.

NRDC President Frances Beinecke, a member of the presidential national oil commission that investigated the BP oil disaster, issued this statement:

“Though the BP criminal case is settled, today’s accident makes clear that the hazards of oil and gas drilling are not in America’s rear view.  It is a sad reminder that offshore drilling is an inherently dangerous business. Workers and communities are put in harm’s way every day and will continue to be as long as we prioritize this risky energy development. Our leaders must keep that squarely in mind when considering where and how to allow further drilling along our coasts and in our communities.”

The Black Elk Energy accident came the day after the U.S. Justice Department announced a criminal settlement with BP involving a record-setting $4.5 billion in fines, indicting three company officials on criminal charges. Civil penalties against BP are still pending.

Many people in the Gulf are still recovering from the BP oil disaster that residents say continues to impact their fisheries and beaches more than two years later. Grand Isle mayor David Camardelle, whose community has been one of the hardest hit by the oil disaster, said he was saddened to learn of the latest offshore oil rig fire and injuries to workers. “It’s a tragic accident and my sympathies go out to the families of the workers who were impacted. But thankfully it appears this is not another BP disaster.”

Tar balls found on Grand Isle, LA, this month            Photo: Mac MacKenzie

Camardelle said his community still has oil and tar balls on its beaches after storms, especially after Hurricane Isaac hit their area last August. And he said many fishermen are suffering from reduced catches and have not been adequately compensated by BP for their losses. “We feel like we’re forgotten sometimes,” he said. “We can put robots on Mars, but we can’t tell how much BP oil is still out in the Gulf. Something’s wrong with that.”

Kindra Arnesen, wife of a fisherman in Buras, LA, said she too was saddened by the accident, which she says hits close to home since so many of her friends and neighbors work in the oil industry. “My heart goes out to those families,” she said. “This may have been a fluke accident, but it makes me wonder, what really has changed in the oil industry since the BP explosion? We’re still using the same blowout preventers, so it seems like we should be doing something better.”

That point was made in a blog this summer by NRDC’s David Pettit, part of a coalition of conservation groups that filed a lawsuit to push for greater drilling safety in the Gulf. He reminded people that many questions raised by the presidential commission still remain unanswered:

Their investigation uncovered serious flaws in oil industry and regulatory practices.  These accidents-waiting-to-happen remain unaddressed, with the Gulf’s battered ecosystems and vital billion-dollar tourism and fisheries hanging in the balance. If drilling is to continue, more must be done to improve drilling safety and safeguard our natural resources.  The largest oil spill in America’s history should have been a wakeup call.  If we refuse to learn from that mistake, it will become a recurring nightmare instead.

That’s a nightmare no one wants to live through again.

Article source: http://switchboard.nrdc.org/blogs/rkistner/an_explosion_and_fire_on.html