When there’s invading seaweed in your neighborhood, who you gonna call? Well, a new study by scientists at Georgia Tech shows that when corals are threatened by toxic algae they use chemical signals to call for help from their “bodyguards”, the unassuming goby fish.
The study, carried out on coral reefs in Fiji and published in the November 8 issue of the journal Science, shows that within moments of the coral’s “911 call” the gobies respond to these chemical distress signals and pick off the offending seaweed. What’s in it for the fish? Gobies spend their entire lives with the same patch of coral, using it for protection from predators and even feeding on mucus produced by the coral. It comes as little surprise then that the goby takes any threat to its shelter very seriously.
"The fish are getting protection in a safe place to live and food from the coral," said Mark Hay, a biology professor at Georgia Tech and the study’s co-author. "The coral gets a bodyguard in exchange for a small amount of food. It's kind of like paying taxes in exchange for police protection."
For one species of goby, feeding on the toxic algae has the secondary effect of making the fish itself more toxic to predators.
Coral is under threat worldwide from pollution and ocean acidification from human activity. When corals are stressed, aggressive algae competing for sunlit patches of ocean floor can represent a death blow to coral reefs and the magnificent ecosystems they support. At least one fish, though, isn’t letting the reef go down without a fight.
While the retreat from rising seas may seem like a distant, if abysmal, end-of-the-century scenario, it is in fact already taking place in some low-lying island communities. For the Guna (pronounced “Kuna”) people of Panama the abandonment of their ancestral homeland, the San Blas Islands, has become the only option after frequent floods have made their way of life impossible.
While the flooding of the San Blas Islands is partly a consequence of rising sea levels, the Guna are not entirely blameless. Coral reefs that once surrounded and buffered the islands from storm surges and flooding have been destroyed after decades of exploitation (ironically, the Guna mined the reefs to build up the islands). It has been enough, according to Reuters “to submerge the Caribbean islands for days on end”.
Above is a good primer on ocean acidification narrated by Dan Laffoley of the International Union for Conservation of Nature (IUCN). The video spans the vulnerable corals of Australia's Great Barrier Reef to the equally vulnerable shellfish industry of the Pacific Northwest, detailing the potential effects of a more acidic ocean.
To those unfamiliar with global warming's "evil twin", the video does a good job of explaining the basics of ocean acidification: simply put, carbon dioxide reacts with ocean water to make carbonic acid. The ocean absorbs about a quarter of civilization's carbon dioxide emissions, and as a result they are now 30 percent more acidic than before the industrial revolution. What does this mean for animals like clams, corals, or oysters that rely on a more stable pH range to build their calcium carbonate skeletons and shells?
Mother nature has provided some of her own experiments, as documented in the video. Near Vesuvius in the Mediterranean carbon dioxide bubbles up from below, rendering a glimpse in to a future, more acidic, and bleaker ocean. Closer to the vents, where the water is more saturated with carbon dioxide, the communities of life become less diverse and invasive algaes thrive.
Off of Australia, the Great Barrier Reef is already struggling in the new man-made environment. As more and more acidic water continues to erode the corals in the coming decades, these ecosystems of otherworldly beauty and diversity could simply go extinct.
Perhaps most worrisome of all is the effect of acidification on pteropods, a shell forming plankton at the very bottom of the ocean's food web, nicknamed the "potato chips of the sea". These animals are especially vulnerable to acidification, and as the narrator ominously intones: "If their shells dissolve a critical part of the food web dissolves with them".
Learn more about ocean acidification and what you can do to help.
As a record-breaking hurricane pummeled the Northeast almost into November--this on the heels of a scorching summer that saw arctic ice shrivel to its smallest extent ever recorded--the specter of climate change lurks just under the surface of any discussion of what can only be described as our freakish recent weather.
Climate scientist Kevin Trenberth of the National Center for Atmospheric Research talked to Slate about Sandy:
Most of what is going on with Sandy is weather, and there is a large chance element to it, but it is all occurring in an environment where the ocean is a bit warmer, the air above the ocean is warmer and moister, and that is fuel for the storm and especially adds to the risk of heavy rainfalls and flooding.
After the necessary caveats about tying any one event to global warming, the New Yorker's Elizabeth Kolbert despairs about the notable absence of the elephant-in-the-room issue in our electoral politics.
The storm fits the general pattern in North America, and indeed around the world, toward more extreme weather, a pattern that, increasingly, can be attributed to climate change . . .”
Coming as it is just a week before Election Day, Sandy makes the fact that climate change has been entirely ignored during this campaign seem all the more grotesque. In a year of record-breaking temperatures across the U.S., record drought conditions in the country’s corn belt, and now a record storm affecting the nation’s most populous cities, neither candidate found the issue to be worthy of discussion.”
Environmentalist and journalist Bill McKibben, who earlier this year penned a jeremiad in Rolling Stone about climate change that went viral, sees in Sandy a frightful spectacle not unlike Frankenstein's monster, as he writes in the Daily Beast:
Our relationship to the world around us is shifting as fast as that world is shifting. “Frankenstorm” is the right name for Sandy, and indeed for many other storms and droughts and heat waves now. They’re stitched together from some spooky combination of the natural and the unnatural.
Sandy was likely influenced by a combination of factors that we know are tied to climate change such as a melting Arctic, a warming Atlantic Ocean and rising sea levels, but to what extent is not yet known. But under the water, and out of sight, the effects of emissions are just as severe. The oceans are absorbing 90 percent of the heat from climate change and carbon dioxide emissions absorbed by the oceans have led to a 30 percent increase in the ocean's acidity since the Industrial Revolution, a trend that threatens to topple coral reefs and food chains worldwide in the coming decades.
Learn more about climate change, what Oceana is doing to fight it, and what you can do to help.
Our friends in Europe have wrapped up the Oceana Ranger's 2012 expedition, capturing more than 100 hours of footage documenting the incredible variety of life, both familiar and bizarre, living on underwater mountains known as seamounts off the coast of Spain and Portugal. What they documented, as seen in these pictures taken at the Seco de los Olivos or Chella Bank seamount a mere 10 miles off the coast of El Ejido, Spain, seems fitting in the run-up to Halloween. Above, the ghoulish specter of a rough shark approaches the Ranger's underwater robot, or ROV. Below, a posse of some 20 conger eels peek out from the sheer face of a seamount cliff.
Oceana's work on the seamount has uncovered octopus, monkfish, Norway lobster, coral communities and even a carnivorous sponge. As Ricardo Aguilar, Research Director of Oceana in Europe says, this is truly unique habitat and one that can be destroyed in an instant by such human activities as bottom trawling:
“The images obtained . . . have confirmed that fact that Seco de los Olivos is one of the marine areas with the highest environmental interest in Spain. However, as this is a small seamount, relatively close to the shore, it is in a state of constant deterioration from recreational and commercial fishing, and so management of the area is urgently needed if we want to preserve its abundant natural wealth”.
Using this footage, in 2013 Oceana will be joining a coordinated effort to try to put conservation measures in place for these biodiversity hotspots. Learn more about the Oceana Ranger here.
All pictures © Oceana
In this thought-provoking piece on the National Geographic's Ocean Views blog, Mediterranean Science Commission director general Frederic Briand discusses the precarious and uncertain fate of ocean creatures staring down extinction. About sharks and rays he writes:
These are not target species in Mediterranean fisheries but increasingly threatened, as unreported bycatch, by highly intensive fishing and bottom trawl. The status of many of them is unclear, even for species as conspicuous as the sawfish Pristis pectinata (last seen in 1902), the mako shark Isurus oxyrinchus, or the sandtiger sharks Carcharias taurus and Odontaspis ferox, once abundant and now presumed locally extinct.
But it is the baiji, or Yangtze River dolphin, the first marine mammal to go extinct in modern times, that captures the imagination--the passenger pigeon or dodo for our day.
Nearly blind, the baiji patrolled the turbid waters of the Yangtze River for millenia but has not been seen in almost a decade. It was declared extinct earlier this year by the Chinese government. The dolphin likely succumbed to decades of development, pollution, entanglements in fishing gear, ship strikes and an increasingly chaotic acoustic environment in the Yangtze that proved lethal to a species almost entirely dependent on sound to communicate, find food and find mates.
Now the vaquita, a porpoise in the Sea of Cortez (literally "little cow") takes up the unenviable mantle of most endangered cetacean in the world. The largest threat faced by the vaquita are gillnets.
Add fish poop to the growing list of unlikely allies in the fight against global warming. A new study published in the journal Scientific Reports outlines the critical role small forage fish, in particular northern anchovies, play in burying carbon in the deep sea.
It turns out that small fish like anchovies, smelt and sardines are a major component of the so-called "biological pump" that takes carbon dioxide out of the atmosphere and sequesters it in the deep, where it can no longer contribute to global warming. That pump begins with photosynthetic, carbon dioxide-absorbing, single-celled algae, like the wonderfully intricate diatoms and dinoflagellates, at the ocean surface. Anchovies then feed on the algae, digest it and release it as fecal pellets which sink to the ocean bottom.
At 22 micrograms of carbon per pellet, the contribution might seem inconsequential, but as the study's authors, Dr. Grace Saba of Rutgers University and professor Deborah Steinberg of the Virginia Institute of Marine Science, explain, the cumulative effect on the carbon cycle by large schools of small forage fish could be considerable.
“Our findings show that—given the right conditions—fish fecal pellets can transport significant amounts of repackaged surface material to depth, and do so relatively quickly,” says Saba.
Those "right conditions" are found off of the western coasts of North and South America where cold, nutrient-rich water from the deep upwells along the continental shelf, and subsequently drive the production of enormous schools of small fish and invertebrates. It's these conditions that are responsible for Peru's anchovy industry or California's iconic sardine industry immortalized in Steinbeck's Cannery Row.
But besides delivering carbon to the deep, forage fish also play a critical role in the larger foodweb, feeding whales, dolphins, seals, larger fish and seabirds. For all these reasons it's critical to employ science-based fisheries management to prevent the collapse of this vital resource. Unfortunately, that has not been the trajectory of forage fisheries management in the Pacific. Learn more about forage fish and Oceana's work to conserve these small but invaluable species.
In the past few weeks Oceana's Ranger expedition has been exploring a series of underwater mountains 130 miles West of Portugal known as the Gorringe bank. Formed along with the Atlantic Ocean as Pangaea pulled apart 145 to 155 million years ago, the Gorringe bank juts from depths of as much as 16,000 feet to only 100 feet below the surface. These underwater mountain ranges are a hotspot for marine life, as nutrient rich water upwells to the seamount peaks.
Closer to the surface a familiar parade of whales, dolphins, swordfish and barracuda visit lush kelp forests, while shearwaters and petrels circle above. As you dive deeper though, as the Ranger expedition has with its underwater robot (ROV), you enter a somewhat stranger world, but one that is no less diverse. This is the domain of the dragon fish, the fan corals, the otherworldly deep-sea sharks, the churlish-looking pink frogmouth and still more species unknown to science. Other animals are ambassadors of the deep, patrolling up and down the seamounts in search of prey
“During last year’s expedition we found some new species whose existence in the Gorringe was unknown, such as branching black coral, hydrocoral, dogfish, bird’s nest sponge, and various gorgonia”, says Ricardo Aguilar, Director of Research at Oceana in Europe. “There are dozens of species which have not been identified yet. We hope that they will provide new data on these ecosystems, and facilitate the protection and conservation of this unique enclave.”
Unfortunately, as the ranger expedition has also discovered, this habitat is also home to an increasing amount of trash, especially abandoned fishing gear.
By documenting and exploring habitat, Oceana is gathering data about this unique ecosystem that will be crucial in formulating conservation plans that will hopefully protect the area from malign human influences like pollution and bottom trawling.