December 18, 2012
Despite covering 70 percent of the earth’s surface, the ocean doesn’t often make it into the news. But when it does, it makes quite a splash (so to speak). Here are the top ten ocean stories we couldn’t stop talking about this year, in no particular order. Add your own in the comments!
2012: The Year of the Squid From the giant squid’s giant eyes (the better to see predatory sperm whales, my dear), to the vampire squid’s eerie diet of remains and feces, the strange adaptations and behavior of these cephalopods amazed us all year. Scientists found a deep-sea squid that dismembers its own glowing arm to distract predators and make a daring escape. But fascinating findings weren’t relegated to the deep: at the surface, some squids will rocket themselves above the waves to fly long distances at top speeds.
James Cameron Explores the Deep Sea Filmmaker James Cameron has never shied away from marine movie plots (See: Titanic, The Abyss), but this year he showed he was truly fearless, becoming the first person to hit the deepest point on the seafloor (35,804 feet) in a solo submarine. While he only managed to bring up a single mud sample from the deepest region, he found thriving biodiversity in the other deep-sea areas his expedition explored, including giant versions of organisms found in shallow water.
Small Fish Make a Big Impact Forage fish—small, schooling fish that are gulped down by predators—should be left in the ocean for larger fish, marine mammals and birds to eat, according to an April report from the Lenfest Forage Fish Task Force. These tiny fish, including anchovies, menhaden, herring and sardines, make up 37% of the world’s catch, but only 10% are consumed by people, with the rest processed into food for farmed fish and livestock. With the evidence mounting that forage fish are worth more as wild fish food, state governments and regional fishery management councils are making moves to protect them from overfishing.
Marine Debris and Plastic Get Around In June, a dock encrusted with barnacles, sea stars, crabs and other sea life washed ashore on the coast of Oregon. It had floated across the Pacific from a Japanese port more than 5,000 miles away—a small piece of the estimated 1.5 million tons of marine debris set afloat by the 2011 Tohoku tsunami. But that’s not the only trash in the sea. Researchers found ten times as much plastic in the “pristine” Antarctic oceans than they expected. Some species are even learning to adapt to the ubiquitous ocean plastic.
Taking Measure of Coral Reef Health Australia’s iconic Great Barrier Reef, so large it can be seen from space, is not doing well. An October study found that since 1986, half of the living coral has died because of warming water, predation and storm damage. And it’s not just Australia: the December Healthy Reefs report gave most Mesoamerican reefs a “poor” rating. It’s hard to escape that gloom, but there were glimmers of hope. Some coral species proved able to adapt to warmer water, and changing circulation caused by the warming ocean may create refuges for coral reef habitat.
Shark Finning Slowing Down? The fishing practice of shark finning—slicing off a shark’s fins before tossing it back in the ocean to slowly sink and suffocate—began its own slow death in 2012. A steady stream of U.S. states have banned the sale of shark fins
ning; the European Union will now require fisherman to land sharks with their fins on; four shark sanctuaries were created in American Samoa, the Cook Islands, Kosrae and French Polynesia; and, in July, China announced that official banquets would be prohibited from serving shark fin soup (although the ban may take up to three years to go into effect).
Arctic Sea Ice Hits All-Time Low On September 16, sea ice extent reached a record low in the Arctic, stretching 3.41 million square kilometers—that’s 49% lower than the 1979-2000 average minimum of 6.7 million square kilometers. What’s more, its melt rate is increasing: 2012 had the largest summer ice loss by more than one million square kilometers. This change is expected to affect ecosystems—from polar bears to phytoplankton—and accelerate warming in the area, eventually melting Greenland’s ice sheet and raising sea level dramatically.
Hurricane Sandy Elevates Awareness of Sea-Level Rise This year certainly opened our eyes to the severity of climate change and sea-level rise. The east coast of the U.S., where scientists project sea-level will rise three to four times faster than the global average, got a glimpse of its effects when Hurricane Sandy caused $65 billion in damage, took at least 253 lives, and flooded Manhattan’s subways in October. The disaster inspired The Economist, Bloomberg Businessweek and other major news sources to take a closer look at climate change and what it means for us all.
Counting Ocean Animals from Space Scientists took advantage of satellite technology this year to learn more about ocean wildlife. The first satellite-driven census of an animal population discovered that there are twice as many emperor penguins in Antarctica as previously thought, including seven new colonies of the large flightless birds. A second study tracked the travels of sea turtles by satellite, which could help researchers get a better idea of where they might interact with fisheries and accidentally end up caught in a net.
The Ocean Gets a Grade The first tool to comprehensively assess ocean health was announced in August 2012—and the ocean as a whole received a score of 60 out of a possible 100. This tool, the Ocean Health Index, is novel in that it considered ten ways the ocean supports people, including economies, biodiversity, and recreation. The U.S. scored a 63, ranking 26th globally, while the uninhabited Jarvis Island took home an 86, the top grade of the 171 rated countries.
–Hannah Waters, Emily Frost and Amanda Feuerstein co-wrote this post
November 8, 2012
Corals are constantly under attack. Sea stars and other predators would love to take a bite, coral diseases lie waiting to take them out and many human-caused stresses persist in the water they inhabit, such as pollution, warming temperatures and rising acidity.
One of the first signs of a sick reef is the takeover of seaweeds, which continually threaten even healthy corals. However, corals aren’t alone in the fight against greenery, according to new research published in Science. When attacked, some corals send out chemical signals to their bodyguards—small goby fish—who scrape off or eat the coral-choking seaweeds.
Turtle weed (Chlorodesmis fastigiata) threatens corals because, upon contact, it releases a noxious chemical that disrupts their food source, the photosynthetic algae (zooxanthellae) that live inside their cells, ultimately leading to coral bleaching. Although most fish don’t have a palate for such toxic seaweed, authors Mark Hay and Danielle Dixson from the Georgia Institute of Technology observed coral gobies—small fish that spend their lives living in a single coral colony—eating it, and they wondered if there was more to this behavior than taste.
Hay and Dixson placed turtle weed on small staghorn coral (Acropora nasuta), a common reef-building coral found in the Pacific and Indian oceans, while in the presence of two goby species. The gobies cleaned up quickly: Within three days, 30% of the turtle weed was gone, and coral bleaching dropped by 70-80% compared to a goby-less seaweed invasion.
“These little fish would come out and mow the seaweed off so it didn’t touch the coral,” said Hay in a press release. “This takes place very rapidly, which means it must be very important to both the coral and the fish.”
In a series of experiments, the researchers worked out how the coral contacts the gobies to let them know that they need their hedges trimmed. Once the coral gets hit with chemicals from the invading turtle weed, it releases its own chemical signal—an emergency call to gobies—within 15 minutes. And, within another 15 minutes or less, gobies receive the message and swoop in to nibble away at the encroaching foliage.
What are the gobies getting out of this arrangement? The broad-barred goby (Gobiodon histrio) got a boost in its own defenses. It produces its own poisonous mucus to deter predators and, after eating the noxious turtle weed, this mucus impaired their predators’ swimming ability more than twice as fast, the researchers found. But the other goby species—the redhead goby (Paragobiodon echinocephalus)—doesn’t eat the seaweed, simply shearing it off the coral. What is its benefit?
“The fish are getting protection in a safe place to live and food from the coral,” Hay said. “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.”
This kind of chemical signaling system is the first observed in coral reef organisms—but it surely isn’t the only one. Many coral reef organisms are interdependent, relying on one or two other species for food or habitat, which means that the loss of just a few species can accelerate the disappearance of many others. For example, if these coral-cleaning gobies were overfished, say for the aquarium trade, the reef would be threatened by seaweed takeover, which could then degrade the entire community.
“Who would have thought that such a small, seemingly insignificant fish might play such a large role in keeping corals from being killed by seaweeds?” said coral reef biologist Nancy Knowlton from the Smithsonian National Museum of Natural History, who did not participate in the research. “It’s a compelling example of why maintaining biodiversity is so important.”
It’s also possible that such subtle chemical signals could be disrupted by ocean acidification. Clownfish and damselfish raised in seawater with the acidity scientists predict we’ll see in the year 2050 have trouble identifying scents in seawater to find their homes or avoid predators. If these gobies have similar problems, the impacts of acidification on reef communities could be greater than expected.