This little goby fish saves its host coral by keeping toxic algae
When coral are threatened by encroaching toxic algae, they do not have the luxury of running from their enemy. That is not to say these stationary creatures are defenseless, though. Acropora coral has evolved to emit a chemical call for help, and within minutes, a goby fish will show up on the scene, ready to nibble off the algae. Researchers recently discovered this underwater partnership in the waters near Fiji. They say this symbiotic relationship is the first known example of a species chemically signaling another in order to remove a competitor species.
Coral reef at the Palmyra Atoll in the northern Pacific Ocean
It’s not a good time to be a coral. Less than a third of coral reefs have legal protection from fishing and other damaging human activity. And as climate change increases oceans’ temperature and acidity, corals are suffering from more bleaching events, when stressed corals spit out the symbiotic algae they need to survive, and weaker skeletons. By 2050, coral reefs might be a lost cause. While some researchers work to protect reefs, others are preparing for conservation to fail—by collecting frozen coral sperm.
As Michelle Nijhuis explains in a New York Times article, marine biologist Mary Hagedorn is gathering reproductive material from many corals so that even as reefs die off, researchers can work at maintaining various species’ genetic diversity and trying to ensure their survival.
It’s just a pile of sand–no wait, is that a tentacle wriggling in the corner? These time-lapse videos taken by researchers at the University of Queensland show that mushroom corals unearth themselves by slowly inflating and then deflating over 10 to 20 hours. See a second coral attempt the same after the jump.
Elkhorn coral infected with white pox.
What’s the News: Over the past decade, diseases, pollution, and warming waters have put coral populations across the globe in a dramatic decline. In an extreme case, the population of elkhorn coral, considered one of the most important reef-building corals in the Caribbean, has decreased by 90–95 percent since 1980, partly due to a disease called white pox.
Now, scientists have traced this lethal disease back to humans. Human feces, which seep into the Florida Keys and the Caribbean from leaky septic tanks, transmit a white pox-causing bacterium to elkhorn coral, researchers report in the journal PLoS ONE. “It is the first time ever that a human disease has been shown to kill an invertebrate,” ecologist James Porter told Livescience. “This is unusual because we humans usually get disease from wildlife, and this is the other way around.”
The Deepwater Horizon spill in the Gulf of Mexico brought us those gut-wrenching pictures of pelicans covered in oil, but up to now there have been mercifully few reports of the disaster causing specific large-scale damage to the Gulf environment. That may be beginning to change: This week oceanographers report a vast swath of coral about seven miles southwest of the Deepwater Horizon site that are coated in brownish-black gunk and dying off. The team says the evidence points to the oil spill as the culprit.
The scientists sailed aboard the National Oceanic and Atmospheric Administration research boat Ronald H. Brown, and used remotely operated submersibles to survey the seafloor and find this devastation.
“The coral were either dead or dying, and in some cases they were simply exposed skeletons,” said team member Timothy Shank of Woods Hole Oceanographic Institution. “I’ve never seen that before. And when we tried to take samples of the coral, this black—I don’t know how to describe it—black, fluffylike substance fell off of them.” [National Geographic]
Brown pelicans smothered by BP’s oil spill may be the symbols of sadness for the disaster in the Gulf, but they are, of course, far from the only animals affected. Marine scientists are watching other species for signs of danger.
Late last week, scientists spotted the first dead whale seen in the Gulf since the leak began gushing oil in April. The National Oceanic and Atmospheric Administration found a 25-foot-long sperm whale washed up, and now it is testing the sea creature for cause of death.
“While it is impossible to confirm whether exposure to oil was the cause of death, NOAA is reviewing whether factors such as ship strikes and entanglement can be eliminated,” the agency said. Samples collected from this carcass will be stored until the Pisces returns to port on July 2, or possibly if another boat is sent to meet the Pisces. Full analysis of the samples will take several weeks [New Orleans Times-Picayune].
So far, it at least appears that manatees have been spared toxic exposure to the ever-growing oil spill. However, a science team hunkered down at Dauphin Island in Alabama—in the path of the oil—say their luck may not hold.
Until recently, biologists believed that manatees rarely ventured west of peninsular Florida, where, so far, no oil has appeared. But in 2007, Ruth Carmichael, who leads the Dauphin Island team, began documenting a relatively large summer migration of manatees to Mobile Bay, Ala. — leading them directly into and through the path of the oil from the Deepwater Horizon leak. From a couple of dozen to as many as 100 come to Mobile Bay for the summer, out of a total North American population of 5,000, she said [The New York Times].