We know dolphins are smart, but a study in the Proceedings of the Royal Society A by Timothy Leighton at the University of Southampton, UK, raises the question as to whether dolphins are actually using complex nonlinear math tricks to hunt. Dolphins sometimes create a “bubble curtain” to corral and concentrate prey like sardines, making it easier to pick them off. But dolphins rely on their sonar when hunting, and all those bubbles would seem to interfere with a dolphin’s ability to distinguish its prey. Bubbles certainly interfere with man-made sonar systems. So the researchers wondered if dolphins, which vary the amplitude of their sonar clicks, use a complex nonlinear processing function to essentially separate the noise from the target. In their experiment, they used such mathematical functions to process the echoes of dolphin-like pulses from targets shrouded in bubble clouds. [Read more…]
For 25 years, the Aquarius Reef Base, an undersea laboratory that sleeps six?off of Key Largo, has served as host to numerous marine biologists and NASA astronauts. Even the Ocean Doctor has paid a visit to Aquarius. But after years of declining budgets, the Obama administration has eliminated the base’s funding, and the world’s last remaining undersea lab is faced with decommissioning — or finding its own funding. NPR reports that Dr. Sylvia Earle and other researchers are now conducting a mission of outreach and education in Aquarius to help save it.
The Environmental News Network (ENN) reports that a federal judge has approved an $880 million plan to restore the Everglades, a decision that could result in the settlement of numerous lawsuits spanning 25 years. In addition, U.S. Agriculture Secretary Tom Vilsack visited Kissimmee, Florida to announce an infusino of an additional $80 million from the federal government to support farmers and ranchers who voluntarily conserve wetlands on agricultural land in the northern portion of the Everglades Ecosystem. [Read more…]
An article in Evolutionary Applications raises concerns about the impacts of plastics in aquatic environments. It has already been well-documented that Bisphenol A (BPA) affects animal development and behavior because it mimics the hormone estrogen. Consequences can include impairing the ability of males to produce offspring. New Scientist reports that the new study, led by Jessica Ward of the University of Minnesota in Saint Paul, demonstrates effects that have further consequences with serious implications for biodiversity.
Fish exposed to BPA were more likely than the unexposed fish to approach fish of the other species and court them.
Red shiners are an invasive species, often introduced to new areas by fishermen who use them as bait. They often hybridise with native species, and exposure to oestrogen-mimicking chemicals like BPA could make it even more likely that they would do so.
Although it has a lower profile than habitat loss and overhunting, interbreeding is a big threat to biodiversity. “Hybridisation is one of the most common and widespread causes of species loss, especially in fish,” Ward says.
The U.S. Food and Drug Administration rejected calls to ban BPA from all plastic food containers earlier this year.
A study published in the April 2012 issue of Ecological Applications uses satellite telemetry data to identify danger zones where sea turtles and fishing trawlers intersect at sea — with deadly consequences. The insights provided by the study will assist regulatory agencies determine limits to fishing, such as seasonal closures, to protect sea turtles, all seven species of which are considered endangered.
The researchers followed 135 females, some from the eastern Pacific and some from the western Pacific, over 15 years as they crisscrossed the ocean hunting for jellyfish. The study found that the migration patterns for the two Pacific populations were different. Western Pacific leatherbacks leave Indonesian nesting sites to feed in the South China Sea, Indonesian seas and southeastern Australia and along the U.S. West Coast, making them vulnerable to fishing nets in many different areas.
The eastern Pacific leatherbacks traveled from nesting sites in Mexico and Costa Rica to the southeastern Pacific, with many getting snagged in fishing gear along the coast of South America. Because the eastern population is more concentrated in range, its risk of extinction is greater, Bailey says.
The new findings could help decision makers plan short-term fishery closures. Bailey credits a recent decision to close a swordfish and thresher shark fishery in California from mid-August to mid-November each year with dramatically reducing leatherback bycatches. (In 2010 no turtles were caught.)
The Christian Science Monitor reports that the speed with which acid levels have risen in the oceans has “caught scientists off-guard.” Ocean acidification was recently described by National Oceanic and Atmospheric Administration (NOAA) Administrator Jane Lubchenco as climate change’s “equally evil twin,” representing one of the biggest threats to life in the oceans. Lubchenco warned that acidification amounts to “osteoporosis of the sea” and threatens coral reefs, food security, and tourism around the world.
Scientists initially assumed that the carbon dioxide absorbed by the water would be sufficiently diluted as the oceans?mixed shallow and deeper waters. But most of the carbon dioxide and the subsequent chemical changes are being concentrated in surface waters, Lubchenco said.
“And those surface waters are changing much more rapidly than initial calculations have suggested,” she said. “It’s yet another reason to be very seriously concerned about the amount of carbon dioxide that is in the atmosphere now and the additional amount we continue to put out.”
Higher acidity levels are especially problematic for creatures such as oysters, because acid slows the growth of their shells. Experiments have shown other animals, such as clown fish, also suffer. In a study that mimicked the level of acidity scientists expect by the end of the century, clown fish began swimming toward predators, instead of away from them, because their sense of smell had been dulled.
…Read the full story at Ocean acidity increases surprise researchers – Christian Science Monitor
In a study led by Lauren T. Toth at Florida Institute of Technology published in the journal, Science, coral reef ecosystems in the tropical eastern Pacific “collapsed for 2500 years, representing as much as 40% of their history, beginning about 4000 years ago.” A series of powerful El Nino events, which include periods of significantly warmer ocean temperature every three to seven years, coincided with the 2,500-year period of coral decline. This was followed by a cycle of La Nina events characterized by much cooler water, beginning 3,200 to 3,800 years ago. Corals recovered during the millenia since but now face a return to extreme weather conditions like those that wiped them out, due to climate change impacts. [Read more…]
The Journal Nature reports that, despite our best efforts to reduce fossil fuel emissions, sea level rise associated with climate change is unstoppable, even under the most aggressive actions on greenhouse gas mitigation. According to the study, the question now is not if sea level rise will continue but to what degree. And that’s the good news. Without concerted mitigation strategies, scientists predict that future sea level rise would be substantial and continue to rise for centuries to come.
Whale populations, still recovering from centuries of hunting, continue to face a myriad of threats. But it’s often a surprise that one of the leading causes of death among whales around the globe is ship strikes. Now researchers are concerned that blue whales — the largest animals that have ever lived on the planet — are especially vulnerable to ship strikes in the Indian Ocean, according to the New York Times: