Dolphin Deaths in Gulf of Mexico – “Perfect Storm” of BP Oil Spill and Cold Water

A C-130 Applies Dispersants During the BP Deepwater Horizon Oil Spill (USCG Photo)

A C-130 Applies Dispersants During the BP Deepwater Horizon Oil Spill (USCG Photo)

In a study published in PLos ONE, investigators studied a large die-off of dolphins in the Northern Gulf of Mexico. During the first four months of 2011, 186 bottlenose dolphins, 86 of which were very young perinatal calves, washed ashore from Louisiana to western Florida. For perinatal dolphins, this stranding rate was nearly 6 times higher than the average number of perinatal strandings in the region during the previous 8 years and nearly twice the historical percentage of total strandings. These dolphin deaths represent the largest marine mammal mortality event in the Northern Gulf of Mexico since 2004, when a red tide killed more than 100 bottlenose dolphins off the Florida panhandle.

What killed so many dolphins? Investigators point to a “perfect storm” of dolphins weakened by the BP oil spill, then killed by colder-than-normal water in the Gulf that took its toll on a vulnerable dolphin population. [Read more…]

Fertilizing the Oceans with Iron Sinks Carbon, But is it a Good Idea?

The Eddy and the Plankton

“The Eddy and the Plankton” A massive plankton bloom observed from space. (Image: NASA Earth Observatory via Flickr)

It’s a controversial idea that has been around for decades. Stimulate the growth of phytoplankton (plant plankton) in remote reaches of the oceans by fertilizing the oceans with iron. Previous studies concluded that such an approach would not be effective. However, the recent analysis of a 2004 ocean fertilization experiment in the Southern Ocean — published in the journal, Nature — shows that use of iron fertilization did stimulate the growth of phytoplankton, which sank into the deep sea after the algae died, serving as a “carbon sink” in the deep where the carbon would be held out of the atmosphere for centuries. [Read more…]

Study: More Than 90 Percent of Dead Pacific Northwest Seabirds in Pacific Northwest Had Ingested Plastic

Northern Fulmar

A pair of northern fulmars (Photo: annecarringtoncotton via Flickr)

There is great concern about the impacts of plastics on marine wildlife in the Pacific, but much of the focus has been in tropical regions like the Northwestern Hawaiian Islands. A new study in Marine Pollution Bulletin and reported by Discovery News shows that plastics are impacting seabird populations in the Pacific Northwest as well, a region that researchers have compared to the highly-polluted North Sea with respect to plastic pollution.


[Read more…]

Do Dolphins Hunt with Mathematics?

White Spinner Dolphin, Kona Hawaii

White Spinner Dolphin (Photo: SteveD. via Flickr)

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…]

Aquarius — World’s Last Undersea Lab — Loses Funding, Faces Decommisioning

Aquarius Reef Base

Aquarius Reef Base (Photo: NOAA)

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.

[Read more…]

Judge Approves $880 Million Everglades Restoration

Everglades National Park

The Everglades (Photo: slack12 via Flickr)

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…]

Plastic Pollution Could Promote Interbreeding, Reduce Biodiversity

 

Red Shiner

Exposure to Bisphenol A (BPA) from plastic pollution could accelerate interbreeding of native species with exotic species, like the red shiner (pictured). (Image by TimeScience via Flickr)

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.

…More at Plastic ingredient makes fish court other species (New Scientist)

The U.S. Food and Drug Administration rejected calls to ban BPA from all plastic food containers earlier this year.

Where Sea Turtles and Fishing Boats Meet

Baula en el Caribe

A leatherback sea turtle hatchling makes its way to the sea (Image by Jual via Flickr)

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.)

…Read the full story at A satellite study pinpoints danger zone where leatherbacks and fishing trawlers meet. (Scientific American)

Rapid Rise of Ocean Acidity Surprises Scientists

Helpful

The speed with which acid levels have risen in the oceans has “caught scientists off-guard.” (Image by B Tal via Flickr)

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

Coral Reefs Collapsed, then Recovered After 2,500 Years

Encouraging or Saddening?

Image by nashworld via Flickr

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…]