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Asian Carp Report Highlights Urgent Need to Save the Great Lakes from Invasion

Asian Carp Report Highlights Urgent Need to Save the Great Lakes from Invasion

EcoWatch

Asian Carp in the Shedd Aquarium, Chicago. Photo by Kate Gardiner via Flickr.

Fisheries and Oceans Canada released a binational risk assessment of Asian carp today detailing the potential threat an invasion imposes on the Great Lakes. The conclusions point to a severe disruption of established ecosystems and re-emphasize an urgency for the federal government to act quickly to mitigate the threat, which thus far it has not.

“This report confirms that the stakes are too high for failure,” said Jennifer Nalbone, director of Navigation and Invasive Species for Great Lakes United. “If Asian carp invade, Canadian and U.S. waters will be changed forever.”

“Both countries must support and implement the best protection from an invasion and break the artificial connection between the Mississippi and Great Lakes basins in the Chicago area,” said Nalbone. “If water doesn’t flow between the two watersheds, this damaging fish can’t swim in.”

“The report underscores the severity of the Asian carp threat and the need for leadership so that we can solve the problem once and for all,” said Andy Buchsbaum, director of National Wildlife Federation's Great Lakes office. “The Asian carp are moving toward the Great Lakes far faster than the government response, and this report shows that the cost of inaction will be devastating. President Obama and Gov. Romney need to declare that they will take the necessary action to build an effective physical barrier to keep the Asian carp out of the Great Lakes," he said.

Some of the report's key findings include (from the Fisheries and Oceans Canada website):

  • The most likely entry point into the Great Lakes basin is the Chicago Area Waterway System (CAWS) into Lake Michigan. The effectiveness of the electrical barrier in the Chicago Sanitary and Ship Canal (CSSC) was not evaluated. Nevertheless, the complex nature of the CAWS and proximity of bigheaded carp populations led to the conclusion this is the most likely entry point.
  • Once bigheaded carps have gained entry into the basin, they are expected to spread to other lakes within 20 years. The spread will be more rapid for lakes Michigan, Huron and Erie, and potentially Lake Superior; longer for Lake Ontario.
  • Bigheaded carps would find suitable food and thermal and spawning habitats in the Great Lakes basin that would allow them to survive and become established. The areas that would be attractive and favorable are Lake Erie, including Lake St. Clair, and high productivity embayments of lakes Superior, Michigan, Huron and Ontario.
  • There is a greater than 50 percent probability of successful mating each year with very few (< 10) adult females (and a similar number of adult males) within the basin of a Great Lake.
  • Population growth is most sensitive to the survivorship of juveniles.
  • The consequences of an established bigheaded carp population are expected to include changes in planktonic communities, reduction in planktivore biomass, reduced recruitment of fishes with early pelagic life stages and reduced stocks of piscivores.
  • To reduce the probability of introduction (either at the arrival, survival, establishment or spread stage) and delay or reduce subsequent ecological consequences, immediate prevention activities would be most effective, especially in conjunction with population management activities at the invasion front.

Visit EcoWatch's BIODIVERSITY page for more related news on this topic.

 

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A net-casting ogre-faced spider. CBG Photography Group, Centre for Biodiversity Genomics / CC BY-SA 3.0

Just in time for Halloween, scientists at Cornell University have published some frightening research, especially if you're an insect!

The ghoulishly named ogre-faced spider can "hear" with its legs and use that ability to catch insects flying behind it, the study published in Current Biology Thursday concluded.

"Spiders are sensitive to airborne sound," Cornell professor emeritus Dr. Charles Walcott, who was not involved with the study, told the Cornell Chronicle. "That's the big message really."

The net-casting, ogre-faced spider (Deinopis spinosa) has a unique hunting strategy, as study coauthor Cornell University postdoctoral researcher Jay Stafstrom explained in a video.

They hunt only at night using a special kind of web: an A-shaped frame made from non-sticky silk that supports a fuzzy rectangle that they hold with their front forelegs and use to trap prey.

They do this in two ways. In a maneuver called a "forward strike," they pounce down on prey moving beneath them on the ground. This is enabled by their large eyes — the biggest of any spider. These eyes give them 2,000 times the night vision that we have, Science explained.

But the spiders can also perform a move called the "backward strike," Stafstrom explained, in which they reach their legs behind them and catch insects flying through the air.

"So here comes a flying bug and somehow the spider gets information on the sound direction and its distance. The spiders time the 200-millisecond leap if the fly is within its capture zone – much like an over-the-shoulder catch. The spider gets its prey. They're accurate," coauthor Ronald Hoy, the D & D Joslovitz Merksamer Professor in the Department of Neurobiology and Behavior in the College of Arts and Sciences, told the Cornell Chronicle.

What the researchers wanted to understand was how the spiders could tell what was moving behind them when they have no ears.

It isn't a question of peripheral vision. In a 2016 study, the same team blindfolded the spiders and sent them out to hunt, Science explained. This prevented the spiders from making their forward strikes, but they were still able to catch prey using the backwards strike. The researchers thought the spiders were "hearing" their prey with the sensors on the tips of their legs. All spiders have these sensors, but scientists had previously thought they were only able to detect vibrations through surfaces, not sounds in the air.

To test how well the ogre-faced spiders could actually hear, the researchers conducted a two-part experiment.

First, they inserted electrodes into removed spider legs and into the brains of intact spiders. They put the spiders and the legs into a vibration-proof booth and played sounds from two meters (approximately 6.5 feet) away. The spiders and the legs responded to sounds from 100 hertz to 10,000 hertz.

Next, they played the five sounds that had triggered the biggest response to 25 spiders in the wild and 51 spiders in the lab. More than half the spiders did the "backward strike" move when they heard sounds that have a lower frequency similar to insect wing beats. When the higher frequency sounds were played, the spiders did not move. This suggests the higher frequencies may mimic the sounds of predators like birds.

University of Cincinnati spider behavioral ecologist George Uetz told Science that the results were a "surprise" that indicated science has much to learn about spiders as a whole. Because all spiders have these receptors on their legs, it is possible that all spiders can hear. This theory was first put forward by Walcott 60 years ago, but was dismissed at the time, according to the Cornell Chronicle. But studies of other spiders have turned up further evidence since. A 2016 study found that a kind of jumping spider can pick up sonic vibrations in the air.

"We don't know diddly about spiders," Uetz told Science. "They are much more complex than people ever thought they were."

Learning more provides scientists with an opportunity to study their sensory abilities in order to improve technology like bio-sensors, directional microphones and visual processing algorithms, Stafstrom told CNN.

Hoy agreed.

"The point is any understudied, underappreciated group has fascinating lives, even a yucky spider, and we can learn something from it," he told CNN.

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