Discovery News: Environmental

Nemo's Nose

Today Discovery News published an article about research showing how orange clownfish follow the smell of leaves and anemones, presumably to find their way back to the reef anemones they live within.

The researchers recorded how much time each fish spent on either side of a chamber where each side contained water from different sources. This allowed them to measure the fishes' preference for different-smelling water. (Read the details here.)

Above is a video from Jelle Atema of Boston University, who developed the chamber, showing how the experiment works.

He tested a juvenile blue damsel fish with water from its home reef and from a reef 15 miles away. Watch how the fish switches sides when Atema swaps which side carries the familiar water. The fish quickly swims back into its homey water.

The researchers in the study described today observed similar behavior with the clownfish they studied.

I particularly enjoyed reporting on this research because it was such a great example of the scientific method.

The experiments were as simple as a school science fair project in their straightforward comparisons: No particle accelerators or DNA extractions required. But the tests were clever and the results were clean.

What was incredibly striking is just how strong the fishes' preferences were. When presented with beach water, anemone-scented water, or rainforest-leaf-scented water, the fish spent anywhere from 89 to 98 percent of their time in those waters compared with what you might call "unscented" water. When offered water laced with the scent of an unfamiliar tree leaf, all of the fish scooted out of it immediately, spending 100 percent of the time in the neutral water.

This struck me because when I was in college, I took a class in behavioral ecology where we had to try to measure some aspect of guppy behavior for a class project. We were each given a dozen guppies and a wading pool and sent back to our dorm rooms to run an experiment.

Our groups' experiment was to see whether the size of a guppy school affected how fast the guppies found food. We put six little feeding stations (fish flakes floating inside loops made of drinking straws) around the perimeter of the pool and released schools of 1, 2, 4, 6 and 12 fish, and timed how long it took them to find food in the station that was stocked with food (randomly selected by rolling a die).

The problem was, first of all, that we didn't get the experiment done before winter break. So, we decided that I would carry the guppies home on the airplane and do the experiment in my parents' basement. We figured I could just buy a kiddie pool when I got home.

Somehow, it didn't occur to us that NOBODY sold wading pools in December in Colorado.

Then, one of the guppies gave birth and died, so I went to the pet store to replace the guppy with another grownup. Pregnancy might have been a confounding factor anyway.

After borrowing a wading pool from some neighbors, I retreated to the basement for the guppy time trials ... which failed miserably. The fish just swam around. There was no real trend, and I didn't really have time to make sure the guppies got hungry again in between searches, so who knows what they were looking for.

The whole experience (which, I should add, followed a project earlier in the semester for which I chased squirrels around a campus lawn trying to monitor their nut-caching behavior) convinced me that trying to make quantitative measurements of animal behavior was impossible, or at the very least would lead to several decades in graduate school waiting for animals to get hungry again.

So that's why I took note that the Jones' groups fish time trials come out so cleanly... I guess I should have realized that all those animal research journals weren't just reporting on aimless guppy wandering, so there must be better observations to be made. Still, it's great that this group for found such opinionated fishes.

(Video: Jelle Atema, Boston University)

Bat Cam

Check out these cool, eerie infrared videos of bats circling wind turbines in the dark.

(A bat repeatedly investigates and briefly lands on the turbine tower while the rotor spins slowly.)

Here's the story:

We reported today on a study showing that the cause of many mysterious bat deaths near wind turbines is not slamming into the blades, as you might expect (except that bats have that whole echolocation thing, so they are pretty good at locating moving objects in the dark)... but rather that their lungs more-or-less pop if they fly through zones of rapid pressure drop near the blades, which causes the air in the lungs to expand rapidly like a scuba diver surfacing too fast. Sad.

Researchers have been trying to figure out what is behind these deaths for a while, and Ed Arnett of Bat Conservation International and the Bat and Wind Energy Cooperative thinks the problem is exacerbated because the bats are attracted to the wind turbines, maybe because of sounds the turbines make, or because they look a bit like the trees bats might roost in.

To try to better understand the bats' behavior around turbines, Arnett and colleagues at Boston University set up thermal infrared cameras at the base of the windmills (can I call them windmills or is that  déclassé?)

According to Arnett, the results of the videos show the bats checking out the turbines. "They go up and investigate the turbines. We've got pictures of them chasing the blade tips."

The videos can't tell the researchers why, but check them out for yourself (more below). You can also read the study that goes with them at the same link.

( A bat investigates moving blades.)

(A bat investigates the turbine tower (monopole), showing typical 'touch-and-go' behavior.)

(One or more bats repeatedly investigate the turbine blades and tower (monopole).)

(Videos: Jason Horn and Bat Conservation International)

Organic Motivations

CNN carried a story about a study concluding that organic produce does not contain more nutrients than the same five fruits and veggies (carrots, kale, mature peas, apples and potatoes) conventionally grown.

That is certainly a bummer for the organic food industry, which would no doubt like to make nutrition claims about the food. But, Michaeal Pollan, in The Omnivore's Dilemma, cites a similar 2003 UC Davis study that found corn, strawberries and blackberries grown organically had more vitamin C and polyphenols than conventionally grown ones in neighboring plots. So, does it vary from plant to plant, place to place, or is something else going on?

More to the point, I don't think most people buy organic food because they believe it has more vitamins. I think they do it because they don't want to risk eating food with any pesticide residues. They may also do it because they want to reduce the amount of pesticides and petrochemical fertilizer entering the environment, or because they want to support agricultural practices in which the workers aren't exposed to such chemicals.

As with so many things, though, organic farming is not an across-the-board win. Sigh. The CNN story mentions a 2006 report by the University of Manchester Business School investigating the environmental impacts of food. While organic food used less pesticide, the land requirements were often greater--presumably because the crop yield was reduced.

The energy requirements for organic milk were less than conventional, but the land use was greater, and the greenhouse gas emissions per gallon were higher for organic. And, according to the study summary, "organic wheat production has higher impact than non-organic," mainly because its eutrophying emissions are higher.

This is just one example of why shopping these days is such a paralyzing experience: when choosing which apple to buy becomes a trade off between deforming the local frogs or drowning the polar bears, it feels easier to go hungry.

Fortunately, Consumer Reports offers some advice on which fruits and veggies are worth buying organic--at least from a pesticide perspective.

(Image: Flickr user Scoobymoo. Some rights reserved.)

Sex in Acid Has Low Returns

You've probably heard that ocean acidification is predicted to cause problems for calcifying sea critters, like certain plankton, which are anticipated to have trouble building their calcium carbonate skeletons in lower pH seas.

Research published today in Current Biology uncovers another possible problem with a more acidic future ocean: sperm-meets-egg may not work as well. At pH levels predicted for the end of this century, Jon Havenhand of Sweden's University of Gothenburg and colleagues found sea urchin sperm swam more sluggishly (that is, both speed and motility were significantly reduced.) They also found a 26 percent reduction in the number of eggs that developed into swimming larvae under such conditions.

Havanhand expects his results will apply to fertilization in other ocean species. "Of course, this is a fairly sweeping extrapolation, and many more data are required before we can say anything definitive on the topic," Havenhand told Discovery News. "However as a first look at the effects of acidification on fertilization in marine invertebrates, this doesn't paint an encouraging picture!"

Energy From Water

Two papers published in today's issue of Science announce breakthroughs in making cheap solar energy a reality.

A big problem with getting energy from the sun has been that the sun doesn't shine all the time, at least down where we are.

Plants get around this by harnessing the sun's energy to split water into hydrogen and oxygen and using the energy in these molecules to make storable sugars. The plants can break these down later, come rain or shine, releasing the stored energy.

Researchers have tried to make this process work without plants, by using catalysts to split water into hydrogen and oxygen and then using a fuel cell to recombine the stored hydrogen and oxygen later to make water and energy. But making this work has required harsh conditions and expensive materials. The new papers get around these problems by finding new catalysts, opening the door to 'round the clock solar energy.

The first paper uses a cheap cobalt-phosphate catalyst to create oxygen from water, and the second gets around the expensive platinum catalyst needed for the hydrogen side of the process, replacing it with one made from organic materials.

There's plenty of development to do to take the process from lab to the real world, but the researchers are clearly fired up about it, and others in the field are, too. Read some more about it:here, here, and here.

(Image: New oxygen catalyst in action, credit: MIT/NSF)