Tag: ecology

Sending Invasive Species to Mars

George Dvorsky summarizes a new study showing six types of bacteria found in Siberia are able to survive, and even thrive, under Mars-like conditions.

The researchers took these cultures [from Siberian permafrost] and exposed them to similar conditions found on Mars, including a severe lack of oxygen, extreme cold temperatures, and very low pressure (about 150 times lower than the Earth’s, about 7 millibars). The experiment was run over the period of 30 days. Over 10,000 isolates were exposed to these conditions — and they all died.

Except six.

And in fact, these six surviving microbes actually did better under these conditions. Surprised by the result, the researchers took a closer look at the survivors, and following a genetic analysis concluded that they all came from the same genus: an extremely hardy extremophile called Carnobacterium.

— Dvorsky (2012): Scientists show that microbes from Earth can survive conditions found on Mars in io9.

So now we have to wonder if we’ve already, inadvertently, sent life to Mars.

Semi-artificial Selection?

Just like drug resistant germs (we’ve discussed earlier), the rats are evolving.

“They’ve also mutated genetically and are bred to be immune to standard poisons.

“We have had to start using different methods such as trapping and gassing, which can be less effective and more costly.”

–Graham Chappell, from Rapid Pest Control in Newbury in Rowley (2012): Home counties demand stronger poison to deal with mutant ‘super rats’ in The Telegraph.

Cranberries and Climate Change

The problem with global climate change and agriculture not only that it will probably make it harder to grow crops as the continents dry, but also that where you can grow thing will also change as ecological regions shift. Places where there are long traditions of crops such as sugar maples and cranberries will have to adapt, and often, adapting isn’t easy. This article from Marketplace looks at cranberries in Massachusetts.

Eating Frankenfish

Ian Simpson has an interesting article on the movement to reduce the numbers of the invasive snakehead fish more appealing to restaurants and their customers.

[Snakeheads have] dense, meaty, white flesh with a mild taste that is ideal for anything from grilling to sauteing.

…

[But] the fish are air breathers that can last for days out of water. Even when gutted and with their throats cut, they gape for breath, said John Rorapaugh, director of sustainability and sales at ProFish, a Washington wholesaler.

“Once they get to mature size, they are on top of the food chain and are ravenous,” he said.

…

Josh Newhard, an expert on the snakehead with the U.S. Fish and Wildlife Service, said it was too early to say what the snakehead’s long-term impact would be on its invaded environment. … “The potential is really high for them to impact other fish species. The fact that people want to remove them from the system is really good,” he said.

–Simpson (2012): U.S. chefs’ solution for invading Frankenfish? Eat ’em from Reuters via Yahoo! News.

My middle-school students are reading Janet Kagan’s short story, “The Loch Moose Monster” as part of our discussion about genetics, ecology and educational environments. This article makes a nice complement.

And the Snakes Ate the Birds who Ate the Spiders

The introduction of snakes to Guam has reverberated through the ecosystem.

Accidentally introduced to the island in the 1940s, the snake decimated the island’s native bird species in one of the most infamous ecological disasters from an invasive species.

By the 1980s, 10 of 12 native bird species had been wiped out.

Since many birds consume spiders, compete with spiders for insect prey and utilize spider webs in their nests, their loss has led to a spider explosion on the island, researchers said.

UPI (2012): Bird loss has island overrun with spiders

Note (for the Algebra students): The scientific article includes a nice box and whisker plot showing how many more spiderwebs there are on Guam compared to other islands.

Number of spider webs on different islands. Guam is the only island shown that has had a severe reduction in birds. Image from Rogers et al., 2012.

Microbe from the Creek

Microbe collected from the TFS Creek on 9/10/2012. Possibly a species of desmid.

The TFS campus has an excellent ecological gradient. It starts at the hydrologic base-level, with the small, usually permanent, creek in the valley. Then the landscape ranges up, past a narrow but dense riparian zone to the anthropomorphic campus, then up a shrub-covered hillslope that transitions abruptly into the advancing, mature, forest of the hill-top nature reserve. My environmental science class is taking advantage of our geographic proximity by doing a year-long ecological survey project.

We’ve just started, this fall, on the stream and riparian zone. I asked each of them to identify and do some research on a single organism. They all chose some type of macro-organism: spiders, crayfish, flowering herbs (note: just because it’s called an herb does not mean it’s edible), mushrooms, and more. There’s quite a bit of biodiversity down there, although, with the creek just now coming back from our particularly dry summer, the fish are few and far between.

Close-up view of the micro-organism under 1000x magnification (oil immersion lens).

Since no-one chose to look for micro-organisms — even though I did suggest they were an important part of the ecology — I decided do so myself.

I found a loosely held together patch of algae, which I collected with the hope that it would harbor its own little microscopic ecological system. And it did. There were amoebas zipping around, the filamentous algae itself, and these little organisms that I can’t quite identify yet. T

hey may be desimids, but I’m not sure. They look slightly green, but I can’t see any clear chloroplasts (like these). I’ll try staining them tomorrow to see if I can identify any organelles.

A terrible picture "showing" the patch of fillamentous algae I collected from the creek.

Ecological Footprints: If the World Lived Like …

What if the entire world population lived like the people in Bangladesh? The amount of land to produce the resources we’d need would take up most of Asia and some of Africa. On the other hand, if we lived like the people in the UAE we’d need 5.4 Earths to support us sustainably. That’s the result of Mathis Wackernagel’s work (Wackernagel, 2006) comparing resource availability to resource demand. Tim De Chant put this data into graphical form:

Ecological footprints needed to support the world population if everyone used resources at the rate of these different countries. Image by Tim De Chant, based on data from Wacknagel (2006).

I showed this image in Environmental Science class today when we talked about ecological footprints, as well as the one showing how much space the world population of seven billion would take up if everyone lived in one big city with the same density of a few different cities (Paris, New York, Houston etc.).

Wacknagel’s original article also includes this useful table of data for different countries that I think I’ll try to get a student to put into bar graph for a project or presentation.

Data from Wackernagel (2006).

↬ Zoë Pollock at The Dish

A Darwinian Debt

Evidence is mounting that fish populations won’t necessarily recover even if overfishing stops. Fishing may be such a powerful evolutionary force that we are running up a Darwinian debt for future generations.

— Loder (2006), Point of No Return in Conservation in Practice.

Darwinian Debt. That’s the elegant phrase Natasha Loder (2006) uses to describe the observation that human pressure on the environment — fishing in this particular example — has forced evolutionary changes that are not soon reversed.

Fishermen prefer to catch larger fish, depleting the population of older fish, and allowing smaller fish to successfully reproduce. Over a period of years this artificial selection — as opposed to natural selection — gives rise to new generations of fish that are permanently smaller than they used to be. And the fisheries find it hard to recover even after decades (Swain, 2007):

Populations where large fish were selectively harvested (as in most fisheries) displayed substantial declines in fecundity, egg volume, larval size at hatch, larval viability, larval growth rates, food consumption rate and conversion efficiency, vertebral number, and willingness to forage. These genetically based changes in numerous traits generally reduce the capacity for population recovery.

— Walsh et al., 2005, Maladaptive changes in multiple traits caused by fishing: impediments to population recovery in Ecology Letters.