•Exam #2 F 6/27 in class (bring cheat sheet)•In class exercise tomorrow, please bring your laptop if possible.

CB 55.13

Not all habitats are equal

How do stable ecosystems develop?

Primary Succession- the first organisms to colonize bare rock

Secondary Succession- recovery from a disturbance

Primary Succession- from non-living to living

CB 53.23Primary succession as this glacier retreats

Primary Successionafter glacier retreat,150-300 years

CB 53.24

Primary Succession: each stage helps enable the next

1 2

3

4 5

Primary succession after a volcanic eruption

CB 53.22

Secondary Succession: after a fire

CB 53.21

Grassland biodiversity and biomass are increased by regular burns

Secondary Succession of a field(20 yrs)

CB 55.21Human vs Natural Disturbances

Chernobyl fireApril 26, 1986

http://video.google.com/videoplay?docid=1108163171078608385

The Chernobyl accident was by far the largest unintentional release of radioactive material into the environment and caused widespread contamination in Europe.

After the accident on April 26, 1986, ~116,000 people were evacuated, most from a zone of 30-km radius. That included about 45,000 people from the town of Pripyat.

The most heavily exposed emergency workers received doses that were sufficiently high to kill them in the weeks and months after the accident.

Chernobyl April 26, 1986

Cancer consequences of the Chernobyl accident: 20 years on J. Radiological Protection26 (2006) 127–140Elisabeth Cardis et al.

Mitosis

Cancer: Cell Division Gone Wrong

CB 19.14

Multiple mutations are required for a single cell to become cancerous.

Environment plays a large role in the chance of contracting cancer.

The rapidity of increased childhood thyroid cancer in the heavily contaminated areas of Belarus, Ukraine and Russia was surprising.

4 years

The issue of the effects on health of the Chernobyl accident has become part of the political debate over the future role of nuclear energy, which has inevitably led to dispute over the level of effects either observed or anticipated.

After the accident on April 26, 1986, ~116,000 people were evacuated, most from a zone of 30-km radius. That included about 45,000 people from the town of Pripyat.

For more pictures: http://www.nikongear.com/Chernobyl/Chernobyl_1.htm

What about non-human inhabitants?

turtle in exclusion zone

The 30-km radius exclusion zone

Initially many organisms died from the huge doses of radiation they received.

The red color of withered pine needles earned one large area near the reactor the name Red Forest.

"Now it is not the Red Forest but a real green forest, due to [growing] birch trees," said Sergey Gaschak from the International Radioecology Laboratory in Kiev, Ukraine.

Science v. 269 pg. 304 7/21/1995

http://earthobservatory.nasa.gov/Newsroom/NewImages/images.php3?img_id=15362

Many human tragedies have been a boon for native animal species:

http://earthobservatory.nasa.gov/Newsroom/NewImages/images.php3?img_id=15362

Korean DMZ: Among the species making their homes in the DMZ are endangered Asian cranes, black-faced spoonbills, angora goats, Amur leopards, and even bears.

Savanah River nuclear site in Georgia:forest remnant

And in the towns where humans have moved out, plants and animals have moved in.

Background radiation levels near the Chernobyl reactor are 3000 times higher than near the Savannah River nuclear reactor

Science v. 269 pg. 304 7/21/1995

Late last year Moller and Mousseau published a paper in the Journal of Animal Ecology showing that reproductive rates and annual survival rates are much lower in the Chernobyl birds than in control populations.

"In Italy around 40 percent of the barn swallows return each year, whereas the annual survival rate is 15 percent or less for Chernobyl.

Mutation isn't the only adverse effect of the radiation. Working in the Red Forest area, James Morris, a USC biologist, has observed some trees with very strange twisted shapes.

The radiation, he says, is confusing the hormone signal that the trees use to determine which direction to grow.

"These trees are having a terrible time knowing which way is up," Morris said.

Unusual growth in “Red Forest” pine trees

Worms contaminated by radioactivity from the Chernobyl nuclear accident have started having sex with each other instead of on their own. According to Ukrainian scientists, they may have changed their sexual behaviour to increase their chances of survival.

Journal of Environmental Radioactivity, vol 66, p 141

Two worm species switched from asexual to sexual reproduction.

Percent of individuals reproducing sexuallySpecies normal lake Chernobyl lakeNais pardalis 5% 22%Nais pseudobtusa 10% 23%

The lakes had similar temperatures and chemical composition, but the worms in the Chernobyl lake had received 20 times as much radiation as those in the other lake.Journal of Environmental Radioactivity, vol 66, p 141

extremely lowgenetic diversity

greater geneticdiversity

vs.Asexual Reproduction

SexualReproduction

The worms may have switched to sexual reproduction in an attempt to protect themselves from the radiation.

Journal of Environmental Radioactivity, vol 66, p 141

The most recent count by the authorities showed that the zone (including a larger contaminated area in neighbouring Belarus) is home to 66 different species of mammals, including 7,000 wild boar, 600 wolves, 3,000 deer, 1,500 beavers, 1,200 foxes, 15 lynx and several thousand elk.

The area is also estimated to be home to 280 species of birds, many of them rare and endangered. Breeding birds include the rare green crane, black stork, white-tailed sea eagle and fish hawk.

But Mousseau is less optimistic. "One of the great ironies of this particular tragedy is that many animals are doing considerably better than when the humans were there," he said.

"But it would be a mistake to conclude they are doing better than in a control area. We just don't know what is normal [for Chernobyl]. There just haven't been enough scientific studies done."

•Exam #2 F 6/27 in class (bring cheat sheet)•In class exercise tomorrow, please bring your laptop if possible.