Exam #2, F 3/5 in class Q&A Th 3/4 from 5-7pm in PAI 3.02 Homework #3 due 3/3 Homework #4 in class on W 3/3

Human vs Natural Disturbances

Chernobyl fire April 26, 1986

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

Increased childhood thyroid cancer in the heavily contaminated areas of Belarus, Ukraine and Russia. 4 years

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.

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 /21/ Many human tragedies have been a boon for native animal species:

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 /21/1995

In 2005 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 /04/0426_060426_chernobyl_2.html

In researchers found increased physiological stress in barn swallows living in the most contaminated areas Increased oxidative stress in barn swallows from the Chernobyl region A Bonisoli-Alquatia, T Mousseau, A Pape Møllec, M Capriolia, N Sainoa (2010) Comparative Biochemistry and Physiology - Part A: Molecular & Integrative Physiology Volume 155, Issue 2, pg

Reduced abundance of insects and spiders linked to radiation at Chernobyl 20 years after the accident Anders Pape Møller and Timothy A. Mousseau in Biol. Lett. 23 June 2009 vol. 5 no

Fig 2. Biol. Lett. 23 June 2009 vol. 5 no bees butterflies grasshoppersdragonfliesgrasshoppers spiders

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

Fig. 3. Morphological changes in pine trees grown on the radioactive burial sites. (A) Absence of needles; (B) giant needles, general growth depression; (C) ‘bushy crown’, disturbance of shoot orientation. Genome hypermethylation in Pinus silvestris of Chernobyl—a mechanism for radiation adaptation? (2003) O Kovalchuk, P Burke, A Arkhipov, N Kuchma, S J James, I Kovalchuk, I Pogribny in Mutation Research/Fundamental and Molecular Mechanisms of Mutagenesis 529: Pine trees in the most contaminated zones have modified their DNA, and grow weirdly

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 sexually Speciesnormal lakeChernobyl lake Nais pardalis5%22% Nais pseudobtusa10%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 low genetic diversity greater genetic diversity vs. Asexual Reproduction Sexual Reproduction

The worms may have switched to sexual reproduction in an attempt to protect themselves from the radiation. Percent of individuals reproducing sexually Speciesnormal lakeChernobyl lake Nais pardalis5%22% Nais pseudobtusa10%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

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 3/5 in class Q&A Th 3/4 from 5-7pm in PAI 3.02 Homework #3 due 3/3 Homework #4 in class on W 3/3