What are the LONG-TERM effects of the chernobyl/FUKUSHIMA disasters on biodiversity in neighbouring areas?
We will be exploring the effects of radiation on biodiversity in Fukushima as a point of comparison to the ecological changes that occurred in Chernobyl as a consequence of the 1986 nuclear disaster.
It must be noted that biologists were unable to collect specimen samples from the site of the disaster till many months after the Chernobyl event. In Fukushima, on the other hand, scientists began data extraction very soon after having seen the effect of the delay on data collection and the loss of vital information at Chernobyl.
The generally accepted hypothesis about the effects of chronic exposure to ionising radiation would suggest that extended periods of exposure leads to an increased rate of mutation and genetic damage, both in somatic and germ cell lines of most species. A 1927 study done by Nobel prize-winning geneticist Hermann Joseph Muller provides concrete evidence for this hypothesis and proves that ‘ionising radiation causes genetic damage, and that the vast majority of such variations are likely to be deleterious’.
It must be noted that biologists were unable to collect specimen samples from the site of the disaster till many months after the Chernobyl event. In Fukushima, on the other hand, scientists began data extraction very soon after having seen the effect of the delay on data collection and the loss of vital information at Chernobyl.
The generally accepted hypothesis about the effects of chronic exposure to ionising radiation would suggest that extended periods of exposure leads to an increased rate of mutation and genetic damage, both in somatic and germ cell lines of most species. A 1927 study done by Nobel prize-winning geneticist Hermann Joseph Muller provides concrete evidence for this hypothesis and proves that ‘ionising radiation causes genetic damage, and that the vast majority of such variations are likely to be deleterious’.
Our Background research
1. How did the explosion affect the surrounding area?
A. Radiation
i. When the radioactive material exploded out of reactor 4, it did not coat the surrounding area uniformly, meaning that certain patches of land were exposed to more radioactive material than others. The amount of nuclear material that animals were exposed to depended on the species, where it lived (in trees, underwater, underground) and the distribution of radiation.
ii. The distribution of radioactive particles is constantly changing due to radioactive decay and environmental/landscape changes. This makes it difficult to accurately measure the effects of the radiation.
1. How did the explosion affect the surrounding area?
A. Radiation
i. When the radioactive material exploded out of reactor 4, it did not coat the surrounding area uniformly, meaning that certain patches of land were exposed to more radioactive material than others. The amount of nuclear material that animals were exposed to depended on the species, where it lived (in trees, underwater, underground) and the distribution of radiation.
ii. The distribution of radioactive particles is constantly changing due to radioactive decay and environmental/landscape changes. This makes it difficult to accurately measure the effects of the radiation.
2. EFFECTS ON ANIMALS
A. Effect on population (Chernobyl)
i. Recent studies surrounding the populations of wild animals living in Chernobyl and Fukushima shows notable genetic, physiological, developmental and fitness effects due to exposure to radioactive contaminants. The studies conducted showed increased rates of genetic damage and mutation rates in birds, bees, butterflies, grasshoppers, dragonflies, spiders, mammals, as well as reduced population sizes in especially radioactive parts of the Chernobyl Exclusion Zone.
i. Recent studies surrounding the populations of wild animals living in Chernobyl and Fukushima shows notable genetic, physiological, developmental and fitness effects due to exposure to radioactive contaminants. The studies conducted showed increased rates of genetic damage and mutation rates in birds, bees, butterflies, grasshoppers, dragonflies, spiders, mammals, as well as reduced population sizes in especially radioactive parts of the Chernobyl Exclusion Zone.
B. Effect on population (Fukushima)
ii. There was considerable variation in their apparent sensitivity to radiation and this reflects in part life history, physiology, behaviour, and evolutionary history. Interestingly, for birds, population declines in Chernobyl can be predicted by historical mitochondrial DNA base-pair substitution rates that may reflect intrinsic DNA repair ability.
ii. In Fukushima, population censuses of birds, butterflies, and cicadas suggested that abundances were negatively impacted by exposure to radioactive contaminants. however, groups such as dragonflies, grasshoppers, bees and spiders did not react in a similar way. Groups such as mammals cannot be accounted for, as there is inadequate data. The contrasts detected between Chernobyl and Fukushima may reflect the different times of exposure and the significance of multigenerational mutation accumulation in Chernobyl compared to Fukushima.
ii. There was considerable variation in their apparent sensitivity to radiation and this reflects in part life history, physiology, behaviour, and evolutionary history. Interestingly, for birds, population declines in Chernobyl can be predicted by historical mitochondrial DNA base-pair substitution rates that may reflect intrinsic DNA repair ability.
ii. In Fukushima, population censuses of birds, butterflies, and cicadas suggested that abundances were negatively impacted by exposure to radioactive contaminants. however, groups such as dragonflies, grasshoppers, bees and spiders did not react in a similar way. Groups such as mammals cannot be accounted for, as there is inadequate data. The contrasts detected between Chernobyl and Fukushima may reflect the different times of exposure and the significance of multigenerational mutation accumulation in Chernobyl compared to Fukushima.
An image of a wild boar.
A map showing the Chernobyl exclusion zone.
C. Effect of the evacuation of human life on population growth.
The Chernobyl nuclear disaster appears to have been a blessing for the local wildlife by forcing the evacuation of human life. There may be radioactive particles, but there are no humans, no road building, no dam building, no deforestation, no farming, no hunting, no planes, trains or automobiles. And as a result, Chernobyl is quickly transforming into a wildlife refuge. Numbers of wild boar, deer, elk, wolf, fox, hare, and beavers have all increased significantly since the Chernobyl accident. Hundreds of species of vertebrate animals inhabit Pripyat and its surrounding area, 50 of which are protected species. The Exclusion Zone has become a breeding area for rare species such as the white-tailed and spotted eagles. So, while the negative health consequences of acute and chronic radiation are undeniable, evidently, they are less disruptive than the presence of human life.
The Chernobyl nuclear disaster appears to have been a blessing for the local wildlife by forcing the evacuation of human life. There may be radioactive particles, but there are no humans, no road building, no dam building, no deforestation, no farming, no hunting, no planes, trains or automobiles. And as a result, Chernobyl is quickly transforming into a wildlife refuge. Numbers of wild boar, deer, elk, wolf, fox, hare, and beavers have all increased significantly since the Chernobyl accident. Hundreds of species of vertebrate animals inhabit Pripyat and its surrounding area, 50 of which are protected species. The Exclusion Zone has become a breeding area for rare species such as the white-tailed and spotted eagles. So, while the negative health consequences of acute and chronic radiation are undeniable, evidently, they are less disruptive than the presence of human life.
3. Specific Species
In order to evaluate the effects of the nuclear disaster in Fukushima, it is worth looking at the specific changes in the genetic makeup of species that once inhabited the area and have either been displaced or forced to adapt to the high levels of radioactivity in the area around the plant.
A. Przewalski horses
Originally an endangered species; introduced to the Chernobyl Exclusion Zone (CEZ) in 1998, following the nuclear disaster in 1986. Given the lack of human intervention with the population in the CEZ, numbers have grown rapidly, with no adverse effects of radiation noted.
B. Barn Swallows and Voles
Research by TImothy Mousseau and A. P. Møller has revealed that the population of barn swallows was negatively affected by the nuclear disaster, with populations rapidly declining within the CEZ. This implies that certain species are unable to survive in the highly-radioactive habitat, resorting to migrating elsewhere or dying out through reduced reproduction. Similar negative health effects and mutagenesis was noted amongst small wild animals such as voles, resulting in a decline in health and population.
In order to evaluate the effects of the nuclear disaster in Fukushima, it is worth looking at the specific changes in the genetic makeup of species that once inhabited the area and have either been displaced or forced to adapt to the high levels of radioactivity in the area around the plant.
A. Przewalski horses
Originally an endangered species; introduced to the Chernobyl Exclusion Zone (CEZ) in 1998, following the nuclear disaster in 1986. Given the lack of human intervention with the population in the CEZ, numbers have grown rapidly, with no adverse effects of radiation noted.
B. Barn Swallows and Voles
Research by TImothy Mousseau and A. P. Møller has revealed that the population of barn swallows was negatively affected by the nuclear disaster, with populations rapidly declining within the CEZ. This implies that certain species are unable to survive in the highly-radioactive habitat, resorting to migrating elsewhere or dying out through reduced reproduction. Similar negative health effects and mutagenesis was noted amongst small wild animals such as voles, resulting in a decline in health and population.
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C. Spiders
Although the Chernobyl nuclear disaster caused an increase in the population of spiders within the exclusion zone, spiders have also shown signs of mutation. Spiders in the CEZ can be seen to create erratic and irregular webs, although besides this, no other negative effects on the spider population have been noted. |
D. Japanese Macaques
One species that has inhabited the region for at least 50 years prior to the event are the Japanese Macaques. Whilst the effects on existing adult macaques in the region is limited, macaque foetuses have exhibited some notable deformations, with many of the newly born macaques having smaller bodies overall, as well as having proportionally smaller heads and brains on top of this. Figure one shows the way in which the body weight of macaques has decreased, with the blue triangles representing the average body weight of macaques before the incident, and the red triangles representing the average body weight after.
Although the ecological composition of Chernobyl and Fukushima vary hugely, both regions are home to a certain type of swallow known as the ‘barn swallow’. One ecologist described the effects of radiation on this species as follows:
"The barn swallows in Fukushima are responding in the same way as what we've seen in Chernobyl. The young birds are not surviving. They are not fledging very well."
This mimics the response of macaques to long term exposure to radiation as it appears the ionising radiation most notably has consequences for the reproduction of different species as opposed to creating immediate and visible changes to existing individuals. This suggests that this increase in early mortality rates amongst barn swallows is not a product of the general environment but of the exposure to radiation following a nuclear disaster.
One species that has inhabited the region for at least 50 years prior to the event are the Japanese Macaques. Whilst the effects on existing adult macaques in the region is limited, macaque foetuses have exhibited some notable deformations, with many of the newly born macaques having smaller bodies overall, as well as having proportionally smaller heads and brains on top of this. Figure one shows the way in which the body weight of macaques has decreased, with the blue triangles representing the average body weight of macaques before the incident, and the red triangles representing the average body weight after.
Although the ecological composition of Chernobyl and Fukushima vary hugely, both regions are home to a certain type of swallow known as the ‘barn swallow’. One ecologist described the effects of radiation on this species as follows:
"The barn swallows in Fukushima are responding in the same way as what we've seen in Chernobyl. The young birds are not surviving. They are not fledging very well."
This mimics the response of macaques to long term exposure to radiation as it appears the ionising radiation most notably has consequences for the reproduction of different species as opposed to creating immediate and visible changes to existing individuals. This suggests that this increase in early mortality rates amongst barn swallows is not a product of the general environment but of the exposure to radiation following a nuclear disaster.
Our Experiment
In order to test the effect of radiation on an organism, we measured the background radiation count of the surroundings of a plant, while moving a light source away from it, as we are unable to physically visit either of the reaction sites in order to collect primary data.
Equipment
Independent variable
Control Variable
Method
Equipment
- Spathiphyllum plant (regular house plant)
- Geiger counter
- Timer
- Lux meter
- Light source
Independent variable
- Distance from the light source
- Null hypothesis - there is no statistically significant correlation between light intensity and radioactivity in an area.
- Alternate hypothesis - there is a statistically significant correlation between light intensity and radioactivity in an area.
- Light intensity
- Radioactivity
Control Variable
- Plant species
- Amount of light given off from light source
Method
- Set up plant, lux meter and the Geiger counter.
- Place lamp 50cm away from the plant, and after 2 minutes, record the Radioactivity count and light intensity
- Repeat with 100cm, 150cm, 200cm, 250cm and 300 cm.
A graph showing the relationship between distance from light source and radioactivity, using our own collected values.
Our data shows a positive correlation between light intensity and radiation count, which confirms that areas closer to the nuclear reactors at Chernobyl and Fukushima were affected more than areas further away, and so the radiation may not have been strong enough after 33 years in order to stop flora from growing and animals from moving in. However, the radiation had stronger effects on organisms with a smaller body mass, such as spiders and butterflies, as research shows that abundance decreased in neighbouring areas.