The ecological threat of nuclear power

Another risk factor associated with nuclear power is the potential damage it has on surrounding animal habitats and the functioning of ecosystems close by. There are four ways in which dangerous radioactive materials can be emitted into the environment through the power generation process .

1). Waste rock at uranium mines used to fuel the reactor

2). Radioactive isotopes released during operation

3). Spent nuclear fuel (often at the reactor site) and general nuclear waste

4). Release during accidents

Interesting the second term is largely insignificant., In fact according to the NCRP, coal plants in the US release 100 times the radioactivity of nuclear plants, a mere 0.048 Sv/year is the annual dose rate living close to a nuclear plant (a typical chest x-ray gives a dose of about 0.06 mSv) (Gabbard, 1993). The largest threat comes from accidents which cause far higher dose rates over far greater areas than the other terms. The dose rates experienced following accidents are still not high enough to wipeout all wildlife as with a Nuclear weapon, the real effects are bore from chronic exposure to low doses of radiation over multiple generations.

The effect of low-level radiation exposure on surrounding wildlife is a controversial and complex topic.  There are very few testing grounds where the long term effects of elevated dose rates can be measured and those that there are, are as a result unsafe (e.g. Chernobyl). In addition it is difficult to get a general impression of ecosystem response, as species respond differently to a given dose of radiation, and the amount of radiation received by any one creature depends on the distribution of radioactive particles, the mobility of the creature, and of course where it lives (i.e. in trees, underwater etc) (Goldenstein, 2012).

This is partly why much uncertainty surrounds the true ecological impact of the recent Fukushima nuclear accident.  Dose rates 10 to 100 times (depending on which radionuclide your measuring) higher than the rates considered safe for terrestrial ecosystems were found in areas surrounding the plant during the first month after the accident (Garnier-Laplace et al, 2011). However the expected impacts are tentative, some indicate that cytogenetic (structure and function of cells) damages will certainly be measurable; however changes in reproduction in plants and animals will be difficult to discern against natural variation. At the high dose rates near the coast marked reproductive effects are expected to be noticeable, however there is still uncertainty (Garnier-Lapace et al, 2012).

Scale of potential effect in marine widlife groups and forest biota for different dose rates yellow dotes and red triangles indicate the dose rates measured (Source: Garnier-Laplace et al, 2011)

Essentially in its present state the areas surrounding Fukushima are likely characterised by elevated mortality and defect rates with many ecosystems in shock as a result of the huge influx of radionuclides. However what happens as more time is allowed to pass, dose rates fall and ecosystems adapt.  At Chernobyl more time has passed, the initial impacts were cataclysmic a whole 10 km² region was coined "the red forest" due to the overwhelming presence of orange coloured pine tree needles from dead trees, numerous morphological changes were witnessed in bird and invertebrate populations, and ultimately the event claimed the lives of thousands of plants and animals (Goldenstein, 2012). However more recently the Chernobyl ecosystem has rebounded, numbers of many species have increased and the region's biodiversity is in fact higher now than it was before the accident (Hopkin, 2005).  

Some 100 threatened species on the IUCN red list are now found in the 4000 sq. km evacuated zone and increasing numbers of macrofauna such as wolves, foxes and wild boar all indicate strong supporting productivity below (Source:Hopkin, 2005)

The reasons for this surge in biodiversity? Firstly no human beings, There may be radioactive particles, but with no deforestation, farming, hunting, or transport, animals have flocked to the isolated region in the Ukraine. Some have also argued that the high radioactivity in the region may in fact be of benefit, whereby weaker organisms die off more quickly, mutated by the fallout.  This leaves behind the most resilient which have not suffered problems with growth and reproduction.

"It's evolution on steroids. There are a lot of deleterious mutations in species but these seem to be very quickly weeded out," James Morris of University of South Carolina (Source: Hopkin, 2005)

The view of Chernobyl as a sanctuary for wildlife is not without opposition, many claim the increase in biodiversity to be a false dawn and question its sustainability.   Strong correlations have been found between highly contaminated areas and physical/reproductive changes in birds such as malformed tails and deformed sperm; similar results have also been found for some invertebrate species (Higginbotham,2011).  Perhaps most significantly in a 2005 study by Timothy Mosseau and Anders Moller studying the migration patterns of birds in and out of the area, it was claimed that the exclusion zone is a sink with low survival and fertility rates. They argue that populations are being falsely sustained by constant immigration of a species drawn in by human absence (Higginbotham, 2011). 

Photo showing normal barn swallow (left) and partial albino bird found in contaminated region (Source:BBC, 2005)

It is clear that the situations at Chernobyl and Fukushima are clearly complex. More research is required on both the affect of long-term radiation exposure on wildlife, and ecosystem responses in the immediate aftermath of nuclear accidents. I would summarise from what I have read that the  effects (excluding human depopulation) of nuclear power generation on wildlife are indeed negative, however I believe the beneficial role of nuclear energy as a carbon mitigator outweighs this particular risk. Especially when considered against the potential ecological impact of climate change, which threatens to acidify our oceans, decrease genetic diversity, promote directional selection, initiate rapid migration, and in a worst-case scenario cause extinction rates that would qualify as the sixth mass extinction (Bellard et al, 2012). The effects of radionuclides may be felt in more ecosystems if waste streams increase as a result of increased nuclear power generation. However in contrast to climate change they are unlikely to threaten biome integrity on a global scale. 

Thanks for reading!