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5 The Consequences and Effects 2: UV Radiation and Ecosystems

We are particularly concerned by the potential impact of increased UV radiation on plants and animals, simply because they form the basis of our food supply. Significant changes in the health or growth of plants and animals may reduce the amount of available food.

Whereas scientists seem to agree that for any individual species, changes may be observed in an organism’s growth capacity, it is much trickier to make observations and forecasts for an entire ecosystem. The task is complicated by the fact that we cannot single out UV radiation and separate it from other changes in atmospheric conditions, such as higher temperatures and CO2 concentrations, or water availability.

UV radiation might affect certain species but also insects and pests, thus counterbalancing the direct negative effects of increased UV radiation. Similarly it might change their ability to compete with other species. In the long term UV-resistant plants may prevail over more vulnerable ones. 

Excessive exposure to UV radiation can cause cancers in mammals, much as humans, and damage their eyesight. Fur protects most animals from overexposure to harmful rays. But radiation may nevertheless damage their nose, paws and skin around the muzzle.

Experiments on food crops have shown lower yields for several key crops such as rice, soy beans and sorghum. The plants minimize their exposure to UV by limiting the surface area of foliage, which in turn impairs growth. However the observed drop in yield does not seem serious enough for scientists to sound the alarm.

Aquatic wildlife is particularly vulnerable

Phytoplankton are at the start of the aquatic food chain, which account for 30 per cent of the world’s intake of animal protein. Phytoplankton productivity is restricted to the upper layer of the water where sufficient light is available. However, even at current levels, solar UV-B radiation limits reproduction and growth. A small increase in UV-B exposure could significantly reduce the size of plankton populations, which affects the environment in two ways. With less organic matter in the upper layers of the water, UV radiation can penetrate deeper into the water and affect more complex plants and animals living there. Solar UV radiation directly damages fish, shrimp, crab, amphibians and other animals during their early development. Pollution of the water by toxic substances may heighten the adverse effects of UV radiation, working its way up the food chain. Furthermore less plankton means less food for the animals that prey on them and a reduction in fish stocks, already depleted by overfishing.

Story ideas
#5a. If there are case studies/science linking UV/ozone depletion to declines in fisheries or plants on which specific local communities or regions depend, stories could focus on the impacts of UV on local livelihoods (fisheries, farming), food security, etc.

#5b. If the impact on phytoplankton is well established, stories could focus on this link and the fate of fisheries, which are already in profound decline.