Disruption of the Food Chain as a Result of O-Zone Depletion
Disruption of the Food Chain as a Result of O-Zone Depletion
Ozone is a form of oxygen that is a human-made pollutant in the troposphere but a naturally produced, essential component in the stratosphere, which encircles our planet some 6 to 28 miles above the surface. The stratosphere contains a layer of ozone that shields the surface from much of the ultraviolet radiation coming from the sun. If ozone was to disappear from the stratosphere Earth would be uninhabitable for most organisms.
The primary cause for this substantial ozone loss is a group of compounds called chlorofluorocarbons (CFCs). CFCs have been used in aerosol cans as propellants, as coolants in air conditioners, and refrigerators, as foam blowing agents for insulation as well as packaging like styrofoam. Other compounds that may attack the ozone include: halons, methyl bromide, methyl chloroform, and carbon tetrachloride. As CFC’s drift up into the atmosphere the UV radiation breaks them down, releasing chlorine. Bromine is released by the breakdown of halons and methyl bromide in the atmosphere. Under certain conditions in the stratosphere, chlorine and bromide are capable of attacking ozone and converting it to oxygen.
UV radiation has the potential to penetrate tens of feet into clear ocean water. As we know, the entire marine food chain is based on phytoplankton, which float on or near the top of water bodies. Phytoplankton are the producers, they are on the first trophic level in the aquatic food chain. Phytoplankton is extremely sensitive to UV levels; scientists have found that phytoplankton decreases mobility, changes in photosynthesis and enzymatic reactions under UV radiation. Studies in Antarctica, directly under the ozone hole, found the rates of phytoplankton production to be depressed relative to similar areas. With a decrease of Phytoplankton in the water other fish will have to rely on other food sources, or they too will begin to decline.
Higher levels of ultraviolet radiation could also reduce global plant coverage, thus enhancing climatic change. Plants have shown direct effects of UV are on photosynthesis and growth. More subtle changes related to UV are a delay in flowering, shift in distribution of leaves, changes in leaf structure, or a change in plant metabolism. The effects of this are wide spread; shifts in plant population and bio-diversity could be dramatically changed. ...