The only thing I know is that no one knows what's really going on, which is kind of scary. I keep reading that the thinning of the ozone layer could be blamed for the damage to coral reefs and plankton but I can't find anything solid that shows that plankton is really being killed.
I remember reading about blindness found in fish and sheep in Tierra del Fuego, which is the southernmost part of South America, during the part of the year when the ozone hole passes over in the early 90's but nothing more on that, so maybe it had nothing to do with the ozone hole.
I did find this article that points to some study that shows that the thinning ozone layer is blamed for the disappearance of frogs (something is certainly killing the frogs) in this except from an article from The Environmental Magazine from 1994, also covered in a New York Times article on 3/1/94:
Investigators at Oregon State University (OSU) decided to tackle the problem. The recent results of their four-year study provide strong evidence that the thinning of the Earth's ozone shield and the resulting increase in dangerous ultraviolet radiation may be the silent stalker of frogs and other amphibians throughout the world.
"We were shocked," said zoology professor Dr. Andrew Blaustein, author of the study. "We didn't think we'd find anything. When we got the results, we still didn't believe it. So we replicated it and now we believe."
In 1973, scientists discovered that human-produced chlorofluorocarbons (CFCs) decimate ozone when they break apart six to 25 miles above the Earth's surface. This ozone destruction allows the more biologically harmful ultraviolet-B rays (UV-B) to reach the Earth's surface. Every one percent decrease in ozone causes a 2.2 percent increase in DNA-damaging UV-B radiation. UV-B is also known to be the primary cause of human skin cancer and is linked to cataracts and immune system suppression. It also damages crops and marine algae. The best-known depletion--the ozone hole above Antarctica--measured nine million square miles in September 1992, a 15 percent increase over 1991. Less well known is the steady depletion of ozone over populated areas worldwide.
Science journal recently reported that UV-B radiation over Toronto, Canada had increased 35 percent per year in the winter and seven percent per year in the summer during the four-year frog study. (Ozone formation is triggered by sunlight, so there is always less ozone in the wintertime.) Toronto is at 44 degrees north latitude--the same latitude as the Oregon sites where Dr. Blaustein conducted his field experiments.
The OSU frog study was the first to prove that UV-B is now killing organisms living at mid-latitudes. "Damage to an animal means there probably will be an effect on humans," notes Blaustein. Scientists had widely believed that habitat loss and agricultural chemicals had been devastating amphibians. Indeed, these have taken their toll. But researchers had no explanation as to why populations also declined in relatively undisturbed regions.
Dr. John Hayes, OSU professor of agricultural chemistry, studied the eggs of 10 Oregon amphibian species. Of those 10, he found that the three with the best ability to repair or resist UV-B radiation were the Pacific tree frog, the Western toad and the Cascades frog.
Dr. Blaustein then studied the eggs of those three species in their natural habitat at Cascade Range lakes. Only 45 to 65 percent of the eggs of the Cascades frog and the Western toad hatched. But each had up to 25 percent more hatchlings when their eggs were shielded with a filter that blocked UV-B radiation. The third species, the Pacific tree frog, had a much stronger resistance: nearly 100 percent of their eggs hatched. Not surprisingly, while Pacific tree frog populations are stable, Cascades frog and Western toad populations have undergone such drastic declines that they are now official candidates for "threatened species" listing.
The study indicates that declining amphibian species lack the ability to protect themselves from increasing UV-B radiation. "The bottom line is that current levels of UV-B radiation in sunlight are killing amphibian eggs," says Dr. Blaustein. Amphibians have no hair, thick hide or feathers to shield them, nor are their eggs protected by leathery or hard shells. These characteristics make them vulnerable to UV-B.
According to herpetologist David Wake, "Amphibians are excellent indicators of environmental stress. Since they live in both aquatic and terrestrial ecological systems, they might tell us faster that something is wrong...they're an early warning system." Dr. Blaustein is now planning to research whether other species and life stages besides eggs also suffer from UV-B radiation.
Over Antarctica, the ozone layer thins by as much as 50 percent in the spring, when the destructive effects of CFCs in the atmosphere are maximized by weather conditions peculiar to this area. Simultaneously, the marine plankton there--the foundation of the ocean food chain--begin to bloom. UV-B has reduced plankton production by six to 12 percent. This may have already had an as-yet-unresearched impact on the marine food chain, extending from plankton to fish, to penguins, seals and whales.