News
ENLARGE
SOUTH LAKE TAHOE, Calif. — “Keeping Tahoe Blue” may be about more than just aesthetics, according to a study published in the March edition of the scientific journal Ecology.
The study — titled “Ultra violet radiation affects invisibility of lake ecosystems by warm-water fish” — shows a murkier Lake Tahoe is providing a foothold for at least one of the invasive species threatening to forever change the lake's ecology.
Lake Tahoe's clarity has been in decline for decades due to fine sediment pollution and algae growth, but has slowed in recent years. Clarity remains well short of regulators' goal of 100 feet of clarity at 69.6 feet.
During experiments conducted in 2007, scientists and colleagues of Miami University's Global Change Limnology Laboratory looked at how UV radiation effected the survival of bluegill fish larva, one of the warm water fish species that was likely introduced into the lake by anglers in the mid-1980's.
They found the dissolved organic material that is prevalent in some near shore areas of the lake, like the Tahoe Keys, has reduced larval fishes exposure to damaging UV radiation and helped the species spread to sites around the lake.
“For example, invasive bluegill can only nest successfully when human disturbance such as shoreline development reduces UV transparency,” said Craig Williamson, head of the Global Change Limnology Lab, in a statement. “This creates a UV refuge, an ‘invasion window,' which enables the bluegill to spawn in the surface waters where the temperatures are warm enough for survival of its embryos and larvae.”
Bluegill larval were unable to survive levels of UV radiation in near shore areas that remain extremely clear, like Sand Harbor, said researcher Andrew Tucker, during a phone interview on Wednesday.
Although the Miami University study looked only at bluegill, Tucker said UV radiation, and therefore clarity, will likely influence whether other warm water fish species like bass are able to continue spreading around the lake.
He said bass species probably have the biggest potential to effect the lake's remaining native species.
Numbers of native minnows appear to have dropped precipitously since bass and bluegill have established themselves in the lake, Tucker added.
Researchers from Miami University will return to the lake this summer for follow up studies looking at the possible development of a “UV threshold” — a benchmark environmental regulators can use to analyze progress in improving Lake Tahoe's health.
The study — titled “Ultra violet radiation affects invisibility of lake ecosystems by warm-water fish” — shows a murkier Lake Tahoe is providing a foothold for at least one of the invasive species threatening to forever change the lake's ecology.
Lake Tahoe's clarity has been in decline for decades due to fine sediment pollution and algae growth, but has slowed in recent years. Clarity remains well short of regulators' goal of 100 feet of clarity at 69.6 feet.
During experiments conducted in 2007, scientists and colleagues of Miami University's Global Change Limnology Laboratory looked at how UV radiation effected the survival of bluegill fish larva, one of the warm water fish species that was likely introduced into the lake by anglers in the mid-1980's.
They found the dissolved organic material that is prevalent in some near shore areas of the lake, like the Tahoe Keys, has reduced larval fishes exposure to damaging UV radiation and helped the species spread to sites around the lake.
“For example, invasive bluegill can only nest successfully when human disturbance such as shoreline development reduces UV transparency,” said Craig Williamson, head of the Global Change Limnology Lab, in a statement. “This creates a UV refuge, an ‘invasion window,' which enables the bluegill to spawn in the surface waters where the temperatures are warm enough for survival of its embryos and larvae.”
Bluegill larval were unable to survive levels of UV radiation in near shore areas that remain extremely clear, like Sand Harbor, said researcher Andrew Tucker, during a phone interview on Wednesday.
Although the Miami University study looked only at bluegill, Tucker said UV radiation, and therefore clarity, will likely influence whether other warm water fish species like bass are able to continue spreading around the lake.
He said bass species probably have the biggest potential to effect the lake's remaining native species.
Numbers of native minnows appear to have dropped precipitously since bass and bluegill have established themselves in the lake, Tucker added.
Researchers from Miami University will return to the lake this summer for follow up studies looking at the possible development of a “UV threshold” — a benchmark environmental regulators can use to analyze progress in improving Lake Tahoe's health.
