ST. PAUL, Minn.
(AP) -- A study has found that the Great Lakes of Huron and Michigan have
surpassed Lake Superior in water clarity.
satellite images from 1998 to 2012 and found that the depth light could
penetrate the water increased by about 20 percent, Minnesota Public Radio
“What surprised us
was the magnitude of the change,” said Robert Shuchman, a study co-author
and co-director of the Michigan Tech Research Institute. “We had no idea the
data was going to tell us that Huron and Michigan have surpassed the water
clarity in Lake Superior. That was the startling piece.”
Scientists say less
phosphorous runoff, climate change and an increase in invasive zebra and
quagga mussels have contributed to the change.
“Lake Michigan now
reminds me of the Caribbean,” Shuchman said, with crystal clear, aqua blue
water and white sand beaches along its eastern shore.
Technological University Senior Research Scientist Gary Fahnenstiel
co-authored the study. He said the mussels filter the water by eating
plankton, which absorb light.
The decrease in
plankton could cause major changes to the ecology in the lakes, Shuchman
said. Plankton is the base of the food chain, so getting rid of it could
cause the rest of the food chain to starve.
The clearer water
has also led to an increase of an algae called cladophora. Harmful bacteria
grow in the algae and can produce botulism toxins that kill fish and birds.
Fahnenstiel said he
hopes the intense clarity of the lakes will lead people to recognize their
beauty and strive to take better care of the resource.