ST. PAUL, Minn.

A study has found that the Great Lakes of Huron and Michigan have surpassed Lake Superior in water clarity.

Scientists analyzed satellite images from 1998 to 2012 and found that the depth light could penetrate the water increased by about 20 percent, Minnesota Public Radio reported.

“What surprised us was the magnitude of the change,” said Robert Shuchman, a study coauthor 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.

Michigan 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.