STOCKHOLM, Sweden — The windmills off Sweden's southeastern coast may not be postcard perfect, but fish and mollusks love them, making them their home and creating thriving new ecosystems, scientists said Tuesday.

In a study of the effects of marine-based wind power plants on marine life, Swedish biologists found that the structures, jutting from concrete platforms in the ocean, promote marine diversity.

"It's almost like an artificial reef," said Marcus Oehberg, a marine biologist at Stockholm University. "We've seen that it encourages more species and that it creates a living environment that wasn't there before."

Since July 2003, biologists from Stockholm University have studied the effects of 12 power plants anchored off the coastline of Kalmarsund, 410 kilometers (255 miles) south of the capital, Stockholm.

"The windmills have become small ecosystems," Oehberg said, adding that thousands of fish have begun making their homes amid the structures and mollusks are attaching themselves to the structures, too.

He also said that putting the windmills off the coast cuts back on the complaints from residents on land concerned about the effect on their views because "at sea, you don't even have to see them." They're typically several kilometers off the shore and, if visible, just specks. Wind power experts said that being at sea also means more wind, which generates more electricity.

Sweden has approximately 20 windmills in operation along its coastlines and on land, most operated by Danish- and French-owned companies. Wind power plants account for 0.4 percent of Sweden's total power generated annually, although optimistic estimates say use of windmills could rise by as much as 7 percent in the next few years.

Denmark generates 20 percent of its total energy production through wind power plants and Germany 6 percent.