WHITTIER, Alaska (AP) - Fifty feet down in the cold waters of Smitty's Cove, a concrete paradise is being built for some of Alaska's most unusual creatures.

Alaska's first artificial reef was recently installed near Whittier - one of Alaska's busiest ports - to provide a haven for small plants and fish, near where barges stacked high with containers bring everything from road graders to toilet paper into the state.

The reef was in response to damage done when Alaska Marine Lines expanded its container facility at Whittier last year.

The federal government required the company to mitigate damage done to marine habitat when it filled in tidal waters to extend a ramp last year.

“They covered all the good stuff,” said Mark Schroeder, a wildlife biologist with the federal Minerals Management Service, who helped promote the project.

The demonstration project involves two types of reef structures - one built with about 100 concrete pyramids and the other with about 100 concrete balls, said Brian Lance, a fisheries biologist with the habitat division of the National Oceanic and Atmospheric Administration.

The reef balls are hollow so that small fish can use them to hide from larger fish. They come with holes that create mini-whirlpools to help mix the water column. And they are thick on the bottom and thin at the top so they won't flip over in stormy seas. A rough exterior encourages algae growth.