The kelp beds off Del Mar are expanding, and their growth could be due to students and scuba divers in San Diego County volunteering with San Diego Baykeeper, the environmental group said in a report yesterday.

Since 2001, members of Baykeeper statewide have helped restore 10,500 square meters of kelp forests and educated 6,800 students from San Diego to Santa Barbara.

The Del Mar project involves a 1,800-square-yard area in 35 feet of water about a half-mile from shore. In March and July 2004, divers transplanted more than 680 giant kelp starts there. The kelp had been cultivated by hundreds of first-through 12th-grade students countywide.

"We definitely have more kelp than we had there before," said Colleen Wisniewski, a marine biologist with Baykeeper who supervised last year's kelp reforestation project.

More study is needed to verify whether the Del Mar kelp bed and others are thriving because of natural marine conditions or the restoration efforts, she said.

But Wisniewski is confident hundreds of San Diego County students are learning more about kelp's importance to the marine ecosystem.

Giant kelp beds, which are nurseries for larvae and juvenile fish, foster the growth and survival of one of every four life forms found in the near-shore environment.

For a variety of reasons – pollution, warm water during El Niño and predation by sea urchins – the kelp beds off Southern California have declined by 70 percent over the past century.

Tending the Del Mar kelp forest takes up about 30 percent of Wisniewski's time. The balance is spent on teaching students about kelp and training them to grow kelp starts in classroom aquariums.

Cultivating kelp begins when divers collect special reproductive "blades," or leaves at the base of the plants. Next, laboratory technicians force spores to emerge from the leaves. The microscopic spores are then transferred to saltwater tanks where they attach themselves to ceramic tile strips or natural fiber rope.

After two months, thousands of tiny kelp plants appear like brown peach fuzz on the tiles, which are taken to saltwater aquariums at 11 schools participating in the countywide kelp-cultivation program. After two more months in the classroom tanks, the kelp are an inch tall and ready for transplantation.

The sea floor off Del Mar was deemed ideal for the restoration effort because it has a rocky reef preferred by kelp. The potential for expansion was also high because, according to long-tenured lifeguards, the kelp forest there used to be much larger, Wisniewski said.

Del Mar lifeguards provided a further incentive for the restoration project by offering the use of their rescue boats and scuba divers to plant and monitor the new kelp. For lifeguards, the diving time gives them a chance to train for underwater recovery and navigation.

• San Diego Union article