MS Research

Restoration techniques for Nereocystis luetkeana (bull kelp)

University of Washington, Seattle- 2003

Anthropogenically induced disturbances, such as shoreline development and sediment loading, can eliminate Nereocystis luetkeana populations and the commercially important associated species, making restoration necessary. Two techniques to establish a N. luetkeana bed in the northwestern waters of Washington, USA were examined and compared. Techniques investigated were as follows: 1) out-planting recently settled zoospores; 2) out-planting the microscopic sporophytes (0.5-1.0 mm blade length); 3) out-planting these directly on natural substrate versus at elevated positions; and, 4) transplanting juvenile sporophytes (< 15 cm stipe length), bypassing the culturing phase. A cost-benefit analysis was done for each method tested. Juvenile transplanting resulted in reproductive adults and was found to be most successful with a restoration cost of 12 US Dollars (USD) per plant. These had a 10-30% higher survival rate than previously reported kelp transplanting efforts using larger individuals. The collection of these smaller recruits for transplanting purposes imposes less of an ecological cost to natural populations than the collection of larger, established plants. Stipe breakage caused by the grazing gastropod Lacuna vincta posed the largest limiting factor on transplant survival. Lack of survival among the out-planted zoospores and microscopic sporophytes indicates that other methods would be more successful. Restoration efforts in the nearshore marine environment will benefit from an adaptive management approach in which techniques can be tailored to the abiotic and biotic conditions at the restoration site.

Tranplanted juvenile Nereocystis holdfast	Me with a transplant at Friday Harbor, WA site	Cultured out-plants at elevated positions