Dr Dan Reed1, Dr. Steve Schroeter1, Dr. Kat Beheshti1
1Marine Science Institute, University of California Santa Barbara, Santa Barbara, USA
Kelp forest restoration often includes seeding or outplanting kelp to overcome perceived limitations in spore dispersal. Here we use the 20-year phased construction of a 151 ha artificial reef complex (i.e. Wheeler North Reef) in southern California, USA to compare the efficacy and heuristic value of outplanting small laboratory-reared juveniles as a means of establishing giant kelp (Macrocystis pyrifera) vs. unassisted colonization via spore dispersal from a nearby natural population. Transplanting kelp during the first phase of the artificial reef was moderately successful in that ~55% of the 840 transplant units supported giant kelp one year after transplantation, and the average size of transplanted kelp was similar to that of kelp that recruited naturally. More notable was the widespread colonization by giant kelp observed throughout the 3.5 km footprint of the artificial reef in the first year following its construction that rendered the transplanting efforts insignificant in facilitating the establishment of giant kelp on the reef. Initially, the density of naturally recruited kelp varied inversely with distance from the nearest natural population, however, this pattern disappeared within three years when a dense surface canopy formed across the entire artificial reef. Subsequent expansions of the artificial reef 10 and 20 years after the initial phase was constructed were similarly colonized by giant kelp without active restoration. Collectively our results highlight the spatial and temporal scales over which natural colonization of giant kelp occurs and the need to identify the causes of kelp decline before implementing methods aimed at restoring natural populations.
Presentation Slides – Dan Reed
Biography:
Dan Reed is a research ecologist in the Marine Science Institute at the University of California Santa Barbara and he has conducted research in kelp forests for over 40 years
