Restore or create kelp forests
Overall effectiveness category Unknown effectiveness (limited evidence)
Number of studies: 1
Background information and definitions
Kelp forests are unique habitats found in mostly cold, nutrient-rich waters. Large kelps such as Macrocystis spp. (the ‘giant kelps’) can grow to 45 m or more, creating ‘underwater forests’ that provide complex habitats and allow extremely productive ecosystems to flourish. However, they are vulnerable to pollution and ecosystem perturbations caused by, for example, the loss of keystone species such as sea otters Enhydra lutris (Jackson et al. 2001).
Jackson, J.B.C., Kirby, M.X., Berger, W.H., Bjorndal, K.A., Botsford, L.W., Bourque, B.J., Bradbury, R.H., Cooke, R., Erlandson, J., Estes, J.A. & others. (2001) Historical overfishing and the recent collapse of coastal ecosystems. Science, 293, 629–637.
Supporting evidence from individual studies
A before-and-after study between 1969-1973 and 1984-1986 on a rocky shoreline in southern California, USA (Bradley & Bradley 1993), found that shorebirds were significantly more numerous after kelp Macrocystis pyrifera forest restoration. Among nine species of shorebird analysed, the density of five (spotted sandpiper Actitus macularia, wandering tattler Heteroscelus incanus, whimbrel Numenius phaeopus, black turnstone Arenaria melanocephala and ruddy turnstone Arenaria interpres) increased. Territorial species (spotted sandpiper, wandering tattler and whimbrel) were twice as abundant in the second census. Species that do not forage in algal windthrow, such as the black-bellied plover Pluvialis squatarola, remained stable over the two census periods. Complete counts of all shorebirds encountered along a 4 km census route were recorded year-round over the years of the two censuses.Study and other actions tested