Disturbance and population dynamics of kelp forest communities

Ecosystem changes

Change in relative abundance of fishes since the mid-1970s.

Since 1976-77, warmer ocean temperatures off the coast of southern California have resulted in declining abundance of fish and lower productivity in the southern California coastal ecosystem. The proportional abundance of cold-water, northern fish species (represented in the figure at the right by the greenspotted rockfish) in the reefs along the shore near Los Angeles has dropped by about half, whereas the proportional abundances of southern, warm-water fish species (represented at right by the Garibaldi) have increased by nearly one half.

The California sea otter.

Another major change facing kelp forest communities in the Santa Barbara Channel is the re-colonization of the region by sea otters. By preying intensively on sea urchins and other herbivorous shellfish, sea otters can greatly alter the structure and dynamics of kelp forest communities. Data from SBC's long-term monitoring of kelp forest sites is documenting ecosystem changes in response to the re-colonization of this area by this keystone predator.