Giant kelp forest off La Jolla provides a rich habitat

Giant kelp near the surface of the water. Photos by Kelly Stewart

Just offshore, we have one of the most productive habitats on Earth that supports extremely high biodiversity. The giant kelp forests of Southern California are dominated by two large brown algae species, the giant kelp (Macrocystis pyrifera) and bull kelp (Nereocystis luetkeana).

Giant kelp near the surface of the water. Photos by Kelly Stewart
Kelp forests provide homes and food for fish like the black sea bass.

Giant kelp grows along rocky coastlines in cool, nutrient-rich waters at depths of up to 90 feet. Attached to the rocky seafloor by a holdfast, which somewhat resemble aboveground roots, kelp rises up through the water column supported by tiny air bladders (pneumatocysts) at the base of each blade.

Once it reaches the surface, it forms a broad canopy with a rich habitat below the surface. Giant kelp thrives in clear water that gets a lot of sunlight, and must always have a wave surge to keep it healthy, so Southern California is a perfect environment.

Kelp may grow up to 2 feet per day, making it one of the quickest growing organisms on Earth.

Kelp forests are home to many fish and invertebrates that depend on the productivity of the forest for food, shelter and survival. Seals and sea lions use the mysterious tall forests as a refuge from predators; gray whales have even been spotted within the kelp forest, presumably avoiding killer whales. Other animals may seek out kelp forests during storms because kelp helps dissipate the energy from waves, thus making a more stable environment.

On the surface of the ocean, kelp looks only like a lifeless brown mat, but for those lucky enough to venture down into the water column, there exists a magical and peaceful green-lit world populated by many cryptic creatures.