The Kelp Forest Community

Updated: Jul 20

What are kelp forests?

Found along the Pacific coast ranging from Alaska to northern Mexico, kelp forests are dense groupings of kelp growing in shallow, near-shore waters. They host a wide variety of creatures amongst their fronds, acting as both shelter and a food source. Meanwhile, kelp itself is full of interesting features.

While the towering strands of kelp might look like trees as they rise meters from the ocean floor, kelp is actually a type of algae. While they get their energy through photosynthesis like most plants, kelp do not have roots or stems like plants do. Instead, they stay secure through the use of holdfasts, which locks onto substrates to hold the kelp in place.

Near the tops of strands, pneumatocysts are pockets filled with gas that help to keep the blades of kelp afloat. This lets them reach the sunlight at the surface, allowing them to undergo photosynthesis.

What animals live in a kelp forest?

Kelp forests host a diverse array of organisms, both simple and complex. For instance, invertebrates like bristle worms, sea urchins, and snails feed on the kelp’s holdfasts. They can sometimes detach kelp entirely from the sea floor.

More complex organisms, including a wide variety of fish, also reside in kelp forests. Many of these species are important to both commercial fishers and fishing birds, such as great blue herons and cormorants. They also provide food to the kelp forest’s larger animals, such as sea lions and otters.

Those larger animals also use the kelp forests for protection. The dense kelp hides sea otters from predators like sharks, and shields them from being battered by storms. In turn, otters are among the animals that prey on sea urchins, which can eat through a kelp forest if left to multiply on their own.

Kelp forests and climate change

The different members of the kelp forest ecosystem are intrinsically connected with each other, and when climate change threatens one member, the entire ecosystem is put at risk.

Though the sea urchins that use kelp for food are usually kept in check by its predators, they can destroy the kelp forest if those predators disappear. This was the case with kelp forests off the northern California coast—rising ocean temperatures related to climate change have devastated the sunflower sea star population, which feeds on the sea urchins. As the sea star population declined, the sea urchins experienced a population boom. They began to consume the kelp at an accelerated rate, leading to the disappearance of 95% of the area’s kelp forests.

Now, scientists at the University of Washington are attempting to revitalize the California kelp forests by breeding sunflower sea stars that may be more resistant to warmer waters. However, addressing the root cause of their decline remains important to maintaining the health of kelp forests and their diverse inhabitants.



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