Kelp Helps All of Us

June 4, 2025

With World Ocean Day on June 8, we are spotlighting kelp—underwater forests teaming with life and that are part of our daily lives. Kelp forms vital ecosystems and provides habitats for marine life such as sea stars, sea otters, and giant sea bass. Kelp also absorbs carbon dioxide and as a result produces oxygen. Many products used by consumers can contain kelp from toothpaste to ice cream. Healthy kelp forests also help protect coastlines.

With the ocean changing due to factors like warming ocean temperatures and sea level rise, kelp is experiencing a decline. The west coast of North America is home to two species of kelp: bull kelp and giant kelp. Both are on display at the Aquarium of the Pacific and are featured in the Aquarium’s Marine Species Report Card—where you can learn more about the threats, their current status, and conservation.

Live Bull Kelp on Display at the Aquarium

Almost two years after storing bull kelp genetic material in specialized fridges for a genetic preservation project that could potentially contribute to future efforts to restore them in the wild, Aquarium staff maintaining the systems have been able to grow and display bull kelp for Aquarium guests to see. The Northern Pacific Preview habitat in the Aquarium’s Great Hall features this important algae species known as bull kelp (Nereocystis luetkeana). Guests can find the yellow-brown colored bull kelp extending from one end of the habitat to the other. This kelp species is most commonly found in nearshore habitats with strong ocean currents north of San Francisco, up through the Eastern Aleutian Islands in Alaska.

Since 2014, the population of bull kelp has dropped as seen in their species report within the Aquarium’s Marine Species Report Card. This decline is due to a combination of rising temperatures and the decline of sea urchin predators, such as the sunflower sea star and the ochre sea star. This prompted a project that the Aquarium joined in 2023, focusing on preserving the genetic material of bull kelp in fridges outfitted to maintain these samples in stasis. The preparation involved with displaying the bull kelp in the Aquarium’s habitats helps the team to be ready when the need arises to outplant the bull kelp in the ocean.

A Giant Kelp Towering Forest

Guests to the Aquarium can also see live giant kelp in the Casino Point habitat at the beginning of the Southern California Gallery. Giant kelp (Macrocytis pyrifera) form magnificent, canopied forests in Southern and Central California. This kelp species can also be found on temperate coastlines along the west coast of North America, South America in Chile and Peru, and even in South Africa and Australia.

The Aquarium is helping by supporting the repopulation of the Southern sea otter (Enhydra lutris nereis) in California’s kelp forests. Sea otters and healthy giant kelp forests have a positive symbiotic relationship, helping each other out. These sea otters are a keystone species and help shape the kelp forest ecosystem. They were hunted to near extinction by the early 1900s before being protected. The work to support sea otters across organizations has helped the population grow from a group of fifty in 1938 to several thousand today.

Even with support for sea otters, human-related threats like pollution from sewage run-off and sedimentation continue to affect not only kelp’s ability to reproduce successfully, but also the animals keeping the kelp forest ecosystem in balance. One example is the sharp increase of sea urchins due to the lack of predators like the critically endangered sunflower sea star.

While giant kelp is in no immediate danger of going extinct, the overall trend since 2003 is a decline. That’s why the Aquarium is also part of organized efforts aimed at restoring sunflower sea stars off the coast of California. Efforts like these provide hope for the future of our vital and iconic kelp forests.