An iconic and beloved image, known well to those living on the West Coast and near the Salish Sea, is that of a tiny, baby otter wrapped in kelp by its mother to keep it from floating away while the mother forages. While the fuzzy otter is the main focus of the image, the kelp blanketing it is just as critical a foundation species. In the Salish Sea, the most common type of kelp is bull kelp, or Nereocystis luetkeana, reaching heights of 80 feet but typically more like 30 feet in Puget Sound. Kelp creates vast underwater forests. Bull kelp is considered a foundation species because it provides nutrients, habitat, and it is an efficient carbon dioxide absorber. These cold, dark, and wet underwater forests provide habitat, food, and resources to a variety of species, many of which are in danger. However, over the past century, there has been an unprecedented decline in these forests leading experts to worry about the impact this will have on the species which inhabit them. This is particularly true in Salish Sea.

kelp vs. rising sea temperatures

Kelp restoration efforts have been launched across the globe, though many are still in the research stages. In Australia, heatwaves had already destroyed the 100 miles of kelp along Tasmania’s coast before the Australian Government launched a restoration effort. In many cases, protecting what little of the seaweed giant that is left is far more effective than trying to completely restore decimated underwater forests that once were. At the Institute for Marine and Antarctic Studies at the University of Tasmania, researchers are exploring the possibility of warm water-tolerant kelp for future restoration.

After having tested 50 different genotypes of kelp, the researchers at the University of Tasmania noted that 10–15% are surviving in water temperatures up to 16–17°C (60-62°F), seven degrees higher than waters in which kelp normally thrives. Here in Pacific Northwest, we can take note of what has been learned Down Under.

photo by Jan Kocian

The gametophytes grown in temperatures between 10 and 16°C survived and produced adult kelp sporophytes, but kelp gametophytes from all populations died at 20°C and did not produce adult kelp sporophytes above 16–18°C.

Some parts of the Salish Sea remain relatively cool due to the Pacific Ocean water entering through the Strait of Juan de Fuca. However, areas in South Puget Sound, which are furthest from the Strait, can warm to temperatures above 16°C during the summer. Dr. Weigel’s results explain why kelp forests in southernmost South Puget Sound have been struggling far more than in other locations that are cooler.

underwater reforestation efforts

Over the past century in South Puget Sound, up to 80% of bull kelp forests have been lost, and currently restoration efforts are underway to bring the bull kelp forests back to their former glory. The importance of kelp is not to be diminished. It provides for some of our most beloved species here in the Pacific Northwest, such as salmon and orcas, as well as other organisms ranging from microscopic bacteria to other mammals. Kelp is an efficient absorber of carbon dioxide, even more efficient than trees. A study published by Dr. Filbee-Dexter and Dr. Wernberg of the University of Western Australia showed that kelp forests account for 30% of total blue carbon that is sequestered annually and 3% annual total carbon emissions globally. As kelp forests continuously grow, they are also able to attenuate storm surges whilst protecting species amongst their towering stipes and blades. The compounding benefits of kelp reforestation should put this issue at the forefront of environmental protection agendas.

Researchers, such as Dr. Weigel and her U.W. team, are providing guidance for the important task of restoring of kelp forests. While still in its initial phases, plans are in place in jurisdictions around the globe to help restore kelp forests. The Kenneth K. Chew Center for Shellfish Research and Restoration is developing techniques, such as a ‘bull kelp seed bank’ where kelp gametophytes are being gathered to cultivate and understand their genetics to create a sort of bull kelp hatchery. In 2020, the local Puget Sound Restoration Fund developed the Puget Sound Kelp Conservation and Recovery Plan to help restore kelp. The actions specifically identified in this plan include the following six goals:

The Puget Sound Recovery plan incorporates research and management aimed at success. A collaborative effort between local government agencies, nonprofits, and local tribes is required to ensure success. Progress is slow, but thanks to these plans, continued research, and growing awareness, kelp may be given another chance to thrive in the Salish Sea and contribute to habitat restoration and carbon absorption. Hopefully these efforts will mean that  bull kelp, sea otters, and other species which have seen dramatic reductions, will make good comebacks in the Pacific Northwest.

two videos about local kelp research

a brief video tour of a kelp forest off pender island, british columbia

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Thanks so much for your interest and your support.