Kelp Garden Experiment

CMEC lab research vessel Enhydra amidst a giant kelp bed as the team collect data from one of the kelp garden sites. Credit: Markus Thompson.

Nurture may trump nature when it comes to kelp growth and survivability.

A kelp gardening experiment in the ocean waters off northern Vancouver Island in July/August 2021 has yielded some promising results in terms of kelp adaptability to changing environmental conditions.

The big-picture context for the experiment is whether transplantation of kelp to areas that are less vulnerable to marine heat waves or other climate impacts could help address the global decline of kelp forests. Locally, the goal is to support Indigenous climate resilient kelp harvest and related fisheries. Finding out if giant kelp could survive and thrive outside of their home environments is a crucial step.

Researchers from the PICS Undersea Forests project collected fronds from six giant kelp beds off the coast of Port Hardy over a 50km range with differing temperatures (spanning 3 °C), salinity and water motion, conditions that affect nutrient levels. Then a total of 108 fronds, which are kelps’ equivalent of tree branches, were attached to floats about 1 metre below the ocean’s surface, with each garden consisting of 18 fronds from all 6 beds. Measurements were taken of the length of each frond and the size and number of blades growing off the fronds, initially and then one month after the experimental gardens were transplanted.

Lead researcher Danielle Denley from Simon Fraser University (SFU) says the experiment shows that kelp grow best when the environmental conditions are good, regardless of where they originated from. Interestingly, transplanted kelp continued to grow in all kelp gardens. The “visitor kelp” even took on the appearance of the “home kelp” within that short time, with dramatic differences in colour and growth.

“This could be good news for kelp because it suggests they are able to respond and grow under different environmental conditions, and may be less sensitive to changes in ocean climate than we expected, at least across the range of conditions we tested,” says Dr. Denley.

These kelp blades grew from the same frond. One blade grew in the kelp's natural or "home" kelp bed, the other blade grew after the frond was transferred to a different kelp bed with different environmental conditions. Credit: Markus Thompson

The kelp gardening experiment was co-conceptualized in collaboration with project partners the Central Coast Indigenous Resource Alliance (CCIRA) and conducted with guidance and field support from the Kwakiutl Nation.

Evaluation of the kelp garden experiment is ongoing through data analysis, lab work on collected kelp tissue, and conversations and knowledge exchange with local experts, including potential risk assessment to avoid unintended consequences of transplanting kelps from outside populations.

Ultimately, the project aims to support climate resilient kelp harvest and related fisheries by determining the resistance of kelp beds to environmental changes and identifying conditions that promote increased growth of giant kelp.

Danielle and Charles Judge Humchitt (Kwakiutl Nation Guardian Watchman) measuring kelp growth from one of the experimental kelp garden floats. Credit: Markus Thompson