Kelp forests are in decline globally. These widely distributed marine habitats are integral to the well being of the ecosystems in which they support as well as support biodiversity of marine plants and animals. Numerous ecosystem services are derived from kelp forests, examples of direct services include: shoreline protection from erosion, carbon storage and valuable habitat for many marine animals. The decline of kelp forests is linked to ocean warming and eutrophication, which are related to effects of human activities. Habitat deterioration and destruction are among the most threatening to ecological function, as well as having major consequences for coastal communities that rely on resources from a healthy ocean.
Traditional efforts to restore kelp forests have been centred around high investment projects (an ongoing theme in the world of sustainability…). These efforts include: fishing and hunting restrictions including the establishment of marine reserves, removal of sea urchins by commercial harvest, and transplanting kelp. The results of these restoration tactics have had limited success and are often labour and skill intensive (often requiring a dive team and highly trained field workers). They are further challenged by the difficulties associated with working underwater, complex species, and large scales of kelp forest loss.
The Rundown on Green Gravel (Effectiveness, Cost, etc.)
The green gravel approach to kelp forest restoration involves seeing small rocks with kelp propagules that are then grown in a lab until 2-3 cm before outplanting them in the field. When sufficiently grown, the gravel is scattered from a boat and does not require highly trained field workers, engineered structures or scuba divers. The juvenile kelp then continues to grow and moves off the rock to attach to the underlying reef or ocean floor. This technique is cost efficient, simple and effective as the outplanted kelp has shown to have a high survival rate. There is also the ability to scale this restoration tactic as needed to treat large areas or could even be used to introduce genes from more resilient kelp populations onto vulnerable reefs.
Green gravel shows great potential as a kelp restoration technique to be used in conjunction with a combination of other approaches to create a multifaceted restoration plan. Establishing protected areas or reducing stressors (eg. harvesting regulations or water quality improvements) are proposed as other tools in the restoration toolkit that would work concurrently and holistically. Fredriksen et al. in the Scientific Reports academic journal recommends that “green gravel should be added to the suite of tools available to combat declining kelp forests. More broadly, the green gravel concept has the potential to be a globally applicable marine restoration method that transcends species and systems” (2020). The simplicity when compared to other restoration tactics can allow for community-based revitalization of waters without as strong of a dependence on outside support.
Current Projects
The green gravel approach is currently being used worldwide in areas such as Norway, Portugal, Australia, Latin America and along the California coastline in the USA. Below, two British Columbia, Canada projects will be highlighted for insight on how green gravel is being deployed locally.
Project: The Kelp Rescue Initiative
Website: www.kelprescue.org
Aims to restore kelp forests along BC’s coast to foster resilient and vibrant ecosystems. Launched at the Bamfield Marine Sciences Center, the project focuses on BC’s two main kelp canopy species Nereocystis and Macrocystis in ecologically significant areas of the Salish Sea and outer coast. The Kelp Rescue Initiative has strong partnerships with First Nations, provincial and federal governments, academics from University of Victoria, UBC and University of Calgary and organizations such as the Pacific Salmon Foundation.
Project: Vital Kelp Restoration Project
Instagram: @vitalkelp
Established in 2018 at an existing permitted aquaculture site on the Sunshine Coast of BC, cultivation trialing began using on-line methods. Cultivated Nereocystis, Saccharina and Alaria were not harvested for commercial use but left in the water for marine habitat development. Each spring tube snouts, Aulorhynchus flavidus eggs are laid in the kelp holdfasts, showcasing the revitalization of the surrounding ecosystems. The Kelp Revitalization Project has support from the shíshálh Nation, the BC Conservation Foundation, the Pacific Salmon Foundation and the Bisgrove post graduate lab at SFU. Securing ongoing and sufficient funding continues to be the most challenging barrier to scaling this community-led initiative.
For more information visit:
https://www.greengravel.org/about
https://ocean.org/blog/green-gravel-initiative-hopes-to-seed-new-kelp-forests-on-canadas-west-coast/
And check out this scientific journal article: https://www.researchgate.net/publication/339686397_Green_gravel_a_novel_restoration_tool_to_combat_kelp_forest_decline