Kelp Restoration: Exploring Options With Heat Resistant Kelp

September 26, 2024

the blades of large brown kelp sway in the currents underwater
Fast-growing giant kelp (Macrocystis pyrifera) creates towering underwater forests that are home to countless marine species. Photo: Steve Lonhart/NOAA

A report from a recent workshop suggests that evolution could help restore declining kelp populations in California, such as in areas like Greater Farallones National Marine Sanctuary where bull kelp (Nereocystis luetkeana) restoration projects are in the early testing stages. Experts believe kelp ecosystems have a better chance of thriving in the face of changing ocean conditions by promoting genetic diversity and supporting locally adapted populations. Kelp is an economically, ecologically, and blue carbon important habitat, and it is essential to restore.

Marine algae, like land plants, are struggling with warming temperatures. Heatwaves can drastically reduce algae productivity, especially in species adapted to cooler waters. Along California's coast, marine algae are at the base of the food web, making their survival critical to the ecosystem.

"Kelp and its ability to adapt to a changing environment is part of a new frontier in kelp restoration," explains Steve Lonhart, research ecologist at Monterey Bay National Marine Sanctuary. "We are in the early stages of understanding how some kelp, locally adapted to warmer conditions, might be moved to distant areas to help spur kelp recovery."

researchers stand next to a seawater flow tank and hold up blades of kelp selected from the tank
Bull kelp restoration research is currently taking place at Greater Farallones National Marine Sanctuary in Northern California. Photo: Jennifer Stock/NOAA

Warming coastal waters, combined with other factors, pose a significant threat to kelp. Higher temperatures can slow growth, reduce productivity, and damage tissue. Studies show that southern populations of giant kelp (Macrocystis pyrifera) are more tolerant of warm water and low nutrient levels compared to northern populations. This suggests that the remaining kelp forests may have evolved heat- and climate-tolerant genes, offering a potential lifeline for restoration efforts

Maintaining kelp's genetic diversity and local adaptations to higher temperatures will be crucial for preserving healthy kelp forests. Genetic information is essential for deciding where and how to restore kelp populations, choosing the right "seed" populations, and assessing the success of restoration projects.

Priorities include: 

  • Mapping kelp genetics
  • Monitoring sentinel and restoration sites
  • Testing different source populations for restoration
  • Preserving genetic samples for future use