A Community Approach Removing Invasive Algae to Restore Native Ecosystems

While the diversity and beauty of plants on land are easily seen by us, we may often overlook their aquatic counterparts hidden beneath the sea. Algae, photosynthetic plants ranging from microscopic phytoplankton to larger seaweeds, live in fresh and seawater and fulfill a variety of important functions, including the production of oxygen and the provision of habitat and food. Although limu, various species of seaweed native to Hawai‘i, are an integral part of the environment, the rapid spread of invasive algae over recent decades has raised concern for the future health of limu and their ecosystems.

Originally, multiple species of invasive algae were purposely brought to Hawaiʻi for commercial aquaculture projects, while others were introduced unintentionally over time by ship fouling. Many of these alien species flourish in high-runof environments characterized by excessive nutrient concentrations and sedimentation. As invasive alien algae (IAA) spread, they cause a cascade of ecological and economic damage. Research has recognized IAA as particularly problematic for Hawaiian reefs as they smother coral reefs and native algal communities, permanently altering natural habitats and reducing biodiversity. Two areas particularly hard hit on Oʻahu were Kāneʻohe Bay and Maunalua Bay.