Toward a Coordinated Global Observing System for Seagrasses and Marine Macroalgae

Seagrasses and macroalgae (macrophytes) are the foundation of submerged vegetated ecosystems in shallow coastal waters throughout the world. They are among the most productive habitats on land or sea, provide critical habitat for a diverse range of animals, including commercial, and subsistence fisheries and species of concern, and provide coastal protection, uptake of terrestrial nutrient runoff, and carbon storage. These habitats and the services they provide are threatened by a range of interacting human activities, notably coastal development, declining water quality, invasive species, climate warming, sea level rise, and storms. Large, perennial organisms such as seagrasses and canopy-forming macroalgae are especially vulnerable to human disturbance and, under repeated and interacting impacts, they often yield dominance to faster-growing opportunistic algae. Growing understanding of the valuable services provided by seagrass and macroalgal stands has strengthened interest in conserving them. Originally, these concerns were based primarily on contributions of coastal vegetated ecosystems to commercial fisheries but have expanded to include their importance to biodiversity and threatened species, artisanal fisheries, good water quality, resilience against climate change, and cultural significance.