Emerging Threats of Harmful Algal Blooms to Seagrass Blue Carbon Resources: Mechanism, Ecological Interactions, and Adaptive Management Strategies

Purpose of Review

Harmful algal blooms (HABs) present a growing threat to seagrass ecosystems, significantly impacting their ecological functions and blue carbon potential. Understanding the complex interactions between HABs and seagrasses is crucial for developing adaptive management strategies to protect seagrass ecosystems.

Recent Findings

Recent studies reveal that global HAB events have significantly expanded both geographically and in frequency over the past two decades. The geomorphological processes and depositional environments of seagrass meadows, along with the effects of climate change, act as contemporary drivers that influence algal invasion, presence, and retention within seagrass ecosystems. Emerging research demonstrates that macroalgal blooms can significantly accelerate seagrass carbon loss by enhancing decomposition rates and increasing greenhouse gas emissions from blue carbon stocks. Seagrass allelopathy and associated algicidal bacteria play crucial roles in natural HAB control. Advanced monitoring techniques combining artificial intelligence with remote sensing have achieved significant improvements in detecting and tracking HAB events and seagrass ecosystems.

Summary

This review provides a comprehensive analysis of HAB-seagrass interactions, documenting diverse types of HABs affecting seagrass beds, including macroalgal and microalgal blooms. We examine key environmental factors contributing to HABs in seagrass ecosystems, particularly eutrophication, global warming, and ocean acidification, and analyze their complex impact mechanisms, including light limitation, resource competition, biogeochemical alterations, and toxin effects. Natural defense mechanisms of seagrasses, particularly allelopathy and algicidal bacteria, offer potential solutions for HAB control. Effective protection of these valuable blue carbon resources requires integrated adaptive management strategies, combining advanced monitoring technologies, water quality improvement measures, and community-based conservation approaches.