As the world grapples with the pressures of climate change, "blue carbon" is increasingly becoming a focal point in marine science and policy discussions. This concept refers to the natural processes and habitat types within marine and coastal ecosystems that absorb and store carbon dioxide. Traditionally, this included mangroves, seagrass meadows, and salt marshes. However, as research continues to advance, scientists are now beginning to incorporate macroalgae into the blue carbon potential system. Kelp forests, specifically those composed of large brown algae, have recently been recognized for their high primary productivity and potential for carbon sequestration, holding promise to play a more significant role in the global carbon cycle.
This scientific attention resonates with the findings of our surveys conducted at Dongsha Atoll National Park. Based on a macroalgae species and coverage survey conducted between June 2023 and October 2024 in the waters surrounding Dongsha Island and Dongsha Atoll, the research team recorded a total of 161 species of macroalgae belonging to 91 genera and 46 families. Among these, 38 species were new records for Taiwan, indicating the remarkable algal diversity in the Dongsha waters. These algae belong to various groups, including green algae, brown algae, red algae, and cyanobacteria. Most of the surveyed benthic environments were seagrass meadows. Notably, in the nearshore areas of Dongsha Island at a depth of 2 meters, the mixed coverage of seagrass and seaweed was more prominent. The survey also showed that seagrass meadows provide suitable habitat for epiphytic and cryptic algae, serving as an important factor in supporting nearshore biodiversity.
In other global waters, such as California and Alaska, kelp forests not only provide rich habitats for fish, sea otters, and invertebrates but also function as an "underwater forest" in carbon fixation and climate adaptation. Research indicates that kelp forests may sequester up to 170 million tons of carbon annually, with potential benefits even surpassing the combined total of currently known blue carbon systems. However, these habitats are facing severe decline. Kelp forests in some coastal areas of California have even decreased by as much as 96%, primarily due to uncontrolled sea urchin populations heavily grazing on the algae, transforming once-dense algal forests into "urchin barrens."
Behind this ecological imbalance lies a complicated history between humans and the ocean. In the 18th and 19th centuries, sea otters were extensively hunted for their valuable fur, bringing the California sea otter to the brink of extinction. Although subsequent international conventions and conservation policies have strived to restore their populations, they now face multiple threats, including reduced food sources, pollution, diseases, and predation by great white sharks, making it difficult for them to reproduce stably and perform their natural function of controlling sea urchin numbers. Ultimately, these cascading effects create a vicious cycle, further weakening the resilience and ecosystem stability of kelp forests.
While Taiwan does not currently possess kelp forests on a scale similar to California's, the algal diversity in Dongsha suggests that macroalgae may also play a significant role in the Dongsha Atoll. Continued scientific investigation in the future, aimed at understanding the interactions between algae and various ecosystems within Dongsha Atoll, especially the ecological significance of algae growing on seagrass meadows, could further integrate biodiversity conservation with climate adaptation goals. This would enable Taiwan to participate in larger-scale blue carbon governance actions from an ecosystem perspective. The core spirit of blue carbon initiatives is not merely to protect a specific type of seaweed or a particular marine area, but to understand and restore the entire marine ecological network.
This scientific attention resonates with the findings of our surveys conducted at Dongsha Atoll National Park. Based on a macroalgae species and coverage survey conducted between June 2023 and October 2024 in the waters surrounding Dongsha Island and Dongsha Atoll, the research team recorded a total of 161 species of macroalgae belonging to 91 genera and 46 families. Among these, 38 species were new records for Taiwan, indicating the remarkable algal diversity in the Dongsha waters. These algae belong to various groups, including green algae, brown algae, red algae, and cyanobacteria. Most of the surveyed benthic environments were seagrass meadows. Notably, in the nearshore areas of Dongsha Island at a depth of 2 meters, the mixed coverage of seagrass and seaweed was more prominent. The survey also showed that seagrass meadows provide suitable habitat for epiphytic and cryptic algae, serving as an important factor in supporting nearshore biodiversity.
In other global waters, such as California and Alaska, kelp forests not only provide rich habitats for fish, sea otters, and invertebrates but also function as an "underwater forest" in carbon fixation and climate adaptation. Research indicates that kelp forests may sequester up to 170 million tons of carbon annually, with potential benefits even surpassing the combined total of currently known blue carbon systems. However, these habitats are facing severe decline. Kelp forests in some coastal areas of California have even decreased by as much as 96%, primarily due to uncontrolled sea urchin populations heavily grazing on the algae, transforming once-dense algal forests into "urchin barrens."
Behind this ecological imbalance lies a complicated history between humans and the ocean. In the 18th and 19th centuries, sea otters were extensively hunted for their valuable fur, bringing the California sea otter to the brink of extinction. Although subsequent international conventions and conservation policies have strived to restore their populations, they now face multiple threats, including reduced food sources, pollution, diseases, and predation by great white sharks, making it difficult for them to reproduce stably and perform their natural function of controlling sea urchin numbers. Ultimately, these cascading effects create a vicious cycle, further weakening the resilience and ecosystem stability of kelp forests.
While Taiwan does not currently possess kelp forests on a scale similar to California's, the algal diversity in Dongsha suggests that macroalgae may also play a significant role in the Dongsha Atoll. Continued scientific investigation in the future, aimed at understanding the interactions between algae and various ecosystems within Dongsha Atoll, especially the ecological significance of algae growing on seagrass meadows, could further integrate biodiversity conservation with climate adaptation goals. This would enable Taiwan to participate in larger-scale blue carbon governance actions from an ecosystem perspective. The core spirit of blue carbon initiatives is not merely to protect a specific type of seaweed or a particular marine area, but to understand and restore the entire marine ecological network.
