Although seagrasses are not true grasses, seagrass meadows resemble underwater prairies swaying under the waves. Unlike seaweed (algae), seagrasses are flowering plants, the only marine plants known to produce flowers. Seagrasses occur in many shapes and sizes and are found in shallow coastal waters where sufficient sunlight can reach them. They are distributed widely across the globe, from cold Arctic waters to the warm waters of the tropics, yet comprise only about 72 species worldwide.
Wherever seagrass occurs, diverse fauna are also present. While relatively few species—such as Brant geese, manatees, dugongs, and sea turtles—feed directly on seagrass, many fish and invertebrates rely on seagrass for shelter, nursery habitat, or foraging areas. Many species that support recreational and commercial fisheries also spend their early life stages protected among the seagrass blades.
“Seagrasses form one of the planet’s most vital yet vulnerable ecosystems, sustaining fisheries, stabilizing coastlines, filtering coastal waters, and capturing carbon at rates rivaling forests, making them indispensable to both marine life and global climate resilience,” explained Dr. Mark Fonseca, CSA’s Chief Sciences Officer, and internationally recognized expert in seagrass ecology and restoration.
Seagrass meadows are, however, highly sensitive environments. Boat propellers can cut scars through meadows, and groundings churn up sediment that smothers the blades. Anchors and fishing nets can also tear through these habitats. Coastal development degrades seagrass systems by increasing suspended sediments and nutrient loads to the water column, which accelerate phytoplankton and macroalgae growth and reduce light availability leading to seagrass die-off. However, seagrasses are expected to show mixed responses to climate change–driven ocean acidification. Elevated CO₂ may enhance coastal their resilience, but benefits can be offset when combined with a warming ocean. Overall, global seagrass meadows have experienced a net loss of approximately 19% of surveyed area since 1880, reflecting widespread long-term declines across all major bioregions. Many regions are seeing accelerated losses due to coastal development, declining water quality, and physical disturbance. Fortunately, seagrass restoration can be highly effective, rapidly boosting biodiversity, stabilizing seafloors, and enhancing long‑term ecosystem resilience — although success is typically greatest at modest project scales.
CSA applies its expertise in seagrass ecology to help clients assess potential impacts, design avoidance and minimization measures, and implement effective restoration and monitoring strategies for coastal projects. By integrating ecological science with practical project planning, CSA supports responsible development while mitigating impacts and promoting seagrass habitat recovery. Through its partnership with APEM Group, CSA further strengthens its ability to deliver science-based seagrass conservation solutions worldwide.
Learn more about CSA’s Coastal Habitat Characterization, Monitoring, and Mitigation services here.