Seagrass Meadows under the Changing Climate: A Review of the Impacts of Climate Stressors

Seagrass meadows provide important ecological functions, particularly by serving as carbon sinks and breeding grounds for marine species. Climate change has threatened seagrass communities, causing their replacement, loss and increased vulnerability. This review examined scholarly articles published between 2010-2021 to comprehensively present the impacts of climate change on seagrass meadows. It shows that ocean warming negatively affects seagrass communities by favouring communities of lower structuring capacities, thus reducing the effectiveness of their ecological functions. Ocean warming also promotes the propagation and spread of invasive species, and changes the trophic structures leading to further loss of seagrasses of value. Higher seawater temperature is associated with shoot mortality and retarded growth of certain seagrasses. Sea level rise causes more wave energy to be received by coastal seagrass communities, thus, creating more damage to the communities. Deepening sea limits light penetration and alters distribution of seagrass meadows. Carbon dioxide enrichment of seawater increases photosynthetic rate of seagrasses but ocean warming and acidification counteract this beneficial effect. Carbon dioxide enrichment affects different seagrass species and different parts of a seagrass species differently, and, where beneficial to seagrass communities, could enhance their ecological services. Temperature extremes could kill seagrasses while marine heatwaves and flooding could act synergistically to increase carbon demand of certain seagrasses and unfavourably change their biomass. These impacts are often aggravated by anthropogenic activities. This review calls for more studies and conservation efforts to understand the impacts of climate change on seagrass communities and future-proof them against the changing climate.