Seagrass Thermal Limits and Vulnerability to Future Warming

Abstract

Seagrass rank among the most threatened habitats in the biosphere. The bulk of losses are attributable to the wasting disease, eutrophication and mechanical damage. However, there are growing reports of seagrass mortality events associated to heat waves. Here we test the hypothesis that seagrass thermal limits decline with increasing latitude, and assess the proximity of extant seagrass meadows to their upper thermal limits as well as the time required for these thermal limits to be met under the business as usual emission scenario (RCP8.5), which is that more closely reflecting realized emission trajectories. We do so by combining a synthesis of reported empirically- or experimentally-determined thermal limits for seagrass and current, derived from reanalyses of ocean surface temperature data and future, derived from projections using global circulation models forced by greenhouse emissions, termal regimes.