A call to consider the contributions of exported marine macrophyte biomass to ecosystem services

As societies increasingly aim to quantify and preserve nature’s benefits, ecosystem services provided by marine ecosystems are increasingly evaluated. However, these evaluations commonly focus on single ecosystems, despite the growing evidence that ecosystems interact. Here, we investigated the ecosystem services provided by macroscopic exported macrophyte biomass (EMB) from seagrass meadows, salt marshes, mangrove forests, and macroalgae forests using a systematic literature review of EMB in marine settings. We found that vegetative biomass exported from marine macrophytes substantially contributed to the provisioning of ecosystem services in recipient ecosystems – habitat provisioning, carbon storage, nutrient cycling, and abiotic alterations, among others – but were rarely documented as such. We identified time since deposition, proximity to donor ecosystem, EMB magnitude, and EMB seasonality as drivers of ecosystem service outcomes. Knowledge gaps related to EMB ecosystem services suggest that more research is needed across 1) vegetated recipient ecosystems, 2) ecosystem service types, 3) contexts in which EMB provides ecosystem services or disservices, 4) potential management strategies, and 5) regions of the world. We call for broader consideration of the contributions of EMB to ecosystem services within ecosystem services frameworks to increase the accuracy of global valuations and enhance strategies for conserving, restoring, and managing marine ecosystems.