Award: OCE-1661683

Habitat fragmentation is the breaking apart of a large area of habitat into many smaller patches. Habitat fragmentation is considered to be a major threat to biodiversity. Habitat fragmentation involves two processes that may happen at the same time - habitat loss (shrinking habitat area) and the breaking apart of habitat in space. While losing habitat is known to hurt biodiversity, whether the breaking apart of habitat adds to this loss in biodiversity is less clear. Additionally, much more is known about habitat fragmentation effects in land ecosystems than marine ones. The goal of this work was to better understand habitat fragmentation in marine ecosystems. We used large experiments conducted in the natural environment together with studies of natural and disturbed seagrass ecosystems. We found that habitat edges (linked to fragmentation) generally had less seagrass, but the effects of edges and fragmentation on animals living in seagrass was not strong. Next, we reviewed 180 past studies on habitat fragmentation in marine systems to determine if there were general patterns. We found that habitat fragmentation (independent of habitat loss) in marine ecosystems did not consistently cause biodiversity loss, and in some cases may increase biodiversity. The exception was hydrologic fragmentation, or the blocking of water flow, which resulted in strong negative impacts on biodiversity and habitat function. While more research is needed to understand all factors that explain when and where habitat fragmentation matters for biodiversity (like species traits or scale of study), managing marine ecosystems to reduce loss in habitat area and prevent hydrologic fragmentation should remain priorities. Last Modified: 03/24/2021 Submitted by: Lauren Yeager