Turf algae redefine the chemical landscape of temperate reefs, limiting kelp forest recovery

In temperate regions experiencing rapid ocean warming, kelp forests are
being replaced by chemically-rich turf algae. Yet, the extent to which
these turf algae alter the surrounding chemical environment or impact the
rebound potential of kelp forests via allelopathy remains unknown. Here,
we used underwater visual surveys, comprehensive chemical profiling, and
laboratory experiments to reveal that turf algae release bioactive
compounds into the water that fundamentally alter the reef “chemical
landscape” and directly suppress kelp recruitment. Our study, therefore,
reveals that allelopathy is critical in shaping modern kelp forest
ecosystems and their resilience. Further, it demonstrates that reversing
climate-driven state shifts will require not only curbing global carbon
emissions, but also targeted local interventions that break harmful
ecological feedback loops and foster recovery.