Data for: Kelp forest loss and emergence of turf algae reshapes energy flow to predators in a rapidly warming ecosystem

Climate change is decimating habitat-forming species in ecosystems around
the world. Yet the impacts of habitat loss on the energetics of the wider
food web remain uncertain for many iconic ecosystems, including cold-water
kelp forests. Here, we assessed how the loss of kelp forests and
subsequent proliferation of low-lying turf algae in the Gulf of Maine has
altered the trophic niches of, and energy acquired by, predatory reef
fishes. Bulk tissue δ13C and δ15N analysis of fish muscle showed that
fishes in kelp forests had larger trophic niches and greater interspecific
niche separation than did fishes on turf reefs. Moreover, δ13C analysis of
essential amino acids revealed that kelp-derived energy accounted for the
majority of energy used by forest fishes (>50 % on average),
whereas fishes on turf reefs compensated for kelp decline via greater
reliance on a phytoplankton-based energy channel. Therefore, ecosystem
state shifts to turf algae – now a global phenomenon – may have
far-reaching impacts on food web energy channels and resilience.