Data from: Biomarkers of recovery: Characterizing trophic flow following ecological restoration

Kelp forest degradation is accelerating globally due to marine heatwaves,
climate stressors, and persistent overgrazing by sea urchins, creating an
urgent need for restoration strategies that rebuild ecosystem function.
Yet how restored kelp subsidies translate into improved food quality and
consumer condition, core indicators of trophic recovery, remains poorly
quantified. We combined fatty acid biomarkers with a
Before–After–Control–Impact Paired Series (BACIPS) experiment to evaluate
how targeted urchin removals in Haida Gwaii, British Columbia, altered the
nutritional landscape for two ecologically and culturally important
grazers: red sea urchins (Mesocentrotus franciscanus) and northern abalone
(Haliotis kamtschatkana). One year after restoration, bull kelp
(Nereocystis luetkeana) increased approximately 67-fold in shallow strata,
while deep kelp biomass rose from 0 to 9.08 stipes/60 m² (± 4.52 SE),
coinciding with marked increases in kelp-associated fatty acids and
improved gonad mass in urchins. In abalone, fatty acid profiles revealed a
size-dependent dietary shift in which larger individuals assimilated more
kelp, and levels of essential fatty acids increased across both species
following kelp recovery. These results provide depth-resolved, field-based
evidence that kelp restoration enhances food quality and consumer
condition in degraded habitats. Fatty-acid biomarkers offer a
scalable tool for detecting early trophic recovery, identifying
high-leverage depth strata for intervention, and evaluating whether
restoration actions are rebuilding the ecosystem functions and
fisheries-relevant nutritional pathways that support resilient kelp forest
ecosystems.