Post-disturbance temperate reef states influence fish contributions to nature and people

Abstract Background Climate-driven habitat reorganization is reshaping the capacity of marine ecosystems to sustain biodiversity and human well-being, with implications for SDG 14 (Life Below Water) and SDG 2 (Zero Hunger). Yet, it remains unclear to what extent post-disturbance reef fish communities continue to support ecological functioning and human nutrition, particularly in temperate kelp forest ecosystems. Here, we quantify reef fish contributions to nature and people across a 600-km post-heatwave kelp forest gradient along the Pacific coast of Baja California, Mexico. Using 545 transect observations from 12 sites surveyed between 2017 and 2024, we integrated standing biomass, secondary productivity, biomass turnover, and micronutrient provisioning within a Nature for Nature and Nature for People framework. Our design captures spatial variability in reef states for 8 years following the 2014–2016 marine heatwave. Results Across the 2017–2024 post-heatwave period, most reef-fish contributions remained temporally stable across regions and exploitation categories, with only limited directional changes detected among non-targeted species. Fish communities appear to have stabilized into regionally distinct configurations shaped by kelp-forest state. Reefs with persistent canopy-forming kelp emerged as bright spots, supporting high contributions to both nature and people, whereas reefs characterized by understory brown algae and/or urchin barrens showed more reduced contributions. Across the study period, total micronutrient supply per hectare remained temporally stable and largely tracked fish biomass, whereas nutritional quality of an average portion of 100 g of fish changed over time for zinc, vitamin A, and selenium due to species turnover in communities not targeted by fisheries. Our analysis further indicated that fish biomass and total micronutrient supply were structured mainly by spatial variation in sea surface temperature and benthic habitat composition, whereas nutrient concentrations in an average portion of 100 g of fish were largely unrelated to environmental drivers. Conclusions Managing post-heatwave kelp forests requires moving beyond one-size-fits-all strategies, because regional reef states differ markedly in the ecological functions they support and in their contributions to people. Sustaining ocean ecosystem services requires recognizing distinct reef states, protecting ecological and social bright spots, restoring habitat complexity in simplified reefs, and managing biodiversity, fisheries, and human well-being as connected parts of the same system.