Cascading impacts of earthquakes and extreme heatwaves have destroyed populations of an iconic marine foundation species

Aim Ecologists traditionally study how contemporary local processes, such as biological interactions and physical stressors, affect the distribution abundance of organisms. By comparison, biogeographers same organisms, but focus on historic, larger-scale processes that can cause mass mortalities, earthquakes. Here we document cascading effects rare biogeographical (seismic) more common ecological (temperature-related) abundances coastal foundation species. Location Intertidal wave-exposed rocky reefs around Kaik?ura, New Zealand, dominated by large, long-lived, iconic southern bull kelps (Durvillaea antarctica Durvillaea willana). Methods In November 2016, a 7.8 Mw earthquake uplifted coastline Kaik?ura up to 2 m, year later region experienced hottest summer record. Extensive sampling intertidal communities over 15 km were done shortly after heatwaves 4 years earthquake. Results lost 75% its canopy uplift reduced canopies had survived an additional 35%. The survey showed not recovered zone in many places now was small turfs foliose seaweed. Main conclusions Cascading impacts from seismic have destroyed populations Kaik?ura. Surviving smaller sparser patches will likely compromise capacity for self-replacement lower resilience future stressors. These results are discussed global biogeographical-ecological context activity extreme highlight these events, which particularly geological context, may long-lasting legacies.