Ocean warming has both direct and indirect physiological and ecological consequences for marine organisms. Sessile animals and macroalgae may be particularly vulnerable to anomalous warming given constraints in resource acquisition and reproduction imposed by sessility. In temperate reef ecosystems, sessile suspension feeding invertebrates are a critical trophic link between the plankton and the benthos, and along with macroalgae, provide food for an array of mobile species. Using 14 years of seasonal benthic community data across five coastal reefs, we evaluated how communities of sessile invertebrates and understory macroalgae in southern California kelp forests responded to the “Blob” marine heat wave, a period of anomalously high temperatures and low phytoplankton production. We show that this event had prolonged consequences for kelp forest ecosystems including reductions in sessile invertebrate cover and species richness. Changes to community structure of invertebrates and macroalgae, including species invasions, have persisted six years post-Blob, suggesting that a climate-driven shift in California kelp forests is underway.

Primary Presenter: Kristen Michaud, University of California Santa Barbara (kmmichaud@ucsb.edu)

Authors:

Kristen Michaud, University of California Santa Barbara, Marine Science Institute  (kmmichaud@ucsb.edu)

Daniel Reed, University of California Santa Barbara, Marine Science Institute  (danreed@ucsb.edu)

Robert Miller, University of California Santa Barbara, Marine Science Institute  (rjmiller@ucsb.edu)