The Blob marine heatwave transforms California kelp forest ecosystems

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

Automated summary

Sessile invertebrates in Californian kelp forests undergo prolonged changes in community structure following a marine heatwave event, indicating a climate-driven shift in the ecosystem.