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New and Unusual Marine Invertebrates Discovered at the California Channel Islands during the 1997-1998 El Nino





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The occurrence of new and unusual subtropical invertebrates at the Channel Islands was documented for the exceptional 1997-1998 El Nino and subsequent 1998-2000 La Nina during periodic shallow subtidal surveys. Six species (Chloeia viridis, Stenorhynchus debilis, Pleurobranchus areolatus, Chromodoris galexorum, Polycera alabe, and Holothuria impatiens) were new to California. Six others (Bunodeopsis sp., Hemisquilla ensigera californiensis, Dromidia larraburei, Pteria sterna, Arbacia incisa, and Centrostephanus coronatus) represented new records at one or more islands. Most new records occurred at the southernmost and easternmost islands (Santa Catalina, San Clemente, and Anacapa). Repeated sightings of progressively larger size classes provided recruitment, growth, and survivorship information for five species. Increased sightings of subtropical species in California likely are due to northward shifts of biogeographic provinces that occurred during more than two decades of above average seawater temperatures.