New record of the endemic coral Porites sverdrupi (Gulf of California): do fluctuations in seawater temperature regulate its southernmost range limit?

Abstract

Rising seawater surface temperatures worldwide may cause reef coral species to shift their geographical range towards cooler environments. Information on such shifts, however, remains scarce. The scleractinian coral Porites sverdrupi (Durham, 1947) is endemic to the Gulf of California, and is considered a threatened species due to its vulnerability to local impacts, low abundance, and limited and fragmented distribution range. Although its historical range extends from the northern Gulf (29°N) to Bahia de Banderas in the south (20°N), to date only two extant populations have been reported in the central portion (25-26°N). Here we report a new record of P. sverdrupi from south of Bahia de La Paz. In 2013, colonies were observed at depths of 5–9 m close to a restored coral area south of Bahia de La Paz, which has been monitored since 2004. Events of local extinction and contraction of the distribution range were related to warm ENSO events (1982 and 2010), while expansion occurred after cold ENSO events in 2008 and 2011. Our results suggest that P. sverdrupi may tolerate the narrowest range of temperatures in its genus, and that the newly recorded range limit may be linked to the physiological limit of temperature tolerance for this species.