Chile and the Salas y Gómez Ridge

Abstract

In Chile, light-dependent benthic taxa have been observed to similar to 280 m with the presence of zooxanthellate cnidarians forming mesophotic coral ecosystems (MCEs) to depths of at least 120 m at Rapa Nui (Easter Island) and Salas y Gomez. Evidence from dredge samples suggests MCEs in the southeast Pacific once extended along the Salas y Gomez Ridge as far east as similar to 85 degrees W, but MCEs in Chile were virtually unexplored prior to 2010. Despite providing critical structural habitat for numerous flora and fauna, including commercially important fishes, basic information about their geographic distribution and community structure are lacking. Here, we review the state of knowledge on these communities and present preliminary results from the most recent surveys at Rapa Nui. Surveys at mesophotic depths (30-280 m) have revealed ecosystems dominated by crustose coralline algae with occasional patches of rhodoliths, undiscovered biodiversity, the first reports of wide-ranging Pacific species, and reports of potential new species in multiple taxa including fishes and echinoderms. Preliminary observations suggest fish communities change with depth and time of day, some habitats support commercially important and juvenile fishes, and MCEs and fisheries at Rapa Nui are in decline due to local, artisanal fishing practices. The recent designation of no-take marine parks in Chile may help to conserve these habitats, but additional information is required to support management decisions and future conservation efforts at Rapa Nui, Salas y Gomez, and seamounts within the Chilean Exclusive Economic Zone.