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Marine Biodiversity in Juan Fernández and Desventuradas Islands, Chile: Global Endemism Hotspots - PubMed

  • ️Fri Jan 01 2016

Marine Biodiversity in Juan Fernández and Desventuradas Islands, Chile: Global Endemism Hotspots

Alan M Friedlander et al. PLoS One. 2016.

Abstract

The Juan Fernández and Desventuradas islands are among the few oceanic islands belonging to Chile. They possess a unique mix of tropical, subtropical, and temperate marine species, and although close to continental South America, elements of the biota have greater affinities with the central and south Pacific owing to the Humboldt Current, which creates a strong biogeographic barrier between these islands and the continent. The Juan Fernández Archipelago has ~700 people, with the major industry being the fishery for the endemic lobster, Jasus frontalis. The Desventuradas Islands are uninhabited except for a small Chilean military garrison on San Félix Island. We compared the marine biodiversity of these islands across multiple taxonomic groups. At San Ambrosio Island (SA), in Desventuradas, the laminarian kelp (Eisenia cokeri), which is limited to Desventuradas in Chile, accounted for >50% of the benthic cover at wave exposed areas, while more sheltered sites were dominated by sea urchin barrens. The benthos at Robinson Crusoe Island (RC), in the Juan Fernández Archipelago, comprised a diverse mix of macroalgae and invertebrates, a number of which are endemic to the region. The biomass of commercially targeted fishes was >2 times higher in remote sites around RC compared to sheltered locations closest to port, and overall biomass was 35% higher around SA compared to RC, likely reflecting fishing effects around RC. The number of endemic fish species was extremely high at both islands, with 87.5% of the species surveyed at RC and 72% at SA consisting of regional endemics. Remarkably, endemics accounted for 99% of the numerical abundance of fishes surveyed at RC and 96% at SA, which is the highest assemblage-level endemism known for any individual marine ecosystem on earth. Our results highlight the uniqueness and global significance of these biodiversity hotspots exposed to very different fishing pressures.

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Conflict of interest statement

Competing Interests: AMF and ES are employed by the National Geographic Society. AMW is employed by Oceana. This does not alter the authors' adherence to all the PLOS ONE policies on sharing data and materials, as detailed online in the guide to authors.

Figures

Fig 1
Fig 1. Sampling sites by wave exposure around Robinson Crusoe and Santa Clara islands in the Juan Fernández Archipelago and San Ambrosio in Desventuradas Islands.

The town of San Juan Bautista on Robinson Crusoe Island is denoted by the red asterisk. Location of the islands in relation to the coast of Chile are shown in the upper right panel. Black lines are Chile’s Exclusive Economic Zones around the islands. The lower right panel shows the locations of these islands in the broader Pacific. Pacific basemaps are ETOPO1 from NOAA’s National Geophysical Data Center [34].

Fig 2
Fig 2. Living sessile taxa most responsible for the dissimilarity between Robinson Crusoe and San Ambrosio islands.

Box plots showing median (black line), mean (red dashed line), upper and lower quartiles, and 5th and 95th percentiles for each taxa. Numbers to the right of bars are average dissimilarities based on Similarity of Percentages (SIMPER) analysis. ECA–erect coralline algae. Endemic species are shown in bold. Eisenia cokeri*—Known from Desventuradas Islands and reported from coastal Peru.

Fig 3
Fig 3. Biplot of results of redundancy analysis on dominant sessile and mobile benthic taxa and environmental data.

Data were squareroot transformed and centered prior to analysis. Statistical results are shown in Table 2.

Fig 4
Fig 4. Comparisons of fish assemblage structure between Robinson Crusoe (RC) and San Ambroio SA.

Box plots showing median (black line), mean (red dashed line), upper and lower quartiles, and 5th and 95th percentiles for each assemblage characteristic. (A) Species density (number of species per transect), (B) Number of individuals (number m-2), (C) Biomass (t ha-1), and (D) Resource fish biomass (t ha-1). See Table 4 for statistical results.

Fig 5
Fig 5. Comparisons of fish trophic groups between Robinson Crusoe and San Ambrosio islands.

Box plots showing median (black line), mean (red dashed line), upper and lower quartiles, and 5th and 95th percentiles. Values are biomass (t ha-1). Invert/Pisc.–invertivores/piscivores. Statistical results of 1-way ANOVAs testing island differences. Trophic groups with *** are significantly different at p < 0.001.

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Grants and funding

ES received funding from Blancpain, Davidoff Cool Water and The National Geographic Society. Oceana provided funding to ATP. CFG was suported by Grant NC120030 from the Millennium Scientific Initiative. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.