SciELO - Scientific Electronic Library Online

 
vol.42 issue4Seabirds of Easter Island, Salas y Gómez Island and Desventuradas Islands, southeastern Pacific OceanSocio-ecological analysis of the artisanal fishing system on Easter Island author indexsubject indexarticles search
Home Pagealphabetic serial listing  

Services on Demand

Journal

Article

Indicators

Related links

  • On index processCited by Google
  • Have no similar articlesSimilars in SciELO
  • On index processSimilars in Google

Share


Latin american journal of aquatic research

On-line version ISSN 0718-560X

Lat. Am. J. Aquat. Res. vol.42 no.4 Valparaíso Oct. 2014

http://dx.doi.org/10.3856/vol42-issue4-fulltext-7 

Review

 

Synthesis of the state of knowledge about species richness of macroalgae, macroinvertebrates and fishes in coastal and oceanic waters of Easter and Salas y Gómez islands

Síntesis del estado del conocimiento sobre la riqueza de especies de macroalgas, macroinvertebrados y peces en aguas costeras y oceánicas de Isla de Pascua e Isla Salas y Gómez

 

Miriam Fernández1, Paula Pappalardo1,2, Montserrat C. Rodríguez-Ruiz1 & Juan Carlos Castilla1

1 Estación Costera de Investigaciones Marinas and Center for Marine Conservation Departamento de Ecología, Pontificia Universidad Católica de Chile P.O. Box 114-D, Santiago, Chile.
2 Odum School of Ecology, University of Georgia, Athens, GA 30602, United States.
Corresponding author: Miriam Fernández (mfernandez@bio.puc.cl)


ABSTRACT. From the beginning of the 19th century on, several small sampling trips as well as large national and international scientific expeditions have been carried out to Easter Island (EI) and Salas y Gómez Island (SGI). The objective of this study is to compile, synthesize and analyze published information about the biodiversity of macroalgae, macroinvertebrates and fishes associated with EI-SGI, updating the state of knowledge and making it available for the development of conservation plans. We searched all the available sources of information, such as scientific publications, scientific expeditions, fisheries data, technical reports, books, databases and online sources. We found 964 species reported within EI-SGI (143 species of macroalgae, 605 macroinvertebrates and 216 fishes), the majority for EI (923); for SGI 171 species have been reported. Species richness has increased over time, without leveling off, as sampling effort increases. However, seamounts and hydrothermal vents have been poorly studied in Chile's Exclusive Economic Zone (EEZ). A high percentage of endemism has been determined for the majority of the taxonomic groups, with mollusks and poriferans exhibiting the highest levels of endemism (33 -34%). Thus, the Rapanuian biogeographic province can be clearly identified, but information to differentiate between EI and SGI, and direct island-specific conservation efforts, is lacking. Nevertheless, the most vulnerable yet unprotected habitats (hydrothermal vents, higher diversity of seamounts size) are located towards the western limit of the EEZ.

Keywords: biodiversity, biogeography, endemism, oceanic islands, seamounts, hydrothermal vents, Chile.


RESUMEN. Desde el comienzo del siglo XIX varios muestreos y expediciones científicas nacionales e internacionales se han realizado en las islas de Pascua (IP) y Salas y Gómez (ISG). El objetivo de este estudio es compilar, sintetizar y analizar la información publicada sobre biodiversidad de macroalgas, macro-invertebrados y peces asociados a IP-ISG, actualizando el estado del conocimiento y haciéndolo disponible para planes de conservación. Se realizaron búsquedas de diferentes fuentes de información (publicaciones, expediciones, datos pesqueros, reportes técnicos, libros y bases de datos online). Se han reportado 964 especies (143 especies de macroalgas, 605 de macroinvertebrados y 216 de peces), la mayoría para IP (923); para ISG se reportaron 171 especies. La riqueza de especies continúa aumentando en el tiempo, a medida que aumenta el esfuerzo de muestreo. Sin embargo, montes submarinos y fuentes hidrotermales han sido escasamente estudiados en la Zona Económica Exclusiva de Chile (ZEE). El alto porcentaje de endemismo estimado para la mayoría de los grupos taxonómicos permite identificar claramente la provincia biogeográfica Rapanuiana. El mayor nivel de endemismo lo exhiben moluscos y poríferos (33-34%). La información disponible no permite identificar diferencias entre la fauna y flora marina de IP y ISG, ni definir esfuerzos de conservación hacia objetos particulares de cada isla. No obstante, es posible sugerir que los esfuerzos de conservación deberían enfocarse en los hábitat más vulnerables aún no protegidos, ubicados hacia el límite oeste de la ZEE (fuentes hidrotermales y diversidad de tamaños de montes submarinos).

Palabras clave: biodiversidad, biogeografía, endemismo, islas oceánicas, montes submarinos, fuentes hidrotermales, Chile.


 

INTRODUCTION

Easter Island and Salas y Gómez Island are located on the Nazca Plate in the southeast subtropical Pacific and are the only visible peaks in a chain of now submerged seamounts in the Salas y Gómez Ridge (DiSalvo et al., 1988). This ridge extends more than 2900 km from east to west with its western limit coinciding with the Exclusive Economic Zone (EEZ) of Easter Island. At its eastern limit, the Salas y Gómez Ridge merges with the western edge of the Nazca Ridge (Gálvez-Larach, 2009). The Salas y Gómez Ridge is 200 km wide on average and includes seamounts of different sizes and elevations, the tallest of which are over 4000 m above the ocean floor (Rodrigo et al., 2014). It is important to emphasize that Easter Island and Salas y Gómez Island are 3700 and 3400 km apart from the South American continent, respectively, in a context of extreme isolation since the nearest islands are Pitcairn Island 2,250 km to the west, Juan Fernández Island 3140 km to the east, and the Galápagos Islands 3872 km to the northeast. Furthermore, these islands are very young (2.5 and 2 million years old respectively) and very small (Easter Island: 164 km2 and Salas y Gómez Island: 2.5 km2; Newman & Foster, 1983) in comparison with other Pacific Islands (i.e., Hawaii: 16,760 km2, Galápagos: 7,845 km2; Boyko, 2003). Together, these factors affect the characteristics of the marine ecosystems associated with Easter Island and Salas y Gómez Island (Newman & Foster, 1983), which have been studied for almost 200 years.

From the beginning of the 19th century on, several small sampling trips as well as large national and international scientific expeditions have been carried out, mainly focused on Easter Island (Table 1). The first reported species is from 1833 [the mollusk Nerita (Heminerita) morio], collected by the 'Discoverer" during a brief stay at Easter Island. The first crustacean reported from Easter Island was collected by the first Chilean Expedition conducted in the island, and it was the lobster we know now as Panulirus pascuensis. The Albatross Expedition from 1904 to 1905 is the first registered expedition, which obtained corals, crustaceans, echinoderms, mollusks and polychaetes (Table 1). Shortly after, a Chilean Expedition (1911) collected a few specimens of cnidarians, crustaceans, echinoderms, mollusks and polychaetes. In 1917 the Swedish Pacific Expedition arrived at the island and collected holothurians, mollusks and polychaetes. The French-Belgian Archaeological Expedition arrived in 1934 and also collected biological material such as crustaceans, mollusks and polychaetes. At the end of that year, the ship ' Mercator' arrived and contributed to the collection of specimens of crustaceans and mollusks that later allowed taxonomic revisions (Holthuis, 1972; Rehder, 1980). In 1958 the Downwind Expedition visited Easter Island obtaining small collections of cnidarians (corals), echinoderms and crustaceans. Concurrently, the Soviet investigation ship "Ob" collected mollusks on Easter Island. One of the most important expeditions was the METEI, which stayed on Easter Island from 1964 to 1965 and obtained numerous specimens of cnidarians (corals), crustaceans, echino-derms, mollusks and polychaetes. Between 1968 and 1972 the investigator Maria Codoceo, from the Museo Nacional de Historia Natural of Santiago de Chile, contributed to the knowledge of the marine diversity of Easter Island collecting and studying echinoderms. An expedition sponsored by the National Geographic Society also collected echinoderms, besides crustaceans, fish, mollusks and polychaetes. Furthermore, the Universidad de Concepción carried out an expedition collecting bryozoans and crustaceans during those years. In 1982 the Pontificia Universidad Católica de Chile carried out the Expedición Sala de Sistemática, collecting invertebrates and fish (Castilla & Rozbaczylo, 1987). Afterwards, the CIMAR 5 expedition obtained a large number of specimens of invertebrates and fish not only from Easter Island but also from Salas y Gómez Island and its surroundings. More recently, in 2011, the National Geographic Society together with Oceana and the Armada de Chile carried out an expedition with the goal of censusing the coastal marine life of both islands and their neighboring seamounts (Friedlander et al., 2013). It is important to emphasize that in addition to these expeditions, numerous projects were carried out registering the marine biodiversity associated with these islands (e.g., Santelices & Abbot, 1987; Wellington et al., 2001). However, critical habitats remain largely unexplored (e.g., hydrothermal vents) or poorly studied (e.g., seamounts, total surveyed area of seamounts: 60 m2; Friedlander et al., 2013) within the EEZ of Chile. By contrast, the seamounts along the Salas y Gómez Ridge outside the EEZ have been broadly explored (Parin et al., 1997; Stocks, 2009).

 

Table 1. Summary of the scientific expeditions conducted to the Exclusive Economic Zone of Chile surrounding Easter and Salas y Gómez islands.
 

 

The growing number of expeditions to Easter and Salas y Gómez islands is correlated with an increasing number of publications and reviews for different taxonomic groups (Table 2). Some of these reviews were analyzed in a compilation of studies about oceanic islands (Castilla, 1987). Nevertheless, in the last 25 years, 13 taxonomic reviews and more than 35 studies of biodiversity of macroinvertebrate and fish ecology of Easter and Salas y Gómez islands have been published. The objective of the present study is to compile, synthesize and analyze the published information about the biodiversity of macroalgae, macroinvertebrates and fishes associated with the biogeographic province of Easter and Salas y Gómez islands (Sullivan-Sealy & Bustamante, 1999), thereby updating the state of knowledge and making it available for the development of conservation plans. Besides biodiversity data, for some taxonomic groups we compiled information on bathy-metric distribution, conservation status and level of endemism for species present within the biogeographic province of Easter and Salas y Gómez islands.

 

Table 2. Number of family and species reported for each taxonomic group, highlighting the main taxonomic reviews conducted in each case.
 
 
We only listed the reviews specific for each taxonomic group, but DiSalo et al. (1988), Castilla & Rozbaczylo (1987), Boyko (2003) reviewed all invertebrates of Easter island.

 

METHODS

Database

In order to compile a database of species richness for marine invertebrates, algae and fishes reported within the study area, we searched all the available sources of information, such as scientific publications, scientific expeditions, fisheries data, technical reports, books, databases and online sources. The information gathered was used to create a database of marine biodiversity for the province of Easter and Salas y Gómez islands. This database includes taxonomic information for the species present as well as synonyms. The list of species included in the database was compiled based on key scientific publications for each taxonomic group written by taxonomic experts and recent reports of the presence of new species in the study area. The taxonomic information for each species was also verified in the web database World Register of Marine Species (WoRMS Editorial Board 2012). AlgaeBase (Guiry & Guiry, 2014), FishBase, SeaLifeBase (Palomares & Pauly, 2014), and Encyclopedia of Life were used to obtain information about geographic distribution, depth and conservation status (IUCN) for the reported species. Given the heterogeneity of available information for taxonomic groups, some analyses were only carried out for subsets of the taxonomic groups.

Data analysis

All species of invertebrates, algae, and marine fishes in the study area were considered in the calculation of species richness. Species identified to the species level (including affinity, indicated aff, or cf, or question mark (?) by the taxonomists) were quantified. Additionally, species described to the level of genus were included if the genus was not previously recorded in this region, and similarly for unidentified species within a family or order not previously described for the area. To evaluate the evolution of species richness as a function of time (using time as a proxy of accumulated sampling effort), saturation curves were created for the main taxonomic groups of macroinvertebrates (mollusks, crustaceans, and corals), for fishes and for the total number of species. The evolution of species richness over time was also evaluated for the areas accumulating the greatest sampling effort in Easter Island (Hanga Roa, Anakena, the Motus: Iti, Nui and Kao Kao, and Vaihu).

For the analyses of bathymetric distribution, the species (only for crustaceans, mollusks, and fishes) were classified by the range of depths they inhabit as: intertidal (intertidal and tide pools), shallow subtidal (0 to 30 m), subtidal (30 to 200 m), deep sea (200 to 1000 m), and abyssal (>1000 m). This classification refers to the depths at which the species range of distribution has been reported, not necessarily based on direct information from the study area. Finally, the conservation status was only considered for fish (no information was found for other groups) and the following categories were used: Endangered, Vulnerable, Near Threatened, Least Concern, and Data Deficient (from the IUCN red list; www.redlist.org). In all cases, the percent of species in each category was estimated.

To calculate endemism, only species identified to the species level (with assigned genus and species) were used. The presence of these species was classified into the following categories based on their distribution: Cosmopolitan (broadly distributed), Indo-Pacific (in the Indian or Pacific oceans), Pacific (only present in the Pacific Ocean), Polynesian (only present in Polynesian islands), and Easter-Salas y Gómez islands (only reported within the study area). Finally, the percent of endemism was calculated for each category and taxonomic group.

Information from studies of seamounts in the Salas y Gómez Ridge outside of Chile's EEZ was collected in order to: (a) evaluate the biodiversity of seamounts in areas adjacent to the EEZ, (b) evaluate the similarity of seamounts that are physically alike, and (c) compare studies from inside and outside of the EEZ. Information on species richness in seamounts from Parin et al. (1997) was complemented with the online database http://seamounts.sdsc.edu (Stocks, 2009) to compile a database of marine biodiversity associated with seamounts in the Salas y Gómez Ridge. Each seamount was characterized by its geographic position, summit depth, and species richness/composition. Since summit depth can affect food availability (Genin & Dower, 2007) and summit depth is positively correlated with species richness (Pitcher et al., 2007), we classified the seamounts in three general categories (a) summit depth between 200 and 300 m, (b) summit depth between 300 and 500 m, and (c) summit depth >500 m. Within each summit depth category, we compared number of shared species as a function of geographic distance between seamounts. We also compared species richness in the seamounts studied in Easter and Salas y Gómez islands with the three closest seamounts outside the EEZ. We ran the analysis using the R software (R Core Team, 2013), constructing the matrix of geographic distance using the function rdist.earth in the R package fields (Furrer et al., 2012) and the matrix of similarity using the function distance in the R package ecodist (Goslee & Urban, 2007).

Furthermore, since the hydrothermal vents within the EEZ have not yet been studied, information about the studied hydrothermal vents closest to the EEZ was compiled in order to report the species richness characteristic of the hydrothermal vents in this biogeographic province (Van Dover et al., 2012).

RESULTS

We consulted 88 publications and 10 online databases that report information about macroalgae, macro-invertebrates and fishes in the biogeographic province of Easter and Salas y Gómez islands. Of these, 52 contained georeferenced information for 2,287 collection sites, which allowed us to map the distribution of sampling effort in this subset of studies. Sampling sites were concentrated around Easter Island; 92.5% of the species collected around the EEZ of Easter Island were located within 12 nm (nautica miles) of the island (1.5% between 12 and 50 nm, and 6% between 50 and 200 nm). The opposite pattern was found in Salas y Gómez Island, where coastal areas were less explored (only 13.5% of species collected around the EEZ of Salas and Gómez Island were found within 12 nm from the island). Most samples were collected between 12 and 50 nm (42.8%) and between 50 and 200 nm (43.7%). These results highlight vast unexplored areas, mostly located toward the north of both islands. Twelve publications reported information about samples collected in Salas y Gómez Island (mainly from the CIMAR 5 Expedition) or its surroundings, while approximately 59 publications reported species collected on Easter Island. Within the Easter Island area, the most sampled sites were Hanga Roa and Anakena.

The number of species found within the study area reached 964, including macroalgae (143 species), marine invertebrates (605 species), and fishes (216 species). However, collection points have only been reported for 570 species. Our study includes more species than previous reviews for each taxonomic group (e.g., Castilla & Rozbaczylo, 1987; Santelices & Abbot, 1987; Boyko, 2003; Randall & Cea, 2011), showing the contribution of recent publications (Fig. 1). Thus, globally this review includes 341 more species than previous reviews (35% more species) although the proportion of new species varies among taxa. Thirteen percent of the species reported remain unidentified, some of which could potentially represent new species for science. The gaps in species identification are very large in some groups such as bryozoans (69.2%), polychaetes (28.6%), poriferans (18.2%), and crustaceans (17.5%). Appendix I includes a list of all of the species reported within the study area.

Among the invertebrates, mollusks and crustaceans show the highest number of species, totaling almost 400 species (Fig. 1). Among mollusks, the highest number of species was reported for gastropods (138 species) and bivalves (70 species; Table 2). Only three cephalopods, three chitons and one scaphopod were reported for the study area. The majority of the crustacean species are decapods (121 species). Besides, 29 species of peracarids, 19 copepods and five barnacle species have been reported (Table 2). Other groups of invertebrates studied include Polychaeta, with 70 species, Bryozoa with 39 species, Cnidaria with 47 species (only 18 species of scleractinian corals), Echinodermata with 34 species, and Porifera with 22 species (Table 2). Only one species of Nemertea has been reported (Table 2).

 

 
Figure 1. Species richness for taxonomic groups: macroalgae (Rodophyta, Chlorophyta and Ochrophyta), macroin-vertebrates (polychaetes, bryozoans, cnidarians, crustaceans, echinoderms, molluscs and poriferans) and fishes reported in the most recent studies and reviews for each taxonomic group. The bars consider only identified species, while the numbers above the bars indicate the number of species that remain unidentified and are new for the study area.

 

Fish species richness in the study area is mostly explained by bony fishes (201; Fig. 1). Only 14 species of cartilaginous fishes and one species of chimera (Chimaeridae) have been reported (Table 2). There are 143 species of macroalgae reported, with red algae showing the highest number of species (56.6%). Eighty-one species of Rodophyta, 35 species of Chlorophyta, and 27 species of Ochrophyta have been reported (Table 2).

The majority of all the taxonomic groups included in this review have been reported for the marine zone of Easter Island (923 species), 14.4% of the species are shared with the Salas y Gómez Island marine zone. For Salas y Gómez Island, 171 species were reported, 78% are species that have also been reported for Easter Island. The species richness for the study area has been continually increasing over time, with a 38% increase in the number of new species reported in the last 25 years, without leveling off (Fig. 2a). This is explained by new studies and reviews that have identified new species as well as the incorporation of new taxonomic groups into the analysis of total species richness. Two large jumps in the number of species are shown (Fig. 2): one in the 1980's, influenced by the works of Redher (1980) and DiSalvo et al. (1988), and a more recent jump associated with the studies of Poupin (2003), Randall & Cea (2011), and Raines & Huber (2012). Even in the most common and conspicuous groups of species, significant changes in the number of reported species are observed (31% increase in the last 25 years in mollusks, Fig. 2b; 43% in crustaceans, Fig. 2c; 30% in fishes, Fig. 2d).

 

 
Figure 2. Patterns of species richness over time in the study area: a) total number of species of macroalgae (Rodophyta, Chlorophyta and Ochrophyta), macroinvertebrates (polychaetes, bryozoans, cnidarians, crustaceans, echinoderms, mollusks, and poriferans) and fishes, b) mollusks only, c) crustaceans only, d) fishes only.

 

The general pattern of increasing species richness over time is also observed in the most studied sites in Easter Island (Fig. 3). Hanga Roa is the site with the highest species richness (Fig. 3a); however, it is also the most sampled site. Based on the best-studied sites, a significant positive correlation was observed between time (proxy for sampling effort) and species richness (r = 0.97, n = 24, P < 0.0001) as well as between the number of publications and species richness (r = 0.87, n = 24, P = 0.001).

 

 
Figure 3. Patterns of species richness over time for coastal areas of a) Hanga Roa, b) Anakena, c) the Motus, d) Vaihu.

 

A high percentage of endemism has been determined for the majority of the groups studied (Fig. 4). The highest level of endemism was found within mollusks and poriferans with 33% and 34% of endemic species, respectively. Crustaceans, fishes, cnidarians, and bryozoans showed over 10% of endemic species (10% indicated by dashed line in Fig. 4). Although few available studies allow the comparison of endemism between Easter and Salas y Gómez islands, the comparative study conducted by Friedlander et al. (2013) using the same method and applying similar sampling effort in both islands show higher numbers of species with limited distribution in Easter Island (19 species) than in Salas y Gómez Island (5 species).

 

 
Figure 4. Percentage of endemic species in the study area and in different regions for the most relevant taxonomic groups. The broken line indicates Briggs' criteria (1974)of 10%endemism to be considered a biogeographic zone.

 

We found published information of bathymetric distribution for 70.9% of mollusks and 81.1% of crustaceans included in our database. The majority of mollusks have been registered as intertidal (32%) or subtidal species (33%, from 30 to 200 m), while 16% are reported as shallow subtidal species (from 0 to 30 m). Only two species of abyssal mollusks have been reported (obtained at depths around 2000 m near Salas y Gómez Island). On the other hand, most crustaceans are subtidal (30 to 200 m; 45.8%), and deep-sea species (200 to 1000 m; 20.6%). Only a few species of crustaceans have been registered deeper than 1000 m (8 species; 7%; SeaLifeBase; Palomares & Pauly, 2014). For the 93% of the species of fish for which bathymetric distribution information has been reported, only 41 species inhabit shallow subtidal zones (<30 m), while the majority of species are found between 30 and 200 m (33%; 69 species) and in the deep ocean (38%; 78 species).

Of the cartilaginous fishes, five shark species are listed under the following conservation statuses: (a) Endangered: the hammerhead shark (Sphyrna lewini), (b) Vulnerable: the shortfin mako shark (Isurus oxyrinchus), the porbeagle shark (Lamna nasusa) and the bigeye thresher shark (Alopias superciliosus), and (c) Near Threatened: the blue shark (Prionace glauca) and the Galápagos shark (Carcharhinus galapagensis). Various bony fish species are also listed in categories of conservation, from Critically Endangered (Thunnus maccoyii, the southern bluefin tuna) to Least Concern (Katsuwonus pelamis, the skipback tuna and Xiphias gladius, the swordfish). Two species have been classified as Vulnerable (Thunnus obesus, bigeye tuna, and Makaira indica, the black marlin) and three as Near Threatened (Thunnus albacares, yellow-fin tuna; Thunnus alalunga, albacore and Tetrapturus audax, striped marlin).

The various gaps in available information highlight the lack of sampling on seamounts in Easter and Salas y Gómez islands, in hydrothermal vents, and a biass toward some taxonomic groups such as brachiopods, poriferans or bryozoans.

Gaps in knowledge: seamounts and hydrothermal vents

The marine area surrounding Easter and Salas y Gómez islands is characterized by the dominance of seamounts that occupy 27% of the seabed (Rappaport et al., 1997). The 383 seamounts identified are not distributed homogenously; the mounts nearest to the two islands are the largest (Rodrigo, 1994). It is also important to note that the largest seamounts are the tallest (the basal area of seamounts is positively related with their height), and that the number of seamounts increases as the size decreases (Rodrigo, 1994; Rappaport et al., 1997). Considering these relationships, it has been estimated that 50% of the total seamounts volume (equal to 61,000 km3) is made up of the 14 largest seamounts (Rappaport et al., 1997). These seamounts are found in the Salas y Gómez zone while the greatest diversity of sizes is found in the Easter Island zone (Rodrigo et al., 2014).

Although the seamounts within the biogeographic province of Easter and Salas y Gómez islands have been physically described (Rappaport et al., 1997; Yáñez et al., 2008), biological information is scarce. Only one study analyzed biodiversity in this environment using a dropcam that sampled to a maximum depth of 1850 m (Friedlander et al., 2013). However, the available information is insufficient to either characterize this type of environment or reveal sites of greatest importance for conservation. Twenty-six species of fishes and 16 invertebrates associated with seamounts were found inside de EEZ in a surveyed area of 60 m2 (Friedlander et al., 2013); however, only 11 species were identified to the species level. A total of 568 species have been reported associated to seamounts in the Salas y Gómez (outside the EEZ) and Nazca ridges (Stocks, 2009). Of the 213 species of fish reported for the seamounts in the Nazca and Salas y Gómez ridges (Parin et al., 1997; Stocks, 2009), only 6 were found within the EEZ (Friedlander et al., 2013). Similarly, only a small percentage of the crustaceans reported for the EEZ (7%) are also associated with seamounts outside the EEZ (reported by Parin et al., 1997).

In our comparisons of species richness between seamounts in the Nazca and Salas y Gómez ridges, we found that the number of species shared tends to decrease as the geographic distance between the seamounts increases. This trend was observed in seamounts with shallow (200-300 m) or intermediate (300-500 m) summit depth (Fig. 5). However, the relationship was significant only for fishes for the shallow summit depth range (200-300 m; r2 = 0.77, P < 0.0001). Similarity indices show great variability for invertebrates, oscillating between 0.1 and 0.5, independent of the distance between mounts (Fig. 5).

 

 
Figure 5. Similarity index showing separately the species of fishes and invertebrates shared between seamounts of the Nazca (black dots) and Salas y Gómez (white dots) ridges in relation to the geographic distance between seamounts. The analysis was performed for seamounts of different summit depths: 200-300 m, 300-500 m and >500 m.

 

A series of hydrothermal vents associated with the Pacific Ridge (between 28°-33°S and 112°-113°W) have been identified southeast of the province of Easter and Salas y Gómez islands. Most remarkably, these hydrothermal vents are situated over a very dynamic system of fault lines, which have the highest rate of plate separation in the world (Rappaport et al., 1997; Hey et al., 2006). The base of primary production in these zones is the upwelling of high temperature metal enriched water at the bottom of the ocean providing an energy source that is used by chemosynthetic bacteria.

This energy source supports highly diverse communities, which are ephemeral (decades). Only two thermal vents have been studied in this region and neither is found within the EEZ of Chile (vents 31° and 32°S; Hey et al., 2006). The fauna described in these two vents, located at the southwest of the Chilean EEZ, is quite varied, represented by 45 species from 6 phyla (Annelida, Cnidaria, Echinodermata, Hemichordata, Mollusca, and Porifera), with mollusks and annelids (polychaetes) as the most numerous groups (Hey et al, 2006). Although communities associated with hydrothermal vents are characterized by species with short larval development, facilitating dispersion between vents (Tyler & Young, 2003; Van Dover et al, 2012), this region is relevant because it has been proposed that the Easter Microplate acts as a barrier for various species, particularly for species with planktotrophic larvae (i.e., bivalves, decapods; Won et al., 2003).

DISCUSSION

The compilation and analysis of the information on marine ecosystems in the waters adjacent to Easter and Salas y Gómez islands reveals not only a constant increase in sampling effort and species identification over time but also important gaps in knowledge, especially for vulnerable habitats. This review further describes and discusses recent contributions to the biogeographic characterization of this zone as well as the importance of this area for conservation, mostly due to its high level of endemism.

The sustained increase in sampling effort, reflected in the number of publications in the last decades, is translated into a substantial increase in the number of species reported here when compared with previous reviews. In total, the number of invertebrate, fish and algae species that have been identified as of yet reaches 964. When comparing the groups with most species, such as mollusks (215 species in Easter and Salas y Gómez islands), we estimated that these small islands concentrate almost 50% (45.9%) as many species of mollusks as continental Chile (Pappalardo & Fernández, 2014). It is important to highlight, however, that the study area and continental Chile only share one mollusk species (Hiatella arctica) and 19 genera, and that in general, a small fraction of the marine species are shared with continental Chile or other oceanic islands (Table 3). If we compare the species diversity estimated in Easter and Salas y Gómez islands with that reported for the Juan Fernández Archipelago, a much higher species richness is observed in our study area (735 species reported for the same taxa in Juan Fernández; Fernández et al., 2012), a pattern that is also observed within taxa (Table 4). Mollusk species richness is four times higher in Easter Island than in the Juan Fernández Archipelago (Table 4). Three times more fish and two times more echinoderm species were reported in Easter Island than in Juan Fernández Archipelago. The percent of shared species between the study area and Juan Fernández Archipelago is only 6.4% (Table 3).

 

Table 3. Number of species reported in the Exclusive Economic Zone surrounding Easter and Salas y Gómez islands that are shared with Juan Fernández Archipelago and mainland Chile (% species shared reported between parentheses).
 

 

Table 4. Comparison of the number of species and the percentage of endemic species between Easter Island and other Pacific oceanic islands; groups included were macroinvertebrates and fish. For most taxonomic groups, information for Hawaii and the Galapagos was modified from the work of Boyko (2003). The question mark (?) indicates a lack of available information. We only included species identified to the species level.
 

 

The most revealing characteristic of coastal fishes in Easter Island is the low number of species in comparison with other oceanic islands such as Hawaii or Indonesia, which house from 1000 to 3000 species (Randall & Cea, 2011). The low number of species is explained by a combination of factors, including the geological age of the island (relatively young), the small diversity of habitats, its isolation, and its intermediate latitude, which makes it very cold for many reef species but also very hot for subtropical species (Randall & Cea, 2011).

Even though the total number of reported species has increased 30% in the last 25 years, recent studies only contributed 15% of the new species (32 species from CIMAR Expedition; Sielfeld & Kawaguchi, 2004). Furthermore, the contribution of the most recent studies to total species richness is particularly low for the most numerous groups compared above. For example, the CIMAR expedition did not contribute new records of mollusks (Coloma et al., 2004). Thus, significant increases in species richness should only result from studying in further detail the least studied groups (i.e., polychaetes, poriferans) and poorly studied habitats (i.e., hydrothermal vents, seamounts). Given the positive correlation between sampling effort and species richness as well as between the number of publications and species richness for the study area, species richness for Salas y Gómez Island could change substantially if sampling effort were to increase. This zone has been scarcely studied. Thus, we suggest that the differences in species richness for the two islands could be explained by differential sampling efforts.

Following the criteria from Briggs (1974), a percentage of endemism higher than 10% allows the identification of a biogeographic zone. For the study area, this criterion is met for the majority of the most species rich groups, with the exception of algae (Table 4). The level of endemism of fishes is 16% higher than that reported for the Galápagos Islands. In terms of coastal fishes, the level of endemism is greater than (22%) or similar to other oceanic islands (Hawaii: 25%; DeMartini & Friedlander, 2004, 2006). However, the level of endemism of cnidarians, and specifically of corals (16.3% and 11%, respectively), is lower than that reported for other Pacific islands (21.2%). Echinoderms and polychaetes also show a low percentage of endemic species in comparison with other Pacific islands (Table 3). Comparison of endemism between the two islands is not possible given the enormous difference in sampling effort observed between them. Nevertheless, based on studies with similar sampling effort (Friedlander et al., 2013), 30% of endemic fishes were estimated for Easter Island while only 8% for Salas y Gómez Island.

Unstudied environments

The percent of ocean floor covered by seamounts (27%) is substantially greater than that observed in comparable areas in the Eastern Pacific (6% cover) and can be explained by the hotspot of volcanic activity, characterized by a large number of volcanic fields, in which our study area is situated. It is important to note that, in this area, more than 3000 volcanic structures and 383 seamounts of different sizes and depths have been identified (Rodrigo et al., 2014). The protected area generated by the Motu Motiro Hiva Marine Park principally covers large seamounts, thereby underre-presenting smaller mounts, which are found at deeper depths (Fig. 2; Rappaport et al., 1997), and other geological features with their associated fauna, such as hydrothermal vents.

The low sampling effort directed towards biological studies in seamounts surrounding Easter and Salas y Gómez islands, and the low number of species associated to seamounts (Friedlander et al., 2013), in comparison with the reported species richness in the nearby seamounts of the Salas y Gómez and Nazca ridges (Stocks, 2009), reveals the lack of knowledge about the important and vulnerable habitat that occupies a large fraction of the seafloor of the EEZ of the biogeographic province of Easter and Salas y Gómez islands (Rodrigo et al., 2014). Based on the significant positive correlation between the number of species in seamounts and number of publications in the area outside the EEZ (r = 0.73; P < 0.001; Fernández et al., 2013) and considering the sampling effort in the EEZ (Friedlander et al., 2013), species richness in this area could be ten times higher than what has been currently reported. However, it is impossible to establish if the same group of species reported in the broadly studied seamounts in the Nazca and Salas y Gómez ridges would be also observed in seamounts in the biogeographic province of Easter and Salas y Gómez islands. Particularly considering the differences in physical conditions and summit depth (Parin et al., 1997) and that indices of similarity for invertebrates and fish can vary by orders of magnitude over distances smaller than 100 km (Fig. 5). These preliminary analyses suggest that the current level of protection of seamounts in Salas y Gómez Island, focusing fundamentally on large and shallow seamounts, might not sufficiently represent the variation in species richness expected for more distant seamounts of diverse sizes.

Biogeographic characterization

Almost all of the taxonomic groups reported in the studied area seem to have originated in the Indo-Pacific: mollusks (Rehder, 1980), polychaetes (Rozbaczylo & Simonetti, 2000), fishes (Randall & Cea, 2011), echinoderms (Fell, 1974; Massin, 1996), poriferans (Desqueyroux-Faúndez, 1990), crustaceans (Poupin, 2008) and algae (Santelices & Abbott, 1987). The affinity of the rest of the fauna present with that of the Indo-Pacific (Massin, 1996; Parin et al., 1997) is explained by the chain of seamounts that connect the French Polynesian Islands with Easter Island, which could favor stepping-stone dispersal for some species, particularly during the late Pliocene when the separation between islands was smaller (Parin et al., 1997). The only exception is corals, with a low number of species and a higher affinity with the East Pacific (Hubbard & Garcia, 2003; Glynn et al., 2007). For corals, it has been proposed that there is an important barrier to the west of the study area, and that the species could have dispersed from the northeast, similarly through stepping-stone dispersal mechanisms along the seamounts of the Nazca and Salas y Gómez ridges.

The Indo-Pacific colonization of seamounts in the Nazca and Salas y Gómez Ridge, in addition to the high levels of endemism from fish to invertebrates, were key elements in the characterization of the Nazca Plate province. Nevertheless, for both groups a break between the Nazca and the Salas y Gómez ridges has been suggested (Parin et al., 1997). In the case of fishes, the fauna associated to the Nazca Ridge exhibits fewer species with larger range of distribution than that inhabiting the Salas y Gómez Ridge. On the other hand, the invertebrate fauna of the Nazca Ridge has a higher affinity with the East Pacific (Parin et al., 1997). Additionally, given the high level on endemism of shallow waters fishes and invertebrates in Easter Island, a Rapanuian biogeographic province has been proposed.

This is also supported by conclusions drawn from different taxonomic groups (crustaceans: Retamal & Moyano, 2010; mollusks: Redher, 1980). The studies carried out on mollusks suggest that the high levels on endemism would justify an independent Rapanuian biogeographic province. However, the data are principally from Easter Island (only three species have been reported exclusively in Salas y Gómez Island; Rehder, 1980; Osorio & Cantuarias, 1989; Coloma et al., 2004). The crustaceans of Easter Island also show a high biogeographic affinity with other Pacific islands, with Pitcairn and Rapa islands to the northeast, with the Kermadec Islands to the west, and with Hawaii to the north (Boyko, 2003; Poupin, 2008). Nevertheless, for mollusks and crustaceans, there is a higher affinity with Pitcairn and Rapa islands (Boyko, 2003; Poupin, 2008). Based on this pattern, Poupin (2008) established that the Rapanuian province would include a larger area that also covers Rapa Island. Retamal & Moyano (2010) also conclude that Easter Island constitutes a province (Rapanuian province), but that the decapod fauna from Salas y Gómez Island is more similar to that of the Nazca Ridge. However, this conclusion is based on deep-sea reports and we must note that samples of decapods from shallow waters in Salas y Gómez Island could be more associated with Easter Island.

Based on the available information, a Rapanuian biogeographic province can be identified, but information to differentiate between Easter Island and Salas y Gómez islands is still lacking since the studies of flora and fauna are not from comparable habitats and depths. This information is critical to develop science-based conservation plans. Nonetheless, the patterns of distribution of vulnerable habitats (hydrothermal vents, diversity of seamounts size) reveals gaps in conservation towards the western limit of the EEZ of Chile and in the areas surrounding Easter Island (seamounts of different sizes and depths) where important seasonal concentrations of chlorophyll are observed in comparison with Salas y Gómez Island and the oligotrophic environment characteristic of the Eastern Pacific Gyre (Andrade et al., 2014; Von Dassow & Collado-Fabbri, 2014).

ACKNOWLEDGEMENTS

We thank the Pew Charitable Trust for funding this study. We also thank Jaime Aguilera for his help georeferencing collection sites. This study is a contribution of the Center for Marine Conservation, Núcleo Milenio at ECIM, Las Cruces (PUC).

 

REFERENCES

AlgaeBase (Guiry, M. D. & Guiry, G. M.). 2014. Algae Base. World-wide electronic publication, National University of Ireland, Galway. [http://www.AlgaeBase.org]. Reviewed July 2014.         [ Links ]

Andrade, I., S. Hormazábal & M. Correa-Ramírez. 2014. Time-space variability of satellite chlorophyll-α in the Easter Island Province, southeastern Pacific Ocean Lat. Am. J. Aquat. Res., 42(4): 871-887.         [ Links ]

Børgensen, F. 1924. Marine algae from Easter Island. In: C. Skottsberg (ed.). The natural history of Juan Fernández and Easter Island. Goteborg, Sweden, 2: 247-309.         [ Links ]

Boyko, C. B. 2001. First record of Baseodiscus hemprichii (Nemertea: Baseodiscidae) on Easter Island (Rapa Nui) and a new eastern distribution boundary for the species. Pac. Sci., 55(1): 41-42.         [ Links ]

Boyko, C. B. 2003. The endemic marine invertebrates of Easter Island: How many species and for how long? In: J. Loret & J. Tanacredi (eds.). Easter Island: scientific exploration into the world's environmental problems in microcosm. Kluwer Academic/Plenum Publishers, New York, pp. 155-175.         [ Links ]

Briggs, J. C. 1974. Marine zoogeography. McGraw-Hill, New York, 475 pp.         [ Links ]

Brooks, F. J. 1998. The coastal molluscan fauna of the northern Kermadec Island, Southwest Pacific Ocean. J. R. Soc. N. Z. Zool., 28(2): 185-233.         [ Links ]

Cañete, J. 1997. Descripción de cinco especies de Polynoidae (Polychaeta) de Isla de Pascua. Rev. Biol. Mar. Oceanogr., 32(2): 189-202.         [ Links ]

Castilla, J. C. 1987. Islas oceánicas chilenas: conocimiento científico y necesidades de investigación. Universidad Católica de Chile, Santiago, 353 pp.         [ Links ]

Castilla, J. C & N. Rozbaczylo. 1987. Invertebrados marinos de Isla de Pascua y Sala y Gómez. In: J.C. Castilla (ed.). Islas oceánicas chilenas: conocimiento científico y necesidades de investigación. Ediciones Universidad Católica de Chile, Santiago, pp. 167-189.         [ Links ]

Chamberlin, R. V. 1919. The Annelida Polychaeta. Mem. Mus. Comp. Zool., 48: 1-154.         [ Links ]

Coloma, C., H. Moyano, V. Ruiz & M. Marchant. 2004. Moluscos litorales de Isla de Pascua, Chile, recolectados por la expedición CIMAR 5- Islas oceánicas I. Cienc. Tecnol. Mar, 27(1): 79-94.         [ Links ]

Database of crustacean (Poupin, J.). 2012. Internet -Database of Crustacea (Decapoda and Stomatopoda), from Central Pacific Islands (French Polynesia, Pitcairn, Easter Island, Clipperton). [http://decapoda.ecole-navale.fr/index.php] and [http://decapoda.free.fr]. Reviewed 15 April 2014.         [ Links ]

Dell'Angelo, B., B. Raines & A. Bonfitto. 2004. The Polyplacophora of Easter Island. Veliger, 47(2): 130-140. 14.         [ Links ]

DeMartini, E. E. & A. M. Friedlander. 2004. Spatial pattern of endemism in shallow water reef fish populations of the northwestern Hawaiian Island. Mar. Ecol. Prog. Ser., 271: 281-296.         [ Links ]

DeMartini, E. E. & A. M. Friedlander. 2006. Predation, endemism, and related processes structuring shallow-water reef fish assemblages of the northwestern Hawaiian Islands. Atoll Res. Bull., 543: 237-256.         [ Links ]

Desqueyrouz-Faúndez, R. 1990. Spongiaires (Desmospongiae) de l'Ile de Pâques (Isla de Pascua). Rev. Suisse. Zool., 97(2): 373-409.         [ Links ]

DiSalvo, L., J. Randall & A. Cea. 1988. Ecological reconnaissance of the Easter Island sublittoral marine environment. Natl. Geogr. Res., 4(4): 451-473.         [ Links ]

Dyer, B. S & M. W. Westneat. 2010. Taxonomy and biogeography of the coastal fishes of Juan Fernandez Archipelago and Desventuradas Islands, Chile. Rev. Biol. Mar. Oceanogr., 45(1): 589-617.         [ Links ]

Etcheverry, H. 1960. Algas marinas de las islas oceánicas chilenas (Juan Fernández, San Félix, San Ambrosio, Pascua). Rev. Biol. Mar., 10: 83-138.         [ Links ]

Fautin, D. G., C. P. Hickman, M. Daly & T. Molodtsova. 2007. Shallow-water sea anemones (Cnidaria: Anthozoa: Actinaria) and tube anemones (Cnidaria: Anthozoa: Ceriantharia) of the Galápagos Islands. Pac. Sci., 61(4): 549-573.         [ Links ]

Fell, J. 1974. The echinoids of Easter Island (Rapa Nui). Pac. Sci., 28(2): 147-158.         [ Links ]

Fernández, M., P. Pappalardo & M. Rodríguez. 2013. Biodiversidad marina en Isla de Pascua. In: M. Fernández & J.C. Castilla (eds.). Informe final: estudio biofísico de la Provincia de Isla de Pascua. The Pew Charitable Trusts, 43 pp.         [ Links ]

Fernández, M., M. Rodríguez, A. Álvarez, C. González, B. Bularz & M. C. Grandi. 2012. Bases para la creación de un área marina costera protegida de múltiples usos en el Archipiélago Juan Fernández. Technical Report, 108 pp.         [ Links ]

Foster, B. A. & W. A. Newman. 1987. Chthamalid barnacles of Easter Island; peripheral pacific isolation of Notochthamalinae new subfamily and Hembeli-group of Euraphiinae (Cirripedia: Chthamaloidea). Bull. Mar. Sci., 41(2): 322-336.         [ Links ]

Friedlander, A. M., E. Ballesteros, J. Beets, E. Berkenpas, C. F. Gaymer, M. Gorny & E. Sala. 2013. Effects of isolation and fishing on the marine ecosystems of Easter Island and Salas y Gómez, Chile. Aquat. Conserv. Mar. Fresh. Ecosyst., 23(4): 515-531.         [ Links ]

Furrer, R., D. Nychka & S. Sain. 2012. Fields: Tools for spatial data. R package version 6.7. http://CRAN.R-project.org/package=fields        [ Links ]

Gálvez-Larach, M. 2009. Montes submarinos de Nazca y Salas y Gómez: una revisión para el manejo y conservación. Lat. Am. J. Aquat. Res., 37(3): 479-500.         [ Links ]

Garth, J. S. 1973. The brachyuran crabs of Easter Island. Proc. Calif. Acad. Sci., 39: 311-336.         [ Links ]

Genin, A. & J. F. Dower. 2007. Seamount plankton dynamics. In: T. J. Pitcher, T. Morato, P. Hart, M. R. Clark, N. Haggan & R. S. Santos (eds.). Seamounts: ecology, fisheries & conservation. Blackwell Publishing, Oxford, 552 pp.         [ Links ]

Gaymer C., P. F. Cárcamo, A. M. Friedlander, A. T. Palma, I.A. Bodin, A. Muñoz, M. García, E. Sorensen, I. Petit, L. Zañartu, B. Rapu, C. Gutierrez & A. Hoffens. 2011. Implementación de una Reserva Marina en la bahía de Hanga Roa: Estudio de línea base. Facultad de Ciencias del Mar, Universidad Católica del Norte, Coquimbo, 142 pp.         [ Links ]

Glynn, P. W., G. M. Wellington, E. A. Wieters & S.A. Navarrete. 2003. Reef- building coral communities of Easter Island (Rapa Nui), Chile. In J. Cortés (ed.). Latin American coral reefs. Elsevier, Amsterdam, pp. 473-494.         [ Links ]

Glynn, P., G. Wellington, E. Wieters & S. Navarrete. 2007. Reef-building coral communities of Easter Island (Rapa Nui), Chile. Pac. Sci., 61(1): 67-90.         [ Links ]

Goddard, M. 2003. Copépodos de pozas intermareales de Isla de Pascua. Cienc. Tecnol. Mar, 26(1): 45-72.         [ Links ]

Gómez, S. & C. B. Boyko. 2006. On a small collection of harpacticoids from Easter Island: the family Laophontidae T. Scott (Crustacea: Copepoda: Harpacticoidea). Zootaxa, 1352: 1-70.         [ Links ]

González, E. R., P. A. Haye, M. Balanda & M. Thiel. 2008. Lista sistemática de especies de peracaridos en Chile (Crustacea-Eumalacostraca). Gayana, 72(2): 157-177.         [ Links ]

Goslee, S. C. & D. L. Urban. 2007. The ecodist package for dissimilarity-based analysis of ecological data. J. Stat. Softw., 22: 1-19.         [ Links ]

Guiry, M. D. & G. M. Guiry. 2014. AlgaeBase. World wide web electronic publication [http://www.algaebase.org]. Reviewed: 10 May 2014.         [ Links ]

Guzmán, G. L. 2004. Decápodos mesopelágicos capturados durante los proyectos CIMAR 5 y CIMAR 6, islas oceánicas chilenas. Cienc. Tecnol. Mar, 27(1): 69-78.         [ Links ]

Hey, R., G. Massoth, R. Vrijenhoek, P. Rona, J. Lupton & D. Butterfield. 2006. Hydrothermal vent geology and biology at earth's fastest spreading rates. Mar. Geophys. Res., 27: 137-153.         [ Links ]

Hoffmann, A. & B. Santelices. 1997. Flora marina de Chile central. Ediciones Universidad Católica de Chile, Santiago, 434 pp.         [ Links ]

Holthuis, L. B. 1972. The crustacean Decapoda Macrura (the Alpheidae excepted) of Easter Island. Zool. Meded., 46(4): 29-54.         [ Links ]

Hubbard, D. K. & M. Garcia. 2003. The corals and coral reefs of Easter Island -a preliminary look. In: J. Loret & J. Tanacredi (eds.). Easter Island: scientific exploration into the world's environmental problems in microcosm. Kluwer Academic/Plenum Publishers, New York, pp. 53-77.         [ Links ]

Informe Técnico (National Geographic, Oceana & Armada de Chile). 2011. Informe expedición a la Isla de Pascua y Salas y Gómez. Informe científico, 56 pp.         [ Links ]

Johnsson, R., C. E. F. Rocha & C. Boyko. 2002. A new species of Cryptopontius (Crustacea: Copepoda: Siphonostomatoida) from Easter Island. Am. Mus. Novit., 3370: 1-8.         [ Links ]

Kensley, B. 2003. Marine isopods crustaceans from Easter Island. Pac. Sci., 57(3): 287-317.         [ Links ]

Kohn, A. & M. C. Lloyd. 1973. Marine polychaete annelids of Easter Island. Int. Rev. Gesamten Hydrobiol., 58: 691-712.         [ Links ]

Lessios, H. A., B. D. Kessing & J. S. Pearse. 2001. Population structure and speciation in tropical seas: global phylogeography of sea urchin Diadema. Evolution, 55: 955-975.         [ Links ]

Letelier, S., M. A. Vega, A. M. Ramos & E. Carreño. 2003. Base de datos del Museo Nacional de Historia Natural: moluscos de Chile. Rev. Biol. Trop., 51(3): 33-137.         [ Links ]

Lorenz, F. & B. K. Raines. 2001. A new species of Cribrarula (Gastropoda: Cypraeidae) from Easter Island. La Conchiglia, 33(299): 27-29.         [ Links ]

Massin, C. 1996. The holothurians of Easter Island. Biologie, 66: 151-178.         [ Links ]

Moyano, H. I. 1973. Briozoos marinos chilenos I. Briozoos de la Isla de Pascua. Gayana Zool., 26: 3-23.         [ Links ]

Moyano, H. I. 1983. Southern Pacific Bryozoa: a general view with emphasis in Chilean species. Gayana Zool., 46: 1-45.         [ Links ]

Moyano, H. I. 2005a. Bryozoa de la Placa de Nazca con énfasis en las Islas Desventuradas. Cien. Tecnol. Mar, 28(1): 75-90.         [ Links ]

Moyano, H. I. 2005b. Bryozoa de la expedición Chilena CIMAR 5 Islas Oceánicas I: El género Jellyella Taylor & Monks 1997 (Bryozoa, Cheilostomatida) en Isla de Pascua. Cienc. Tecnol. Mar, 28(2): 87-90.         [ Links ]

Newman, W. & B. Foster. 1983. The Rapanuian faunal district (Easter and Salas y Gómez), in search of ancient archipelagos. Bull. Mar. Sci., 33(3): 633-644.         [ Links ]

Osorio, C. & V. Cantuarias. 1989. Vertical distribution of mollusk on the rocky intertidal of Easter Island. Pac. Sci., 43(4): 302-315. Species richness in Easter Island and Salas y Gómez Island 15        [ Links ]

Palma, S. 1999. Sifonóforos (Cnidaria, Hydrozoa) de aguas superficiales de Isla de Pascua. Invest. Mar., Valparaíso, 27: 19-23.         [ Links ]

Palma, S. & N. Silva. 2006. Epipelagic siphonophore assemblages associated with water masses along a transect between Chile and Easter Island (eastern South Pacific Ocean). J. Plankton Res., 28(12): 1143-1151.         [ Links ]

Palomares, M. L. D. & D. Pauly. 2014. SeaLifeBase. World Wide Web electronic publication. [www.sealifebase.org]. Reviewed 10 May 2014.         [ Links ]

Pappalardo, P. & M. Fernández. 2013. Mode of larval development as a key factor to explain contrasting effects of temperature on species richness across oceans. Global Ecol. Biogeogr., 13: 12-23        [ Links ]

Parin, N., A. Mironov & K. Nesis. 1997. Biology of the Nazca and Salas y Gómez Submarine Ridges, an outpost of the Indo-West Pacific fauna in the Eastern Pacific Ocean: composition and distribution of the fauna, its communities and history. Adv. Mar. Biol., 32: 147-242.         [ Links ]

Pequeño, G. & J. Lamilla. 2000. The littoral fish assemblage of the desventuradas Islands (Chile), has zoogeographical affinities with the western Pacific. Global Ecol. Biogeogr., 9: 431-437.         [ Links ]

Pitcher, T. J., T. Morato, P. J. B. Hart, M. R. Clark, N. Haggan & R.S. Santos. 2007. Seamounts: ecology, fisheries and conservation. Blackwell Publishing, Oxford, 552 pp.         [ Links ]

Poupin, J. 2003. Crustacea Decapoda and Stomatopoda of Easter Island and surrounding areas. A documented checklist with historical overview and biogeographic comments. Atoll Res. Bull., 500(1-4): 1-50.         [ Links ]

Poupin, J. 2008. Biogeography of the decapod and stomatopod crustacea of the Tropical Pacific: issues and prospects. Pac. Sci., 62(3): 377-383.         [ Links ]

R Core Team. 2013. R: A language and environment for statistical computing. Foundation for statistical computing, Vienna, Austria. ISBN 3-900051-07-0, URL http://www.R-project.org/.         [ Links ]

Raines, B. K. 2002. Contributions to the knowledge of Easter Island Mollusca. La Conchiglia, 304: 11-40.         [ Links ]

Raines, B. K. 2007. New molluscan records from Easter Island, with the description of a new Ethminolia. Visaya, 2(1): 70-90.         [ Links ]

Raines, B. & M. Huber. 2012. Biodiversity quadrupled-revision of Easter Island and Salas y Gómez bivalves. Zootaxa, 3217: 1-106.         [ Links ]

Ramirez, M. E. & D. G. Müller. 1991. New records of benthic marine algae from Easter Island. Bot. Mar., 34: 133-137.         [ Links ]

Randall, J. & A. Cea. 2011. Shore fishes of Easter Island. University of Hawaii Press, Honolulu, 176 pp.         [ Links ]

Rappaport, Y., D. F. Naar, C. C. Barton, Z. J. Liu & R. N. Hey. 1997. Morphology and distribution of seamounts surrounding Easter Island. J. Geophys. Res., 102: 24713-24728.         [ Links ]

Rehder, H. 1980. The marine mollusks of Easter Island (Isla de Pascua) and Salas y Gómez. Smithson. Contr. Zool., 289: 1-167.         [ Links ]

Retamal, M. A. 2004. Decápodos de las islas oceánicas chilenas: Pascua y Salas y Gómez. Cienc. Tecnol. Mar, 27(2): 55-68.         [ Links ]

Retamal, M. & H. Moyano. 2010. Zoogeografía de los crustáceos decápodos chilenos marinos y dulceacuícolas. Lat. Am. J. Aquat. Res., 38(3): 302-328.         [ Links ]

Rodrigo, C. 1994. Características morfológicas, geológicas y geofísicas del alineamiento submarino de Pascua. Tesis de Oceanografía, Pontificia Universidad Católica de Valparaíso, Valparaíso, 150 pp.         [ Links ]

Rodrigo, C., J. Díaz & A. González-Fernández. 2014. Origin of the Easter Submarine Alignment: morphology and structural lineaments. Lat. Am. J. Aquat. Res., 42(4): 857-870.         [ Links ]

Rozbaczylo, N. & J. C. Castilla. 1988. A new species of polychaete, Scolelepis anakenae (Polychaeta: Polynoidae). Proc. Biol. Soc. Wash., 101: 767-772.         [ Links ]

Rozbaczylo, N. & J. Simonetti. 2000. Diversity and distribution of Chilean benthic marine polychaetes: state of the art. Bull. Mar. Sci., 67(1): 359-372.         [ Links ]

Rozbaczylo, N., R. A. Moreno, G. Guzmán & J. Jaque. 2004. Poliquetos pelágicos (Annelida, Polychaeta) del Pacífico suroriental frente a Chile e islas oceánicas. Invest. Mar., Valparaíso, 32(2): 11-22.         [ Links ]

Santelices, B. & I. Abbott. 1987. Geographic and marine isolation: an assessment of the marine algae of Easter Island. Pac. Sci., 41: 1-4.         [ Links ]

SeaLifeBase (Palomares, M. L. D. & D. Pauly). 2014. SeaLifeBase. World Wide Web electronic publication. [www.sealifebase.org]. Reviewed: 12 July 2014.         [ Links ]

Senders, J. & P. Martin. 1987. Description d'une nouvelle sous-espece de Cypraeidae en provenance de Ile de Pâques. Apex, 2: 13-22.         [ Links ]

Sielfeld, W. & A. Kawaguchi. 2004. Peces mesopelágicos capturados entre Caldera (26o59'41"S/71o46'00"W) e Isla de Pascua (26°59'49"S/107°35'00"W) durante el Crucero CIMAR 5-Islas oceánicas. Cienc. Tecnol. Mar, 27(2): 77-85.         [ Links ]

Steiner, G., & A. R. Kabat. 2004. Catalog of species group names of Recent and fossil Scaphopoda (Mollusca). Zoosystema, 26(4): 549-726.         [ Links ]

Stocks, K. 2009. Seamounts online: an online information system for seamount biology. Version 2009-1. World Wide Web electronic publication. http://seamounts.sdsc.edu]. Reviewed: 24 November 2013.         [ Links ]

Sullivan-Sealey, K. & G. Bustamante. 1999. Setting geographic priorities for marine conservation in Latin America and the Caribbean. The Nature Conservancy, Arlington, Virginia, 146 pp.         [ Links ]

Tyler, P. A. & C. M. Young. 2003. Dispersal at hydrothermal vents: a summary of recent progress. Hydrobiologia, 503: 9-19.         [ Links ]

Van Dover, C. L., C. R. German, K. G. Speer, L. M. Parson & R. C. Vrijenhoek. 2012. Evolution and biogeography of deep-sea vent and seep invertebrates. Science, 295: 1253-1257.         [ Links ]

Vega, R., R. Licandeo, G. Rosson & E. Yañez. 2009. Species catch composition, length structure and reproductive indices of swordfish (Xiphias gladius) at Easter Island zone. Lat. Am. J. Aquat. Res., 37(1): 83-95.         [ Links ]

Von Dassow, P. & S. Collado-Fabbri. 2014. The biological oceanography, biogeochemical cycles, and pelagic ecosystem functioning of the east-central South Pacific Gyre: focus on Easter Island and Salas-y-Gómez. Lat. Am. J. Aquat. Res., 42(4): 703-742.         [ Links ]

Wellington, G. M., P. W. Glynn, A. E. Strong, S. A. Navarrete, E. Wieters & D. Hubbard. 2001. Crisis on coral reefs linked to climate change. Eos, Trans. Am. Geophys. Union, 82(1): 1-12.         [ Links ]

Wells, J. W. 1972. Notes on Indo-Pacific Scleractinian corals. Part 81. Scleractinian corals from Easter Island. Pac. Sci., 26: 183-190.         [ Links ]

Won, Y., C. R. Young, R.A. Lutz & R. C. Vrijenhoek. 2003. Dispersal barriers and isolation among deep-sea mussel populations (Mytilidae: Bathymodiolus) from eastern Pacific hydrothermal vents. Mol. Ecol., 12: 169-184.         [ Links ]

WoRMS Editorial Board. 2012. World register of marine Species. Accessed at http://www.marinespecies.org at VLIZ.         [ Links ]

Young, P. S. 2004. Globuloverruca spongophila gen. nov., sp. nov. a sponge-associated verrucid (Crustacea: Cirripedia: Thoracica) from Easter Island, with discussion on the morphology of the plate tubules. Zootaxa, 420: 1-10.         [ Links ]

 

Appendix 1: List of species in the study area winth current taxonomic classification (from WoRMS) and their distribution.
 

 

Creative Commons License All the contents of this journal, except where otherwise noted, is licensed under a Creative Commons Attribution License