Distribution Patterns in Antarctic and Subantarctic Echinoderms
Total Page：16
File Type：pdf, Size：1020Kb
Polar Biol (2015) 38:799–813 DOI 10.1007/s00300-014-1640-5 ORIGINAL PAPER Distribution patterns in Antarctic and Subantarctic echinoderms Juan Moles • Blanca Figuerola • Neus Campanya`-Llovet • Toni Monleo´n-Getino • Sergi Taboada • Conxita Avila Received: 25 April 2014 / Revised: 11 December 2014 / Accepted: 27 December 2014 / Published online: 23 January 2015 Ó Springer-Verlag Berlin Heidelberg 2015 Abstract Echinoderms are the dominant megafaunal taxa differences in species composition across depths corre- in Antarctic and Subantarctic waters in terms of abundance sponding to sublittoral, upper and lower bathyal, and and diversity, having a predominant role in structuring abyssal. Bathymetric distribution was analyzed considering communities. The current study presents new data on the biological aspects for each class. As expected, circumpolar asteroids, holothuroids, and ophiuroids (three of the five trends were found, although hydrographic currents may be extant classes of echinoderms) collected in seven scientific the cause of differences in species composition among SO campaigns (1995–2012) from Bouvet Is., South Shetland areas. Our analyses suggest zoogeographic links between Is., and the Eastern Weddell Sea, from a wide bathymetric Antarctica and the adjacent ocean basins, being the Scotia range (0–1,525 m). Among the 316 echinoderms collected, Arc the most remarkable. This study contributes to the we extended the bathymetric ranges of 15 species and knowledge of large-scale diversity and distribution patterns expanded the geographic distribution of 36 of them. This in an Antarctic key group. novel dataset was analyzed together with previous reports in order to establish general patterns of geographic and Keywords Asteroidea Á Holothuroidea Á Ophiuroidea Á bathymetric distribution in echinoderms of the Southern Bathymetric distribution Á Geographic distribution Á Ocean (SO). Nearly 57 % of the assembled-data species Southern Ocean resulted endemic of the SO, although further taxonomic efforts in less accessible areas are needed. Interestingly, some islands presented high levels of species richness even Introduction comparable to large geographic areas. While generally exhibiting a wide range of eurybathy, there were The separation of Antarctica from South America allowed the formation of the Antarctic Circumpolar Current (ACC) Electronic supplementary material The online version of this and the establishment of the Polar Front (PF). This thermal article (doi:10.1007/s00300-014-1640-5) contains supplementary and hydrographic barrier hampers marine organisms’ dis- material, which is available to authorized users. persion from north to south and vice versa at the Southern Ocean (SO; Barker and Thomas 2004). Simultaneously, the J. Moles (&) Á B. Figuerola Á S. Taboada Á C. Avila Department of Animal Biology (Invertebrates) and Biodiversity PF promotes the dispersal of marine organisms—larvae or Research Institute (IrBIO), University of Barcelona, Barcelona, adults—from west to east around Antarctica (Fell 1962; Catalonia, Spain Olbers et al. 2004), and the East Wind Drift along the e-mail: [email protected] Antarctic coast deeply affects the distribution of shelf N. Campanya`-Llovet fauna. The combination of geographic isolation and cli- Department of Biology, Memorial University of Newfoundland, mate change has led to a rich marine Antarctic biota with St. John’s, NL, Canada high number of endemic taxa (Brandt and Gutt 2011). However, numerous species are also shared between the T. Monleo´n-Getino Department of Statistics, University of Barcelona, Barcelona, SO and the nearest geographic neighbors mainly due to Catalonia, Spain their connections during the Cenozoic (Clarke et al. 2005). 123 800 Polar Biol (2015) 38:799–813 The Magellanic region, through the Drake Passage and echinoderms, with Asteroidea (208 species; De Broyer Scotia Arc, especially acts as a potential faunal exchange et al. 2011), Holothuroidea (187 species; O’Loughlin pathway (Clarke et al. 2005; Brandt et al. 2007a). Despite et al. 2011), and Ophiuroidea (126 species; Sto¨hr et al. the present day knowledge, essential baseline data on 2012), being the most speciose classes. Although echi- marine biodiversity and biogeography are still lacking for noderm species richness is higher in the continental shelf, most regions of the SO (Kaiser et al. 2013). This is urgently where dense communities of sessile suspension feeders required to identify biological responses to predicted and its wandering associated fauna dominate, they also environmental changes in Antarctica. Gutt et al. (2004) show a high diversity along the slope and on the deep- pointed out the need of comparative studies between Ant- sea plains (Billett et al. 2001; Aronson et al. 2007). arctic and South-American fauna to better understand At the beginning of the twentieth century, the South species’ dispersion capabilities and the effect of isolation Shetland Is. and the Weddell Sea echinoderm fauna were of populations on their distribution. widely explored (e.g., Ludwig 1903; Vaney 1914; Diachronic anchor ice greatly influences Antarctic Koehler 1917). More recently, high species richness of benthic community structure. Short-term seasonal and asteroids, ophiuroids, and holothuroids has been found on spatial variations from anchor and sea ice contribute to the a regular basis in these areas (Gutt 1990a, b; Gutt and patchiness of benthic communities in the Antarctic conti- Piepenburg 1991; Massin 1992a; Piepenburg et al. 1997; nental shelf (Ragua´-Gil et al. 2004). At the same time, Presler and Figielska 1997; Manjo´n-Cabeza et al. 2001; long-term glacial and interglacial cycles allowed allopatric Manjo´n-Cabeza and Ramos 2003). In addition, within the speciation (Thatje et al. 2005), thus promoting diversifi- last decades, new collections and re-examinations of cation and wide bathymetric tolerances for several Ant- previously collected material have contributed to the arctic taxa (Brandt et al. 2007a; Rogers 2007). description of new species (Carriol and Fe´ral 1985; Gutt Furthermore, due to a very deep continental shelf and a 1990a, b; Massin 1992a; Stampanato and Jangoux 1993; weakly stratified water column, circumantarctic distribu- O’Loughlin 2002, 2009; Massin and He´te´rier 2004; tions and broad depth ranges are also widespread charac- O’Loughlin and Ahearn 2008; Janosik and Halanych teristic features of marine Antarctic fauna (Brey et al. 2010). Other than the South Shetland Is. and the Weddell 1996; Soler i Membrives et al. 2009; Hemery et al. 2012). Sea, echinoderm fauna from Subantarctic areas such as This suggests that the deep-sea fauna around Antarctica, the remote Bouvet Is. has been also surveyed within the largely consisting of taxa with high dispersal capabilities, last years (Arntz 2006). Interestingly, it appears to be that may be related both to adjacent shelf communities and to the major reason for the impoverished fauna occurring in deep-sea fauna from other oceans, being directly connected the vicinities of Bouvet Is. is under-sampling rather than below 3,000 m (Brandt et al. 2007a, b; Pawlowski et al. isolation or geological youth (Arntz et al. 2006). This 2007). In fact, differences in the reproductive mode might island has been proposed as a missing link in the SO, explain composition variations between sites and depths connecting macrozoobenthic fauna with the adjacent (Ragua´-Gil et al. 2004). Thus, long-range dispersion by Magellanic South America, the Antarctic Peninsula, and pelagic planktotrophic and lecithotrophic larvae facilitates the high Antarctic Weddell Sea (Arntz et al. 2006; Gutt the spreading of many species and increases their coloni- et al. 2006), although little is known about its echinoderm zation capacity of highly disturbed habitats, contrary to fauna. brooding organisms that have lower dispersal capabilities Bearing in mind the ecological importance of echino- (Shilling and Manahan 1994; Poulin et al. 2002). derms as one of the major groups structuring the Antarctic Recently, total species richness of macrozoobenthic and Subantarctic benthos, our aim was twofold: first, to organisms inhabiting the Antarctic continental shelf has enhance the present knowledge of Antarctic echinoderms been estimated to comprise between 11,000 and 17,000 species and their geographic and bathymetric distribution species, of which over 8,800 are presently known and by identifying species from widely studied (Eastern Wed- described (Griffiths 2010; De Broyer et al. 2011). Ant- dell Sea and South Shetland Is.) and poorly explored arctic benthic fauna is characterized by the lack of (Bouvet Is.) areas; second, to determine the bathymetric durophagous species either as competitors or as predators and geographic distributions of Antarctic echinoderms in (Clarke et al. 2004). Thus, echinoderms are the dominant the SO combining our data with all bibliographic resources errant megafaunal taxa in the SO in terms of abundance available so far. Species composition of the areas studied and diversity and have a predominant role in structuring was compared to the adjacent ocean basins and discussed. benthic communities (Dayton et al. 1974; Clarke and Asteroids, ophiuroids, and holothuroids were selected as Johnston 2003; Chiantore et al. 2006). Around 10 % of target classes within echinoderms to address both the known Antarctic macrozoobenthic species are objectives. 123 Polar Biol (2015) 38:799–813 801 Materials and methods complemented with the Antarctic Marine Invertebrates