Acta Oceanol. Sin., 2013, Vol. 32, No. 6, P. 1-7 DOI: 10.1007/s13131-013-0290-8 http://www.hyxb.org.cn E-mail: hyxbe@263.net Enhancement of the benthic communities around an isolated island in the Antarctic Ocean Jos´ e I Saiz 1∗ , Nuria Anad ´ on 2 , Francisco J Cristobo 3 , Oscar Garcia-Alvarez 4 , Gerardo Garcia-Castrillo 5 , Eduardo L´ opez 6 , Cruz Palacín 7 , Jes ´ us S Troncoso 8 , Ana Ramos 9 1 Departamento de Zooloía y Biología Celular Animal, Universidad del País Vasco, Apartado 644, 48080 Bilbao, Spain 2 Departamento de Biología de Organismos y Sistemas, c/ Rodrigo Uría s/n, Universidad de Oviedo, 33071 Oviedo, Spain 3 Instituto Espa ˜ nol de Oceanografía; Centro Oceanogr´ afico de Gij ´ on, Príncipe de Asturias 70bis, 33212 Gij´ on, Spain 4 Departamento de Zooloxía e Antropoloxía Física. Universidade de Santiago de Compostela, Campus Sur, 15706 Santiago de Compostela, Spain 5 Museo Marítimo del Cant´ abrico, c/ San Martín de Bajamar s/n. 39004 Santander, Spain 6 Departamento de Biología, Facultad de Ciencias, Universidad Aut´ onoma de Madrid, 28049 Madrid, Spain 7 Departament de Biologia Animal, Universitat de Barcelona, Avinguda Diagonal 645, 08028 Barcelona, Spain 8 Departamento de Ecoloxía e Bioloxía e Animal, Universidade de Vigo, Campus Lagoas-Marcosende s/n, 36200 Vigo, Spain 9 Instituto Espa ˜ nol de Oceanografía, Punta del Apio, Apartado 1552, 36200 Vigo, Spain Received 16 February 2012; accepted 3 December 2012 ©The Chinese Society of Oceanography and Springer-Verlag Berlin Heidelberg 2013 Abstract Insular marine biotas are often richer in faunal diversity than those from the open sea in the same geo- graphical region. The existence of particular island effects were tested under polar conditions by compar- ing infaunal benthic assemblages on Peter I Island with those of similar latitudes in the open ocean at the Bellingshausen Sea and also from the coast of the Antarctic Peninsula. Sampling was carried out aboard the RV Hesp ´ e rides during the expedition named BENTART-2003 from 24 January to 3 March 2003. Benthic samples were collected at 18 stations ranging from 90 to 2 044 m depth, using an USNEL-type box corer (BC) dredge. Representatives of 32 higher taxa of invertebrates were found. Univariate and multivariate analyses revealed various patterns in the data. First, significant differences in polychaete abundance were detect- ed between the stations located in the open sea and the remaining sites (island plus mainland sites) and analyzed. Bivalve abundances were also distinct between island and mainland sampling sites. Sediment columns taken from the island seafloor exhibited the highest rate of bioturbation by the infauna. These findings confirm the model that islands develop distinct assemblages characterized by the enhancement of the benthic communities even in cold waters. Several abiotic factors were measured simultaneously at the seafloor and along the water column to investigate faunal distribution patterns. Significant correlations were found between the benthic assemblages and a combination of two environmental variables: “island effect” (measured as a categorical variable) and the redox state of sediments. Richer and more complex benthic assemblages were found in Peter I Island’s sea bottom, whereas the more depauperate bottoms remained in the open sea. Key words: Antarctica, Bellingshausen Sea, benthos, Peter I Island, PRIMER Citation: Jos´ e I Saiz, Nuria Anad´ on, Francisco J Cristobo, Oscar Garcia-Alvarez, Gerardo Garcia-Castrillo, Eduardo L´ opez, Cruz Palacín, Jes´ us S Troncoso, Ana Ramos. 2013. Enhancement of the benthic communities around an isolated island in the Antarctic Ocean. Acta Oceanologica Sinica, 32(6): 1–7, doi: 10.1007/s13131-013-0290-8 1 Introduction Investigations of island ecosystems around the world, such as the emblematic Galapagos Archipelago, have provid- ed key insights to fundamental questions in evolution and e- cology (Arntz, 2006; Gonz´ alez et al., 2008). The theory of island biogeography by MacArthur and Wilson (1967) was the first at- tempt to develop a unifying concept for biodiversity research across islands. In essence, biological insularization appears to be determined by a combination of several biogeographical factors such as island size and island isolation from mainland plus the additional effects of habitat fragmentation and climate (Whittaker and Fern´ andez-Palacios, 2007). Marine ecosystems are said to be less tractable than ter- restrial ecosystems (Vincent and Clarke, 1995; Myers, 1997; Carr et al., 2003) and few studies have been devoted to compare the marine benthic fauna of islands with either open sea or main- Foundation item: The “BENTART-03” cruise was funded by the Antarctic Program REN2001-1074/ANT of the Spanish Government. The completion of the manuscript was aided by a grant “Acci´ on Especial” from the University of Basque Country/EHU (Spain). *Corresponding author, E-mail: ji.saiz@ehu.es 1