http://journals.cambridge.org Downloaded: 11 Dec 2013 IP address: 27.24.158.130 Antarctic Science 22(4), 343–360 (2010) & Antarctic Science Ltd 2010 doi:10.1017/S0954102010000179 Recent benthic foraminiferal distribution and related environmental factors in Ezcurra Inlet, King George Island, Antarctica ANDRE ´ ROSCH RODRIGUES, JOA ˜ O CARLOS CATTINI MALUF, ELISABETE DE SANTIS BRAGA and BEATRIZ BECK EICHLER Instituto Oceanogra ´fico/Universidade de Sa ˜o Paulo, USP, Prac ¸a do Oceanogra ´fico, 191, Cidade Universita ´ria, Sa ˜o Paulo, SP 05508-900, Brazil andrerr@usp.br Abstract: This investigation attempts to determine which environmental parameters of the bottom water and sediment control recent foraminifera fauna at Ezcurra Inlet (King George Island, Antarctica), using data collected during four summers (2002/03, 2003/04, 2004/05 and 2006/07). The study revealed that Ezcurra Inlet contain typical Antarctic foraminifera fauna with three distinct assemblages and few differences in environmental parameters. The species Bolivina pseudopunctata, Fursenkoina fusiformis, Portatrochammina antarctica, and Adercotryma glomerata were abundant in the samples. An elevated abundance, richness and diversity were common at the entrance of the inlet at depths greater than 55 m, where the inlet was characterized by low temperatures and muddy sand. In the inner part of the inlet (depth 30–55 m), richness and diversity were low and the most significant species were Cassidulinoides parkerianus, C. porrectus, and Psammosphaera fusca. Shallow waters showed low values of richness and abundance and high temperatures coupled with coarser sediment. In areas with high suspended matter concentrations and pH values associated with low salinity the most representative species were Hippocrepinella hirudinea and Hemisphaerammina bradyi. Received 22 May 2009, accepted 10 December 2009 Key words: Antarctic foraminifera, bottom sediment, bottom water, nutrient content, oceanographic biomarkers, South Shetland Islands Introduction The ecosystems of the Antarctic continent have unique characteristics because of their distance from direct anthropogenic influence. The continent still has almost pristine environments that depend mainly on the marine ecosystems, particularly by the near-shore waters (Hedgpeth 1977, Rakusa-Suszczewski 1980). Because of the variety of factors influencing marine ecosystems, the study of the relationships between organisms and abiotic parameters is necessary to gain an understanding of the whole ecosystem. In marine ecosystems benthic foraminifera are abundant, ubiquitous and easily sampled (Culver 1987) and are traditionally considered good environmental indicators. They are distributed in all marine environments from marshes and bays to abyssal depths, and hundreds of individuals and many different species can be found in a few millilitres of sediment. Research on recent foraminifera in Antarctic environments flourished in the early part of the 20th century (Mikhalevich 2004) and has been intensively carried out ever since, most recently by Ward & Webb (1986), Bernhard (1987), Ward et al. (1987), Mackensen et al. (1990), Ishman & Domack (1994), Violanti (1996), Igarashi et al. (2001), Murray & Pudsey (2004) and Mikhalevich (2004). Some foraminiferal work was also carried out in the South Shetland Islands (Finger & Lipps 1981, Ishman & Domack 1994, Chang & Yoon 1995, Li et al. 2000, Mayer 2000, Majewski 2005, Majewski et al. 2007 and Majewski & Tatur 2009). This study attempts to elucidate the relationship between several oceanographic factors with recent foraminifera assemblages in an Antarctic inlet (Ezcurra Inlet) using material sampled during four summers and numerical analyses such as Multi Dimensional Scaling (MDS). Materials and methods Study area The Ezcurra Inlet is located in western Admiralty Bay, the largest bay of King George Island (Fig. 1), South Shetland Islands. Admiralty Bay shoreline is 25.3 km long (Rakusa- Suszczewski 1995) surrounded by mountains and icefalls, with steep slopes that reach altitudes of 200–450 m above sea level and submerged depths more than 400 m below sea level at the entrance to Admiralty Bay (Bojanowski 1983). The shores of the Ezcurra Inlet coastline are 57.8% mineral material and 42.2% glacial (Marsz 1983). The inlet can be divided into two distinct regions: one at the entrance of the 343