Abstract
This study assessed the spatial distribution pa- ttern of soft-sediment polychaetes on the near-shore of Admiralty Bay, King George Island, Antarctica. In the early and late summer of 2003 /04, seven sites at three different depths (20,30 and 60 meters) were sampled using a van Veen grab. 8,668 individuals all told, belonging to 67 species and 23 families, were identified. The families Terebellidae, Syllidae and Maldanidae were the most speciose. Mean densities ranged from 45.2 to 388.1 ind. 0.1 m-2 in the early summer, and from 29 to 183 ind.0.1m-2 in the late. The species Aphelochaeta cincinnata, Levinsenia gracilis and Rhodine antarctica were the most frequent and abundant. Initially, mean biomass ranged from 0.11 to 5.27 g.0.1 m-2, in the early season and from 0.35 to 5.86 g.0.1 m-2 towards the end. Aglaophamus trissophyllus, Eupolymnia sp. and Barrukia cristata were the species with the highest biomass. Polychaete taxocoenosis structure remained similar in both periods. In the early summer, mean densities, biomass and number of species were lower at 30 meters and higher at 60, whereas in the late, these differences were higher among transects. Ice impacts, mainly anchor-ice, in the early summer, as well as icebergs later on, most likely caused the differences encountered.
Highlights
The Antarctic benthos is characterized by pronounced endemism and a marked dependence on physical condi-tions, such as sediment patterns, waves and ice effects [1]
Seven transects located in the Mackellar and Martel inlets were sampled (Figure 1): Research Station “Comandante Ferraz” (CFA, CFB and CFC), Botany Point (BP), Hennequin Point (HE), Machu Picchu (MP) and Thomas Point (AR), during the austral summer of 20032004
Calcium carbonate content was slightly higher in the late summer, whereas in the early season, this was lower at 20 and 30 meters, with the lowest (6.5%) at MP
Summary
Distribution of the benthic community in shallow waters (up to 100 m) could be influenced by depth [2]. Polychaete composition and distribution in Admiralty Bay was already studied by several authors [6,13,14,15,16,17,18,19] and can be summarized in the following zonation patterns: the dominance of Leitoscoloplos kerguelensis, Ophryotrocha notialis and Microspio cf moorei on shallow bottoms (down to 12 m) and higher densities of Aphelochaeta cincinnata, Apistobranchus glacierae, Rhodine antarctica and Levinsenia gracilis further down. Barbosa et al / Natural Science 2 (2010) 1155-1163 ing ice-disturbed areas [21,22] The aim of this survey was to investigate polychaete spatial distribution in the nearshore soft-sediments at three depths in Admiralty Bay, during the early and late austral summer
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