Benthic megafauna of the nearshore zone of Martel Inlet (King George Island, South Shetland Islands, Antarctica): depth zonation and underwater observations

Nonato, Edmundo Ferraz; Brito, Tânia Aparecida Silva; Paiva, Paulo Cesar; Petti, Mônica Angélica Varella; Corbisier, Thaís Navajas

doi:10.1007/s003000000129

Cited by 57 publications

(16 citation statements)

References 15 publications

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“…A sharper division was evident at shallower areas, where a transition between macroalgae to faunal dominance was registered at around 8 to 10 m depth. At greater depths, the zonation was not as sharp and marked as that described in Antarctic coastal benthos (Gambi et al , Sahade et al , Nonato et al , Barnes and Brockington , Smale , Sahade et al ). Species richness, diversity and evenness showed slight differences with depth, but differed from the pattern exhibited by these factors in the cove and in the majority of Antarctic coastal areas, where a marked trend of increased diversity with increasing depth was reported (Dayton et al , Sahade et al , Nonato et al , Barnes and Brockington , Smale ).…”

Section: Discussionmentioning

confidence: 67%

Climate change, glacier retreat and a new ice‐free island offer new insights on Antarctic benthic responses

et al. 2017

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The Antarctic Peninsula is among the places on Earth that registered major warming in the last 60 yr. Massive ice losses, represented by glacier retreat, ice‐shelf collapses and sea‐ice reduction are among the main impacts of this regional warming. The loss of sea‐bed ice coverage, on the one hand has been affecting benthic assemblages, but on the other it is opening up new areas for benthic colonisation. Potter Cove (South Shetland Islands) offered the opportunity of assessing both processes. We recently reported a sudden shift of benthic assemblages related to increased sedimentation rates caused by glacier retreat. This glacier retreat also uncovered a new island that presents a natural experiment to study Antarctic benthic colonisation and succession. We sampled the new island by photo‐transects taken up to 30 m depth. Here, we report an unexpected benthic assemblage characterised by high species richness, diversity and structural complexity with a well‐developed three‐dimensional structure and epibiotic relationships. Filter feeders comprised the largest trophic group at all depths, mainly ascidians, sponges and bryozoans. Densities were also surprising, recording only six ascidian species with a mean of ∼310 ind. m–2. These values are at least an order of magnitude higher than previous Antarctic reports on early colonisation. This finding challenges the extended idea of a slow and continuous recruitment in Antarctica. However, it also opens the question of whether these complex assemblages could have been present under the glacier in ice‐free refuges that are now exposed to open sea conditions. Under the current scenario of climate change, these results acquire high relevance as they suggest a two‐fold effect of the Antarctic Peninsula warming: the environmental shifts that threaten coastal ecosystems, and also the opening up of new areas for colonisation that may occur at a previously unimagined speed.

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Section: Discussionmentioning

confidence: 67%

Climate change, glacier retreat and a new ice‐free island offer new insights on Antarctic benthic responses

et al. 2017

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“…The central basin and the Martel Inlet are not as strongly influenced by sedimentation processes. The shallowest sublittoral zone down to about 30 m, however, is shaped by growlers and smaller icebergs (Nonato et al 2000;. The central basin is the deepest part of the Admiralty Bay (about 550 m) and is directly influenced by waters entering from the Bransfield Strait .…”

Section: Study Areamentioning

confidence: 99%

Low abundance and high species richness: the structure of the soft-bottom isopod fauna of a West Antarctic glacial fjord

et al. 2017

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Isopods belong to the most speciose groups of the Antarctic benthic fauna, although the knowledge on their diversity and small-scale distribution patterns is still limited. Here we analyze the diversity of the isopod fauna in the Admiralty Bay, a glacial fjord on the King George Island. The basin is located in the region of the Antarctic Peninsula, the fastest warming area of the Southern Ocean. The study provides important baseline data for future research, particularly with respect to temporal fluctuations in benthic fauna, associated with global changes observed in that part of the world. Forty species of isopods representing 19 families were recorded on the soft bottom of the Admiralty Bay. The analyses were based on 99 quantitative samples collected, within the 20-502-m depth range, with a 0.1 m 2 van Veen grab. The materials for the analyses were obtained in the austral summer seasons of 1984/1985 and 1985/1986. The data revealed a high number of isopod species occurring at a low abundance, the mean abundance amounting to 4.8 ± 8.6 ind./0.1 m 2 . Most of the species occurred at low abundances, 25% of the species being represented by singletons. Caecognathia polaris, the most abundant species, showed the mean abundance of merely 1.2 ± 4.2 ind./0.1 m 2 . Species richness, diversity and abundance of the isopod fauna were much higher in the central basin of the Admiralty Bay than in the Ezcurra Inlet, an area affected by a strong disturbance of glacial origin.

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“…The study area is located in the nearshore zone of Martel Inlet, in front of the Brazilian Antarctic Station ''Comandante Ferraz" (62°05'S-58°23'W). The bottom topography in front of the station includes a steep slope down to 30 m, with multiple deep scours and troughs from ice action at a depth around 18 m. At 100 m from the coast, the depth is 25 m. In general, the sediments include gravely sand at 6 m, becoming muddy sand at 30 m (Nonato et al 2000). Salinity and temperature are relatively stable throughout the whole bay.…”

Section: Study Areamentioning

confidence: 99%

Bathymetric distribution of the meiofaunal polychaetes in the nearshore zone of Martel Inlet, King George Island, Antarctica

Petti¹,

Nonato²,

Skowronski³

et al. 2006

Antartic science

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Polychaetes, the dominant macrofaunal taxa of the Antarctic soft sediments, provided more than 40% of the animals found in Martel Inlet. However, little information is available on the composition of meiofaunal communities in polar areas. This study identified the meiofaunal polychaete species and described their bathymetric distribution in the nearshore zone. Sediment cores were taken by divers from 6-25 m depth in the summer of 1991 and 1994 in front of the Brazilian Antarctic Station (Martel Inlet, Admiralty Bay). Additional sampling was done at the 18 m depth in 1994 in order to study the influence of ice scouring. A total of 1895 specimens in 17 families were found. Three species (Apistobranchus glacierae, Leitoscoloplos kerguelensis and Ophryotrocha notialis), all of them belonging to the temporary meiofauna, provided more than 70% of the total polychaete fraction. This meiofaunal component showed similar distributional patterns to those of the macrofaunal polychaetes in this area.

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Benthic megafauna of the nearshore zone of Martel Inlet (King George Island, South Shetland Islands, Antarctica): depth zonation and underwater observations

Cited by 57 publications

References 15 publications

Climate change, glacier retreat and a new ice‐free island offer new insights on Antarctic benthic responses

Climate change, glacier retreat and a new ice‐free island offer new insights on Antarctic benthic responses

Low abundance and high species richness: the structure of the soft-bottom isopod fauna of a West Antarctic glacial fjord

Bathymetric distribution of the meiofaunal polychaetes in the nearshore zone of Martel Inlet, King George Island, Antarctica

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