Functional analysis of the spatiotemporal distribution of the macrobenthos associated to bathylithological aspects and environmental variables at the Mackellar Inlet, King George Island, Antarctica (original) (raw)
Related papers
Polar Biology, 1998
During the BENTART 95 Expedition, 24 Agassiz trawls for macrozoobenthos sampling were carried out at depths of 40–850 m, from north of Livingston Island to the Antarctic Peninsula. The samples were analysed using a semi-quantitative method, and with the resulting numerical data, transformed into a six-point scale, we constructed a Bray-Curtis similarity matrix. A total of 74,624 specimens, belonging to 38 taxonomic groups, were collected. The most abundant group was Polychaeta Sedentaria, with 36% of the total, whereas the highest relative masses were from Ascidiacea (23%), Echinoidea Regularia (18%) and Ophiuroidea (16%). The maximum number of specimens recorded was 15,600 ind./50 l. Cluster analysis separated stations located in Foster Bay (Deception Island), characterised by low taxonomic richness and high relative mass (average: 26.7 kg). A zonation of ascidians, regular sea urchins and ophiuroids was observed at Deception Island, clearly related to depth and substratum type. The remaining stations were separated into two groups. The first one comprised the shallowest stations (40–130 m), dominated by sessile active filter-feeders, belonging to Ascidiacea, Demospongia and Bryozoa, and probably related to high primary production zones. The second group comprised deeper stations and was dominated by classes exhibiting a diversity of trophic strategies: Ophiuroidea and Asteroidea, to 400 m, and Polychaeta Sedentaria at greater depths.
High Antarctic macrobenthic community production
Journal of Experimental Marine Biology and Ecology, 1998
Production and productivity (P/B ratio) of the high Antarctic Weddell Sea and Lazarev Sea macrozoobenthos are estimated by an empirical multiple non-linear model (artificial neural network) based on biomass data and other biotic and abiotic parameters. Average community 22 21 22 21 production decreases with depth from 4.8 g C m year (100-300 m) to 0.1 g C m year 21 21 (1500-4300 m). Community P/B ratio increases with depth from 0.18 year to 0.55 year. Taking into account the effects of water depth on production and of temperature on P/B ratio, Antarctic communities show no evidence of unique characteristics with respect to overall energy flow.
Polar Biology, 2006
Temporal variations in composition and density of the benthic macrofauna at two stations (12 and 25 m depth) were studied in Admiralty Bay, King George Island, Antarctica. Samples where carried out using an van Veen sampler between March and December 1999 (winter) and December 2000 and March 2001 (summer), comprising a discontinuous annual cycle. Sediment organic matter showed a marked seasonal cycle, with lowest values at middle winter. Communities showed little variations in density and composition. Temporal variations were not detected at 25 m depth. Variations at 12 m were related to one iceberg impact and to wind generated hydrodinamism, as a function of wind direction, intensity and fetch. As winter scarcity of primary production did not seem to affect macrofaunal community densities, nutrient availability for the benthos in winter can be related to the remineralization of sediment organic matter by bacterial activity.
Quantitative analysis of macrobenthic soft-bottom assemblages in South Shetland waters (Antarctica)
Polar Biology, 1997
Macrobenthic assemblages were investigated at 26 stations located around Livingston Island, Deception Island and the Bransfield Strait at depths ranging from 42 to 671 m. Representatives of 30 major taxa were found. The maximal density was 5,260 specimens · m\ at Livingston Island; the mean abundance per station ranged from 160 to 4,380 specimens · m\. The total biomass of the macrozoobenthos declined with depth, with mean values of 3,201 g · m\ at shallower depths ( (100 m) and 210 g · m\ further down ( '100 m). After multivariate analysis (cluster analysis, MDS) based on Bray-Curtis dissimilarities, most stations could be assigned to one of three groups on the basis of distinct biomass differences between sites. The first cluster with a rich Ascidiacea biomass is common on shallower bottoms. The second, with Ophiuroidea as a characteristic group, is common on deeper bottoms. The absence of an 'indicator' taxon is characteristic of the remaining cluster of those stations with the lowest biomass values. No significant correlations were detected between macrobenthic biomass and any sediment parameters measured, probably because part of the benthos (i.e. the epifauna) could be better explained by the coupling with a highly productive water column. The role of the epi-infauna sensu Gallardo as the main factor structuring benthic assemblages in the investigated area is discussed.
INCT-APA Annual Activity Report, 2010
The short-term variability of the benthic macrofauna community in the shallow coastal area off the Brazilian Antarctic Station Comandante Ferraz (EACF) was investigated during the austral summer of 2008. Three replicates of sediment samples were obtained by a van Veen grab (0.0275 m²) at 20 m depth, in six periods from 1 st February to 7 th March. Macrofaunal densities and sediment composition varied during this period and were correlated to the wind field. Annelids (Polychaeta and Oligochaeta) were the most abundant group with density values ranging from 202 ind.0.0275m -² to 330 ind.0.0275m -² followed by Mollusca and Crustacea. The Principal Component Analysis (PCA) showed that the main sediment components that distinguish the samples were the percentage of gravel, silt and clay. These variations may be influenced by many factors and the climatic conditions play an important role in the local hydrodynamics that affect the benthic community, mainly the organisms with swimming capacity. Meteorological events may influence differently the sediment composition and the macrofauna community. Additional analysis is ongoing to better understand the short-term variability of the macrofauna, including the identification of the polychaetes. Moreover, studies concerning the local hydrodynamics and the interaction between wind, water and sediment in Admiralty Bay are needed. Objective This study aims to evaluate the wind influence on the short-term variation of the macrofaunal community and sediment composition during the austral summer of 2008 at the shallow coastal area, closer to the Brazilian Antarctic Station (Figure 2a). Methodology Six samples (three replicates each) of sediment were obtained using a van Veen grab (0.0275 m²) (Figure 2b) at 20 m depth almost weekly, from 1 st February to 7 th March 2008. In laboratory, the sediment volumes were measured and then washed through sieves of 0.5 mm mesh size. The
Ecological work carried out on the Antarctic and Magellan shelves since the first IBMANT conference held at the UMAG, Punta Arenas in 1997 is summarized to identify areas where progress has been made and others, where important gaps have remained in understanding past and present interaction between the Antarctic and the southern tip of South America. This information is complementary to a review on shallow-water work along the Scotia Arc (Barnes, 2005) and recent work done in the deep sea (Brandt and Hilbig, 2004). While principally referring to shipboard work in deeper water, above all during the recent international EASIZ and LAMPOS campaigns, relevant work from shore stations is also included. Six years after the first IBMANT symposium, significant progress has been made along the latitudinal gradient from the Magellan region to the high Antarctic in the fields of biodiversity, biogeography and community structure, life strategies and adaptations, the role of disturbance and its significance for biodiversity, and trophic coupling of the benthic realm with the water column and sea ice. A better understanding has developed of the role of evolutionary and ecological factors in shaping past and present-day environmental conditions, species composition and distribution, and ecosystem functioning. Furthermore, the science community engaged in unravelling Antarctic-Magellan interactions has advanced in methodological aspects such as new analytical approaches for comparing biodiversity derived from visual methods, growth and age determination, trophic modelling using stable isotope ratios, and molecular approaches for taxonomic and phylogenetic purposes. At the same time, much effort has been invested to complement the species inventory of the two adjacent regions. However, much work remains to be done to fill the numerous gaps. Some perspectives are outlined in this review, and suggestions are made where particular emphasis should be placed in future work, much of which will be developed in the frame of SCAR's EBA (Evolution and Biodiversity in the Antarctic) programme.
Polar Biology
Antarctic marine ecosystems are largely thought to be among the planet’s least impacted, yet habitats adjacent to research stations can be heavily polluted. Despite long-term monitoring and remediation being high priorities for international environmental protection, the ecological responses to contaminants and stressors remains poorly characterised, limiting our ability to manage and reduce human impacts. This study compares epifaunal community composition at two sites close to Scott Base with a reference site further away. We couple these data with environmental characteristics, including current data, sediment properties, and contaminant concentrations within the sediment and in the tissues of two epifaunal species, both from this survey and those previously reported. Previously high concentrations of polychlorinated biphenyls and polyaromatic hydrocarbons are now undetectable and concentrations of heavy metals were mostly similar or reduced compared to previous data from 2002. H...
Polar Biology, 1999
Composition, abundance and strati®cation of soft-bottom macrobenthos were studied at three selected sites on the Ross Sea shelf (Antarctica) with dierent geomorphology and sedimentation regimes. Sites A (southwest Ross Sea, 810 m depth) and B (Joides basin, 580 m depth) were characterized by biogenic mud and clay sediments, whereas site C (Mawson bank, 450 m depth) featured sandy sediments mixed with a conspicuous biogenic component characterized by shells and tests of calcareous invertebrates (mainly barnacles of the genus Bathylasma). The macrofauna of sites A and B was mainly composed of infaunal polychaetes and bivalves. The assemblages comprised both surface and sub-surface deposit feeders, including some conveyorbelt polychaetes (Maldanidae and Capitellidae) that are responsible for high sediment mixing and bioturbation. The macrobenthos of site C was dominated by crustaceans, polychaetes and echinoderms (ophiuroids), and mainly by ®lter feeders and epifaunal or interstitial forms. Abundances were higher (up to 1040 ind. m A2 ) at site B than at sites A and C (430 and 516 ind. m A2 , respectively). At sites A and B the benthos was mainly concentrated in the upper 5 cm of the sediment, and abundances declined sharply in the deeper sediment layers. These results indicate a high degree of consistency between sediment features and benthic community structure, which are both strongly related to local hydrography and bottom dynamics. Sites A and B represent areas where the organic input to the sea¯oor by vertical sedimentation from the upper water column is high. Site C, however, is characterized by high sediment instability and food particles advecting mainly horizontally. The community is more physically controlled by unpredictable, and probably frequent, disturbance events (e.g., bottom turbid currents, sediment reworking and displacement). Individuals were relatively small, indicating that probably they are not able to grow up to the adult size and reproduce. The community may be represented by``pseudopopulations'' depending on the settlement of larvae invading from neighbouring areas.