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Major hotspots detected along the Scotia Ridge in autumn for southern right whales Eubalaena australis, Antarctic fur seals Arctocephalus gazella and Antarctic prions Pachyptila desolata
Get PDFWe investigated the role of hydrological features, such as water masses, fronts, eddies, and sea ice, in affecting the distribution of upper trophic level species in the Scotia Sea region during autumn. On board RV Polarstern, we performed 365 30-min strip transects recording seabirds and marine mammals along the North Scotia Ridge and the South Sandwich Trench in March—April 2013. Among the 7 identified cetacean species recorded, the humpback whale Megaptera novaeangliae was the most abundant baleen whale (40 individuals), and noteworthy were sightings of six southern right whales Eubalaena australis. Pinnipeds (3 species, 1650 individuals) were dominated by Antarctic fur seal Arctocephalus gazella (99%), and seabirds (36 species, 18900 individuals) by Antarctic prion Pachyptila desolata (~50%). The distribution of these top predators was highly patchy with the majority of observations concentrated in a few counts. This heterogeneity is likely a result of prey availability, and we discuss how hydrological features may have caused the patchiness
Identification of Antarctic culturable bacteria able to produce diverse enzymes of potential biotechnological interest
Get PDFIt is estimated that more than three quarters of the Earth’s biosphere is in perennially cold environments. Despite the extreme environmental conditions of desiccation and freezing, microbes can colonize these habitats through the adaptation of metabolic functions and the synthesis of structurally adapted enzymes. Enzymes within psychrophilic microbes exhibit high specific activity at low and moderate temperature, with low thermostability. In this study we used a classic microbiological approach to isolate Antarctic bacteria with cellulolytic, lipolytic, and ligninolytic activities. From 15 different environmental samples, we generated a collection of approximately 800 bacterial isolates that could grow on R2A or Marine medium at 4°C. This collection was then screened for the presence of the three types of activity at 4°C. We found that 47.7% of the isolates displayed lipolytic activity, 10.2% had cellulase/xylanase activity, and 7.7% showed guaiacol oxidase activity. Of these, 10% displayed two different types of activity, while 0.25% displayed all three types of activity. Our results indicate that cold environments represent outstanding resources for bioprospecting and the study of enzymatic adaptation
Effects of UV radiation on the RNA/DNA ratio of Copepods from Antarctica and Chile
Get PDFThe effect of ultraviolet (UV) radiation on marine organisms has been an important focus of recent research, with depletion of the ozone layer resulting in increased UV radiation at high latitudes. Several studies have identified negative impacts of UV radiation on the biology of zooplanktonic organisms. This study used the RNA/DNA ratio as a measure of stress in copepod assemblages from Fíldes Bay in Antarctica and Quintay Bay on the central coast of Chile, two areas with high UV radiation but different photobiologic histories. Controlled time-light experiments were performed with copepods from the two locations, exposing them to white light, UV light, or darkness. The results showed different responses to UV radiation. Copepods from Fíldes Bay showed a slow metabolic response to UV radiation after 4 and 8 h of exposure. Copepods from Quintay Bay showed a fast metabolic response after 4 h of exposure (4 orders of magnitude higher than that for Fíldes Bay copepods) followed by a rapid return toward baseline after 8 h of exposure. These different responses probably reflect the time the copepod assemblages
have been exposed to increased UV radiation and the extent of adaptive stress responses to cope with that increased UV radiation. The results of this study show that the RNA/DNA ratio is a useful indicator of the physiologic status of marine organisms and is
a useful tool to measure the effects of changing environmental conditions on marine ecosystems, such as those associated with global climate change
Seasonal variations in aerosol compositions at Great Wall Station in Antarctica
Get PDFHigh volume aerosol samplers at Great Wall Station in Antarctica were used to collect 73 aerosol samples between January 2012 and November 2013. The main ions in these aerosol samples, Cl−, NO3−, SO4 2−, Na+, K+, Ca2+, Mg2+, NH4+, as well as methane sulfonic acid, were analyzed using ion chromatography. Trace metals in these samples, including Pb, Cu, Cd, V, Zn, Fe, and Al, were determined by inductively-coupled plasma mass spectrometry. Results showed that sea salt was the main component in aerosols at Great Wall Station. Most ions exhibited significant seasonal variations, with higher concentrations in summer and autumn than in winter and spring. Variations in ions and trace metals were related to several processes (or sources), including sea salt emission, secondary aerosol formation, and anthropogenic pollution from both local and distant sources. The sources of ions and trace metals were identified using enrichment factor, correlation, and factor analyses. Clearly, Na+, K+, Ca2+, and Mg2+ were from marine sources, while Cu, Pb, Zn, and Cd were from anthropogenic pollution, and Al and V were mainly from crustal sources
Assessment and application of electromagnetic induction method to measure Arctic sea ice thickness
Get PDFThe electromagnetic induction method is widely used to measure sea ice thickness. Based on the electrical properties of sea ice and seawater, the method measures the apparent conductivity, which represents the conductivity of the half-space, and calculates the thickness of the sea ice. During the fourth Chinese National Arctic Research Expedition in summer 2010, an integrated electromagnetic induction system was set up on the icebreaker R/V XUE LONG to measure sea ice thickness along the ship’s tracks to the north of the Chukchi Sea. The conductivities of sea ice, seawater, and brine were measured and a simple forward model was used to explain the effect of changes in those conductivities on the apparent conductivity over a horizontal layered structure. The results of this analysis indicated that when using the electromagnetic induction method to measure sea ice thickness, the conductivity of sea ice could be neglected and the conductivity of seawater could be treated as a constant. The ice distribution results derived from the electromagnetic induction method showed that the typical sea ice thickness was 160 cm and 90 cm during the outbound and the return legs of the voyage, respectively
Geographic ranges of ascidians from Antarctica and the southeastern Pacific
Get PDFHistorical and novel data on the geographic and bathymetric distribution of ascidians from Antarctic, Magellan and Chilean waters are compiled, and an inventory of taxa comprising 162 species reported over a 150 year period from the Antarctic region South Polar Province (SPP) compiled. The ascidian fauna from the South Shetland Islands (SSI) is compared with that of the Magellan region, Patagonia and the Chilean coast. We collected 46 ascidian species along the Chilean coast, and during four expeditions to King George Island (SSI) by SCUBA between 2003–2012. About 15% of King George Island (SSI) species are observed to occur also in shallow waters of southern Chile (SCL). Few species known from warm temperate southeastern Pacific (Northern Chile, NCL) waters are absent from the Chilean part of the Magellan Province (SCL). With most data contributed from the Chilean coast coming from the SCL, and with limited sampling having been undertaken at depths exceeding 100 m in the NCL, apparent differences in species richness along the Chilean coast could be attributed to differential sampling effort. We detail 12 species from our Antarctic and Chilean collections in detail, including one, Diplosoma listerianum, not previously reported from Chilean waters, and the genus Botryllus, previously known from them on the basis of a single record
Sources and distribution of particulate organic carbon in Great Wall Cove and Ardley Cove, King George Island, West Antarctica
Get PDFConcentrations of chlorophyll-a (Chl-a), particulate organic carbon (POC) and its stable carbon isotope composition (δ13C) were analyzed to investigate the biogeochemical characteristics and sources of POC in Great Wall Cove (GWC) and Ardley Cove (AC) during the austral summer. POC concentrations ranged from 50.51 to 115.41 μg·L−1 (mean±1 standard deviation: 77.69±17.27 μg·L−1) in GWC and from 63.42 to 101.79 μg·L−1 (82.67±11.83 μg·L−1) in AC. The POC δ13C ranged from −30.83‰ to −26.12‰ (−27.40‰±0.96‰) in GWC and from −28.21‰ to −26.65‰ (−27.45‰±0.47‰) in AC. The temperature and salinity results showed distinct runoff signals in both GWC and AC, although the δ13C data and POC distribution indicate a negligible influence of land sources upon POC. The δ13C values suggest that POC is of predominantly marine origin. The POC/Chl-a ratio and the relationship between POC and Chl-a indicate that phytoplankton, organic detritus and heterotrophic organisms are significant contributors to POC in GWC and AC
Long-term study of at-sea distribution of seabirds and marine mammals in the Scotia Sea, Antarctica
Get PDFThe Scotia Sea is one of the most biologically rich regions of Antarctica, and it hosts a large community of upper trophic-level predators. Long-term at-sea monitoring provides valuable information on the Antarctic marine ecosystem and relationships among top predators. This paper presents the results of at-sea monitoring of seabirds and cetaceans over five consecutive summer seasons (2010—2014) in the Scotia Sea, Antarctica. A total of 11 656 flying birds belonging to 24 species were recorded in 884 ten-minute counts. Six Procellariiformes species were abundant: Black-browed Albatross, Cape Petrel, Southern Fulmar, Antarctic Prion, Wilson’s Storm-petrel, and Black-bellied Storm-petrel. Only three of these species accounted for 82% of the total abundance: Antarctic Prion (40%), Southern Fulmar (22%), and Cape Petrel (20%). A total of 678 baleen whales belonging to five species were recorded along a sampling effort of 2 351 nautical miles: Humpback, Sei, Southern Right, Fin, and Minke whales, which had different abundances during the study. The Fin Whale had the highest mean encounter rate for the 5 years (0.29 whales per nautical mile), followed by the Humpback Whale (0.09 whales per nautical mile). Annual dissimilarity in abundance of both seabirds and cetaceans occurred in conjunction with changes in the sea surface temperature and ice cover, showing the dependence of top predators on environmental changes. The largest aggregations of all top predators (seabirds and cetaceans) were recorded in two regions, west and south of the South Orkney Islands, suggesting important prey availability (especially krill) in those areas
Characteristics of trace metals in marine aerosols and their source identification over the Southern Ocean
Get PDFAtmospheric trace metals (Cu, Zn, Cd, Pb, Fe, V, and Cr), As, Al and Na in marine aerosols were studied over the Southern Ocean during the 28th Chinese National Antarctic Research Expedition. Fe was the most abundant of the analyzed trace metals, with an average concentration of 28.824 ng∙m-3. V and Zn concentrations were also high, and their average concentrations were 5.541 ng∙m-3 and 2.584 ng∙m-3, respectively. Although sea spray significantly influenced the marine aerosol particles measured (Na had the highest concentrations of the analyzed elements, with an average concentration of 2.65 μg∙m-3), multivariate analyses (enrichment factor and principal components analysis) indicated that most of the elements were not associated with oceanic sources. Over the Southern Ocean, Fe, Cd, As, Al and Cr in the aerosols mainly originated from crustal sources, while Cu, Pb, V and Zn originated from crustal sources and anthropogenic emissions. The enrichment factors (EFcrust) for most elements (Fe, Al, As, Cr, Cd, Cu and V) were much lower in the northern latitudes, indicating that when the sampling occurred closer to land the concentrations of these elements in aerosols were strongly affected by terrestrial crustal sources
Distribution patterns of typical enzyme activities in tundra soils on the Fildes Peninsula of maritime Antarctica
Get PDFSoil enzyme activities can be used as indicators of microbial activity and soil fertility. In this paper, the activities of invertase (IA), phosphatase (PA) and urease (UA) were investigated in tundra soils collected from marine animal colonies, areas of human activity and background areas on Fildes Peninsula, maritime Antarctica. Soil enzyme activities were in the range of 1.0 82.7 mg·kg-1·h-1 for IA, 0.2–8.2 mg·kg-1·h-1 for PA and 0.2–39.8 mg·kg-1·h-1 for UA. The spatial distribution patterns for soil enzyme activities corresponded strongly with marine animal activity and human activity. Significantly higher soil IA and PA activities occurred in penguin colony soils, whereas seal colony soils showed higher UA activity. Statistical analysis indicated that soil IA activity was controlled by the levels of soil nutrients (TOC, TN and TP), PA activity was closely related with TP, and UA activity was affected by the soil pH. Overall, the deposition amount of penguin guano or seal excreta could impact the distribution of enzyme activity in Antarctic tundra soils. Multiple stepwise regression models were established between the enzyme activities, soil physicochemical properties and heavy metals Cu and Zn ([IA]=0.7[TP] 0.2[Cu]+22.3[TN]+15.1, [PA]=0.3[TP]+0.03[Mc]+0.2, [UA]=16.7[pH]–0.5[Cu]+ 0.4[Zn]–72.6). These models could be used to predict enzyme activities in the tundra soils, which could be helpful to study the effects of marine animal activity and environmental change on tundra ecosystems in maritime Antarctica