Irene Schloss
Université du Québec à Rimouski, ISMER, Department Member
Physical oceanography measured at three station in Potter cove, Western Antarctic Peninsula. This data collection gives the yearly measurements from 1991 to 2012.
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Abstract Light and temperature demands for photosynthesis and growth of two benthic diatoms from Potter Cove, a shallow bay in King George Island, South Shetland Islands (Antarctica), were determined in laboratory cultures. The species... more
Abstract Light and temperature demands for photosynthesis and growth of two benthic diatoms from Potter Cove, a shallow bay in King George Island, South Shetland Islands (Antarctica), were determined in laboratory cultures. The species investigated were Gyrosigma subsalinum var. antarctica and the Antarctic endemic Odontella litigiosa. The algae exhibited different light requirements for growth and photosynthesis. G. subsalinum was adapted to low light conditions, with a high light utilisation coefficient (α) and low saturating photon irradiances for photosynthesis and growth (~25 μmol m−2 s−1 and 11 μmol m−2 s−1, respectively). Photosynthesis and growth in O. litigiosa were saturated at a photon irradiance of ~100 μmol m−2 s−1. Both benthic diatoms exhibited extremely low upper survival temperature (UST, 5–7 °C) and growth only occurred over a narrow range from 0 and 7 °C. Optimal temperature for growth (0 °C) was slightly lower than optimum temperature for photosynthesis (5 °C). The results suggest that G. subsalinum is well-adapted to the low light and constant low temperature conditions present in water depths below 10 m where it occurs. In contrast, O. litigiosa requires more light and is able to tolerate the higher temperatures typical of shallow waters and tide pools. The northern distribution limit of G. subsalinum is the 4 °C summer isotherm, i.e. at the northern boundary of the Antarctic region. In contrast, O. litigiosa could potentially also occur in the sub-Antarctic region up to the 7 °C summer isotherm.
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FOR DOWNLOAD THE COMPLETE FILE PLEASE USE THE "OTHER VERSION".363322 values, 1037 CTD profiles (Conductivity, Temperature & Density), salinity, voltage and pressure data compiled at 123 stations, spatially distribute in entire... more
FOR DOWNLOAD THE COMPLETE FILE PLEASE USE THE "OTHER VERSION".363322 values, 1037 CTD profiles (Conductivity, Temperature & Density), salinity, voltage and pressure data compiled at 123 stations, spatially distribute in entire Potter Cove. Variable available: Coordinates of stations, depth sampling [m], water temperature [°C], potential temperature [°C], salinity [psu], density [kg/m^3], conductivity [mS/cm], turbidity [NTU], voltage [V], press [dbar].The depth has been classified into three categories 0-5 m; 5-15 m and over 15 m. 5 stations were monthly sampled: E1, E2, E3 (18, 17, 6 years, respectively); Faro and Peñon de Pesca (all months except June & July for 2 and 3 years, respectively). The other 118 stations belong to summer season only covering 1 to 5 years sampling. Transects for summer 1996/1997, 2007 and 2008 have been georeferenced and newly available. Device used: CTD/Rosette (CTD-RO).
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Food web structure plays an important role in determining ecosystem stability against perturbations. High-latitude marine ecosystems are being affected by environmental stressors and biological invasions. In the West Antarctic Peninsula... more
Food web structure plays an important role in determining ecosystem stability against perturbations. High-latitude marine ecosystems are being affected by environmental stressors and biological invasions. In the West Antarctic Peninsula these transformations are mainly driven by climate change, while in the sub-Antarctic region by anthropogenic activities. Understanding the differences between these areas is necessary to monitor the changes that are expected to occur in the upcoming decades. Here, we compared the structure and stability of Antarctic (Potter Cove) and sub-Antarctic (Beagle Channel) marine food webs. We compiled species trophic interactions (predator-prey) and calculated complexity, structure and stability metrics. Even if both food webs presented the same connectance, we found important differences between them. The Beagle Channel food web is more complex, but less stable and sensitive to the loss of its most connected species, while the Potter Cove food web presented lower complexity and greater stability against perturbations.
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Marine phytoplankton can utilize different strategies to cope with ocean warming and freshening from glacial melting in polar regions, which are disproportionally impacted by global warming. In the present study, we investigated the... more
Marine phytoplankton can utilize different strategies to cope with ocean warming and freshening from glacial melting in polar regions, which are disproportionally impacted by global warming. In the present study, we investigated the individual and combined effects of a 4 °C increase in seawater temperature (T+) and a 4 psu decrease in salinity (S-) from ambient values on biomass, nutrient use, fatty acid composition and lipid damage biochemistry of natural phytoplankton assemblages from Potter Cove (25 de Mayo/King George Island, Antarctica). Experiments were conducted by exposing the assemblages to four treatments during a 7-day incubation period using microcosm located along shore from January 23 to 31, 2016. The N:P ratio decreased in all treatments from day 4 onwards, but especially under high temperature (T+). Lipid damage was mainly detected under S0T+ and S-T+ conditions, and it decreased when the production of the antioxidant α-tocopherol increased. This antioxidant protection resulted in a build-up of phytoplankton biomass, especially at T+. Under the combined effect of both stressors (S-T+), the concentration of ω3 fatty acids increased, potentially leading to higher-quality FA composition. These results, which were related to the dominance of sub-Antarctic species in phytoplankton assemblages, contribute to the understanding of the potential consequences of ocean warming and increase seawater freshening on the trophic webs of the Southern Ocean.
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The West Antarctic Peninsula (WAP) is a climatically sensitive region where periods of strong warming have caused significant changes in the marine ecosystem and food-web processes. Tight coupling between phytoplankton and higher trophic... more
The West Antarctic Peninsula (WAP) is a climatically sensitive region where periods of strong warming have caused significant changes in the marine ecosystem and food-web processes. Tight coupling between phytoplankton and higher trophic levels implies that the coastal WAP is a bottom-up controlled system, where changes in phytoplankton dynamics may largely impact other food-web components. Here, we analysed the inter-decadal time series of year-round chlorophyll-<i>a</i> (Chl) collected from three stations along the coastal WAP: Carlini Station at Potter Cove (PC) on King George Island, Palmer Station on Anvers Island and Rothera Station on Adelaide Island. There were trends towards increased phytoplankton biomass at Carlini Station (PC) and Palmer Station, while phytoplankton biomass declined significantly at Rothera Station over the studied period. The impacts of two relevant climate modes to the WAP, the El Niño-Southern Oscillation and the Southern Annular Mode, on winter and spring phytoplankton biomass appear to be different among the three sampling stations, suggesting an important role of local-scale forcing than large-scale forcing on phytoplankton dynamics at each station. The inter-annual variability of seasonal bloom progression derived from considering all three stations together captured ecologically meaningful, seasonally co-occurring bloom patterns which were primarily constrained by water-column stability strength. Our findings highlight a coupled link between phytoplankton and physical and climate dynamics along the coastal WAP, which may improve our understanding of overall WAP food-web responses to climate change and variability.This article is part of the theme issue 'The marine system of the West Antarctic Peninsula: status and strategy for progress in a region of rapid change'.
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Climate change-induced glacial melt affects benthic ecosystems along the West Antarctic Peninsula, but current understanding of the effects on benthic primary production and respiration is limited. Here we demonstrate with a series of in... more
Climate change-induced glacial melt affects benthic ecosystems along the West Antarctic Peninsula, but current understanding of the effects on benthic primary production and respiration is limited. Here we demonstrate with a series of in situ community metabolism measurements that climate-related glacial melt disturbance shifts benthic communities from net autotrophy to heterotrophy. With little glacial melt disturbance (during cold El Niño spring 2015), clear waters enabled high benthic microalgal production, resulting in net autotrophic benthic communities. In contrast, water column turbidity caused by increased glacial melt run-off (summer 2015 and warm La Niña spring 2016) limited benthic microalgal production and turned the benthic communities net heterotrophic. Ongoing accelerations in glacial melt and run-off may steer shallow Antarctic seafloor ecosystems towards net heterotrophy, altering the metabolic balance of benthic communities and potentially impacting the carbon bala...
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Aquatic Sciences Meeting, Aquatic Sciences: Global And Regional Perspectives - North Meets South, 22-27 February 2015, Granada, SpainZooplankton faecal pellets are an important source of organic carbon, providing high energy pulses to the... more
Aquatic Sciences Meeting, Aquatic Sciences: Global And Regional Perspectives - North Meets South, 22-27 February 2015, Granada, SpainZooplankton faecal pellets are an important source of organic carbon, providing high energy pulses to the benthic realm. In shallow coastal environments, this pathway becomes very important since particles reach the bottom fast, so that faecal pellets degradation and recycling in the water column is low. However, the way in which zooplankton use and process food resources affects the biogeochemical fate of their faecal pellets and, consequently, benthic energy budgets. Potter Cove (King George Island, South Shetlands) is a small Antarctic fjord where a rich benthic fauna exists, in spite of generally low primary production; food sources sustaining the benthic production remain unclear. To better understand the link between plankton and benthos we selected the Antarctic krill, a key species in polar ecosystems, and an abundant ascidian species as key organisms to construct a simple organic matter pathway model. We tested a variety of potential food sources for krill in terms of assimilation efficiency, faecal pellets production and energetic quality to evaluate the contribution of the species to the organic carbon flux to the benthos in this Antarctic coastal ecosystemPeer Reviewe
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The Drake Passage (DP) links the Southern Pacific and Atlantic Oceans, and acts as a physical narrowing for the largest current of the World Ocean, the Antarctic Circumpolar Current (ACC). This result in a constriction of the main... more
The Drake Passage (DP) links the Southern Pacific and Atlantic Oceans, and acts as a physical narrowing for the largest current of the World Ocean, the Antarctic Circumpolar Current (ACC). This result in a constriction of the main circumpolar fronts related to the ACC: the Subantarctic Front, the Polar Front, the Southern Antarctic Circumpolar Current Front and the Continental Water Boundary Front. Previous studies showed that the DP is a high-nutrient low-chlorophyll (HNLC) region, but studies on the interannual and seasonal macronutrients’ fluctuations in relation with chlorophyll and frontal areas in the DP are scarce. This study analyzes the spatial and temporal trends of nitrate, phosphate, and silicate on surface samples from 113 oceanographic stations in the DP during summer and early fall of 2001 to 2004, in relation with the different fronts and chlorophyll-a concentration. The results revealed an increase of nutrients towards the south. Nitrate showed values from 3 μM at 5...
Research Interests: Environmental Science, Oceanography, Salinity, Nitrate, Temperature, and 15 moreSeasonal variation, Nutrient, Silicate, Temperatura, Salinidad, Phosphate, Enseñanza - Aprendizaje Ciencias Naturales Y Exactas, Chlorophyll a, Polar Front, variación estacional, Fosfato, nitrato, Clorofila a, Interannual variation, and Biogeochemical Cycle
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Research Interests: Marine Biology, Environmental Science, Aquatic Ecology, Environmental Toxicology, Toxicology, and 12 moreBiology, Harmful algal blooms, Medicine, Toxicity, Bivalves, Paralytic shellfish poisoning, Environmental Risk Assessment, Alexandrium catenella, Shellfish, Enseñanza - Aprendizaje Ciencias Naturales Y Exactas, Bay, and SCALLOP
In order to set a base line for the observation of planktonic community changes due to global change, protistan plankton sampling in combination with phycotoxin measurements and solid phase adsorption toxin tracking (SPATT) was performed... more
In order to set a base line for the observation of planktonic community changes due to global change, protistan plankton sampling in combination with phycotoxin measurements and solid phase adsorption toxin tracking (SPATT) was performed in two bays of King George Island (KGI) in January 2013 and 2014. In addition, SPATT sampling was performed in Potter Cove during a one-year period from January 2014 until January 2015. Known toxigenic taxa were not firmly identified in plankton samples but there was microscopical evidence for background level presence of Dinophysis spp. in the area. This was consistent with environmental conditions during the sampling periods, especially strong mixing of the water column and low water temperatures that do not favor dinoflagellate proliferations. Due to the lack of significant abundance of thecate toxigenic dinoflagellate species in microplankton samples, no phycotoxins were found in net tow samples. In contrast, SPATT sampling revealed the presence...
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The Western Antarctic Peninsula (WAP) is a hotspot for environmental change and has a strong environmental gradient from North to South. Here, for the first time we used adult individuals of the bivalve Aequiyoldia eightsii to evaluate... more
The Western Antarctic Peninsula (WAP) is a hotspot for environmental change and has a strong environmental gradient from North to South. Here, for the first time we used adult individuals of the bivalve Aequiyoldia eightsii to evaluate large-scale spatial variation in the biochemical composition (measured as lipid, protein and fatty acids) and energy content, as a proxy for nutritional condition, of three populations along the WAP: O’Higgins Research Station in the north (63.3°S), Yelcho Research Station in mid-WAP (64.9°S) and Rothera Research Station further south (67.6°S). The results reveal significantly higher quantities of lipids (L), proteins (P), energy (E) and total fatty acids (FA) in the northern population (O’Higgins) (L: 8.33 ± 1.32%; P: 22.34 ± 3.16%; E: 171.53 ± 17.70 Joules; FA: 16.33 ± 0.98 mg g) than in the mid-WAP population (Yelcho) (L: 6.23 ± 0.84%; P: 18.63 ± 1.17%; E: 136.67 ± 7.08 Joules; FA: 10.93 ± 0.63 mg g) and southern population (Rothera) (L: 4.60 ± 0.5...
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(Table 1) Characteristics of air temperature, sea surface temperature, sea surface salinity, nutrients, and total particulate matter for Admiralty Bay and Potter Cove, King George Island, Antarctica, supplement to: Schloss, Irene R; Wasilowska, Agnieszka; Dumont, Dany; Almandoz, Gastón Osvaldo; H...more
Since the early 1990s, phytoplankton has been studied and monitored in Potter Cove (PC) and Admiralty Bay (AB), King George/25 de Mayo Island (KGI), South Shetlands. Phytoplankton biomass is typically low compared to other Antarctic shelf... more
Since the early 1990s, phytoplankton has been studied and monitored in Potter Cove (PC) and Admiralty Bay (AB), King George/25 de Mayo Island (KGI), South Shetlands. Phytoplankton biomass is typically low compared to other Antarctic shelf environments, with average spring - summer values below 1 mg chlorophyll a (Chl a)/m**3. The physical conditions in the area (reduced irradiance induced by particles originated from the land, intense winds) limit the coastal productivity at KGI, as a result of shallow Sverdrup's critical depths (Zc) and large turbulent mixing depths (Zt). In January 2010 a large phytoplankton bloom with a maximum of around 20 mg Chl a/m**3, and monthly averages of 4 (PC) and 6 (AB) mg Chl a/m**3, was observed in the area, making it by far the largest recorded bloom over the last 20 yr. Dominant phytoplankton species were the typical bloom-forming diatoms that are usually found in the western Antarctic Peninsula area. Anomalously cold air temperature and dominan...
La Peninsula Antartica (PA) es una de las regiones mas afectadas por el calentamiento global, lo cual promueve el derretimiento glaciario y, en consecuencia, una disminucion de la salinidad por incremento de agua dulce al medio marino... more
La Peninsula Antartica (PA) es una de las regiones mas afectadas por el calentamiento global, lo cual promueve el derretimiento glaciario y, en consecuencia, una disminucion de la salinidad por incremento de agua dulce al medio marino costero. En este estudio se analizo la respuesta de la comunidad fitoplanctonica de Caleta Potter (Isla 25 de Mayo, Shetlands del Sur, al norte de la PA) al aumento de 4°C de temperatura (T+S0), disminucion de la salinidad de 34 a 30 (T0S-), y la combinacion de ambas variables (T+S-), con respecto al control (T0S0) durante 8 dias de experimento en microcosmos. Se analizo la biomasa y composicion especifica mediante analisis de pigmentos (HPLC), recuentos celulares y observaciones con microscopiaelectronica. Los maximos de biomasa (Cl-a) y densidad celular se observaron el dia 3 (23-28 µgL-1 y 8-9,5x106 celulasL-1) en T+S- y T+S0, y el dia 5 (17-18 µgL-1 y 5-7x106 celulasL-1) en T0S0 y T0S-. La comunidad estuvo ampliamente dominada por diatomeas a lo la...
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Intense regional warming was observed in the Western Antarctic Peninsula (WAP) over the last 50 years. Here we investigate the impact of climate change on primary production (PP) in this highly productive region. This study is based on... more
Intense regional warming was observed in the Western Antarctic Peninsula (WAP) over the last 50 years. Here we investigate the impact of climate change on primary production (PP) in this highly productive region. This study is based on temporal data series of ozone thickness (1972-2010), sea ice concentration (1978-2010), sea surface temperature (1990-2010), incident irradiance (1988-2010) and satellite-derived chlorophyll-a concentration (Chl-a, 1997-2010) for the coastal WAP. In addition, we apply a photosynthesis/photoinhibition spectral model to satellite-derived data (19972010) to compute PP and examine the separate impacts of environmental forcings. Since 1978, sea ice retreat has been occurring earlier in the season (in March in 1978 and in late October during the 2000s) while the ozone hole is present in early spring (i.e. August to November) since the early 1990s, increasing the intensity of UltraViolet B Radiation (UVBR, 280-320 nm). The WAP waters have also warmed over 19...
Urgent necessity to understand the effect of climatic change on scleractinian cold-water coral (CWC) ecosystems arises from increasing ocean warming and acidification over the last decades. Here, presence-absence records of 12... more
Urgent necessity to understand the effect of climatic change on scleractinian cold-water coral (CWC) ecosystems arises from increasing ocean warming and acidification over the last decades. Here, presence-absence records of 12 scleractinian CWC species from research expeditions and literature were compiled and merged with model-generated pseudo-absence data and 14 environmental variables. The best results of nine species distribution models (SDM) were combined to an ensemble habitat suitability model for CWCs in the northern Southern Ocean (Weddell Sea and Antarctic Peninsula) by means of the open source R package ‘biomod2’. Furthermore, two future scenarios of increasing bottom sea temperature were used to investigate the spatial response of scleractinians to temperature change. The resulting (current scenario) potential ecological niches were evaluated with good to excellent statistical measures. The results predict that present areas of highest probability of CWC occurrence are around the Antarctic Peninsula, South Orkney Islands and Queen Maud Land with preference to geomorphic features such as seamounts. The distribution of CWC habitats is mainly driven by distance to coast and ice shelves, bathymetry, benthic calcium carbonate, as well as temperature. Under warming conditions, CWCs are predicted to expand their distribution range by 6 and 10% in 2037 and 2150, respectively, compared to present distribution. The future models using increased bottom temperature revealed a stable CWC distribution for most parts of the study area. However, habitat shifts are expected to the Filchner Trough region, the adjacent continental shelves, as well as to the eastern side of the Antarctic Peninsula.
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We expose the difficulties we encountered to obtain from industry environmental information that is crucial for impact studies and decision-making related to the potential development of offshore oil and gas in the Gulf of St. Lawrence,... more
We expose the difficulties we encountered to obtain from industry environmental information that is crucial for impact studies and decision-making related to the potential development of offshore oil and gas in the Gulf of St. Lawrence, Canada. This case concerns the information disseminated by the oil company Corridor Resources that there are six persistent, natural oil seeps emanating from the flanks of the Old Harry geological structure in the Gulf of St. Lawrence. According to Corridor, these seeps rise through the water column and appear at the sea surface directly above the prospect, forming permanent oil slicks visible from satellite imagery. Corridor believes this is an indication that the Old Harry prospect contains oil. While this information might be credible, it has been impossible for us to verify its accuracy because the sources are kept secret under the argument of “commercially sensitive.” Yet, such information about the possible presence of natural oil and its sourc...
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The West Antarctic Peninsula (WAP) is a climatically sensitive region where periods of strong warming have caused significant changes in the marine ecosystem and food-web processes. Tight coupling between phytoplankton and higher trophic... more
The West Antarctic Peninsula (WAP) is a climatically sensitive region where periods of strong warming have caused significant changes in the marine ecosystem and food-web processes. Tight coupling between phytoplankton and higher trophic levels implies that the coastal WAP is a bottom-up controlled system, where changes in phytoplankton dynamics may largely impact other food-web components. Here, we analysed the inter-decadal time series of year-round chlorophyll-<i>a</i> (Chl) collected from three stations along the coastal WAP: Carlini Station at Potter Cove (PC) on King George Island, Palmer Station on Anvers Island and Rothera Station on Adelaide Island. There were trends towards increased phytoplankton biomass at Carlini Station (PC) and Palmer Station, while phytoplankton biomass declined significantly at Rothera Station over the studied period. The impacts of two relevant climate modes to the WAP, the El Niño-Southern Oscillation and the Southern Annular Mode, on ...
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A quantitative assessment of observed and projected environmental changes in the Southern Ocean (SO) with a potential impact on the marine ecosystem shows: (i) large proportions of the SO are and will be affected by one or more climate... more
A quantitative assessment of observed and projected environmental changes in the Southern Ocean (SO) with a potential impact on the marine ecosystem shows: (i) large proportions of the SO are and will be affected by one or more climate change processes; areas projected to be affected in the future are larger than areas that are already under environmental stress, (ii) areas affected by changes in sea-ice in the past and likely in the future are much larger than areas affected by ocean warming. The smallest areas (<1% area of the SO) are affected by glacier retreat and warming in the deeper euphotic layer. In the future, decrease in the sea-ice is expected to be widespread. Changes in iceberg impact resulting from further collapse of ice-shelves can potentially affect large parts of shelf and ephemerally in the off-shore regions. However, aragonite undersaturation (acidification) might become one of the biggest problems for the Antarctic marine ecosystem by affecting almost the en...
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Methods Mediated modeling is a process of facilitated model building in which stakeholders are involved in all aspects and steps (van den Belt 2004). Stakeholders decide what goes into the model they collaboratively construct, and... more
Methods Mediated modeling is a process of facilitated model building in which stakeholders are involved in all aspects and steps (van den Belt 2004). Stakeholders decide what goes into the model they collaboratively construct, and therefore they understand the value (and limitations) of the results. In this project, the 15 participants included scientists involved in UVBR research and local stakeholders, both working on science and social issues.