Impact of climate induced glacial melting on coastal marine systems in the Western Antarctic Peninsula region

IMCOAST is an international research program that features a multidisciplinary approach involving geo and biological sciences, field investigations, remote sensing and modeling and knowledge into the hydrographical and biological history of the marine coastal ecosystems of the Western Antarctic Peninsula region

Nitric oxide mediates metabolic functions in the bivalve Arctica islandica under hypoxia

The free radical nitric oxide (NO) is a powerful metabolic regulator in vertebrates and invertebrates. At cellular concentrations in the nanomolar range, and simultaneously reduced internal oxygen partial pressures (pO2), NO completely inhibits cytochrome-c-oxidase (CytOx) activity and hence mitochondrial- and whole-tissue respiration. The infaunal clam Arctica islandica regulates pO2 of hemolymph and mantle cavity water to mean values of <5 kPa, even in a completely oxygen-saturated environment of 21 kPa. These low internal pO2 values support a longer NO lifespan and NO accumulation in the body fluids and can thus trigger a depression of metabolic rate in the clams. Measurable amounts of NO formation were detected in hemocyte cells (~110 pmol NO 100−1 hemocytes h-1 at 6 kPa), which was not prevented in the presence of the NO synthase inhibitor L-NAME, and in the gill filaments of A. islandica. Adding a NO donor to intact gills and tissue homogenate significantly inhibited gill respiration and CytOx activity below 10 kPa. Meanwhile, the addition of the NO-oxidation product nitrite did not affect metabolic rates. The high nitrite levels found in the hemolymph of experimental mussels under anoxia do not indicate cellular NO production, but could be an indication of nitrate reduction by facultative anaerobic bacteria associated with tissue and/or hemolymph biofilms. Our results suggest that NO plays an important role in the initiation of metabolic depression during self-induced burrowing and shell closure of A. islandica. Furthermore, NO appears to reduce mitochondrial oxygen radical formation during surfacing and cellular reoxygenation after prolonged periods of hypoxia and anoxia

Toward the morphometric calibration of the environmental biorecorder Arctica islandica

Owing to its extremely long life span and occurrence in the entire North Atlantic, the Arctic boreal Arctica islandica has become of particular significance for monitoring the environment, because information on past environmental conditions is archived in morphological and biogeochemical properties of the calcareous shell. To evaluate whether such properties are comparable between different localities, shell and soft body morphometry of six A. islandica populations, Norwegian Coast, Kattegat, Kiel Bay (Baltic), White Sea, German Bight (North Sea), and off NE Iceland, were compared. Discriminant analysis indicated distinct differences between populations, albeit not related to geographical distance, but more likely to local hydrography, bottom morphology, and food regime

Shorter but thicker: analysis of internal growth bands in shells of intertidal vs. subtidal Antarctic limpets, Nacella concinna, reflects their environmental adaptation

The limpet Nacella concinna is a dominant macroinvertebrate along the coastal Antarctic Peninsula with two ecotypes inhabiting intertidal and subtidal areas, respectively. The ecological aim of the study was to understand whether higher stress competence and migratory energy expenses in intertidal Antarctic limpets shorten their lifetime and limit the shell growth rate compared to their sublittoral conspecific. We evaluated shell morphometry, age and internal shell growth bands in a large number of intertidal and subtidal N. concinna shells in Potter Cove, South Shetland Islands. Comparisons of their morphometrics showed that intertidal limpets are relatively shorter and less wide, and have higher shell mass, i.e. at common shell height, intertidal shells are relatively thicker and heavier than those of subtidal specimens. Internal shell growth bands showed alternating wide opaque (faster growth in summer) and thin translucent bands (slow growth in winter). The maximum age read was close to 20-years for both groups. Comparisons of von Bertalanffy growth curves showed for shell length and shell width lower growth rate k in intertidal animals than in subtidal ones associated to a great variability, with no differences in other growth constants. However, when shell height vs. age is considered, no differences were observed for any growth parameter. Curtailed variability of growth rates in the intertidal population reflects either a limitation of the food reserves or feeding time, or an energy gap for shell growth due to the costs for migratory movements and stress defense

Hypoxically Induced Nitric Oxide: Potential Role as a Vasodilator in Mytilus edulis Gills

Intertidal Mytilus edulis experience rapid transgression to hypoxia when they close theirvalves during low tide. This induces a physiological stress response aiming to stabilizetissue perfusion against declining oxygen partial pressure in shell water.We hypothesizedthat nitric oxide (NO) accumulation supports blood vessel opening in hypoxia andused live imaging techniques to measure NO and superoxide anion (O?−2 ) formationin hypoxia-exposed gill filaments. Thirty minutes of moderate (7 kPa pO2) and severehypoxia (1 kPa pO2) caused 1.6- and 2.4-fold increase, respectively, of NO accumulationin the endothelial muscle cells of the hemolymphatic vessels of the gill filaments. This ledto a dilatation of blood vessel diameter by 43% (7 kPa) and 56% (1 kPa), which facilitatesblood flow. Experiments in which we applied the chemical NO-donor Spermine NONOate(concentrations ranging from 1 to 6mM) under normoxic conditions corroborate thedilatational effect of NO on the blood vessel. The formation of O?−2 within the filamentepithelial cells increased 1.5 (7 kPa) and 2-fold (1 kPa) upon treatment. Biochemicalanalysis of mitochondrial electron transport complexes in hypoxia-exposed gill tissueindicates decreased activity of complexes I and III in both hypoxic conditions; whereascomplex IV (cytochrome-c oxidase) activity increased at 7 kPa and decreased at 1kPa compared to normoxic exposure conditions. This corresponds to the pattern ofpO2-dependent gill respiration rates recorded in ex-vivo experiments. Severe hypoxia(1 kPa) appears to have a stabilizing effect on NO accumulation in gill cells, sinceless O2 is available for NO oxidation to nitrite/nitrate. Hypoxia thus supports theNO dependent inhibition of complex IV activity, a mechanism that could fine tunemitochondrial respiration to the local O2 availability in a tissue. Our study highlights abasal function of NO in improving perfusion of hypoxic invertebrate tissues, which couldbe a key mechanism of tolerance toward environmental O2 variations.Fil: González, Paula Mariela. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Bioquímica y Medicina Molecular. Universidad de Buenos Aires. Facultad Medicina. Instituto de Bioquímica y Medicina Molecular; ArgentinaFil: Rocchetta, Iara. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Instituto de Investigaciones en Biodiversidad y Medioambiente. Universidad Nacional del Comahue. Centro Regional Universidad Bariloche. Instituto de Investigaciones en Biodiversidad y Medioambiente; ArgentinaFil: Abele, Doris. Alfred Wegener Institute For Polar And Marine Research; AlemaniaFil: Rivera Ingraham, Georgina A.. Alfred Wegener Institute For Polar And Marine Research; Alemani

Default versus configured-geostatistical modeling of suspended particulate matter in Potter Cove, West Antarctic Peninsula

The glacier retreat observed during the last decades at Potter Cove (PC) causes an increasing amount of suspended particulate matter (SPM) in the water column, which has a high impact on sessile filter feeder? species at PC located at the West Antarctic Peninsula. SPM presents a highly-fluctuating dynamic pattern on a daily, monthly, seasonal, and interannual basis. Geostatistical interpolation techniques are widely used by default to generate reliable spatial information and thereby to improve the ecological understanding of environmental variables, which is often fundamental for guiding decision-makers and scientists. In this study, we compared the results of default and configured settings of three geostatistical algorithms (Simple Kriging, Ordinary Kriging, and Empirical Bayesian) and developed a performance index. In order to interpolate SPM data from the summer season 2010/2011 at PC, the best performance was obtained with Empirical Bayesian Kriging (standard mean = −0.001 and root mean square standardized = 0.995). It showed an excellent performance (performance index = 0.004), improving both evaluation parameters when radio and neighborhood were configured. About 69% of the models showed improved standard means when configured compared to the default settings following a here proposed guidelineFil: Neder, Camila. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Diversidad y Ecología Animal. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Instituto de Diversidad y Ecología Animal; ArgentinaFil: Sahade, Ricardo Jose. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Diversidad y Ecología Animal. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Instituto de Diversidad y Ecología Animal; ArgentinaFil: Abele, Doris. Alfred-Wegener-Institut, Helmholtz-Zentrum für Polar- und Meeresforschung; AlemaniaFil: Pesch, Roland. Jade University of Applied Sciences; AlemaniaFil: Jerosch, Kerstin. Alfred-Wegener-Institut, Helmholtz-Zentrum für Polar- und Meeresforschung; Alemani