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Academic literature on the topic 'Biomasse – Arctique'
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Journal articles on the topic "Biomasse – Arctique"
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Paul, A. J., D. W. Schindler, A. K. Hardie, and P. R. Leavitt. "Direct and indirect effects of predation by a calanoid copepod (subgenus: Hesperodiaptomus) and of nytrients in a fishless alpine lake." Canadian Journal of Fisheries and Aquatic Sciences 52, no. 12 (December 1, 1995): 2628–38. http://dx.doi.org/10.1139/f95-852.
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The calanoid copepod Diaptomus (subgenus: Hesperodiaptomus) arcticus is a keystone predator in fishless alpine lakes of the Canadian Rockies. We quantified the effects of predation by D. arcticus on other copepods, rotifers, and algae in large mesocosm experiments (2250 L) using two levels of predator (present and absent) and two levels of nutrient addition (ambient and 4×). Standing stocks of algal taxa were assessed by high performance liquid chromatography of phytoplankton pigments. Diaptomus arcticus suppressed the biomass of rotifers and cyclopoid nauplii at both nutrient levels. The indirect effect of D. arcticus on algal biomass was minimal under ambient nutrient conditions, possibly owing to high rates of nutrient recycling by grazers. Biomass of algae, cyclopoid nauplii, and rotifers responded positively to nutrient additions. Nutrient addition increased algal standing crop 2- to 4-fold and changed dominance from diatoms and chrysophytes to blue-green algae. Diaptomus arcticus accelerated these changes, possibly by eliminating grazing by rotifers. These results suggest that in the absence of increased nutrients D. arcticus directly limits the biomass of herbivorous zooplankton but the indirect effect on phytoplankton is minimal.
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Koksharov, Sergey A., Olga V. Lepilova, and Svetlana V. Aleeva. "Technology for Preparation of Hybrid Sorbents Based on Plant Raw Materials and Montmorillonite." Solid State Phenomena 316 (April 2021): 142–46. http://dx.doi.org/10.4028/www.scientific.net/ssp.316.142.
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The possibility of preparation of hybrid nanocomposites, based on Burdock Arctium Lappa L biomass, modified with enzymes and montmorillonite, was substantiated. It was founded that bio-modification allowing releasing pectin into the biomass Burdock structure that allow fixing clay mineral particles onto biomass. It was found that the increase of pore spaces occurs at the expense of increasing mesopore spaces to 93 %. It allows increasing the adsorption capacity of hybrid nanocomposites to zinc ions and methylene blue to 52.2 and 166.9 mg g-1 respectively; that is 3.5 and 9 times more than adsorption capacityfor initial plant Burdock
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Leavitt, P. R., D. E. Schindler, A. J. Paul, A. K. Hardie, and D. W. Schindler. "Fossil Pigment Records of Phytoplankton in Trout-stocked Alpine Lakes." Canadian Journal of Fisheries and Aquatic Sciences 51, no. 11 (November 1, 1994): 2411–23. http://dx.doi.org/10.1139/f94-241.
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Paleolimnology, bioenergetics modelling, and mesocosm experiments were used to quantify changes in phytoplankton following introduction of trout into fishless alpine lakes in the Canadian Rocky Mountains. During the 1960s, Snowflake and Pipit lakes were stocked with brook (Salvelinus fontinalis), cutthroat (Oncorhynchus clarkii) and rainbow trout (O. mykiss) either singly or in combination. Stocked trout eliminated large invertebrates (Daphnia spp., Hesperodiaptomus arcticus, Gamrnarus lacustris), but the fish died within 15 yr. High performance liquid chromatographic analysis of carotenoids and chlorophylls in sediments inferred that algal abundance increased 4- to 10-fold shortly after fish stocking. In contrast, phytoplankton composition and biomass were constant in nearby, unstocked Harrison Lake, as inferred from fossils. Pigment analysis of mesocosms showed that phytoplankton were sensitive to moderate fertilization: 11 μg P∙L−1 resulted in four- to six-fold increases in algal biomass. Bioenergetics modelling was used to estimate phosphorus (P) excretion from trout. The flux of excreted P was highly correlated (r2 = 0.76, p < 0.0001, N = 12) to changes in algal biomass, as estimated from fossil pheophytin b. Consequently, we infer that nutrient recycling by stocked trout was one of several mechanisms that contributed to increased algal biomass.
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Hayden, Anita L. "Aeroponic and Hydroponic Systems for Medicinal Herb, Rhizome, and Root Crops." HortScience 41, no. 3 (June 2006): 536–38. http://dx.doi.org/10.21273/hortsci.41.3.536.
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Hydroponic and aeroponic production of medicinal crops in controlled environments provides opportunities for improving quality, purity, consistency, bioactivity, and biomass production on a commercial scale. Ideally, the goal is to optimize the environment and systems to maximize all five characteristics. Examples of crop production systems using perlite hydroponics, nutrient film technique (NFT), ebb and flow, and aeroponics were studied for various root, rhizome, and herb leaf crops. Biomass data comparing aeroponic vs. soilless culture or field grown production of burdock root (Arctium lappa), stinging nettles herb and rhizome (Urtica dioica), and yerba mansa root and rhizome (Anemopsis californica) are presented, as well as smaller scale projects observing ginger rhizome (Zingiber officinale) and skullcap herb (Scutellaria lateriflora). Phytochemical concentration of marker compounds for burdock and yerba mansa in different growing systems are presented.
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Cadieux, Marie-Christine, Gilles Gauthier, and R. John Hughes. "Feeding Ecology of Canada Geese (Branta Canadensis Interior) in Sub-Arctic Inland Tundra During Brood-Rearing." Auk 122, no. 1 (January 1, 2005): 144–57. http://dx.doi.org/10.1093/auk/122.1.144.
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AbstractThe diet of adult Canada Geese (Branta canadensis interior) and their goslings was determined during the brood-rearing season in a freshwater tundra habitat using esophageal contents from 25 adult females, 27 adult males, and 59 goslings. Habitat use by geese and the availability and quality of aboveground biomass in wet sedge meadows and around ponds in lichen-heath tundra were also evaluated throughout the summer. During the first four weeks of brood-rearing, adult Canada Geese ate primarily graminoids (>65%), especially leaves of the short form of Carex aquatilis and Eriophorum spp., which had the highest nitrogen concentration (2.5–3.5%). Although graminoids were also important for goslings, they consumed a greater variety of other plant species (68%) than adults, especially in the first two weeks, possibly because of their inexperience. Late in the brood-rearing period, as the nitrogen concentration of graminoid plants declined, adults shifted to a diet composed mainly of berries (>40%, mostly Empetrum nigrum). At that time, goslings consumed fewer berries (24%) and maintained a higher proportion of nitrogen-rich plants in their diet (53% leaves, mostly graminoids) than adults, presumably to complete their growth. Plant species consumed by geese over the summer indicated a preference for high-quality plants (i.e. those with a high nitrogen concentration). Consequently, wet sedge meadow, the habitat that offered plant species of highest quality, was the habitat most heavily used throughout the summer, particularly around peak hatch. Goose grazing had no effect on seasonal production of aboveground biomass of graminoids, probably because of the relatively low density of the goose population.Écologie alimentaire de Branta canadensis interior pendant la période d’élevage des jeunes dans un milieu d’eau douce sub-arctique
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Poole, K. G., and D. A. Boag. "Ecology of gyrfalcons, Falco rusticolus, in the central Canadian Arctic: diet and feeding behaviour." Canadian Journal of Zoology 66, no. 2 (February 1, 1988): 334–44. http://dx.doi.org/10.1139/z88-050.
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Diet and aspects of feeding behaviour in a population of gyrfalcons (Falco rusticolus) in the Northwest Territories were examined between 1984 and 1986. Three prey species, rock ptarmigan (Lagopus mutus), arctic ground squirrel (Spermophilus parryii), and arctic hare (Lepus arcticus), composed 96.5% of total prey biomass identified. Ptarmigan and hares were taken in May and June of all years (98.2% of biomass). Juvenile squirrels were used extensively in July and August of 1984 and 1985 but not in 1986, when squirrel production fell to almost zero; ptarmigan continued to be the dominant prey species throughout that summer. Because densities of breeding ptarmigan remained relatively constant during the study, but those of juvenile ground squirrels did not, it appeared that gyrfalcons responded functionally to varying availability of prey. Mean weight (250 g) of prey taken by male gyrfalcons was significantly less than the weight (330 g) of prey taken by females. As predicted by optimal foraging theory, average size of prey brought to the nest increased as time away from the nest increased. Conditions of food abundance were observed at most nests, suggesting that the amount of food available during the nestling period was not limiting production. We suggest that annual production is a function of spacing of pairs, which is set during courtship and prelaying, when prey availability is at its yearly low and when males must forage for both members of the pair. The fact that most gyrfalcon pairs initiated laying only after the spring arrival of migrating ptarmigan is consistent with this conclusion.
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Ringelstein, Julien, Claire Pusineri, Sami Hassani, Laureline Meynier, Rémi Nicolas, and Vincent Ridoux. "Food and feeding ecology of the striped dolphin, Stenella coeruleoalba, in the oceanic waters of the north-east Atlantic." Journal of the Marine Biological Association of the United Kingdom 86, no. 4 (June 15, 2006): 909–18. http://dx.doi.org/10.1017/s0025315406013865.
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The food and feeding ecology of the striped dolphin, Stenella coeruleoalba, in the oceanic waters of the north-east Atlantic were studied using the stomach contents of 60 striped dolphins caught in the albacore drift-net fishery throughout the summer months of 1992 and 1993 off the Bay of Biscay. Thirty-eight per cent of these dolphins were calves (0–1 years old), 25% were juveniles (2–8) and 37% were mature adults (9–32, of which 7 females and 14 males). The diet was found to be primarily composed of fish (39% by mass (M)) and cephalopods (56% M) and secondarily of crustaceans (5% M). The most significant fish family identified was the lanternfish (24% M) with Notoscopelus kroeyeri and Lobianchia gemellarii being predominant. Among squid, the oceanic Teuthowenia megalops and Histioteuthis spp. were the most significant. The pelagic shrimp Sergastes arcticus and Pasiphaea multidentata were the most prevalent crustaceans. Prey sizes ranging from 30 to 170 mm accounted for 80% of the prey items while 80% of the reconstituted biomass consisted of prey measuring between 60 and 270 mm. Prey composition and size-range differed slightly with sex and age or body size of the dolphins. The state of digestion of food remains suggested that predation took place at dusk or during the early hours of the night on which the dolphins were caught.
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Häkkinen, Suvi T., Heli Nygren, Liisa Nohynek, Riitta Puupponen-Pimiä, Raija-Liisa Heiniö, Natalia Maiorova, Heiko Rischer, and Anneli Ritala. "Plant cell cultures as food—aspects of sustainability and safety." Plant Cell Reports 39, no. 12 (September 6, 2020): 1655–68. http://dx.doi.org/10.1007/s00299-020-02592-2.
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Abstract Key message Sustainability and safety aspects of plant cell cultures as food are presented. Applicability of dairy side streams as carbon source and use of natural growth enhancers in cultivation are shown. Abstract Biotechnologically produced cellular products are currently emerging to replace and add into the portfolio of agriculturally derived commodities. Plant cell cultures used for food could supplement current food production. However, still many aspects need to be resolved before this new food concept can enter the market. Issues related to sustainability and safety for human consumption are relevant for both consumers and regulators. In this study, two plant cell cultures, deriving from arctic bramble (Rubus arcticus) and birch (Betula pendula), were cultivated using lactose-rich dairy side streams as alternative carbon sources to replace sucrose. Biomasses were comparable to those of original plant cell culture media when up to 83% and 75% of the original sucrose was replaced by these side streams for arctic bramble and birch cell cultures, respectively. Furthermore, nutritional composition or sensory properties were not compromised. Synthetic plant growth regulators were replaced by natural components, such as coconut water and IAA for several subculture cycles. Finally, it was shown that only trace amounts of free growth regulators are present in the cells at the harvesting point and assessment by freshwater crustaceans assay indicated that toxicity of the cells was not exceeding that of traditionally consumed bilberry fruit.
Dissertations / Theses on the topic "Biomasse – Arctique"
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Pommier, Matthieu. "Caractérisation de la pollution dans la troposphère arctique : utilisation des données satellitaires et aéroportées dans le cadre de la campagne API/POLARCAT." Phd thesis, Université Pierre et Marie Curie - Paris VI, 2011. http://tel.archives-ouvertes.fr/tel-00587583.
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L'Arctique est une région qui malgré l'absence et l'éloignement de sources d'émission de polluants, est l'une des plus touchées par le transport à longue échelle de la pollution, qui peut affecter les niveaux de fond de pollution et qui influence le changement climatique à l'échelle régionale et mondiale. Malgré l'amélioration des systèmes d'observations et des modèles numériques durant ces dernières décennies, il reste encore difficile de reproduire les épisodes de pollution observés en Arctique notamment en été. Une explication possible est la sous-estimation de la production d'ozone (O3) modélisée dans les panaches des feux de forêt. Le monoxyde de carbone (CO) est utilisé comme un traceur du transport de la pollution du fait de sa longue durée de vie (plusieurs semaines) dans la troposphère. Ce gaz est produit par la combustion des énergies fossiles et des feux de biomasse. De plus, étant régulé par sa réaction avec le radical OH, il joue aussi un rôle important dans le bilan de l'O3 troposphérique. Le but de mes travaux de thèse a donc été de contribuer à une meilleure compréhension du transport et des mécanismes chimiques de formation des polluants secondaires dans la troposphère arctique. Pour cela j'ai utilisé en parallèle les nouvelles mesures de CO de l'instrument satellitaire IASI qui a été lancé en octobre 2006 à bord du satellite MetOp-A et les données récoltées par des avions instrumentés lors des campagnes POLARCAT de l'Année Polaire Internationale (API), au printemps et en été 2008. Les observations CO IASI ont tout d'abord été validées en les comparant avec les mesures aéroportées in situ montrant leurs capacités à observer des panaches de signatures élevées en CO comme près des régions sources. Le deuxième volet de la thèse illustre l'apport de l'assimilation (filtre de Kalman) des mesures quotidiennes de CO IASI dans le modèle global LMDz-INCA dans l'amélioration de notre compréhension sur les émissions et des chemins de transport des polluants influençant sur la troposphère arctique. L'assimilation a ainsi permis d'améliorer la modélisation des épisodes de pollution en CO dans la troposphère libre arctique. Enfin les résultats du modèle ont également été évalués en utilisant les observations POLARCAT et utilisés pour examiner la sensibilité des concentrations de polluants en Arctique (à savoir une surestimation de la distribution de l'O3 et une sous-estimation de celle du PAN) provenant des différentes régions et en particulier des feux de forêt boréale.
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Lavoué, David. "Transport vers la region arctique de l'aerosol carbone emis par les feux de biomasse des regions boreales et temperees." Paris 7, 2000. http://www.theses.fr/2000PA077128.
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Pour la premiere fois, les feux de vegetation des regions boreales et temperees ont ete etudies de facon exhaustive en termes de surfaces brulees, de biomasse brulee et d'emission en aerosol carbone. La localisation et la quantite de particules emises par les feux boreaux dependent des conditions meteorologiques, et montrent une tres grande variabilite interannuelle. Les emissions boreales et temperees peuvent etre significatives a l'echelle globale, et atteindre 9% et 20% respectivement du carbone suie et de la matiere organique particulaire emis par les feux de biomasse a l'echelle mondiale. Les panaches des feux ne peuvent etre detectes au niveau de l'ocean arctique en raison de l'injection des particules a haute altitude, de la grande stabilite de l'air, de l'effet orographique des montagnes entourant l'arctique et de processus de lessivage tres efficaces pendant le transport. Cependant le haut plateau groenlandais peut etre impacte de nos jours par les feux des forets boreales canadiennes. La hauteur d'injection et le profil vertical dans les regions sources sont des parametres determinants en modelisation du transport des particules. La confrontation des resultats d'un archivage de carbone suie dans une carotte de glace de summit avec un historique des feux nord-americains du xix e m e siecle montre un bon enregistrement des feux du passe dans la glace : le profil de concentration met en evidence un ralentissement de l'activite des feux naturels lors des 30 premieres annees correspondant a la derniere phase du petit age glaciaire, suivi d'une recrudescence importante des emissions jusqu'a la fin du siecle, provenant des feux anthropiques de la colonisation americaine. Enfin, une etude des feux boreaux dans le cadre