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15N in symbiotic fungi and plants estimates nitrogen and carbon flux rates in Arctic tundra.

https://arctichealth.org/en/permalink/ahliterature82286
Source
Ecology. 2006 Apr;87(4):816-22
Publication Type
Article
Date
Apr-2006
Author
Hobbie John E
Hobbie Erik A
Author Affiliation
The Ecosystems Center, Marine Biological Laboratory, Woods Hole, Massachusetts 02543, USA. jhobbie@mbl.edu
Source
Ecology. 2006 Apr;87(4):816-22
Date
Apr-2006
Language
English
Publication Type
Article
Keywords
Arctic Regions
Carbon - metabolism
Fungi - metabolism
Nitrogen Isotopes - metabolism
Plants - metabolism
Abstract
When soil nitrogen is in short supply, most terrestrial plants form symbioses with fungi (mycorrhizae): hyphae take up soil nitrogen, transport it into plant roots, and receive plant sugars in return. In ecosystems, the transfers within the pathway fractionate nitrogen isotopes so that the natural abundance of 15N in fungi differs from that in their host plants by as much as 12% per hundred. Here we present a new method to quantify carbon and nitrogen fluxes in the symbiosis based on the fractionation against 15N during transfer of nitrogen from fungi to plant roots. We tested this method, which is based on the mass balance of 15N, with data from arctic Alaska where the nitrogen cycle is well studied. Mycorrhizal fungi provided 61-86% of the nitrogen in plants; plants provided 8-17% of their photosynthetic carbon to the fungi for growth and respiration. This method of analysis avoids the disturbance of the soil-microbe-root relationship caused by collecting samples, mixing the soil, or changing substrate concentrations. This analytical technique also can be applied to other nitrogen-limited ecosystems, such as many temperate and boreal forests, to quantify the importance for terrestrial carbon and nitrogen cycling of nutrient transfers mediated by mycorrhizae at the plant-soil interface.
PubMed ID
16676524 View in PubMed
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Climate change effects on aquatic biota, ecosystem structure and function.

https://arctichealth.org/en/permalink/ahliterature95667
Source
Ambio. 2006 Nov;35(7):359-69
Publication Type
Article
Date
Nov-2006
Author
Wrona Frederick J
Prowse Terry D
Reist James D
Hobbie John E
Lévesque Lucie M J
Vincent Warwick F
Author Affiliation
National Water Research Institute of Environment Canada, Department of Geography, University of Victoria, BC. fred.wrona@ec.gc.ca
Source
Ambio. 2006 Nov;35(7):359-69
Date
Nov-2006
Language
English
Publication Type
Article
Keywords
Animals
Arctic Regions
Birds
Cold Climate
Ecosystem
Fresh Water
Greenhouse Effect
Mammals
Population Dynamics
Abstract
Climate change is projected to cause significant alterations to aquatic biogeochemical processes, (including carbon dynamics), aquatic food web structure, dynamics and biodiversity, primary and secondary production; and, affect the range, distribution and habitat quality/quantity of aquatic mammals and waterfowl. Projected enhanced permafrost thawing is very likely to increase nutrient, sediment, and carbon loadings to aquatic systems, resulting in both positive and negative effects on freshwater chemistry. Nutrient and carbon enrichment will enhance nutrient cycling and productivity, and alter the generation and consumption of carbon-based trace gases. Consequently, the status of aquatic ecosystems as carbon sinks or sources is very likely to change. Climate change will also very likely affect the biodiversity of freshwater ecosystems across most of the Arctic. The magnitude, extent, and duration of the impacts and responses will be system- and location-dependent. Projected effects on aquatic mammals and waterfowl include altered migration routes and timing; a possible increase in the incidence of mortality and decreased growth and productivity from disease and/or parasites; and, probable changes in habitat suitability and timing of availability.
PubMed ID
17256640 View in PubMed
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Climate change effects on hydroecology of arctic freshwater ecosystems.

https://arctichealth.org/en/permalink/ahliterature95668
Source
Ambio. 2006 Nov;35(7):347-58
Publication Type
Article
Date
Nov-2006
Author
Prowse Terry D
Wrona Frederick J
Reist James D
Gibson John J
Hobbie John E
Lévesque Lucie M J
Vincent Warwick F
Author Affiliation
Water and Climate Impacts Research Centre, National Water Research Institute of Environment Canada, Department of Geography, University of Victoria, BC. terry.prowse@ec.gc.ca
Source
Ambio. 2006 Nov;35(7):347-58
Date
Nov-2006
Language
English
Publication Type
Article
Keywords
Animals
Arctic Regions
Cold Climate
Ecology
Ecosystem
Fresh Water
Greenhouse Effect
Ice
Abstract
In general, the arctic freshwater-terrestrial system will warm more rapidly than the global average, particularly during the autumn and winter season. The decline or loss of many cryospheric components and a shift from a nival to an increasingly pluvial system will produce numerous physical effects on freshwater ecosystems. Of particular note will be reductions in the dominance of the spring freshet and changes in the intensity of river-ice breakup. Increased evaporation/evapotranspiration due to longer ice-free seasons, higher air/water temperatures and greater transpiring vegetation along with increase infiltration because of permafrost thaw will decrease surface water levels and coverage. Loss of ice and permafrost, increased water temperatures and vegetation shifts will alter water chemistry, the general result being an increase in lotic and lentic productivity. Changes in ice and water flow/levels will lead to regime-specific increases and decreases in habitat availability/quality across the circumpolar Arctic.
PubMed ID
17256639 View in PubMed
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Climate impacts on arctic freshwater ecosystems and fisheries: background, rationale and approach of the Arctic Climate Impact Assessment (ACIA).

https://arctichealth.org/en/permalink/ahliterature95671
Source
Ambio. 2006 Nov;35(7):326-9
Publication Type
Article
Date
Nov-2006
Author
Wrona Frederick J
Prowse Terry D
Reist James D
Hobbie John E
Lévesque Lucie M J
Vincent Warwick F
Author Affiliation
National Water Research Institute of Environment Canada, Department of Geography, University of Victoria, BC, Canada. fred.wrona@ec.gc.ca
Source
Ambio. 2006 Nov;35(7):326-9
Date
Nov-2006
Language
English
Publication Type
Article
Keywords
Animals
Arctic Regions
Cold Climate
Ecosystem
Fisheries
Fishes
Fresh Water
Greenhouse Effect
Humans
Abstract
Changes in climate and ultraviolet radiation levels in the Arctic will have far-reaching impacts, affecting aquatic species at various trophic levels, the physical and chemical environment that makes up their habitat, and the processes that act on and within freshwater ecosystems. Interactions of climatic variables, such as temperature and precipitation, with freshwater ecosystems are highly complex and can propagate through the ecosystem in ways that are difficult to project. This is partly due to a poor understanding of arctic freshwater systems and their basic interrelationships with climate and other environmental variables, and partly due to a paucity of long-term freshwater monitoring sites and integrated hydro-ecological research programs in the Arctic. The papers in this special issue are an abstraction of the analyses performed by 25 international experts and their associated networks on Arctic freshwater hydrology and related aquatic ecosystems that was initially published by the Arctic Climate Impact Assessment (ACIA) in 2005 as "Chapter 8--Freshwater Ecosystems and Fisheries". The papers provide a broad overview of the general hydrological and ecological features of the various freshwater ecosystems in the Arctic, including descriptions of each ACIA region, followed by a review of historical changes in freshwater systems during the Holocene. This is followed by an assessment of the effects of climate change on broad-scale hydro-ecology; aquatic biota and ecosystem structure and function; and arctic fish and fisheries. Potential synergistic and cumulative effects are also discussed, as are the roles of ultraviolet radiation and contaminants. The nature and complexity of many of the effects are illustrated using case studies from around the circumpolar north, together with a discussion of important threshold responses (i.e., those that produce stepwise and/or nonlinear effects). The issue concludes with summary the key findings, a list of gaps in scientific understanding, and policy-related recommendations.
PubMed ID
17256636 View in PubMed
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Effects of ultraviolet radiation and contaminant-related stressors on arctic freshwater ecosystems.

https://arctichealth.org/en/permalink/ahliterature95664
Source
Ambio. 2006 Nov;35(7):388-401
Publication Type
Article
Date
Nov-2006
Author
Wrona Frederick J
Prowse Terry D
Reist James D
Hobbie John E
Lévesque Lucie M J
Macdonald Robie W
Vincent Warwick F
Author Affiliation
National Water Research Institute of Environment Canada, Department of Geography, University of Victoria, BC. fred.wrona@ec.gc.ca
Source
Ambio. 2006 Nov;35(7):388-401
Date
Nov-2006
Language
English
Publication Type
Article
Keywords
Adaptation, Biological
Animals
Arctic Regions
Cold Climate
Ecosystem
Fresh Water
Greenhouse Effect
Ice
Mercury
Snow
Ultraviolet Rays
Water Pollutants
Abstract
Climate change is likely to act as a multiple stressor, leading to cumulative and/or synergistic impacts on aquatic systems. Projected increases in temperature and corresponding alterations in precipitation regimes will enhance contaminant influxes to aquatic systems, and independently increase the susceptibility of aquatic organisms to contaminant exposure and effects. The consequences for the biota will in most cases be additive (cumulative) and multiplicative (synergistic). The overall result will be higher contaminant loads and biomagnification in aquatic ecosystems. Changes in stratospheric ozone and corresponding ultraviolet radiation regimes are also expected to produce cumulative and/or synergistic effects on aquatic ecosystem structure and function. Reduced ice cover is likely to have a much greater effect on underwater UV radiation exposure than the projected levels of stratospheric ozone depletion. A major increase in UV radiation levels will cause enhanced damage to organisms (biomolecular, cellular, and physiological damage, and alterations in species composition). Allocations of energy and resources by aquatic biota to UV radiation protection will increase, probably decreasing trophic-level productivity. Elemental fluxes will increase via photochemical pathways.
PubMed ID
17256643 View in PubMed
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General features of the arctic relevant to climate change in freshwater ecosystems.

https://arctichealth.org/en/permalink/ahliterature95670
Source
Ambio. 2006 Nov;35(7):330-8
Publication Type
Article
Date
Nov-2006
Author
Prowse Terry D
Wrona Frederick J
Reist James D
Hobbie John E
Lévesque Lucie M J
Vincent Warwick F
Author Affiliation
Water and Climate Impacts Research Centre, National Water Research Institute of Environment Canada, Department of Geography, University of Victoria, BC. Terry.prowse@ec.gc.ca
Source
Ambio. 2006 Nov;35(7):330-8
Date
Nov-2006
Language
English
Publication Type
Article
Keywords
Animals
Arctic Regions
Cold Climate
Ecosystem
Food chain
Fresh Water
Wetlands
Abstract
Large variations exist in the size, abundance and biota of the two principal categories of freshwater ecosystems, lotic (flowing water; e.g., rivers, streams, deltas and estuaries) and lentic (standing water; lakes, ponds and wetlands) found across the circumpolar Arctic. Arctic climate, many components of which exhibit strong variations along latitudinal gradients, directly affects a range of physical, chemical and biological processes in these aquatic systems. Furthermore, arctic climate creates additional indirect ecological effects through the control of terrestrial hydrologic systems and processes, particularly those associated with cryospheric components such as permafrost, freshwater ice and snow accumulation/ablation. The ecological structure and function of arctic freshwater systems are also controlled by external processes and conditions, particularly those in the headwaters of the major arctic rivers and in the adjacent marine environment. The movement of physical, chemical and biotic components through the interlinked lentic and lotic freshwater systems are major determinants of arctic freshwater ecology.
PubMed ID
17256637 View in PubMed
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Historical changes in arctic freshwater ecosystems.

https://arctichealth.org/en/permalink/ahliterature95669
Source
Ambio. 2006 Nov;35(7):339-46
Publication Type
Article
Date
Nov-2006
Author
Prowse Terry D
Wrona Frederick J
Reist James D
Gibson John J
Hobbie John E
Lévesque Lucie M J
Vincent Warwick F
Author Affiliation
Water and Climate Impacts Research Centre, National Water Research Institute of Environment Canada, Department of Geography, University of Victoria, BC. terry.prowse@ec.gc.ca
Source
Ambio. 2006 Nov;35(7):339-46
Date
Nov-2006
Language
English
Publication Type
Article
Keywords
Animals
Arctic Regions
Cold Climate
Ecosystem
Fresh Water
Greenhouse Effect
History, Ancient
Abstract
Various types of ecosystem-based climate proxies have been used to assess past arctic change. Although lotic records are relatively poor because of the constant reworking of riverine material, high-quality lentic data have been assembled back to the end of the Pleistocene and deglaciation of the circumpolar Arctic. In general, climatic variations in the Holocene, partly due to changes in the shrinking effect of glacier coverage, produced significant temporal and spatial variations in arctic hydrology and freshwater ecosystems. Of particular note were the vast expansions of northern peatlands during major protracted periods of wetting. More recent lake biota and sedimentiological data reflect the general warming trend that has occurred over the last one to two centuries and indicate major changes to freshwater characteristics such as ice-cover duration and thermal stratification. Such data provide an excellent baseline against which future effects of climate change can be both projected and measured.
PubMed ID
17256638 View in PubMed
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Key findings, science gaps and policy recommendations.

https://arctichealth.org/en/permalink/ahliterature78998
Source
Ambio. 2006 Nov;35(7):411-5
Publication Type
Article
Date
Nov-2006
Author
Wrona Frederick J
Prowse Terry D
Reist James D
Hobbie John E
Lévesque Lucie M J
Vincent Warwick F
Author Affiliation
National Water Research Institute of Environment Canada, Department of Geography, University of Victoria, BC. fred.wrona@ec.gc.ca
Source
Ambio. 2006 Nov;35(7):411-5
Date
Nov-2006
Language
English
Publication Type
Article
Keywords
Animals
Arctic Regions
Birds
Cold Climate
Conservation of Natural Resources
Ecosystem
Fisheries
Fishes
Fresh Water
Greenhouse Effect
Ice
Mammals
Public Policy
Ultraviolet Rays
PubMed ID
17256645 View in PubMed
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8 records – page 1 of 1.