Carbon Sources and Trophic Connectivity in Seafloor Food Webs in the Alaska Arctic and Sub-Arctic

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ISBN 13 :
Total Pages : 238 pages
Book Rating : 4.:/5 (948 download)

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Book Synopsis Carbon Sources and Trophic Connectivity in Seafloor Food Webs in the Alaska Arctic and Sub-Arctic by : Laura Elizabeth Oxtoby

Download or read book Carbon Sources and Trophic Connectivity in Seafloor Food Webs in the Alaska Arctic and Sub-Arctic written by Laura Elizabeth Oxtoby and published by . This book was released on 2016 with total page 238 pages. Available in PDF, EPUB and Kindle. Book excerpt: Stable isotope analysis offers critical insight into organic matter pathways that sustain and link consumers in a food web. Indirect examination of organic matter sources and consumer diets using stable isotope analysis is especially valuable in the Alaska Arctic and sub-Arctic marine realm, where organisms of interest are difficult to observe given their remote habitat and elusive behavior. The research objective of this body of work was to use novel applications of stable isotope analysis to extend our understanding of organic matter sources, trophic pathways, and resource competition among benthic consumers. Microphytobenthos, a community of photosynthesizing unicellular microscopic algal cells on the seafloor sediment, has not been included in stable isotope food web models in the Alaska Arctic and sub-Arctic due to challenges associated with sample collection and analysis. I constrained the isotopic composition of this potential algal source by integrating field measurements, physiological relationships previously established by laboratory studies, and a range of algal growth rates specific to high latitude primary production. Relative to other sources of primary production in the Arctic, sub-Arctic, and lower latitude ecosystems, estimates for stable carbon isotope values of total organic carbon from microphytobenthos in the Beaufort and Chukchi seas were higher than those for Arctic riverine organic matter, but lower than ice algal sources and microphytobenthos measurements from lower latitudes. To further elucidate trophic pathways and resource partitioning among benthic invertebrate consumers, I combined compound-specific stable isotope analysis, a relatively new analytical tool, with fatty acid analysis to estimate proportional contributions of algal sources from ice, open ocean, and surface sediments to common polychaete and bivalve consumers in the Bering Sea. Benthic invertebrates were collected in 2009-2010 and represented a diverse range of feeding strategies, including the suspension/surface deposit-feeding bivalves Macoma calcarea and Ennucula tenuis, the subsurface deposit-feeding bivalve, Nuculana radiata, the head down deposit-feeding polychaete Leitoscoloplos pugettensis, and the predator/scavenger Nephtys spp. Differences in dominant algal sources to these invertebrate consumers corresponded, for the most part, to feeding strategy. Bivalves primarily obtained fatty acids from surface sediments, whereas L. pugettensis obtained fatty acids from a microbially altered phytodetrital fatty acid pool, and Nephtys spp. from ice algal fatty acids acquired indirectly through predation. This multi-proxy compound-specific stable isotope approach was then applied to examine dietary overlap between Pacific walruses (Odobenus rosmarus divergens) and bearded seals (Erignathus barbatus) in 2009-2011 who feed primarily on benthic invertebrate prey. Differences in the relative proportions of fatty acids produced exclusively by benthic prey (non-methylene interrupted fatty acids) indicated that walruses and bearded seals had divergent diets. Proportional contributions of algal sources from ice, open ocean, and surface sediments to the prey consumed by walruses and bearded seals also varied. Walruses consumed prey that relied primarily on benthic and pelagic carbon sources (i.e., suspension/surface and subsurface deposit-feeding bivalves). In contrast, bearded seals consumed prey that relied on benthic and ice algal carbon sources (i.e., omnivorous and predatory benthic invertebrates). In conclusion, this research revealed that, in the recent study years, benthic food webs in the Alaska Arctic and sub-Arctic contained several trophic pathways linking consumers to distinct organic matter sources. Consequently, projected changes in algal production with future climate warming may elicit species-specific responses among benthic organisms.

The Organic Carbon Cycle in the Arctic Ocean

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Publisher : Springer Science & Business Media
ISBN 13 : 3642189121
Total Pages : 394 pages
Book Rating : 4.6/5 (421 download)

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Book Synopsis The Organic Carbon Cycle in the Arctic Ocean by : Rüdiger Stein

Download or read book The Organic Carbon Cycle in the Arctic Ocean written by Rüdiger Stein and published by Springer Science & Business Media. This book was released on 2011-06-27 with total page 394 pages. Available in PDF, EPUB and Kindle. Book excerpt: The flux, preservation, and accumulation of organic carbon in marine systems are controlled by various mechanisms including primary p- duction of the surface water, supply of terrigenous organic matter from the surrounding continents, biogeochemical processes in the water column and at the seafloor, and sedimentation rate. For the world's oceans, phytoplankton productivity is by far the largest organic carbon 9 source, estimated to be about 30 to 50 Gt (10 tonnes) per year (Berger et al. 1989; Hedges and Keil 1995). By comparison, rivers contribute -1 about 0. 15 to 0. 23 Gt y of particulate organi.

Tracking Carbon Sources Through an Arctic Marine Food Web

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ISBN 13 :
Total Pages : 318 pages
Book Rating : 4.:/5 (894 download)

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Book Synopsis Tracking Carbon Sources Through an Arctic Marine Food Web by : 王小葳

Download or read book Tracking Carbon Sources Through an Arctic Marine Food Web written by 王小葳 and published by . This book was released on 2014 with total page 318 pages. Available in PDF, EPUB and Kindle. Book excerpt: Marine production across the Bering-Chukchi continental shelf is influenced by seasonal sea ice dynamics and climatic conditions. Of particular importance is variability in the magnitude and timing of annual phytoplankton production in the water column and in sea ice, and effects of such variability on food web composition and productivity. Of primary concern is the long-term effect of the projected loss of Arctic sea ice on ecosystem productivity and stability, and the fate of upper trophic level species. I examined a portion of the Bering-Chukchi Sea food web by analyzing the fatty acid composition and stable carbon isotope ratios of individual fatty acids in particulate organic matter from sea ice and the water column. These techniques were used to make inferences about diets of three species of zooplankton (Themisto libellula, Calanus marshallae/glacialis, Thysanoessa raschii) sampled during a recent climatically cold, relatively heavy sea ice period in the Bering Sea. I also analyzed fatty acids of four species of ice-associated seals--ringed (Pusa/Phoca hispida), bearded (Erignathus barbatus), spotted (Phoca largha), and ribbon seals (Histriophoca fasciata)--sampled during the same relatively cold period (2007-2010) as well as a preceding warm (2002-2005), relatively low sea ice period in the Bering Sea. Particulate organic matter from sea ice and the water column had different fatty acid characteristics, most likely stemming from differences in algal composition. My results also showed that in the Bering Sea cold period, the amphipod T. libellula was predominately carnivorous, and the copepod C. marshallae/glacialis and euphausiid T. raschii were primarily herbivorous, but displayed some degree of omnivory. Across all years (2002-2010), fatty acid composition of ice seals showed clear evidence of resource partitioning among them, and little niche separation between spotted and ribbon seals, which is consistent with previous studies. The fatty acid composition of primarily pelagic feeding adult ringed seals and predominantly benthic feeding adult bearded seals did not differ between the recent warm (2002-2005) and cold (2007-2010) periods in the Bering Sea, suggesting that their diets and possibly food web structures were not affected by these large multiyear environmental fluctuations. Notably however, the stable carbon isotope ratios of individual fatty acids of bearded seals from the Bering Sea cold period were higher than those from the warm period, which suggests that their prey base in the Bering Sea was receiving more input from particulate organic matter from sea ice than the water column during those years. By using the stable carbon isotope ratios of individual fatty acids of particulate organic matter from sea ice and the water column in a series of stable isotope mixing models, I estimated the proportional contribution of fatty acids from sea ice particulate organic matter in T. libellula, C. marshallae/glacialis, and T. raschii collected in 2009 and 2010 as 36-72%, 27-63%, and 39-71%, respectively. Using a similar set of mixing models, I estimated that adult bearded seals had the highest level of fatty acids from sea ice particulate organic matter (62-80%), followed by spotted seals (51-62%), and then ringed seals (21-60%) in 2009 and 2010. Although estimates could not be made for ribbon seals due to lack of samples in 2009 and 2010, their stable carbon isotope ratios of individual fatty acids from 2003 were very similar to those of spotted seals suggesting that the proportional contribution of fatty acids from sea ice particulate organic matter to ribbons seals was similar to that of spotted seals. Assuming that seals sourced their sympagic fatty acids from the Bering Sea, these results suggest that sympagic production is currently an important contributor to food webs supporting both benthic and pelagic upper trophic level species in years with heavy ice cover in the Bering Sea. Thus, the question is raised--with the projected continuing loss of seasonal sea ice in the Arctic, will organic matter input from sympagic production also decline, and will it be compensated for by pelagic production to balance both pelagic and benthic carbon and energy budgets?

Trophodynamics of the Benthic Food Webs in the Chukchi and Beaufort Seas, Alaska

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ISBN 13 :
Total Pages : 310 pages
Book Rating : 4.:/5 (872 download)

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Book Synopsis Trophodynamics of the Benthic Food Webs in the Chukchi and Beaufort Seas, Alaska by : Nathan David McTigue

Download or read book Trophodynamics of the Benthic Food Webs in the Chukchi and Beaufort Seas, Alaska written by Nathan David McTigue and published by . This book was released on 2013 with total page 310 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Chukchi and Beaufort Sea shelves host diverse and productive seafloor ecosystems important for carbon and nitrogen cycling for the Arctic Ocean. The benthic food web transfers energy from primary producers to high trophic level organisms (e.g., birds, fish, and mammals), which are important for cultural practices and subsistence hunting by Native Alaskans. This work focuses on the trophic ecology of arctic food webs through use of several different approaches. First, variation in the natural abundance of stable carbon and nitrogen isotopes facilitated the identification of trophic pathways and, subsequently, allowed the comparison of trophic guilds and food webs from the Chukchi and Beaufort Seas. Compared to water column and sedimentary organic matter end-members, second trophic level grazers and suspension feeders were conspicuously 13C-enriched throughout the Chukchi Sea, which supports the hypothesis that microbial degradation of organic matter occurred prior to metazoan assimilation. Second, food web recovery from disturbances caused by exploratory oil drilling at the seafloor that had occurred approximately 20 years prior were assessed in both the Chukchi and Beaufort Seas. Based on isotopic trophic niche overlap between organisms common to drilled and reference sites in the Chukchi and Beaufort Seas, the oil drilling sites had similar food web structure, indicating recovery from the activity associated with the drilling process. Third, photosynthetic pigment biomarkers were used to better understand the diagenetic process, specifically focusing on how both microbial and metazoan grazing pathways degrade organic matter in relation to seasonal sea ice retreat in the Chukchi Sea. The benthic macrofaunal and microbial food web caused rapid degradation of organic matter upon the initial pulse of microalgal food sources to the seafloor. These diagenetic pathways are linked to the 13C-enrichment of residual organic matter, which corresponds to the stable isotope values measured in the benthic macrofauna. Lastly, high-precision liquid chromatography and spectrophotometry were compared for estimating sedimentary pigments in the marine environment. Substantial differences in pheopigment (chlorophyll degradation products) concentrations were observed between the two techniques, suggesting the need for revisions to the monochromatic spectrophotometric equation that relates absorbance to pigment concentrations. One pheopigment, pheophorbide, was found to interfere with the accuracy of the spectrophotometric equation and caused the overestimation of pheopigments.

Deep-Sea Food Chains and the Global Carbon Cycle

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Publisher : Springer Science & Business Media
ISBN 13 : 9401124523
Total Pages : 403 pages
Book Rating : 4.4/5 (11 download)

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Book Synopsis Deep-Sea Food Chains and the Global Carbon Cycle by : G.T. Rowe

Download or read book Deep-Sea Food Chains and the Global Carbon Cycle written by G.T. Rowe and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 403 pages. Available in PDF, EPUB and Kindle. Book excerpt: Carbon dioxide and other `greenhouse' gases are increasing in the atmosphere due to the burning of fossil fuels, the destruction of rain forests, etc., leading to predictions of a gradual global warming which will perturb the global biosphere. An important process which counters this trend toward potential climate change is the removal of carbon dioxide from the surface ocean by photosynthesis. This process packages carbon in phytoplankton which enter the food chain or sink into the deep sea. Their ultimate fate is a `rain' of organic debris out of the surface-mixed layer of the ocean. On a global scale, the mechanisms and overall rate of this process are poorly known. The authors of the 25 papers in this volume present their state-of-the-art approaches to quantifying the mechanisms by which the `rain' of biogenic debris nourishes deep ocean life. Prominent deep sea ecologists, geochemists and modelers address relationships between data and models of carbon fluxes and food chains in the deep ocean. An attempt is made to estimate the fate of carbon in the deep sea on a global scale by summing up the utilization of organic matter among all the populations of the abyssal biosphere. Comparisons are made between these ecological approaches and estimates of geochemical fluxes based on sediment trapping, one-dimensional geochemical models and horizontal (physical) input from continental margins. Planning interdisciplinary enterprises between geochemists and ecologists, including new field programs, are summarized in the final chapter. The summary includes a list of the important gaps in understanding which must be addressed before the role of the deep-sea biota in global-scale processes can be put in perspective.

Carbon Bridge to the Arctic

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Publisher : Frontiers Media SA
ISBN 13 : 2889637514
Total Pages : 325 pages
Book Rating : 4.8/5 (896 download)

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Book Synopsis Carbon Bridge to the Arctic by : Marit Reigstad

Download or read book Carbon Bridge to the Arctic written by Marit Reigstad and published by Frontiers Media SA. This book was released on 2020-06-22 with total page 325 pages. Available in PDF, EPUB and Kindle. Book excerpt: This eBook is a collection of articles from a Frontiers Research Topic. Frontiers Research Topics are very popular trademarks of the Frontiers Journals Series: they are collections of at least ten articles, all centered on a particular subject. With their unique mix of varied contributions from Original Research to Review Articles, Frontiers Research Topics unify the most influential researchers, the latest key findings and historical advances in a hot research area! Find out more on how to host your own Frontiers Research Topic or contribute to one as an author by contacting the Frontiers Editorial Office: frontiersin.org/about/contact.

Surface Water Connectivity of Arctic Lakes Drives Patterns of Fish Species Richness and Composition, and Food Web Structure

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ISBN 13 :
Total Pages : 342 pages
Book Rating : 4.:/5 (1 download)

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Book Synopsis Surface Water Connectivity of Arctic Lakes Drives Patterns of Fish Species Richness and Composition, and Food Web Structure by : Sarah M. Laske

Download or read book Surface Water Connectivity of Arctic Lakes Drives Patterns of Fish Species Richness and Composition, and Food Web Structure written by Sarah M. Laske and published by . This book was released on 2017 with total page 342 pages. Available in PDF, EPUB and Kindle. Book excerpt: Hydrological processes regulate fish habitat, largely controlling availability and suitability of habitat for freshwater fishes. Seasonal fluctuations in surface water distribution and abundance on the Arctic Coastal Plain, Alaska, influence individual fish species occupancy in lentic habitats. On low-relief tundra, permafrost processes and climate are chiefly responsible for lake formation and surface water dynamics, such as the timing, duration, and availability of water that affects fish species distributions. However, it is unclear how these relationships scale up to influence fish community richness and composition, or food web structure. Further, each of these processes is also likely to change with rapid climate warming occurring in the Arctic. By observing patterns of fish species occupancy, we examined how fish species richness and composition in Arctic lakes varied with surface water connectivity at coarse and spatial fine scales. Through experiments and observation, we determined the structure of food webs as they related to surface water connectivity and foraging habits of associated fish species. We found surface water connectivity was a driver of fish species richness and assemblage patterns. Permanently connected lakes contained nearly twice as many species as disconnected lakes; and the most strongly connected lakes contained an average of four additional species compared to isolated lakes. Functional traits of fishes, like life history or body morphology, likely dictate their ability to colonize habitats. Given reduced colonization potential, isolated lakes either never supported or could not retain larger predatory fishes. In isolated systems only one fish predator occurred consistently, and this species showed strong top-down control of invertebrate prey in experimental systems. Yet, in natural environments single-predator systems have fewer trophic links than multi-predator systems, and therefore, less trophic redundancy across species. The loss of species due to isolation reduced the total number of trophic links and shortened food chains. However, I argue that the complexity and addition of top-predators in surface water connected lakes adds trophic redundancy, stabilizes energy flow, and potentially enhances persistence within in food webs and across the meta-community of food webs. Changes to fish species richness, composition, or food web structure from climate warming may be dampened by the resilience of food webs locally, but across the broader landscape it is likely that some food webs will be restructured due to changes in colonization potential regulated by surface water connectivity.

An Arctic Ecosystem

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Publisher : Stroudsburg, Pa. : Dowden, Hutchinson & Ross ; [New York] : Distributed world-wide by Academic Press
ISBN 13 :
Total Pages : 614 pages
Book Rating : 4.:/5 (318 download)

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Book Synopsis An Arctic Ecosystem by : Jerry Brown

Download or read book An Arctic Ecosystem written by Jerry Brown and published by Stroudsburg, Pa. : Dowden, Hutchinson & Ross ; [New York] : Distributed world-wide by Academic Press. This book was released on 1980 with total page 614 pages. Available in PDF, EPUB and Kindle. Book excerpt: One of a series of volumes reporting results of research under the International Biological Program concerning the ecology of the Alaskan arctic coastal plain.

Ocean Acidification

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Publisher : National Academies Press
ISBN 13 : 030916155X
Total Pages : 200 pages
Book Rating : 4.3/5 (91 download)

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Book Synopsis Ocean Acidification by : National Research Council

Download or read book Ocean Acidification written by National Research Council and published by National Academies Press. This book was released on 2010-09-14 with total page 200 pages. Available in PDF, EPUB and Kindle. Book excerpt: The ocean has absorbed a significant portion of all human-made carbon dioxide emissions. This benefits human society by moderating the rate of climate change, but also causes unprecedented changes to ocean chemistry. Carbon dioxide taken up by the ocean decreases the pH of the water and leads to a suite of chemical changes collectively known as ocean acidification. The long term consequences of ocean acidification are not known, but are expected to result in changes to many ecosystems and the services they provide to society. Ocean Acidification: A National Strategy to Meet the Challenges of a Changing Ocean reviews the current state of knowledge, explores gaps in understanding, and identifies several key findings. Like climate change, ocean acidification is a growing global problem that will intensify with continued CO2 emissions and has the potential to change marine ecosystems and affect benefits to society. The federal government has taken positive initial steps by developing a national ocean acidification program, but more information is needed to fully understand and address the threat that ocean acidification may pose to marine ecosystems and the services they provide. In addition, a global observation network of chemical and biological sensors is needed to monitor changes in ocean conditions attributable to acidification.

Ecosystems Naturally Labeled with Carbon-13

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Publisher :
ISBN 13 :
Total Pages : 254 pages
Book Rating : 4.:/5 (342 download)

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Book Synopsis Ecosystems Naturally Labeled with Carbon-13 by : Ted Alan McConnaughey

Download or read book Ecosystems Naturally Labeled with Carbon-13 written by Ted Alan McConnaughey and published by . This book was released on 1977 with total page 254 pages. Available in PDF, EPUB and Kindle. Book excerpt: "Natural abundance 13C/12C ratios provide a tracer for the origin of organic carbon in complex coastal marine food-webs and also appear to be useful for examining trophic organization and food transfer efficiencies in more strictly oceanic environments. The tracer approach proved useful for analyzing the role of eel-grass (Zostera marina) in the food-web of Izembek Lagoon, Alaska. Both eelgrass and phytoplankton contribute to the productivity of that community. That analysis was complicated by non-ideal tracer behavior, however. Animal 13C/12C ratios appeared to depend on biochemical composition, and ways to deal with this were investigated. Furthermore, animal metabolism tended to retain 13C relative to 12C, resulting in progressive elevation of 13C/12C ratios in higher trophic levels. By assuming a uniform relation between 13C enrichment and metabolic stoichiometry, it was possible to deduce animal 'trophic positions' and food transfer efficiencies from 13C/12C data taken from the Bering Sea"--Leaf [iii].

Trophic Relationships in an Arctic Marine Foodweb and Implications for Trace Element Dynamics

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ISBN 13 :
Total Pages : 580 pages
Book Rating : 4.:/5 (622 download)

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Book Synopsis Trophic Relationships in an Arctic Marine Foodweb and Implications for Trace Element Dynamics by : Larissa-A. Dehn

Download or read book Trophic Relationships in an Arctic Marine Foodweb and Implications for Trace Element Dynamics written by Larissa-A. Dehn and published by . This book was released on 2005 with total page 580 pages. Available in PDF, EPUB and Kindle. Book excerpt: Tissues of subsistence-harvested Arctic marine and terrestrial mammals and potential prey species were analyzed for isotopes of carbon and nitrogen and selected trace elements describing contaminant pathways in the food web. Feeding habits of ice seals were characterized using stable isotopes and gastric contents analysis. Bearded seals (Erignathus barbatus) relied on the benthic food chain. Zooplankton and fishes were significant prey for ringed seals (Phoca hispida), while fishes were the principal prey in spotted seals (Phoca largha). Gastric prey composition and isotope ratios varied with age and sex. Effects of age, trophic level, and prey prevalence on trace element concentrations in seal tissues were investigated. Most trace elements differed significantly in phocid tissues. Bearded seals had the highest cadmium (Cd) concentrations and spotted seals the lowest. This indicates a connection of Cd with invertebrate prey, while mercury (Hg), in particular the proportion of organic to total Hg (THg), accumulated in the piscivorous food web. Silver (Ag) showed possible association to benthic feeding habits. Altered trace element accumulation patterns were observed in compromised seals. Stable isotopes illustrated belugas (Delphinapterus leucas) occupied a higher trophic level than bowheads (Balaena mysticetus) and gray whales (Eschrichtius robustus). Trace element concentrations also differed significantly among these cetaceans. Observed relationships with age or length in species analyzed were complex and nonlinear rather than previously reported continuous bioaccumulation with age. Cd was similar in belugas and bowheads but lowest in gray whales. THg was highest in belugas and near detection limit in mysticetes, supporting the connection of Hg with fish and Cd with invertebrates. The hepatic selenium (Se):THg ratio exceeded the frequently described equimolarity in all species. Se:THg molar ratios and tissue concentrations of zinc (Zn) may show promise as indicators of immune status and animal health. Polar bears (Ursus maritimus) feed on the highest trophic level, though Cd concentrations were either similar to, or significantly lower than those in belugas or ice seals. Conversely, THg increased significantly from seal to bear. Generally, trace elements in Alaska-harvested animals were lower than for other Arctic regions, and trace metal magnification in the Arctic food web was not significant"--Leaves iii-iv.

Turnover of Trophic Markers and Lipid Carbon in Arctic Marine Food Webs

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ISBN 13 :
Total Pages : 0 pages
Book Rating : 4.:/5 (99 download)

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Book Synopsis Turnover of Trophic Markers and Lipid Carbon in Arctic Marine Food Webs by : Lauris Boissonnot

Download or read book Turnover of Trophic Markers and Lipid Carbon in Arctic Marine Food Webs written by Lauris Boissonnot and published by . This book was released on 2017 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Fisheries Investigations Along the North Slope and Beaufort Sea Coast in Alaska with Emphasis on Arctic Char

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Publisher : Calgary? : Aquatic Environments Limited
ISBN 13 :
Total Pages : 228 pages
Book Rating : 4.3/5 (91 download)

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Book Synopsis Fisheries Investigations Along the North Slope and Beaufort Sea Coast in Alaska with Emphasis on Arctic Char by : Aquatic Environments Limited

Download or read book Fisheries Investigations Along the North Slope and Beaufort Sea Coast in Alaska with Emphasis on Arctic Char written by Aquatic Environments Limited and published by Calgary? : Aquatic Environments Limited. This book was released on 1977 with total page 228 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Influence of Northward Redistribution of Marine Prey and Predator Species on the Trophic Dynamics of Environmental Contaminants and Nutrients in Arctic Marine Food Webs

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ISBN 13 :
Total Pages : pages
Book Rating : 4.:/5 (119 download)

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Book Synopsis Influence of Northward Redistribution of Marine Prey and Predator Species on the Trophic Dynamics of Environmental Contaminants and Nutrients in Arctic Marine Food Webs by : Sara Pereira Pedro

Download or read book Influence of Northward Redistribution of Marine Prey and Predator Species on the Trophic Dynamics of Environmental Contaminants and Nutrients in Arctic Marine Food Webs written by Sara Pereira Pedro and published by . This book was released on 2019 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The northward-range expansion of sub-Arctic species is altering species interactions, affecting the dynamics of nutrients and contaminants, in Arctic food webs. Arctic marine piscivores are switching from a diet historically dominated by Arctic cod to one comprised of sub-Arctic capelin and sand lance. Another change is the occurrence of killer whales in the Arctic and the presumed switch from a fish-based diet in temperate waters to one richer in marine mammals in the Arctic. My goal was to evaluate some of the consequences of these climate-driven ecological changes, by comparing contaminant and nutrient concentrations in shifting Arctic marine communities. Potentially due to migratory patterns, capelin had higher tissue concentrations and higher proportions of less volatile persistent organic pollutants (POPs), compared to Arctic cod. Yet, the magnitude of these differences was small. Furthermore, mercury concentrations were higher in Arctic cod relative to capelin. Concentrations of essential fatty acids were similar among these species, while selenium was higher in sand lance compared to Arctic cod. Thus, the replacement of Arctic cod with capelin and sand lance may not substantially decrease the food quality of prey available for predators. However, fatty acid markers suggested that capelin and sand lance were less dependent on sea ice-primary production, and their fatty acid and stable isotope feeding niches were wider compared to that of Arctic cod, suggesting an ecological advantage for these sub-Arctic fish over Arctic cod under climate change. Killer whales had blubber POP concentrations exceeding previously calculated effects thresholds for cetaceans, likely related to feeding on high trophic level prey in Arctic waters. A negative association of POPs with blubber concentrations of the biomarker vitamin E, but not vitamin A, in killer whales with fatty acid markers consistent with marine mammal consumption, suggested that feeding on this prey may put killer whales at higher risk of POP adverse effects on vitamin E homoeostasis. My research showed that changes in prey related to northward range-shifts can have consequences for predators, especially those at high trophic levels, highlighting the importance of considering top consumers and their interactions when studying climate change impacts on Arctic ecosystems.

Marine and Not Terrestrial Resources Support Nearshore Food Webs Across a Gradient of Glacial Watersheds in the Northern Gulf of Alaska

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Publisher :
ISBN 13 :
Total Pages : 0 pages
Book Rating : 4.:/5 (133 download)

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Book Synopsis Marine and Not Terrestrial Resources Support Nearshore Food Webs Across a Gradient of Glacial Watersheds in the Northern Gulf of Alaska by : James W. Schloemer

Download or read book Marine and Not Terrestrial Resources Support Nearshore Food Webs Across a Gradient of Glacial Watersheds in the Northern Gulf of Alaska written by James W. Schloemer and published by . This book was released on 2022 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Estuaries are among the most productive ecosystems on Earth, yet are especially at risk in high-latitude regions due to climate-driven effects on the connected terrestrial and marine realms. Warming in these regions exceeds the global average and is a major cause of the rapid melting of glaciers. As a result, the timing and magnitude of freshwater discharge into estuaries are subject to increase during the peak in glacial meltwater, ultimately affecting the riverine flux of nutrients and organic matter (OM) from the land to coastal environments. Intertidal communities near the outflow of rivers often rely on supplementing local (marine) food sources with allochthonous (terrestrial) subsidies, despite the fact that terrestrial OM can be problematic for marine consumers to assimilate. We investigated if terrestrial matter subsidizes nearshore food webs in northern Gulf of Alaska watersheds, and if the relative proportion of terrestrial versus marine OM supporting these food webs differed with watershed glaciation characteristics and with seasonal glacial discharge regimes. We employed a Bayesian stable isotope mixing model to determine the contribution of marine (phytoplankton, particulate OM, macroalgae) and terrestrial (vascular plant) sources to the diets of grazing/detritivore and filter/suspension-feeding coastal invertebrates at the outflows of watersheds of varying glacial influence and across various discharge periods. Additionally, we conducted a distance-based redundancy analysis to investigate the effects of watershed-characteristic sourcing and transport of terrestrial OM on nearshore consumer diets. The diets of both feeding groups were predominantly marine (>90%) and varied little among sites or glacial discharge periods. However, consumers were depleted in 13C isotopes with increasing glaciation; the significant watershed descriptors suggest that this change was more associated with discharge effects on marine primary production rather than consumption of terrestrial OM by the invertebrates. These results suggest that, while watershed exports may influence the stable isotope composition of OM sources, the diets of these feeding groups are mostly decoupled from terrestrial influence during the time of sampling. It is possible that marine OM availability in the study system is not limiting, and terrestrial OM subsidies in such productive systems are not needed to support nearshore food webs.

The Ocean and Cryosphere in a Changing Climate

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Publisher : Cambridge University Press
ISBN 13 : 9781009157971
Total Pages : 755 pages
Book Rating : 4.1/5 (579 download)

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Book Synopsis The Ocean and Cryosphere in a Changing Climate by : Intergovernmental Panel on Climate Change (IPCC)

Download or read book The Ocean and Cryosphere in a Changing Climate written by Intergovernmental Panel on Climate Change (IPCC) and published by Cambridge University Press. This book was released on 2022-04-30 with total page 755 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Intergovernmental Panel on Climate Change (IPCC) is the leading international body for assessing the science related to climate change. It provides policymakers with regular assessments of the scientific basis of human-induced climate change, its impacts and future risks, and options for adaptation and mitigation. This IPCC Special Report on the Ocean and Cryosphere in a Changing Climate is the most comprehensive and up-to-date assessment of the observed and projected changes to the ocean and cryosphere and their associated impacts and risks, with a focus on resilience, risk management response options, and adaptation measures, considering both their potential and limitations. It brings together knowledge on physical and biogeochemical changes, the interplay with ecosystem changes, and the implications for human communities. It serves policymakers, decision makers, stakeholders, and all interested parties with unbiased, up-to-date, policy-relevant information. This title is also available as Open Access on Cambridge Core.

53rd Arctic Science Conference

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ISBN 13 :
Total Pages : 265 pages
Book Rating : 4.:/5 (496 download)

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Book Synopsis 53rd Arctic Science Conference by : American association for the advancement of science

Download or read book 53rd Arctic Science Conference written by American association for the advancement of science and published by . This book was released on 2002 with total page 265 pages. Available in PDF, EPUB and Kindle. Book excerpt: