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  • 1
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    Degrading permafrost river catchments and their impact on Arctic Ocean nearshore processes (2022)
    Springer Nature
    In:  EPIC3Ambio, Springer Nature, ISSN: 0044-7447
    Details
    Publication Date: 2024-01-22
    Description: Arctic warming is causing ancient perennially frozen ground (permafrost) to thaw, resulting in ground collapse, and reshaping of landscapes. This threatens Arctic peoples' infrastructure, cultural sites, and land-based natural resources. Terrestrial permafrost thaw and ongoing intensification of hydrological cycles also enhance the amount and alter the type of organic carbon (OC) delivered from land to Arctic nearshore environments. These changes may affect coastal processes, food web dynamics and marine resources on which many traditional ways of life rely. Here, we examine how future projected increases in runoff and permafrost thaw from two permafrost-dominated Siberian watersheds—the Kolyma and Lena, may alter carbon turnover rates and OC distributions through river networks. We demonstrate that the unique composition of terrestrial permafrost-derived OC can cause significant increases to aquatic carbon degradation rates (20 to 60% faster rates with 1% permafrost OC). We compile results on aquatic OC degradation and examine how strengthening Arctic hydrological cycles may increase the connectivity between terrestrial landscapes and receiving nearshore ecosystems, with potential ramifications for coastal carbon budgets and ecosystem structure. To address the future challenges Arctic coastal communities will face, we argue that it will become essential to consider how nearshore ecosystems will respond to changing coastal inputs and identify how these may affect the resiliency and availability of essential food resources.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , isiRev
    Location Call Number Limitation Availability
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    PAPER (OA)
  • 2
    Electronic Resource
    Electronic Resource
    Epilithic bacterial and algal colonization in a stream run, riffle, and pool: a test of biomass covariation (1996)
    Springer
    Hydrobiologia 332 (1996), S. 159-166 
    Details
    ISSN: 1573-5117
    Keywords: Stream ecosystem ; biofilm ; epilithic algae ; epilithic bacteria
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Epilithic bacterial and algal biomass were compared among a run, riffle, and pool along an open-canopy section of a third-order, temperate stream. Epilithic biofilms were sampled after 3, 7, 14, 21, 28, and 35 days colonization on unglazed ceramic tiles that were attached to plastic trays (n = 3) placed across each of the three habitats (i.e., run, riffle, pool). The diverse habitats and sampling regime were selected to provide a range in algal biomass so that potential covariation between epilithic bacterial and algal biomass could be assessed. There were significant differences among habitats and among trays within each habitat for both chlorophyll a and AFDM. Chlorophyll a and AFDM increased in the run and pool throughout the colonization period. In the riffle, chlorophyll a and AFDM increased rapidly early in colonization, then decreased. Epilithic bacterial biomass increased rapidly with no significant differences among the three habitats throughout colonization. Further, bacterial biomass did not correlate with either chlorophyll a or AFDM in any of the three habitats or on any of the sampling days. These results suggest that epilithic algal and bacterial biomass may be regulated by independent controls in some stream environments.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00031921
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    Paper (German National Licenses)
    Fulltext
  • 3
    Electronic Resource
    Electronic Resource
    Relationships between bacterial productivity and organic carbon at a soil—stream interface (1998)
    Springer
    Hydrobiologia 386 (1998), S. 45-53 
    Details
    ISSN: 1573-5117
    Keywords: stream sediments ; riparian zone ; dissolved organic carbon (DOC) ; particulate organic carbon (POC) ; FAME yield ; bacterial productivity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Microbial communities at soil-stream interfaces may be particularly important in regulating amounts and forms of nutrients that leave upland soils and enter stream ecosystems. While microbial communities are thought to be responsible for key nutrient transformations within near-stream sediments, there is relatively little mechanistic information on factors that control microbial activities in these areas. In this study, we examine the roles of dissolved organic carbon (DOC) vs. particulate organic carbon (POC) as potential controls on rates of bacterial productivity (measured as incorporation of [3H]thymidine into bacterial DNA) and amounts of bacterial biomass (measured as fatty acid yield) in sediments along a transect perpendicular to a soil–stream interface. We hypothesized that spatial patterns in bacterial productivity would vary in response to strong and persistent patterns in pore-water concentrations of DOC that were observed along a soil-stream transect throughout a 2-year period. Our results did not support the existence of such a link between pore-water DOC and bacterial productivity. In contrast, we found bacterial productivity and biomass were related to small-scale spatial variations in sediment POC on 3 of 4 sample dates. While our results indicate that total bacterial productivity in near-stream sediments is not consistently linked to spatial variations in pore-water DOC, it is likely that DOC and POC are not mutually exclusive and the relative contribution of DOC and POC to sedimentary microbes varies temporally and spatially in different riparian habitats.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1003583813445
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    Paper (German National Licenses)
    Fulltext
  • 4
    Electronic Resource
    Electronic Resource
    The impact of extremely low frequency electromagnetic fields on stream periphyton: an eleven-year study (2000)
    Springer
    Hydrobiologia 439 (2000), S. 61-76 
    Details
    ISSN: 1573-5117
    Keywords: ELF electromagnetic fields ; stream periphyton ; electric fields ; algal communities ; algae ; electromagnetic fields
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Potential effects of extremely low frequency (ELF) electromagnetic fields on periphyton were studied from 1983 to 1993 using a Before, After, Control and Impact design. The study was conducted at two sites on the Ford River, a fourth-order brown water trout stream in Dickinson County, Michigan. The Reference site received 4.9–6.5 times less exposure to ground electric fields and from 300 to 334 times less exposure to magnetic flux from 1989 to 1993 when the antenna was operational at 76 Hz than did the Antenna site. The objective of the study was to determine if ELF electromagnetic fields had caused changes in structure and/or function of algal communities in the Ford River. Significant differences in chlorophyll a standing crop and daily accumulation rate (a surrogate for primary productivity), and organic matter standing crop and daily accumulation rate were observed between the Reference and Antenna site after the antenna became operational. These four related community function variables all increased at the Antenna site with largest and most consistent increases occurring for chlorophyll measures. Compared to pre-operational data, the increase in chlorophyll at the Antenna site also occurred during a period of low amperage testing in 1986–1988, and did not increase further when the antenna became fully operational in 1989, indicating a low threshold for response. There was no significant differences between the Antenna and Reference sites in community structure variables such as diversity, evenness and the relative abundance of dominant diatoms. Thus, 76 Hz ELF electromagnetic radiation apparently did not change the basic makeup of the diatom community but did increase accumulation rates and standing crops of chlorophyll a and organic matter.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1004101719678
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    Paper (German National Licenses)
    Fulltext
  • 5
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    Epilithic bacterial responses to variations in algal biomass and labile dissolved organic carbon during biofilm colonization (1996)
    North American Benthological Society
    In:  Journal of The North American Benthological Society, 15 (2). pp. 143-154.
    Details
    Publication Date: 2017-07-03
    Description: This study experimentally examines potential shifts in epilithic bacterial biomass and productivity in response to variations in epilithic algal biomass and labile dissolved organic carbon (DOC) during stream biofilm colonization. I predicted that epilithic bacteria would respond positively to allochthonous DOC early in biofilm colonization and respond positively to increased algal biomass late in biofilm colonization. Using once-through, experimental-stream channels, a 2 × 2 factorial design was employed in which light (shaded vs. non-shaded) and labile DOC (glucose-amended vs. ambient) were manipulated. Ceramic tiles were used as substrates for biofilm colonization and were sampled at different colonization stages. Shading significantly reduced chlorophyll a, live-algal bio-volume, and ash-free dry mass throughout colonization. Bacterial biomass increased significantly during biofilm colonization, but was not significantly different among treatments. Incorporation of [〈sup〉3〈/sup〉H]thymidine into bacterial DNA, which was measured as a surrogate for bacterial productivity, was significantly greater in the glucose-amended channels throughout colonization, but it increased in the unshaded, ambient treatment in late colonization as well. These results suggest that labile DOC in the water column can potentially function as a control for epilithic bacteria throughout biofilm colonization, whereas epilithic algae can stimulate bacteria late in biofilm colonization in productive stream ecosystems.
    Type: Article , PeerReviewed
    Format: text
    DOI: 10.2307/1467944
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    OceanRep: Article in a Scientific Journal - peer-reviewed
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