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  • 1
    Electronic Resource
    Electronic Resource
    Modelling the effects of artificial mixing and copper sulphate dosing on phytoplankton in an Australian reservoir (2003)
    Oxford, UK : Blackwell Science, Ltd
    Lakes & reservoirs 8 (2003), S. 0 
    Details
    ISSN: 1440-1770
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Geography
    Notes: An artificially destratified reservoir was simulated with the freshwater phytoplankton model PROTECH (Phytoplankton Responses To Environmental Change). The chosen site for validation was a highly managed drinking water supply reservoir (Myponga Reservoir, South Australia). Chemical dosing using copper sulphate (CuSO4) and artificial mixing via an aerator and two raft-mounted mechanical surface mixers (hereafter referred to as surface mixers) are used at Myponga to manage water quality, in particular the threat of cyanobacteria growth. The phytoplankton community was adequately modelled and showed that the community was dominated by species tolerant of low light doses (R-type strategists). The light limitation in the water body was found to be the controlling factor on phytoplankton succession. Subsequently, small fast-growing species and larger motile phytoplankton (C and CS-type, respectively) do not have the opportunity to dominate under all simulated conditions, diminishing the need for CuSO4 dosing. These simulations demonstrated that the individual and combined impact of the management strategies reduces the total algal biomass, but have minimal effect upon phytoplankton functional-type succession, and R-type species continued to dominate under all simulated scenarios. It was concluded that, due to the light-limitation and current nutrient availability in Myponga Reservoir, the probability of persistent populations of undesirable scum-forming cyanobacteria is minimal, even in the absence of artificial control.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1440-1770.2003.00209.x
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    Paper (German National Licenses)
    Fulltext
  • 2
    Electronic Resource
    Electronic Resource
    The mechanism of zinc uptake in plants (1996)
    Springer
    Planta 198 (1996), S. 39-45 
    Details
    ISSN: 1432-2048
    Keywords: Chara ; Cell wall and zinc ; Micronutrient ; Triticum ; Zinc uptake
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The mechanism of zinc influx was investigated using giant algal cells (Chara corallina Klein ex Will.esk. R.D. Wood), in which it was possible to discriminate clearly between tracer zinc bound in the cell wall and actual uptake into the cell. It was shown that despite lengthy desorption, retention of zinc in slowly exchanging zinc pools in the cell wall can invalidate tracer influx measurements. A comparative study of zinc desorption from isolated cell walls of wheat (Triticum aestivum L.) roots indicated exchange characteristics similar to that of Chara. Fractionation of Chara internodal cells taken directly from cultures showed that most of the cell-associated zinc was in the cell walls. The cytoplasmic and vacuolar zinc concentrations were 56 mmol·m−3 and 32 mmol·m−3, respectively, for cells grown in a zinc concentration of 0.1 mmol·m−3. Influx of 65Zn in Chara was linear over several hours, with rapid transfer to the vacuole, but only slow efflux. Influx occurred in a biphasic manner, which was tentatively attributed to the operation of two separate transport systems, a high-affinity system which is saturated at 0.1 mmol·m−3 and a low-affinity system which showed a linear dependence on concentration up to at least 50 mmol·m−3. Only the low-affinity system was examined in detail. Influx through this system showed a strong dependence on external pH with an optimum around 7 and was also stimulated by cytoplasmic acidification. Influx was sensitive to metabolic inhibition, but not to blockers of Ca2+ and K+ channels. Other characteristics included a slight sensitivity to Mn2+ and Fe2+ but little sensitivity to high concentrations of K+ or Na+. Influx was independent of membrane potential difference in cells voltage-clamped at − 65 to − 300 mV.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00197584
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    Paper (German National Licenses)
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  • 3
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    Ocean urea fertilization for carbon credits poses high ecological risks (2008)
    Details
    Publication Date: 2022-05-26
    Description: Author Posting. © Elsevier B.V., 2008. This is the author's version of the work. It is posted here by permission of Elsevier B.V. for personal use, not for redistribution. The definitive version was published in Marine Pollution Bulletin 56 (2008): 1049-1056, doi:10.1016/j.marpolbul.2008.03.010.
    Description: The proposed plan for enrichment of the Sulu Sea, Philippines, a region of rich marine biodiversity, with thousands of tonnes of urea in order to stimulate algal blooms and sequester carbon is flawed for multiple reasons. Urea is preferentially used as a nitrogen source by some cyanobacteria and dinoflagellates, many of which are neutrally or positively buoyant. Biological pumps to the deep sea are classically leaky, and the inefficient burial of new biomass makes the estimation of a net loss of carbon from the atmosphere questionable at best. The potential for growth of toxic dinoflagellates is also high, as many grow well on urea and some even increase their toxicity when grown on urea. Many toxic dinoflagellates form cysts which can settle to the sediment and germinate in subsequent years, forming new blooms even without further fertilization. If large-scale blooms do occur, it is likely that they will contribute to hypoxia in the bottom waters upon decomposition. Lastly, urea production requires fossil fuel usage, further limiting the potential for net carbon sequestration. The environmental and economic impacts are potentially great and need to be rigorously assessed.
    Description: This paper was developed under the Global Ecology and Oceanography of Harmful Algal Blooms (GEOHAB) core research project on HABs and Eutrophication and the GEOHAB regional focus on HABs in Asia. GEOHAB is supported by the International Oceanographic Commission (IOC) of UNESCO and by the Scientific Committee on Oceanic Research (SCOR), which are, in turn, supported by multiple agencies, including NSF and NOAA of the USA.
    Keywords: Urea dumping ; Ocean fertilization ; Carbon credits ; Sulu Sea ; Carbon sequestration ; Harmful algae ; Toxic dinoflagellates ; Cyanobacteria ; Hypoxia
    Repository Name: Woods Hole Open Access Server
    Type: Preprint
    Format: application/pdf
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    PAPER (OA)
  • 4
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    Determining the probability of cyanobacterial blooms: the application of Bayesian networks in multiple lake systems (2015)
    ESA
    In:  Ecological Applications, 25 (1). pp. 186-199.
    Details
    Publication Date: 2017-09-20
    Description: A Bayesian network model was developed to assess the combined influence of nutrient conditions and climate on the occurrence of cyanobacterial blooms within lakes of diverse hydrology and nutrient supply. Physicochemical, biological, and meteorological observations were collated from 20 lakes located at different latitudes and characterized by a range of sizes and trophic states. Using these data, we built a Bayesian network to (1) analyze the sensitivity of cyanobacterial bloom development to different environmental factors and (2) determine the probability that cyanobacterial blooms would occur. Blooms were classified in three categories of hazard (low, moderate, and high) based on cell abundances. The most important factors determining cyanobacterial bloom occurrence were water temperature, nutrient availability, and the ratio of mixing depth to euphotic depth. The probability of cyanobacterial blooms was evaluated under different combinations of total phosphorus and water temperature. The Bayesian network was then applied to quantify the probability of blooms under a future climate warming scenario. The probability of the “high hazardous” category of cyanobacterial blooms increased 5% in response to either an increase in water temperature of 0.8°C (initial water temperature above 24°C) or an increase in total phosphorus from 0.01 mg/L to 0.02 mg/L. Mesotrophic lakes were particularly vulnerable to warming. Reducing nutrient concentrations counteracts the increased cyanobacterial risk associated with higher temperatures.
    Type: Article , PeerReviewed
    Format: text
    DOI: 10.1890/13-1677.1
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    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 5
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    Applications of ecological stoichiometry for sustainable acquisition of ecosystem services (2005)
    Wiley-Blackwell
    In:  Oikos, 109 . pp. 52-62.
    Details
    Publication Date: 2017-01-31
    Description: Human activities have differentially altered biogeochemical cycling at local, regional and global scales. We propose that a stoichiometric approach, examining the fluxes of multiple elements and the ratio between them, may be a useful tool for better understanding human effects on ecosystem processes and services. The different scale of impacts of the elements carbon, nitrogen and phosphorus and the different nature of their biogeochemical cycles, imply a large variation of their stoichiometric ratios in space and time and thus divergent impacts on biota. In this paper, we examine the effects of anthropogenic perturbations on nutrient ratios in ecosystems in two examples and one case study. Altered stoichiometry in agricultural systems (example 1) can affect not only crop yield and quality but also the interactions between plants and their pollinators, pests and pathogens. Human activities have also altered stoichiometry in coastal ecosystems (example 2). Increased N loading has especially lead to increased N:P and reduced Si:N ratios, with detrimental effects on ecosystem services derived from coastal pelagic food webs, such as fish yield and water quality. The terrestrial–aquatic linkage in stoichiometric alterations is illustrated with a case study, the Mississippi River watershed, where anthropogenic activities have caused stoichiometric changes that have propagated through the watershed into the northern Gulf of Mexico. Coupled with altered stoichiometric nutrient inputs are the inherent differences in variation and sensitivity of different ecosystems to anthropogenic disturbance. Furthermore, the connections among the components of a watershed may result in downstream cascades of disrupted functioning. Applying a multiple element perspective to understanding and addressing societal needs is a new direction for both ecological stoichiometry and sustainability.
    Type: Article , PeerReviewed
    Format: text
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    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 6
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    Determining the probability of cyanobacterial blooms: the application of Bayesian networks in multiple lake systems (2015)
    Wiley-Blackwell
    Details
    Publication Date: 2015-01-01
    Description: A Bayesian network model was developed to assess the combined influence of nutrient conditions and climate on the occurrence of cyanobacterial blooms within lakes of diverse hydrology and nutrient supply. Physicochemical, biological, and meteorological observations were collated from 20 lakes located at different latitudes and characterized by a range of sizes and trophic states. Using these data, we built a Bayesian network to (1) analyze the sensitivity of cyanobacterial bloom development to different environmental factors and (2) determine the probability that cyanobacterial blooms would occur. Blooms were classified in three categories of hazard (low, moderate, and high) based on cell abundances. The most important factors determining cyanobacterial bloom occurrence were water temperature, nutrient availability, and the ratio of mixing depth to euphotic depth. The probability of cyanobacterial blooms was evaluated under different combinations of total phosphorus and water temperature. The Bayesian network was then applied to quantify the probability of blooms under a future climate warming scenario. The probability of the ?high hazardous? category of cyanobacterial blooms increased 5% in response to either an increase in water temperature of 0.8°C (initial water temperature above 24°C) or an increase in total phosphorus from 0.01 mg/L to 0.02 mg/L. Mesotrophic lakes were particularly vulnerable to warming. Reducing nutrient concentrations counteracts the increased cyanobacterial risk associated with higher temperatures. # doi:10.1890/13-1677.1
    Print ISSN: 1051-0761
    Electronic ISSN: 1939-5582
    Topics: Biology
    Published by Wiley-Blackwell on behalf of The Ecological Society of America (ESA).
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    PAPER CURRENT
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