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111.
Norbert P. Psuty Andrea Spahn Tanya M. Silveira William Schmelz 《Journal of Coastal Conservation》2014,18(5):515-528
Persistent erosion at Plumb Beach, New York, USA, has been countered by a series of isolated actions to stabilize the shoreline. Sediment placed at the erosion site has quickly been removed and re-deposited in downdrift locations to the detriment of the existing habitats. In a renewed effort to better understand the dimensions of change at Plumb Beach, detailed spatial analysis of shoreline displacement, dune-beach profile evolution, and sediment budget has been undertaken through intensive surveying and comparisons of Digital Elevation Models. Products derived from these surveys establish that the sector of maximum erosion has shifted downdrift and that the scale of the changes is twice the volume exchange as previously estimated. Improved knowledge of the dimensions and spatial distributions of the changes is used to create a focused approach that is functioning within the scale of the local sediment budget and reducing its impacts. 相似文献
112.
Feasibility versus sustainability in urban water management 总被引:1,自引:0,他引:1
Decision making in urban water management is exemplified by the case of Austria: Although researchers define a comprehensible concept of sustainability, practitioners emphasize feasibility and accept limitations in sustainability. Could the specification of particular methods, chosen from some decision support methodology, remedy this situation? While an integrative assessment of sustainability should not be based on prescribed or standardized criteria, or even a certain assessment method, it should force the decision makers to make their chosen premise more visible. To this end a change of the decision making process is proposed, which will allow the decision makers to adapt the decision making process to the circumstances of a specific project in a way that is accepted by the stakeholders. 相似文献
113.
The metabolism of 4,4′-dichlorobiphenyl by mixed cultures of bacteria, isolated from activated sludge, was studied in shake cultures and in soil, both in presence and absence of alternative carbon sources. When 4,4′-dichlorobiphenyl was used as sole carbon source, 4-chlorobenzoic acid and 4,4′-dichloro-2,3-biphenyldiol could be isolated from the culture medium. Polar metabolites however, could not be detected in soil and in media in which alternative carbon sources such as glucose, glycerol, peptone, yeast-extract, humic acid or activated sludge were present. No hydroxylated or carboxylic acid derivatives could be isolated when 2,4′, 5-tri-, 2,2′,5,5′,-textra-, 2,2′,3,4,5′-penta-, 2,2′,3,4,5,5′-hexa- and decachlorobiphenyl were used as the sole carbon sources for incubation with bacteria in shake culture. 相似文献
114.
115.
Translocation of 14C-labelled assimilates in Laminaria hyperborea and L. saccharina is strictly basipetal within the thallus. The lowermost 20 cm of the frond accumulates 71% (L. hyperborea) or 63% (L. saccharina) of the basipetallymoving translocate after a period of 96 h from initial feeding with NaH14CO3. Whereas translocation was found to occur at all seasons in L. saccharina, which grows throughout the year, no translocation of newly synthesized photosynthate occurred in L. hyperborea in October, when no frond enlargement takes place, nor in January, when the new fond occurs as a tiny outgrowth. In L. hyperborea, organic material, assimilated by the old frond during the period of rapid growth, is exported at the rate of 0.5 mg C · dm-2 · h-1. In L. saccharina, 14 to 18 cm frond length are necessary for an elongation rate of the growing zone, situated in lowermost 10 cm of the frond, of 1 cm per week. The significance of translocation in the two Laminaria species is demonstrated by comparison of export rates with growth rates measured in situ and in the laboratory.Dedicated to Professor Dr. Otto Stocker on his 85th birthday. 相似文献
116.
A survey of translocation in laminariales (Phaeophyceae) 总被引:1,自引:0,他引:1
A survey of translocation of photoassimilates in 13 genera of Laminariales is presented. All showed long-distance transport of 14C-labeled products from mature source tissue to meristematic sinks (haptera and intercalary growing regions). In plants with several laminae forming one frond, older laminae may provide assimilates for the growth of younger ones, and in Macrocystis spp., where fronds of different ages and developmental stage arise from a common holdfast, mature fronds initiate and support new fronds. Translocation velocities vary from species to species but are in the range of 55 to 570 mm/h. The results strongly support the hypothesis that Laminariales in general have an effective translocation system, on which their thallus growth depends. 相似文献
117.
From individuals to ecosystem function: toward an integration of evolutionary and ecosystem ecology 总被引:1,自引:0,他引:1
Schmitz OJ Grabowski JH Peckarsky BL Preisser EL Trussell GC Vonesh JR 《Ecology》2008,89(9):2436-2445
An important goal in ecology is developing general theory on how the species composition of ecosystems is related to ecosystem properties and functions. Progress on this front is limited partly because of the need to identify mechanisms controlling functions that are common to a wide range of ecosystem types. We propose that one general mechanism, rooted in the evolutionary ecology of all species, is adaptive foraging behavior in response to predation risk. To support our claim, we present two kinds of empirical evidence from plant-based and detritus-based food chains of terrestrial and aquatic ecosystems. The first kind comes from experiments that explicitly trace how adaptive foraging influences ecosystem properties and functions. The second kind comes from a synthesis of studies that individually examine complementary components of particular ecosystems that together provide an integrated perspective on the link between adaptive foraging and ecosystem function. We show that the indirect effects of predators on plant diversity, plant productivity, nutrient cycling, trophic transfer efficiencies, and energy flux caused by consumer foraging shifts in response to risk are qualitatively different from effects caused by reductions in prey density due to direct predation. We argue that a perspective of ecosystem function that considers effects of consumer behavior in response to predation risk will broaden our capacity to explain the range of outcomes and contingencies in trophic control of ecosystems. This perspective also provides an operational way to integrate evolutionary and ecosystem ecology, which is an important challenge in ecology. 相似文献
118.
Predator diversity and trophic interactions 总被引:3,自引:0,他引:3
Schmitz OJ 《Ecology》2007,88(10):2415-2426
The recognition that predators play important roles in ecosystems has prompted research to resolve how combinations of predator species influence ecosystem functions. Interactions among predator species and their prey can lead to a host of linear and nonlinear effects. Understanding the conditions causing these effects is critical for assigning predator species to functional groups in ways that lead to predictive theory of predator diversity effects on trophic interactions. To this end, I provide a synthesis of experiments examining multiple-predator-species effects on mortality of single shared prey. I show how experimental design and experimental venue can determine the conclusion about the importance of predator diversity on trophic interactions. In addition, I link natural history insights on predator species habitat and hunting behavior with linear and nonlinear multiple-predator effects to derive a new concept of predator diversity effects on trophic interactions. This concept holds that the nature of predator diversity effects is contingent upon predator species hunting mode plus predator and prey species habitat domain (defined as the spatial extent to which a microhabitat is used by a species). This concept allows the classification of multiple-predator effects into four broad functional categories: substitutable, nonlinear due to predator species interference, nonlinear due to intraguild predation, and nonlinear due to predator species synergism. Experimental evidence so far provides ample and comparatively equal support for substitutable, interference, and intraguild effects, and equivocal support for nonlinear synergisms. The paper closes by discussing ways to further a research program aimed at using the building blocks presented here to understand predator functional diversity and trophic interactions in complex ecological systems. 相似文献
119.
Ohne Zusammenfassung
The online version of the original article can be found at 相似文献
120.
Maike A. Seiler Detlef Jensen Udo Neist Ursula K. Deister Franz Schmitz 《Environmental Sciences Europe》2017,29(1):30