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Campbell D.E.,US Ecology | Lu H.,CAS South China Botanical Garden | Lin B.-L.,Japan National Institute of Advanced Industrial Science and Technology
Ecological Modelling | Year: 2014

Estimates of the emergy carried by the flows of biologically active elements (BAE) and compounds are needed to accurately evaluate the near and far-field effects of anthropogenic wastes. The transformities and specific emergies of these elements and of their different chemical species are also needed to quantify the inputs to many ecological and economic production functions. In this study, we performed emergy evaluations of the global biogeochemical cycles of the BAE, carbon, C, nitrogen, N, sulfur, S, phosphorus, P, oxygen, O2 and silica, Si, as well as the global cycles of two compounds (+2), methane, CH4 and water, H2O. We assembled budgets for the global flows of the "BAE+2" from the literature for the Preindustrial Era and the Industrial Age. The emergy basis for these elemental flows was obtained by documenting the global inflows of renewable and nonrenewable emergy for the Preindustrial Era (i.e., circa 1850) and for the Industrial Age. The nonrenewable emergy inputs in the Industrial Age were documented using a variable time window corresponding to the period of observation when the different elemental budgets were evaluated. We calculated specific emergies and some transformities of the total flows of the elements and of some of their chemical species. The elemental cycles were diagrammed in Energy Systems Language (ESL) and tables of specific emergies are provided for use in subsequent emergy evaluations. The accuracy of evaluating the global cycles of the BAE+2 at intermediate complexity was assessed by comparison to the results of an earlier detailed analysis of the global N cycle. Joint evaluation of the BAE+2 allowed us to examine these elemental cycles with respect to commonalities and differences in their structure, function, and potential impacts of their perturbations on the global ecosystem. We characterize the coupling of the BAE in terms of a fast biogeochemical loop and a slow geochemical loop, an insight which emerged from the process of diagramming the nitrogen cycle in ESL. Finally, we compared our emergy evaluation results to other means of ranking greenhouse gases (GHGs) and other wastes and developed specific recommendations that more research and management attention should be focused on N2O, S and CH4, while continuing present efforts to better understand and manage CO2 and reactive N. © 2013 Elsevier B.V. Source

Shafer D.J.,U.S. Army | Kaldy J.E.,US Ecology | Gaeckle J.L.,Nearshore Habitat Program
Environmental Management | Year: 2014

Healthy seagrass is considered a prime indicator of estuarine ecosystem function. On the Pacific coast of North America, at least two congeners of Zostera occur: native Zostera marina, and introduced, Zostera japonica. Z. japonica is considered "invasive" and therefore, ecologically and economically harmful by some, while others consider it benign or perhaps beneficial. Z. japonica does not appear on the Federal or the Oregon invasive species or noxious weed lists. However, the State of California lists it as both an invasive and noxious weed; Washington State recently listed it as a noxious weed. We describe the management dynamics in North America with respect to these congener species and highlight the science and policies behind these decisions. In recent years, management strategies at the state level have ranged from historical protection of Z. japonica as a priority habitat in Washington to eradication in California. Oregon and British Columbia, Canada appear to have no specific policies with regard to Z. japonica. This fractured management approach contradicts efforts to conserve and protect seagrass in other regions of the US and around the world. Science must play a critical role in the assessment of Z. japonica ecology and the immediate and long-term effects of management actions. The information and recommendations provided here can serve as a basis for providing scientific data in order to develop better informed management decisions and aid in defining a uniform management strategy for Z. japonica. © 2013 Springer Science+Business Media New York (outside the USA). Source

Hoffman J.C.,US Ecology | Sutton T.T.,Virginia Institute of Marine Science
Deep-Sea Research Part I: Oceanographic Research Papers | Year: 2010

Stable isotope analysis of fish tissue can aid studies of deep-sea food webs because sampling difficulties severely limit sample sizes of fish for traditional diet studies. The carbon stable isotope ratio (δ13C) is widely used in food web studies, but it must be corrected to remove variability associated with varying lipid content in the tissue. A lipid correction has not been determined for any deep-sea fish. These fishes are ideal for studying lipid correction because lipid content varies widely among species. Our objective was to evaluate an application of a mass balance δ13C correction to a taxonomically diverse group of deep-sea fishes by determining the effect of lipid extraction on the stable isotope ratios, examining the quality of the model parameters derived for the mass balance correction, and comparing the correction to published results. We measured the lipid extraction effect on the nitrogen stable isotope ratio (δ15N) and δ13C of muscle tissue from 30 North Atlantic species. Lipid extraction significantly increased tissue δ15N (+0.66%o) and δ13C values, but the treatment effect on δ13C was dependent on C:N, a proxy for lipid content. We compared the lipid-extracted δ13C to the δ13C predicted by the mass balance correction using model variables estimated from either all individuals (pooled) or species-by-species or using published values from other species. The correction using the species-by-species approach performed best; however, all three approaches produced corrected values that were generally within 0.5%o of the measured lipid-free δ13C and that had a small over-all bias (<0.5%o). We conclude that a generalized mass balance correction works well for correcting δ13C in deep-sea fishes, is similar to that developed for other fishes, and recommend caution when applying a generalized correction to fish with high lipid content (C:N >8). © 2010. Source

Zostera japonica is a non-indigenous seagrass that is expanding along the Pacific Coast of North America. The ecophysiology of this seagrass is poorly studied and management of the species is fragmented. This split-plot mesocosm experiment was designed to evaluate the response of Z. japonica to chronic, extreme temperature and salinity stress to facilitate development of models to predict potential Z. japonica colonization. We collected Z. japonica plants from Padilla Bay, Washington and Yaquina Bay and Coos Bay, Oregon and exposed them to a constant water temperature of 15 C or 35 C at three different salinities (5, 20 and 35). After 7 days exposure, shoot survival ranged between 6% and 42%; after 9 days exposure, only a few plants from the Yaquina Bay population survived. At a ambient temperature (15 C), no differences were detected among the three salinity treatments. However, at a temperature of 35 C, the survival of plants grown at a salinity of 5 was significantly lower than at higher salinities (20 and 35). Although the effect of population was weak, the northern population appeared to be more susceptible to the combined effects of heat stress and low salinity than the southern populations. We suggest that Z. japonica will continue to spread southward along the Pacific coast of North America until it reaches systems that regularly exceed the temperature tolerances of this non-indigenous seagrass. © 2013 by Walter de Gruyter Berlin Boston 2013. Source

Aust A.E.,Utah State University | Cook P.M.,US Ecology | Dodson R.F.,Dodson Environmental Consulting Inc.
Journal of Toxicology and Environmental Health - Part B: Critical Reviews | Year: 2011

Much of our understanding regarding the mechanisms for induction of disease following inhalation of respirable elongated mineral particles (REMP) is based on studies involving the biological effects of asbestos fibers. The factors governing the disease potential of an exposure include duration and frequency of exposures; tissue-specific dose over time; impacts on dose persistence from in vivo REMP dissolution, comminution, and clearance; individual susceptibility; and the mineral type and surface characteristics. The mechanisms associated with asbestos particle toxicity involve two facets for each particle's contribution: (1) the physical features of the inhaled REMP, which include width, length, aspect ratio, and effective surface area available for cell contact; and (2) the surface chemical composition and reactivity of the individual fiber/elongated particle. Studies in cell-free systems and with cultured cells suggest an important way in which REMP from asbestos damage cellular molecules or influence cellular processes. This may involve an unfortunate combination of the ability of REMP to chemically generate potentially damaging reactive oxygen species, through surface iron, and the interaction of the unique surfaces with cell membranes to trigger membrane receptor activation. Together these events appear to lead to a cascade of cellular events, including the production of damaging reactive nitrogen species, which may contribute to the disease process. Thus, there is a need to be more cognizant of the potential impact that the total surface area of REMP contributes to the generation of events resulting in pathological changes in biological systems. The information presented has applicability to inhaled dusts, in general, and specifically to respirable elongated mineral particles. Copyright © Taylor & Francis Group, LLC. Source

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