A stage-structured,stochastic population model for the giant kelpMacrocystis pyrifera

We have developed a population model for the giant kelpMacrocystis pyrifera (L.) C. Agardh in southern California, USA. The model includes five life-history stages and takes into account environmental and demographic stochasticity, as well as density-dependent interactions. The density of each stage is predicted on a monthly basis for up to 20 yr, and extinction probability is determined for adult sporophytes. Survival probabilities and rates of reproduction and growth are based on stage-specific responses to environmental conditions (irradiance and temperature), including the occurrence of El Niño events. The model is validated by comparing simulation results to empirical data from natural kelp populations. Results of the model provide insight into patterns observed in natural populations and have applications in resource management.To obtain a copy of the model, please contact Applied Biomathematics, 100 North Country Road, Setauket, New York 11733, USA     

Toward a scientifically rigorous basis for developing mapped ecological regions

Despite the wide use of ecological regions in conservation and resource-management evaluations and assessments, a commonly accepted theoretical basis for ecological regionalization does not exist. This fact, along with the paucity of focus on ecological regionalization by professional associations, journals, and faculties, has inhibited the advancement of a broadly acceptable scientific basis for the development, use, and verification of ecological regions. The central contention of this article is that ecological regions should improve our understanding of geographic and ecological phenomena associated with biotic and abiotic processes occurring in individual regions and also of processes characteristic of interactions and dependencies among multiple regions. Research associated with any ecoregional framework should facilitate development of hypotheses about ecological phenomena and dominant landscape elements associated with these phenomena, how these phenomena are structured in space, and how they function in a hierarchy. Success in addressing the research recommendations outlined in this article cannot occur within an ad hoc, largely uncoordinated research environment. Successful implementation of this plan will require activities--coordination, funding, and education--that are both scientific and administrative in nature. Perhaps the most important element of an infrastructure to support the scientific work of ecoregionalization would be a national or international authority similar to the Water and Science Technology Board of the National Academy of Sciences.     

Cost-benefit analysis as a tool for decision making in environmental projects

BACKGROUND, AIM AND SCOPE: The Damage-Function method is an efficient tool recently used in decision-making processes concerning environmental management. It is based on finding the relation between the origin of an environmental charge, and its impact on human health and the environment. The aim of the present investigation was to assess the positive impacts, also called benefits, of changes in environmental quality, and the economic viability of an industrial project on reduction of PCDD/F emissions. It has been developed with monetary criteria of two worldwide ambits: USA and European-Union countries. METHODS: The current study is a continuation of a previous investigation in which Substance Flow Analysis and Control Analysis Techniques were used to identify and to analyze all main flow values of PCDD/Fs inside the system of Tarragona Province (Spain). In the present study, Cost-Benefit Analysis (CBA) has been employed. The benefits derived from a minimization in the incidence of cancer due to a reduction in the emission of PCDD/Fs have been evaluated considering the value of a statistically saved life (VSL). Statistical analysis about uncertainty has also been incorporated. Here, the Monte Carlo simulation technique has been used. RESULTS: It is shown that CBS results depend firstly on the kind of VSL used. In fact, the differences between the decisions as a result of applying monetary criteria in USA and EU can be explained by differences between VSL values. CONCLUSION AND RECOMMENDATION: It is concluded that, for prices estimated in Euros, the emission cleaning project in the industrial plant is not feasible under any circumstance. However, although CBA seems to be a good analytical method, the final decision corresponds to the managers, who must weigh up not only the monetary criteria, but factors such as social questions.     

Soil resource supply influences faunal size–specific distributions in natural food webs

The large range of body-mass values of soil organisms provides a tool to assess the ecological organization of soil communities. The goal of this paper is to identify graphical and quantitative indicators of soil community composition and ecosystem functioning, and to illustrate their application to real soil food webs. The relationships between log-transformed mass and abundance of soil organisms in 20 Dutch meadows and heathlands were investigated. Using principles of allometry, maximal use can be made of ecological theory to build and explain food webs. The aggregate contribution of small invertebrates such as nematodes to the entire community is high under low soil phosphorus content and causes shifts in the mass–abundance relationships and in the trophic structures. We show for the first time that the average of the trophic link lengths is a reliable predictor for assessing soil fertility responses. Ordered trophic link pairs suggest a self-organizing structure of food webs according to resource availability and can predict environmental shifts in ecologically meaningful ways. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to all users.     

Experimental evaluation of the usefulness of feathers as a non-destructive biomonitor for polychlorinated biphenyls (PCBs) using silastic implants as a novel method of exposure

Risk assessment of pollutants requires both monitoring studies in the field and experimental exposure studies. In this study, we evaluated silastic implants as an alternative method of exposure for use in toxicological studies and at the same time evaluated the usefulness of feathers as a non-destructive biomonitor for PCBs. European starlings (Sturnus vulgaris) were exposed to different doses (including a control group) of environmentally relevant concentrations of PCB 153 during a 15-week period using silastic implants with both ends/only one end sealed. After implantation, there was a rapid and significant increase in PCB 153 blood concentration in the exposed groups. The significant differences in blood concentrations among the treatment groups show that silastic implants are useful as a method of exposure. Moreover, the ratio between the tissue concentrations of two treatment groups reflected the difference in implantation doses between these groups. There was also a clear difference in tissue concentrations among the treatment groups, although we could not test this statistically due to the small sample sizes. The slow release kinetics for a prolonged period and the relatively stable blood concentrations during the 15-week period render silastic tubes very interesting to study the effects of chronic exposure to pollutants. Our results also revealed that sealing both ends of the implant instead of only one did not significantly affect the exposure. There were strong, significant positive correlations between the blood and the tissues, which confirm the use of blood to monitor PCBs. To evaluate the usefulness of feathers as a non-destructive biomonitor for PCBs, we plucked the original and newly grown wing and tail feathers. We observed strong, significant positive correlations between the concentrations in the newly grown feathers and concentrations in the muscle, liver, brain and blood. PCB 153 concentrations in the newly grown feathers differed among the treatment groups. To our knowledge, our results provide the first experimental evidence that feathers are useful as a non-destructive biomonitoring tool for PCBs.     

Synergetic integration of laccase and versatile peroxidase with magnetic silica microspheres towards remediation of biorefinery wastewater

In this study, a tailor-made biocatalyst consisting of a co-immobilized lignolytic enzyme cascade on multi-functionalized magnetic silica microspheres (MSMS) was developed. Physical adsorption was the most promising strategy for the synthesis of individual immobilized laccase (IL), immobilized versatile peroxidase (IP), as well as co-immobilized laccase (Lac) and versatile peroxidase (VP) with an enzyme activity recovery of about 79, 93, 27, and 27.5%, respectively. Similarly, the biocatalytic load of 116, 183, 23.6, and 31 U/g was obtained for IL, IP, and co-immobilized Lac and VP, respectively. The co-immobilized enzyme system exhibited better pH stability than the free and individual immobilized system by retaining more than 100% residual activity at pH 7.0 after a 150-h incubation; whereas, the thermal stability and kinetics of the co-immobilized biocatalyst were not much improved. IL and IP could be recycled for 10 cycles after which they retained 31 and 44% of their initial activities. Co-immobilized Lac and VP were reused for ten consecutive cycles at the end of which Lac activity was depleted, and 37% of VP activity was left. Free enzymes, IL, IP, co-immobilized Lac, and VP were applied to biorefinery wastewater (BRW) in a batch study to investigate the transformation of phenolic contaminants over a period of 5 days. The major classes of phenolic constituents in terms of their order of removal in a Lac-VP system was phenol >2-chlorophenol > trichlorophenol > dichlorophenol > cresols > dimethylphenol >2 methyl- 4, 6-dinitrophenol > 4-nitrophenol > tetrachlorophenols > pentachlorophenol. The free enzymes and individually immobilized enzymes resulted in 80% dephenolization in 5 days. By contrast, the co-immobilized biocatalyst provided rapid dephenolization yielding the same 80% removal within 24 h and 96% removal of phenols in 60 h after which the system stabilized, which is the major advantage of the co-immobilized biocatalyst.

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Dynamic exchange of gaseous elemental mercury during polar night and day

From February 29 until June 15 2008 gaseous elemental mercury (GEM) fluxes above a snow covered surface was measured in Ny-Ålesund, Svalbard using a GEM flux gradient method. A clear seasonal pattern in the meteorological variables associated with the GEM flux was observed. For the first time in Ny-Ålesund a net deposition of GEM was recorded during polar night, despite the lack of Atmospheric Mercury Depletion Events (AMDE). 7500 ng m⁻² GEM was emitted from the surface snow to the air during the entire study. The depositions of GEM and reactive gaseous mercury (RGM) were calculated to be 1500 and 1000 ng m⁻², respectively, during the same time period. The GEM fluxes reported in this study were found to be comparable to GEM fluxes measured at other Arctic locations (i.e. Alert and Barrow), suggesting that GEM acts in a similar way throughout the Arctic. An assessment of the GEM flux gradient method used discovered a non-linear GEM concentration profile. The nonlinearity was explained by a non-stationary turbulence regime. The GEM flux calculated was not found to be representative for the entire surface boundary layer.