Functional and community-level soil microbial responses to zinc addition may depend on test system biocomplexity

The effect of zinc on soil nitrification and composition of the microbial community in soil was investigated using a full factorial experiment with five zinc concentrations and four levels of biological complexity (microbes only, microbes and earthworms (Eisenia fetida), microbes and Italian ryegrass (Lolium multiflorum var. Macho), and microbes, ryegrass and earthworms). After 6 weeks of exposure, the activity of soil nitrifying bacteria was measured and the microbial community structure was characterized by phospholipid fatty acid (PLFA) analysis. Soil nitrification and several PLFA markers were significantly influenced by either zinc addition and/or the presence of earthworms or ryegrass, and one of the most pronounced changes was the increase of fungi and decrease of bacteria with increasing concentrations of zinc. Of particular interest, however, was the potential interaction between the presence of plants and/or earthworms and the effect of zinc, which the factorial study design allowed us to explore. Such an effect was observed in two cases: Earthworms reduced the positive effect of zinc on the fungal biomass (ANOVA, p=0.03), and the effect of earthworms on the soil nitrification activity depended on zinc concentration (ANOVA, p<0.05). The effect of earthworm presence was not very large, but it does show that multispecies tests might give information about metal toxicity or bioavailability that cannot be predicted from single-species tests.     

Effect of increasing salinity on the acute toxicity of a commercial endosulfan formulation to the bdelloid rotifer Philodina acuticornis odiosa

Pesticides, such as endosulfan, can enter surface waters such as lakes and rivers, potentially posing an ecological risk. Rotifers are a dominant zooplankton species in many inland freshwater lakes in Australia; such lakes can also experience increased salinities. Acute toxicity tests (24?h) were conducted to determine the toxicity of a commercial formaulation of endosulfan to the freshwater rotifer Philodina sp. and to investigate the influence of increasing salinity on endosulfan toxicity. Rotifers were found to be relatively tolerant to endosulfan with an EC50 of 1.75?mg?L^?1 (a.i.), with results also suggesting that there are no interactive effects of salinity on endosulfan toxicity.     

An evaluation of three alternative formats for probation violator hearings

The purpose of the project was to improve the traffic safety impact and net benefits of the negligent operator probation violator hearing conducted by the California Department of Motor Vehicles. The three hearing formats evaluated varied in several aspects including use of license restrictions (rather than suspension or revocation), hearing duration, use of negotiation and contingency contracting, and use of caseload assignment. The two experimental programs differed primarily in the timing of restriction removal, one employing a single fixed-interval restriction and the other a sequential multiphase restriction strategy. The licensing actions used at the project entry hearing were more liberal than anticipated in all hearing formats. The standard hearing format was superior to the others both in overall traffic safety impact and net benefits. The differences between hearing formats in fatal and injury accidents and in countable convictions tended to favor the standard format. Implementation of either alternative format would probably (p≈.80) result in a decline in program net benefits. The application of a behavior modification paradigm was not successful in the project reported here.     

Integrated hydro- and wind power generation: a game changer towards environmental flow in the Sub-middle and Lower São Francisco River Basin?

Many renewable resources for the generation of electricity, such as hydropower and wind power, are dependent on climatic factors. Reservoirs have been created to overcome the stochastic nature of river flows and to make water supply more reliable. However, reservoirs are affecting the ecological status of river ecosystems, e.g., by modifying the flow regime, triggering discussions regarding the discharge of reservoirs. In Brazil’s northeast region, the installed capacity for wind power generation has increased substantially in recent years. Setting up a modeling system for simulating wind power and hydropower generation in this study, it is analyzed whether wind power generation, peaking in the dry season, can help to achieve a more environmentally oriented flow regime in the Sub-middle and Lower São Francisco River Basin. Simulated higher discharges from reservoirs during the rainy season and lower discharges during the dry season, representing a more natural flow regime, will reduce hydropower generation in the dry season. Under recent conditions, the resulting gap in electricity generation can only be partially covered by wind power. A large share needs to be generated by thermal power plants or be imported from other regions in Brazil. The planned future increase in installed wind power capacity can change this picture; the demand for electricity generated by thermal power plants and imported will decrease. Adopting an integrated approach for hydropower and wind power generation, the flow regime in the Sub-middle and Lower São Francisco River Basin can be modified to improve the ecological status of the river system.     

Particulate Loads Caused by Wind Erosion in the Great Plains

Dust is always present in the air, but when wind erosion occurs, both the flux of soil particles into the air and the particulate concentration increase by orders of magnitude. Previous research¹ indicated that median duststorm concentration was 4.85 mg/m³ and median annual hours with duststorms was 45 in the Great Plains during the 1950’s. Of the total soil moved by wind, the suspended particulates probably represent 10% or less.²-³     

Collaborative Modeling for Decision Support in Water Resources: Principles and Best Practices

Collaborative Modeling for Decision Support integrates collaborative modeling with participatory processes to inform natural resources decisions. Practitioners and advocates claim that the approach will lead to better water management, balancing interests more effectively and reducing the likelihood of costly legal delays. These claims are easy to make, but the benefits will only be realized if the process is conducted effectively. To provide guidance for how to conduct an effective collaborative modeling process, a task committee cosponsored by the Environmental Water Resources Institute (EWRI) of the American Society of Civil Engineers and by the U.S. Army Corps of Engineers' Institute for Water Resources developed a set of Principles and Best Practices for anyone who might convene or conduct collaborative modeling processes. The guidance is intended for both conflict resolution professionals and modelers, and our goal is to integrate these two fields in a way that will improve water resources planning and decision making. Here, the set of eight principles is presented along with a selection of associated best practices, illustrated by two different case examples. The complete document is available at: http://www.computeraideddisputeresolution.us/bestpractices/ .     

Spatially differentiated management-revised discharge scenarios for an integrated analysis of multi-realisation climate and land use scenarios for the Elbe River basin

A spatially differentiated, management-revised projection of natural water availability up to 2053 was requested for a basin-wide scenario study about the impact of global change in the Elbe River basin. Detailed discharge and weather information of the recent years 1951–2003 were available for model calibration and validation. However, the straightforward “classic” approach of calibrating a hydrological model on observed data and running it with a climate scenario could not be taken, because most observed river runoffs in Central Europe are modified by human management. This paper reports how the problem was addressed and how a major projection bias could be avoided. The eco-hydrological model SWIM was set up to simulate the discharge dynamics on a daily time step. The simulation area of 134,890?km2 was divided into 2,278 sub-basins that were subdivided into more than 47,500 homogeneous landscape units (hydrotopes). For each hydrotope, plant growth and water fluxes were simulated while river routing calculation was based on the sub-basin structure. The groundwater module of SWIM had to be extended for accurate modelling of low flow periods. After basin-scale model calibration and revisions for known effects of lignite mining and water management, evapotranspiration and groundwater dynamics were adjusted individually for more than 100 sub-areas largely covering the entire area. A quasi-natural hydrograph was finally derived for each sub-area taking into account management data for the years 2002 (extremely wet) and 2003 (extremely dry). The validated model was used to access the effect of two climate change scenarios consisting of 100 realisations each and resembling temperature increases of 2 and 3?K, respectively. Additionally, four different land use scenarios were considered. In all scenario projections, discharge decreases strongly: The observed average discharge rate in the reference period 1961–1990 is 171?mm/a, and the scenario projections for the middle of the twenty-first century give 91–110?mm/a, mainly depending on the climate scenario. The area-averaged evapotranspiration increases only marginally within the scenario period, e.g., from about 570 to about 580?mm/a for the temperature increase of 2?K, while potential evapotranspiration increases considerably from about 780 to more than 900?mm/a. Both discharge and evapotranspiration changes vary strongly within the basin, correlating with elevation. The runoff coefficient that globally decreases from 0.244 to 0.160 in the 2?K scenario is locally governed primarily by land use; 68% of the variance of the decreases can be attributed to this factor.     

Salps in the Lazarev Sea,Southern Ocean: I. Feeding dynamics

Feeding dynamics of the Antarctic salps Ihlea racovitzai and Salpa thompsoni were studied in the Lazarev Sea in fall 2004, summer 2005–2006 and winter 2006. Pigment concentrations in the guts of both species were positively correlated with ambient surface chlorophyll a (chl a). No evidence was found for salp clogging even at dense surface concentrations of up to 7 μg chl a L⁻¹. However, gut pigment concentrations had a lower range than ambient pigment concentrations, suggesting that salps increased retention times of ingested material in low-food environments. For medium-sized I. racovitzai and S. thompsoni, estimated individual daily rations reached 7–10 and >100% of body carbon in winter and summer, respectively. Daily respiratory needs of I. racovitzai and S. thompsoni accounted for 28 and 22% of daily carbon assimilation based on pigment ingestion rates in winter, and for 2 and 1% in summer, respectively. The grazing impact of the salp populations on the phytoplankton standing stock was negligible during all seasons due to generally low salp densities. Fatty acid trophic biomarkers in the salps suggest high year-round contributions of flagellates and modest contributions of diatoms to the salp’s diet. These markers showed low seasonal variability for I. racovitzai. The more pronounced seasonality of trophic markers in S. thompsoni were likely related to their generally deeper residence depth in winter linked to a seasonal alternation of sexual and asexual generations.     

Age-related multi-year associations in female humpback whales (Megaptera novaeangliae)

Analyses of social structures in baleen whales are rare, and so far, they are thought to consist of mostly short and unstable associations. We investigated the association patterns of individual humpback whales from a summer feeding aggregation in the Gulf of St. Lawrence from 1997 to 2005. Photo-identified animals were sexed using genetic methods and were grouped into five categories: juvenile males/females, mature males and lactating/non-lactating females. We calculated half-weight association indices within and between the groups and found that 45% of the observation showed single animals and another 45% small groups (two to three) consisting mainly of mature animals besides lactating females. Using permutation tests, we found evidence for long-term associations between mature males and non-lactating females as well as among non-lactating females. Standardised lagged association rates revealed that these male–female groups disassociated quickly over about 2 weeks, whereas associations increased again towards the beginning of the breeding season. Non-lactating females of similar age engaged in multi-seasonal stable pairs for up to six consecutive feeding seasons; no mature male–female association was observed in consecutive years. The females with the most stable and long-term associations also had the highest reproductive output. While the risk of predation could not explain these long-term bonds, feeding cooperation seemed the most plausible explanation for group forming behaviour during the summer months.     

Comparative toxicity of acrylic acid to marine and freshwater microalgae and the significance for environmental effects assessments.

In this study, we compared the sensitivity of freshwater and marine organisms to two structurally similar substances, acrylic acid and methacrylic acid. Reported acute toxicity data (L(E)C50-values) for freshwater organisms range from 0.1 to 222 mg/l and 85 to >130 mg/l for acrylic acid and methacrylic acid, respectively. The large variation in toxicity data for acrylic acid is due to a specific toxicity to certain species of freshwater microalgae, with algae EC50-values being two to three orders of magnitude lower than L(E)C50-values reported for fish and invertebrates. To evaluate the sensitivity of marine organisms, ecotoxicity data was generated for ten species of microalgae, one invertebrate species and one fish species. For methacrylic acid, we found a marine acute toxicity that ranged from 110 to >1260 mg/l, which is comparable to reported data on freshwater organisms. In strong contrast, the resulting L(E)C50-values for acrylic acid ranged from 50 to >1000 mg/l, and there was no specific sensitivity of marine algae when compared to marine invertebrates and fish. For acrylic acid, therefore, use of the available freshwater toxicity data for an effects assessment for the marine environment is likely to overestimate the hazard and risk from this substance. Overall, the results of the study suggest that ecotoxicity data generated on freshwater species may not always be appropriate for the effects assessments of organic chemicals in the marine environment, thus emphasising the importance of using ecologically relevant data to assess environmental risk.