Effects of crowding and wave exposure on penis morphology of the acorn barnacle, Semibalanus balanoides

Wave action and low population density can strongly reduce the ability of sessile acorn barnacles to find mates and copulate. For Semibalanus balanoides, penis morphology varies with wave exposure and with characteristics of the mating neighborhood. Field experiments were conducted at five intertidal sites on Long Island, New York, USA from July to December 2005 to determine how wave exposure and aggregation structure influence the length, diameter, mass, and number of annulated folds of the penis. Sparsely crowded barnacles had more annulations in the penis and are inferred to have greater ability to stretch. At higher wave exposure, the diameter of the penis was greater, but the mass was not. This study identifies density of crowding as the most important cue that barnacles respond to when perceiving their mating group and details how penis morphology varies in response to wave exposure.     

The relationship between blend miscibility and biodegradation of cellulose acetate and poly(ethylene Succmate) blends

The miscibility of cellulose acetate (CA; degree of substitution = 2.5) and poly(ethylene succinate) (PES) has been investigated using a variety of thermal techniques and by solid-state carbon13 NMR spectroscopy. The blends containing greater than ca. 70% CA were found to be miscible. In the case of blends containing less than ca. 70% CA, a combination of thermal and NMR analyses suggests that these blends are not fully miscible on a 2.5- to 5-nm scale. On the scale which can be probed by dynamic mechanical thermal analysis (15 nm), the low-percentage CA blends exhibit “significant local concentration fluctuations≓. Investigation of the biodegradation of the blend components and of the blends revealed that PES degraded relatively rapidly and that CA degraded slowly. The blends degraded at a rate essentially identical to that of CA. Miscibility (75% CA blend) or crystallization of PES (30% CA blend) had no significant effect. These data suggest that a significant mode of degradation ófPES during composting involves chemical hydrolysis of the polymer followed by biological assimilation of monomers. Degradation of the blends is initiated in the amorphous phase. Because CA is a significant component of the amorphous phase, a small amount of CA significantly impacts the biodegradation rates of the blends.     

Pollution and Genetic Structure of North American Populations of the Common Dandelion (Taraxacum Officinale)

Assessing the genetic structure of natural populations differentially impacted by anthropogenic contaminants can be a useful tool for evaluating the population genetic consequences of exposure to pollution. In this study, measures of genetic diversity at variable-number-tandem-repeat loci in six dandelion populations (3 urban and 3 rural) showed patterns that may have been influenced by exposure to environmental contaminants. Mean genetic similarity among individuals within a population was significantly and positively correlated with increasing levels of airborne particulate matter ( 10 m, PM₁₀) and soil concentrations of four metals (Cd, Fe, Ni and Pb). In addition, mean genetic similarity was always significantly higher at the urban sites compared to rural sites. There was a significant negative correlation between the number of genotypes at a site and increasing amounts of PM₁₀, concentrations of five soil metals (Cd, Cu, Fe, Ni and Pb), leaf tissue levels of Fe and a significant positive correlation between the extent of clonality at a site and levels of PM₁₀ and soil concentrations of five metals (Cd, Cu, Fe, Ni and Pb). Although, this study does not directly establish a causal link between the specific contaminants detected at the study sites and differences in genetic diversity, our data are consistent with the hypothesis that pollution-induced selection has contributed in some fashion to the lower genetic diversity found at the urban sites.     

The corporate impact of addressing social issues: a financial case study of a project in Peru

Large, multinational resource development projects can affectmany aspects, including social, economic and ecological realities, in the regions where they operate. Social and environmental issues that are usually ignored in such projectsare increasingly affecting the financial future of multinationalcorporations in negative ways. In this article, we advance the argument that corporations can successfully manage these issuesand that if they choose to view these management efforts as an investment rather than an expense, they may well acquire a competitive advantage over companies that do not. We describe asa case study the Camisea natural gas and condensates developmentproject in Peru, operated by Shell Prospecting and Development Peru (SPDP). Camisea is one of the first projects anywhere inthe world to conduct a detailed analysis of key industry-relatedsocial issues and the processes, required investment and financial impact of managing them. The Camisea example supportsthe argument that addressing social and environmental concerns makes financial sense. In present value terms, the benefit ofmanaging these concerns was expected to surpass the cost investment by approximately US$50 million.     

Mercury photoreduction and photooxidation in lakes: Effects of filtration and dissolved organic carbon concentration

Mercury is a globally distributed, environmental contaminant. Quantifying the retention and loss of mercury is integral for predicting mercury-sensitive ecosystems. There is little information on how dissolved organic carbon(DOC) concentrations and particulates affect mercury photoreaction kinetics in freshwater lakes. To address this knowledge gap,samples were collected from ten lakes in Kejimkujik National Park, Nova Scotia(DOC: 2.6–15.4 mg/L). Filtered(0.2 μm) and unfiltered samples were analysed for gross photoreduction, gross photooxidation, and net reduction rates of mercury using pseudo first-order curves. Unfiltered samples had higher concentrations(p = 0.04) of photoreducible divalent mercury(Hg(II)RED)(mean of 754 ± 253 pg/L) than filtered samples(mean of 482 ± 206 pg/L);however, gross photoreduction and photooxidation rate constants were not significantly different in filtered or unfiltered samples in early summer. DOC was not significantly related to gross photoreduction rate constants in filtered(R~2= 0.43; p = 0.08) and unfiltered(R~2= 0.02; p = 0.71) samples; DOC was also not significantly related to gross photooxidation rate constants in filtered or unfiltered samples. However, DOC was significantly negatively related with Hg(Ⅱ)_(RED) in unfiltered(R2= 0.53; p = 0.04), but not in filtered samples(R~2= 0.04;p = 0.60). These trends indicate that DOC is a factor in determining dissolved mercury photoreduction rates and particles partially control available Hg(Ⅱ)_(RED) in lake water. This research also demonstrates that within these lakes gross photoreduction and photooxidation processes are close to being in balance. Changes to catchment inputs of particulate matter and DOC may alter mercury retention in these lakes and could partially explain observed increases of mercury accumulation in biota.     

Pasture diversification to combat climate change impacts on grazing dairy production

Among livestock systems, grazing is likely to be most impacted by climate change because of its dependency to feed quality and availability. In order to reduce the impact of climate change on grazing livestock systems, adaptation measures should be implemented. The goal of this study is to identify the best pasture composition for a representative grazing dairy farm in Michigan in order to reduce the impacts of climate change on production. In order to achieve the goal of this study, three objectives were sought: (1) identify the best pasture composition, (2) assess economic and resource use impacts of pasture compositions under future climate scenarios, and (3) evaluate the resiliency of pasture compositions. A representative farm was developed based on a livestock practices survey and incorporated into the Integrated Farm System Model (IFSM). For the pasture compositions, four cool-season grass species and two legumes were evaluated under both current and future climate scenarios. The effectiveness of adaptation measures based on economic and resource use criteria was evaluated. Overall, the pasture composition with 50% perennial ryegrass (Lolium multiflorum) and 50% red clover (Trifolium pratense) was identified as the best. In addition, the increase in precipitation and temperature of the most intensive climate scenario could significantly improve farm net return per cow (Bos taurus) and whole farm profit while no significant impact was observed on resource use criteria. Finally, the overall sensitivity assessment showed that the most resilient pasture composition under future climate scenarios was ryegrass with red clover and the least resilient was orchardgrass (Dactylis glomerata) with white clover (Trifolium repens).     

INTEGRATED MANAGEMENT OF IN‐FIELD,EDGE‐OF‐FIELD,AND AFTER‐FIELD BUFFERS1

This review summarizes how conservation benefits are maximized when in‐field and edge‐of‐field buffers are integrated with each other and with other conservation practices such as residue management and grade control structures. Buffers improve both surface and subsurface water quality. Soils under permanent buffer vegetation generally have higher organic carbon concentrations, higher infiltration capacities, and more active microbial populations than similar soils under annual cropping. Sediment can be trapped with rather narrow buffers, but extensive buffers are better at transforming dissolved pollutants. Buffers improve surface runoff water quality most efficiently when flows through them are slow, shallow, and diffuse. Vegetative barriers ‐ narrow strips of dense, erect grass ‐ can slow and spread concentrated runoff. Subsurface processing is best on shallow soils that provide increased hydrologic contact between the ground water plume and buffer vegetation. Vegetated ditches and constructed wetlands can act as “after‐field” conservation buffers, processing pollutants that escape from fields. For these buffers to function efficiently, it is critical that in‐field and edge‐of‐field practices limit peak runoff rate and sediment yield in order to maximize contact time with buffer vegetation and minimize the need for cleanout excavation that destroys vegetation and its processing capacity.     

Controls on leaching of N species in upland moorland catchments

Spatial and temporal changes in mobility of N species have been studied for three UK upland river networks, the Etherow in the South Pennines, the Nether Beck in the Lake District and the Dee in NE Scotland. The catchments are subject to N deposition at 35.1, 22.0 and 10.8–15.6 kg N ha^?1 yr^?1, respectively. The NH⁺ ₄ leaching appears to be predominantly regulated by flow path in more polluted upland catchments. It is greatest where water draining acidified peaty soils contributes more to total discharge. Soluble organic matter may provide the dominant counter anion. In the Etherow and Dee catchments, which are dominated by acid mineral and organic soils, at high discharge NO^? ₃ also appears to be associated with greater input of water from acidified soils. In contrast, for the Nether Beck, higher NO^? ₃ concentrations are associated with tributaries draining soils contributing water with higher alkalinity, suggesting nitrification is important. For the Etherow and Dee, dissolved organic N (DON) appears to originate predominantly from acidified, peaty soils. Spiking experiments with peat soil from the Etherow catchment confirmed the limited capacity of these soils to utilize inorganic N inputs, favouring equilibration with NH⁺ ₄ inputs and leaching losses of inorganic N throughout the year.     

Operating windows to assess whether monitored natural attenuation is a technically feasible remediation option for BTEX‐contaminated groundwater

When used in combination with source management strategies, monitored natural attenuation (MNA) is likely to be a technically feasible remediation option if the contaminant persistence time along the flow path is less than (a) the transport time to the compliance point and (b) the time available for groundwater remediation objectives to be achieved. Biodegradation is often the most significant natural attenuation process for benzene, toluene, ethylbenzene, and xylenes (BTEX) in groundwater. While BTEX transport rates increase with groundwater velocity, examination of data obtained from the published literature for seven sites undergoing MNA revealed significant positive correlations between groundwater velocity and first‐order biodegradation rates for toluene (r = 0.83, P < 0.05), ethylbenzene (r = 0.93, P < 0.01), m‐ and p‐xylene (r = 0.96, P < 0.01), and o‐xylene (r = 0.78, P < 0.05). This is attributed to increased dispersion at higher velocities leading to more mixing of electron acceptors with the contaminant plume. There was no positive correlation between groundwater velocity and first‐order biodegradation rates for benzene due to noise in the relationship caused by variations in (a) the concentrations of electron acceptors in the uncontaminated groundwater and (b) the proportions of benzene in the total BTEX concentration in the source area. A regression model of the relationship between groundwater velocity and the first‐order biodegradation rate can be used to delineate operating windows for groundwater velocity within which the contaminant persistence time is less than the transport and remediation times for a given source concentration, target concentration, distance to compliance point, retardation factor, and remediation time. The operating windows can provide decision makers with a rapid indication of whether MNA is likely to be a technically feasible remediation option at a given site. © 2005 Wiley Periodicals, Inc.