Evaluation of Methods for Delineating Riparian Zones in a Semi‐Arid Montane Watershed

Riparian zones in semi‐arid, mountainous regions provide a disproportionate amount of the available wildlife habitat and ecosystem services. Despite their importance, there is little guidance on the best way to map riparian zones for broad spatial extents (e.g., large watersheds) when detailed maps from field data or high‐resolution imagery and terrain data are not available. Using well‐established accuracy metrics (e.g., kappa, precision, computational complexity), we evaluated eight methods commonly used to map riparian zones. Focusing on a semi‐arid, mountainous watershed, we found that the most accurate and robust method for mapping riparian zones combines data on upstream drainage area and valley topography. That method performed best regardless of stream order, and was most effective when implemented with fine resolution topographic and stream line data. Other commonly used methods to model riparian zones, such as those based on fixed‐width buffers, yielded inaccurate results. We recommend that until very‐high resolution (<1 m) elevation data are available at broad extents, models of riparian zones for semi‐arid mountainous regions should incorporate drainage area, valley topography, and quantify uncertainty.     

Sustaining food self-sufficiency of a nation: The case of Sri Lankan rice production and related water and fertilizer demands

Rising human demand and climatic variability have created greater uncertainty regarding global food trade and its effects on the food security of nations. To reduce reliance on imported food, many countries have focused on increasing their domestic food production in recent years. With clear goals for the complete self-sufficiency of rice production, Sri Lanka provides an ideal case study for examining the projected growth in domestic rice supply, how this compares to future national demand, and what the associated impacts from water and fertilizer demands may be. Using national rice statistics and estimates of intensification, this study finds that improvements in rice production can feed 25.3 million Sri Lankans (compared to a projected population of 23.8 million people) by 2050. However, to achieve this growth, consumptive water use and nitrogen fertilizer application may need to increase by as much as 69 and 23 %, respectively. This assessment demonstrates that targets for maintaining self-sufficiency should better incorporate avenues for improving resource use efficiency.

Electronic supplementary material

The online version of this article (doi:10.1007/s13280-015-0720-2) contains supplementary material, which is available to authorized users.     

Buy Me a River: Purchasing Water Rights to Restore River Flows in the Western USA

In recent decades, public and private environmental entities have been purchasing or leasing water rights across the Western United States (U.S.) in efforts to restore river flows and aquatic ecosystems. The need to pay for flow restoration arises from the fact that state governments did not begin to reserve water for instream purposes until the 1970s, long after water rights had become over‐appropriated and flows were substantially depleted in most rivers. As a consequence, flow depletion has become the leading cause of fish endangerment in the U.S., including the imperilment of two‐thirds of all native fish species in the Colorado River system. This paper takes stock of the progress made in buying water for the environment, specifically by reviewing and analyzing more than 50 transactions executed by public and private entities and the sources of funding underpinning these transactions. We conclude that nongovernmental actors — such as environmental organizations and state water trusts — are integral to regional efforts to restore river flows; these nongovernmental actors executed more than two‐thirds of the transactions we documented. However, we also conclude that the long‐term success of these nongovernmental actors depends upon the availability of sustained public funding that enables them to build capacity and engage in the large number of transactions needed to restore flows across each state.     

Long-term atmospheric deposition of current-use and banned pesticides in Atlantic Canada; 1980-2000

The occurrence of current-use and banned pesticides is reported in wet-precipitation collected from four sites across Atlantic Canada during the period 1980-2000. The most frequently detected compounds were alpha-HCH, gamma-HCH (lindane), chlorothalonil, pentachlorophenol, atrazine, and endosulfan. Median site concentrations varied between not-detected and 10.2 ng l(-1). Deposition of HCHs (hexachlorocyclohexane), chlorothalonil, and endosulfan at Kejimkujik (Keji) and Jackson, Nova Scotia, were generally similar. Significant spatial differences (p<0.05), however, were found for the HCH isomers and endosulfan at Keji and Gros Morne (Newfoundland and Labrador), areas geographically separated by the northern Gulf of St. Lawrence. Long-term deposition of alpha-HCH decreased (p<0.05) at both Keji (1980-2000) and Gros Morne (1994-2000), with half-lives of 5.9 and 4.5 y, respectively. A decreasing trend was also found for pentachlorophenol with a half-life of 4.9 y at Jackson. Significant negative trends (p<0.05) were observed for alpha-/gamma-HCH ratios during the study at Keji and Jackson, possibly reflecting changes in production and use patterns of technical HCH and lindane on a continental and perhaps hemispheric scale. Seasonal trends for alpha-HCH and gamma-HCH were found to vary over the 20-y study period at Keji, however, spatial trends were generally similar between sites. Seasonal trends were observed with peak deposition generally occurring during the growing period (spring-summer) for the HCHs, chlorothalonil, endosulfan, and atrazine. Bimodal seasonal trends were also observed for these compounds with the exception of endosulfan.     

Bioaccumulation of trace elements in pelagic fish from the Western Indian Ocean

Trace elements were analyzed in fish of commercial interest to determine their importance in marine systems of the Western Indian Ocean and their bioaccumulation patterns. The results are equivalent or lower than levels reported in ichthyofauna worldwide. Certain values of muscular Cd, Hg, Pb and Zn were, however, above thresholds for human consumption. Levels varied among tissues, species and fish length, but were seldom influenced by the nutritional condition of the fish, its gender and its reproductive status. Correlations between hepatic Hg and Se levels in Swordfish (r2=0.747) and Yellowfin Tunas (r2=0.226), and among metallothionein linking metals imply the existence of detoxification processes in these species. Level differences between fish from the Mozambique Channel and Reunion Island reflect differences of diets rather than differences of elemental availability in both environments.     

Influence of the insecticides acetamiprid and carbofuran on arylamidase and myrosinase activities in the tropical black and red clay soils

The objective of this study was to determine the effects of two insecticides, namely, acetamiprid and carbofuran on the enzymatic activities of arylamidase (as glucose formed from sinigrin) and myrosinase (as β-naphthylamine formed from l-leucine β-naphthylamide) in the black and red clay soils collected from a fallow groundnut (Arachis hypogaea L.) fields in the Anantapur District, Andhra Pradesh, India. The study was realized within the framework of the laboratory experiments in which the acetamiprid and carbofuran were applied to the soils at different doses (1.0, 2.5, 5.0, 7.5, 10.0 kg ha^?1). Initially, the physicochechemical properties of the soil samples were analyzed. After 10 days of pesticide application, the soil samples were analyzed for the enzyme activities. Acetamiprid and carbofuran stimulated the arylamidase and myrosinase activities at lower concentrations after 10 days incubation. Striking stimulation in soil enzyme activities was noticed at 2.5 kg ha^?1, persists for 20 days in both the soils. Overall, higher concentrations (5.0–10.0 kg ha^?1) of acetamiprid and carbofuran were toxic or innocuous to the arylamidase and myrosinase activities. Nevertheless, the outcomes of the present study clearly indicate that the use of these insecticides (at field application rates) in the groundnut fields (black and red clay soils) stimulated the enzyme (arylamidase and myrosinase) activities.     

H NMR-based metabolomics investigation of Daphnia magna responses to sub-lethal exposure to arsenic,copper and lithium

Metal and metalloid contamination constitutes a major concern in aquatic ecosystems. Thus it is important to find rapid and reliable indicators of metal stress to aquatic organisms. In this study, we tested the use of ¹H nuclear magnetic resonance (NMR) – based metabolomics to examine the response of Daphnia magna neonates after a 48 h exposure to sub-lethal concentrations of arsenic (49 μg L⁻¹), copper (12.4 μg L⁻¹) or lithium (1150 μg L⁻¹). Metabolomic responses for all conditions were compared to a control using principal component analysis (PCA) and metabolites that contributed to the variation between the exposures and the control condition were identified and quantified. The PCA showed that copper and lithium exposures result in statistically significant metabolite variations from the control. Contributing to this variation was a number of amino acids such as: phenylalanine, leucine, lysine, glutamine, glycine, alanine, methionine and glutamine as well as the nucleobase uracil and osmolyte glycerophosphocholine. The similarities in metabolome changes suggest that lithium has an analogous mode of toxicity to that of copper, and may be impairing energy production and ionoregulation. The PCA also showed that arsenic exposure resulted in a metabolic shift in comparison to the control population but this change was not statistically significant. However, significant changes in specific metabolites such as alanine and lysine were observed, suggesting that energy metabolism is indeed disrupted. This research demonstrates that ¹H NMR-based metabolomics is a viable platform for discerning metabolomic changes and mode of toxicity of D. magna in response to metal stressors in the environment.     

Vulnerability of coastal livelihoods to shrimp farming: Insights from Mozambique

Millions of people around the world depend on shrimp aquaculture for their livelihoods. Yet, the phenomenal growth of shrimp farming has often given rise to considerable environmental and social damage. This article examines the impacts of commercial, export-oriented shrimp aquaculture on local livelihood vulnerability by comparing the exposure, sensitivity, and adaptive capacity of shrimp farm employees with non-farm employees in rural Mozambique. Exposure to stressors was similar between the two groups. Shrimp farm employees had higher assets and higher adaptive capacity than non-farm employees. However, because their income is heavily dependent on a single commodity, shrimp farm employees were highly susceptible to the boom crop nature of intensive shrimp farming. The implications for aquaculture policy and vulnerability research are discussed. The article argues that coastal vulnerability is dynamic, variable, and influenced by multiple processes operating at multiple scales.     

Characteristics of rear-end crashes involving passenger vehicles with automatic emergency braking

Abstract

Objectives: Automatic emergency braking (AEB) is a proven effective countermeasure for preventing front-to-rear crashes, but it has not yet fully lived up to its estimated potential. This study identified the types of rear-end crashes in which striking vehicles with AEB are overrepresented to determine whether the system is more effective in some situations than in others, so that additional opportunities for increasing AEB effectiveness might be explored.

Methods: Rear-end crash involvements were extracted from 23?U.S. states during 2009–2016 for striking passenger vehicles with and without AEB among models where the system was optional. Logistic regression was used to examine the odds that rear-end crashes with various characteristics involved a striking vehicle with AEB, controlling for driver and vehicle features.

Results: Striking vehicles were significantly more likely to have AEB in crashes where the striking vehicle was turning relative to when it was moving straight (odds ratio [OR]?=?2.35; 95% confidence interval [CI], 1.76, 3.13); when the struck vehicle was turning (OR = 1.66; 95% CI, 1.25, 2.21) or changing lanes (OR = 2.05; 95% CI, 1.13, 3.72) relative to when it was slowing or stopped; when the struck vehicle was not a passenger vehicle or was a special use vehicle relative to a car (OR = 1.61; 95% CI, 1.01, 2.55); on snowy or icy roads relative to dry roads (OR = 1.83; 95% CI, 1.16, 2.86); or on roads with speed limits of 70+ mph relative to those with 40 to 45?mph speed limits (OR = 1.49; 95% CI, 1.10, 2.03). Overall, 25.3% of crashes where the striking vehicle had AEB had at least one of these overrepresented characteristics, compared with 15.9% of strikes by vehicles without AEB.

Conclusions: The typical rear-end crash occurs when 2 passenger vehicles are proceeding in line, on a dry road, and at lower speeds. Because atypical crash circumstances are overrepresented among rear-end crashes by striking vehicles with AEB, it appears that the system is doing a better job of preventing the more typical crash scenario. Consumer information testing programs of AEB use a test configuration that models the typical rear-end crash type. Testing programs promoting good AEB performance in crash circumstances where vehicles with AEB are overrepresented could guide future development of AEB systems that perform well in these additional rear-end collision scenarios.