Effects of seascape connectivity on reserve performance along exposed coastlines

Seascape connectivity (landscape connectivity in the sea) can modify reserve performance in low-energy marine ecosystems (e.g., coral reefs, mangroves, and seagrass), but it is not clear whether similar spatial linkages also shape reserve effectiveness on high-energy, exposed coastlines. We used the surf zones of ocean beaches in eastern Australia as a model system to test how seascape connectivity and reserve attributes combine to shape conservation outcomes. Spatial patterns in fish assemblages were measured using baited remote underwater video stations in 12 marine reserves and 15 fished beaches across 2000 km of exposed coastline. Reserve performance was shaped by both the characteristics of reserves and the spatial properties of the coastal seascapes in which reserves were embedded. Number of fish species and abundance of harvested fishes were highest in surf-zone reserves that encompassed >1.5 km of the surf zone; were located < 100 m to rocky headlands; and included pocket beaches in a heterogeneous seascape. Conservation outcomes for exposed coastlines may, therefore, be enhanced by prioritizing sufficiently large areas of seascapes that are strongly linked to abutting complementary habitats. Our findings have broader implications for coastal conservation planning. Empirical data to describe how the ecological features of high-energy shorelines influence conservation outcomes are lacking, and we suggest that seascape connectivity may have similar ecological effects on reserve performance on both sheltered and exposed coastlines.     

Assemblage shift following population collapse of a non-indigenous bivalve in an urban lagoon

The quahog Mercenaria mercenaria has been introduced repeatedly to the Pacific coast of North America, but only one population is known to have become established. In the 1970s, the population of M. mercenaria at Colorado Lagoon, in Los Angeles County, California (33^o46′16″N, 118^o08′05″W), was estimated at more than 300,000 individuals. To determine the current status of this non-indigenous species (NIS), in 2009, we sampled 57 intertidal and 20 shallow subtidal plots, identifying and quantifying collected bivalves. No quahogs were found among the 2,490 living bivalves in our plots, though two were found intertidally outside of our plots. The M. mercenaria population has thus collapsed since 1980, but the native community has not recovered. Six of the fourteen living bivalve species we encountered were NIS; three are new records for the location, including the clam Venerupis philippinarum, which made up 87.6% of collected individuals. Though M. mercenaria is likely on its way to extinction on the US Pacific coast, the bivalve assemblage at this location remains heavily dominated by NIS.     

Marginal costs of abating greenhouse gases in the global ruminant livestock sector

Livestock [inclusive of ruminant species, namely cattle (Bos Taurus and Bos indicus), sheep (Ovis aries), goats (Capra hircus), and buffaloes (Bubalus bubalis), and non-ruminant species, namely pigs (Sus scrofa domesticus) and chickens (Gallus domesticus)] are both affected by climate change and contribute as much as 14.5 % of global anthropogenic greenhouse gas (GHG) emissions, most of which is from ruminant animals (Gerber et al. 2013). This study aims to estimate the marginal costs of reducing GHG emissions for a selection of practices in the ruminant livestock sector (inclusive of the major ruminant species—cattle, sheep, and goats) globally. It advances on previous assessments by calculating marginal costs rather than commonly reported average costs of abatement and can thus provide insights about abatement responses at different carbon prices. We selected the most promising abatement options based on their effectiveness and feasibility. Improved grazing management and legume sowing are the main practices assessed in grazing systems. The urea (CO(NH₂)₂) treatment of crop straws is the main practice applied in mixed crop–livestock systems, while the feeding of dietary lipids and nitrates are confined to more intensive production systems. These practices were estimated to reduce emissions by up to 379 metric megatons of carbon dioxide (CO₂) equivalent emissions per year (MtCO₂-eq yr^?1). Two thirds of this reduction was estimated to be possible at a carbon price of 20 US dollars per metric ton of CO₂ equivalent emissions ($20 tCO₂-eq^?1). This study also provides strategic guidance as to where abatement efforts could be most cost effectively targeted. For example, improved grazing management was particularly cost effective in Latin America and Sub-Saharan Africa, while legume sowing appeared to work best in Western Europe and Latin America.     

SOURCES OF VARIABILITY IN CONDUCTING PEBBLE COUNTS: THEIR POTENTIAL INFLUENCE ON THE RESULTS OF STREAM MONITORING PROGRAMS1

Pebble counts have been used for a variety of monitoring projects and are an important component of stream evaluation efforts throughout the United States. The utility of pebble counts as a monitoring tool is, however, based on the monitoring objectives and the assumption that data are collected with sufficient precision to meet those objectives. Depending upon the objective, sources of variability that can limit the precision of pebble count data include substrate heterogeneity at a site, differences in substrate among sample locations within a stream reach, substrate variability among streams, differences in when the substrate sample is collected, differences in how and where technicians pick up substrate particles, and how consistently technicians measure the intermediate axis of a selected particle. This study found that each of these sources of variability is of sufficient magnitude to affect results of monitoring projects. Therefore, actions such as observer training, increasing the number of pebbles measured, evaluating several riffles within a reach, evaluating permanent sites, and narrowing the time window during which pebble counts are conducted should be considered in order to minimize variability. The failure to account for sources of variability associated with pebble counts within the study design may result in failing to meet monitoring objectives.     

USING INFILTRATION ENHANCEMENT AND SOIL WATER MANAGEMENT TO REDUCE DIAZINON IN RUNOFF1

ABSTRACT: Pesticide runoff from dormant sprayed orchards is a major water quality problem in California's Central Valley. During the past several years, diazinon levels in the Sacramento and San Joaquin Rivers have exceeded water quality criteria for aquatic organisms. Orchard water management, via post‐application irrigation, and infiltration enhancement, through the use of a vegetative ground cover, are management practices that are believed to reduce pesticide loading to surface waters. Field experiments were conducted in Davis, California, to measure the effectiveness of these management practices in reducing the toxicity of storm water runoff. Treatments using a vegetative ground cover significantly reduced peak concentrations and cumulative pesticide mass in runoff for first flush experiments compared with bare soil treatments. Post‐application irrigation was found to be an effective means of reducing peak concentrations and cumulative mass in runoff from bare soil treatments, but showed no significant effect on vegetated treatments.     

A GAMING EVALUATION OF COLORADO RWER DROUGHT MANAGEMENT INSTITUTIONAL OPTIONS1

ABSTRACT: Researchers representing each of the Colorado River Basin states as well as the Secretary of the Interior were presented with an interactive computer simulation of a progressively increasing drought and were given the collective opportunity to change the ways in which basin-wide and within-state water management were conducted. The purpose of this “gaming” exercise was to identify rules for managing the Colorado River which are effective in preventing drought-caused damages to basin water users. This water management game was conducted three times, varying the collective choice roles for management of the river yet staying substantially within the current institution for management of the Colorado River known as the “Law of the River.” The Law of the River was quite effective in minimizing drought impacts upon consumptive water uses. Additional effective drought-coping measures to protect consumptive uses consisted mostly of intrastate water management improvements which states were able to implement independently. The Law of the River did not protect non-consumptive water uses, such as hydroelectric power generation, water-based recreation, endangered species, and water quality from drought, as well as it protected consumptive water uses. Players reached collective choice decisions to cope with rising salinity, equalize storage between the upper and lower basins, and protect endangered species. While these measures had some success, only reductions in withdrawals for consumptive uses, particularly in the upper basin, could have substantially lessened adverse impacts.     

An agenda for research and action toward diverse and just futures for life on Earth

Decades of research and policy interventions on biodiversity have insufficiently addressed the dual issues of biodiversity degradation and social justice. New approaches are therefore needed. We devised a research and action agenda that calls for a collective task of revisiting biodiversity toward the goal of sustaining diverse and just futures for life on Earth. Revisiting biodiversity involves critically reflecting on past and present research, policy, and practice concerning biodiversity to inspire creative thinking about the future. The agenda was developed through a 2-year dialogue process that involved close to 300 experts from diverse disciplines and locations. This process was informed by social science insights that show biodiversity research and action is underpinned by choices about how problems are conceptualized. Recognizing knowledge, action, and ethics as inseparable, we synthesized a set of principles that help navigate the task of revisiting biodiversity. The agenda articulates 4 thematic areas for future research. First, researchers need to revisit biodiversity narratives by challenging conceptualizations that exclude diversity and entrench the separation of humans, cultures, economies, and societies from nature. Second, researchers should focus on the relationships between the Anthropocene, biodiversity, and culture by considering humanity and biodiversity as tied together in specific contexts. Third, researchers should focus on nature and economies by better accounting for the interacting structures of economic and financial systems as core drivers of biodiversity loss. Finally, researchers should enable transformative biodiversity research and action by reconfiguring relationships between human and nonhuman communities in and through science, policy, and practice. Revisiting biodiversity necessitates a renewed focus on dialogue among biodiversity communities and beyond that critically reflects on the past to channel research and action toward fostering just and diverse futures for human and nonhuman life on Earth.     

Three-dimensional density-dependent flow and multicomponent reactive transport modeling of chlorinated solvent oxidation by potassium permanganate

A popular method for the treatment of aquifers contaminated with chlorinated solvents is chemical oxidation based on the injection of potassium permanganate (KMnO₄). Both the high density (1025 gL^− 1) and reactivity of the treatment solution influence the fate of permanganate (MnO₄) in the subsurface and affect the degree of contaminant treatment. The MIN3P multicomponent reactive transport code was enhanced to simulate permanganate-based remediation, to evaluate the pathways of MnO₄ utilization, and to assess the role of density contrasts for the delivery of the treatment solution. The modified code (MIN3P-D) provides a direct coupling between density-dependent fluid flow, solute transport, contaminant treatment, and geochemical reactions. The model is used to simulate a field trial of TCE oxidation in a sandy aquifer that is underlain by an aquitard. Three-dimensional simulations are conducted for a coupled reactive system comprised of ten aqueous components, two mineral phases, TCE (dissolved, adsorbed, and NAPL), reactive organic matter, and including ion exchange reactions. Model parameters are constrained by literature data and a detailed data set from the field site under investigation. The general spatial and transient evolution in observed concentrations of the oxidant, dissolved TCE, and reaction products are adequately reproduced by the simulations. The model elucidates the important role of density-induced flow and transport on the distribution of the treatment solution into NAPL containing regions located at the aquifer–aquitard interface. Model results further suggest that reactions that do not directly affect the stability of MnO₄ have a negligible effect on solution density and MnO₄ delivery.     

Uptake and accumulation of antimicrobials,triclocarban and triclosan,by food crops in a hydroponic system

Commonly used in personal care products, triclocarban (TCC) and triclosan (TCS) are two chemicals with antimicrobial properties that have recently been recognized as environmental contaminants with the potential to adversely affect human health. The objective of the study described herein was to evaluate the potential of food crops to uptake TCC and TCS. Eleven food crops, grown in hydroponic nutrient media, were exposed to a mixture of 500 μg L^?1 TCC and TCS. After 4 weeks of exposure, roots accumulated 86–1,350 mg kg^?1 of antimicrobials and shoots had accumulated 0.33–5.35 mg kg^?1 of antimicrobials. Translocation from roots to shoots was less than 1.9 % for TCC and 3.7 % for TCS, with the greatest translocation for TCC observed for pepper, celery, and asparagus and for TCS observed for cabbage, broccoli, and asparagus. For edible tuber- or bulb-producing crops, the concentrations of both TCC and TCS were lower in the tubers than in the roots. Exposure calculations using national consumption data indicated that the average exposure to TCC and TCS from eating contaminated crops was substantially less than the exposure expected to cause adverse effects, but exceeded the predicted exposure from drinking water. Exposure to antimicrobials through food crops would be substantially reduced through limiting consumption of beets and onions.