Life history correlates of alternative migratory strategies in American Dippers

Partial migration is thought to be a critical step in the evolution of avian migration, but data on the life history correlates of alternative migratory strategies are extremely limited. We have studied a partially migratory population of American Dippers since 1999. This population is composed of sedentary individuals (residents) that maintain the same territory year round and altitudinal migrants that share winter grounds with residents, but move to higher elevations to breed. We used seven years of data on individually marked birds to (1) determine if individuals consistently use the same migratory strategy, (2) determine if offspring have the same strategy as their parents, and (3) estimate reproductive and survival rates of the two migratory strategies. We evaluate hypotheses for the persistence of partial migration and discuss their implication for the evolution of migration in sedentary populations. Individual American Dippers rarely switched migratory strategy (4/169 monitored more than one year). An individual's strategy, however, was not always that of its parents, indicating that, while migratory behavior may have a genetic component, environmental or social conditions probably influence the migratory strategy that an individual adopts. Sedentary dippers consistently had higher annual productivity (approximately 1.4 more fledglings/year) than migratory dippers, but mark-recapture models suggested that migratory dippers may have slightly higher survival than residents (approximately 3.4%). Migrants were estimated to have lower lifetime reproductive success than residents because their higher survival was insufficient to offset their lower productivity. Our data suggest that alternative migratory strategies in American Dippers are unlikely to be a fixed genetic dimorphism that persists because the two strategies have equal fitness, or because the relative fitness of the two strategies fluctuates over time. Migratory strategies in American Dippers are more likely to be condition dependent, and the two strategies persist because migrants "make the best of a bad job" by moving to higher elevations to breed. Because migrants obtained no fitness benefits by moving to seasonal breeding territories, our data are consistent with the hypothesis that migration could evolve in sedentary populations if competition for limited resources forces some individuals to seek breeding opportunities outside their initial range.     

Sense and Influence: Environmental Monitoring Tools and the Power of Citizen Science

Automated monitoring devices are useful technologies for communities seeking to document and solve environmental problems. However, without deeper scrutiny of their design and deployment, there is a risk that they will fail to have the impact that many of their promoters intend. We develop a rubric for analysing how different kinds of monitoring devices help environmental advocates influence public debates. We apply this rubric in a study of environmental organizations in Pennsylvania that are choosing between recruiting volunteer citizen scientists and using automated sensor-based devices to gather water quality data in streams threatened by hydraulic fracturing for natural gas. Many organizations rely on volunteers using simple monitoring tools because they are affordable and produce easily managed data sets. An argument for this method of monitoring is that volunteering in the field also fosters citizen engagement in environmental debates. By comparison, we find the increased use of automated devices tends to reinforce hierarchies of expertise and constrains the agendas of nonprofessionals who participate in monitoring projects. We argue that these findings suggest that automated technologies, however effective they may be in gathering data on environmental quality, are not well designed to support broad public participation in environmental science and politics.     

Native Perennial Forb Variation Between Mountain Big Sagebrush and Wyoming Big Sagebrush Plant Communities

Big sagebrush (Artemisia tridentata Nutt.) occupies large portions of the western United States and provides valuable wildlife habitat. However, information is lacking quantifying differences in native perennial forb characteristics between mountain big sagebrush [A. tridentata spp. vaseyana (Rydb.) Beetle] and Wyoming big sagebrush [A. tridentata spp. wyomingensis (Beetle & A. Young) S.L. Welsh] plant communities. This information is critical to accurately evaluate the quality of habitat and forage that these communities can produce because many wildlife species consume large quantities of native perennial forbs and depend on them for hiding cover. To compare native perennial forb characteristics on sites dominated by these two subspecies of big sagebrush, we sampled 106 intact big sagebrush plant communities. Mountain big sagebrush plant communities produced almost 4.5-fold more native perennial forb biomass and had greater native perennial forb species richness and diversity compared to Wyoming big sagebrush plant communities (P < 0.001). Nonmetric multidimensional scaling (NMS) and the multiple-response permutation procedure (MRPP) demonstrated that native perennial forb composition varied between these plant communities (P < 0.001). Native perennial forb composition was more similar within plant communities grouped by big sagebrush subspecies than expected by chance (A = 0.112) and composition varied between community groups (P < 0.001). Indicator analysis did not identify any perennial forbs that were completely exclusive and faithful, but did identify several perennial forbs that were relatively good indicators of either mountain big sagebrush or Wyoming big sagebrush plant communities. Our results suggest that management plans and habitat guidelines should recognize differences in native perennial forb characteristics between mountain and Wyoming big sagebrush plant communities.     

The extractability and mineralisation of cypermethrin aged in four UK soils

Cypermethrin is a widely used insecticide that has caused concern due to its toxicity in the aquatic environment. As with all land applied pesticides, the most significant source of water pollution is from the soil, either due to leaching or washoff. The behaviour of cypermethrin in the soil controls the likelihood of future pollution incidents, with two of the most significant processes being the formation of bound residues and microbial degradation. The formation of bound residues and mineralisation was measured in four organically managed soils from the UK. The formation of bound residues was measured using three different extraction solutions, 0.01 M CaCl₂, 0.05 M HPCD and acetonitrile. Biodegradation was assessed by measurement of mineralisation of cypermethrin to CO₂. The formation of bound residues varied according to extraction method, soil type and length of ageing. In two of the four soils studied, acetonitrile extractability decreased from 100% initially to 12-14% following 100 d ageing. The extent of mineralisation increased after 10-21 d ageing, reaching 33% of remaining activity in one soil, however following 100 d ageing the extent of mineralisation was significantly reduced in three out of the four soils. As with the formation of bound residues, mineralisation was impacted by soil type and length of ageing.     

Impact of Zn and Cu on the development of phenanthrene catabolism in soil

Mixtures of polycyclic aromatic hydrocarbons (PAHs) and heavy metals are of major concern in contaminated soil. Biodegradation of PAHs in metal-contaminated soils is complicated because metals are toxic and cannot be degraded by biological processes. This investigation considered the effects of Zn and Cu (50, 100, 500 and 1,000 mg/kg) on ¹⁴C-phenanthrene biodegradation in soil over 60-day contact time. The presence of Zn at all concentrations and low concentrations of Cu (50 and 100 mg/kg) had no significant effect (p?>?0.05) on the development of phenanthrene catabolism; however, at higher Cu concentrations, the development of phenanthrene catabolism and bacterial cell numbers were significantly reduced (p?<?0.05). This suggests that Cu is more toxic than Zn to soil microbial PAH catabolic activity. Metal/PAH-contaminated soils represent one of the most difficult remedial challenges and insights into PAH biodegradation in the presence of metals is necessary in order to assess the potential for bioremediation.     

Evaluation of land use and water quality in an agricultural watershed in the USA indicates multiple sources of bacterial impairment

Pathogens are the number one cause of impairments of assessed rivers and streams in the USA and pose a significant human health hazard. The Dry Run Creek Watershed in Northeast Iowa has been designated as impaired by the State of Iowa because of high levels of Escherichia coli bacteria. To investigate the nature of this impairment, land use and stream bank assessments were coupled with comprehensive water quality monitoring. Physical, chemical, and biological parameters were measured at 13 different sites in the watershed, including pH, temperature, conductivity, dissolved oxygen, turbidity, total Kjeldahl nitrogen, ammonia-N, nitrate?+?nitrite-N, total phosphorus, and E. coli. In addition, benthic macroinvertebrate communities were analyzed at seven sites, and optical brightener tests were performed late in the season. Results identified segments of the watershed that were more prominent contributors of E. coli, and correlations were observed between levels of E. coli and several chemical parameters, including ammonia-N, total Kjeldahl nitrogen, and total phosphorus. Interestingly, distinct sites emerged as more prominent contributors of these elements during rain vs. non-rain events, suggesting different types of sources. Both the amount of rainfall and the time elapsed between the rain event and the sampling influenced E. coli levels during wet weather conditions. Nitrate?+?nitrite-N displayed a unique response to rain events compared with the other parameters, suggesting a different delivery route. Analyses of benthic macroinvertebrate communities were consistent with pollution trends. Collectively, these data suggest distinct agriculturally related E. coli contributions, as well as specific areas and practices for water quality improvement strategies. This study can serve as a resource for evaluating agricultural watersheds that are impaired for bacteria.     

Antibiotic losses from unprotected manure stockpiles

Manure management is a major concern in livestock production systems. Although historically the primary concerns have been nutrients and pathogens, manure is also a source of emerging contaminants, such as antibiotics, to the environment. There is a growing concern that antibiotics in manure are reaching surface and ground waters and contributing to the development and spread of antibiotic resistance in the environment. One such pathway is through leaching and runoff from manure stockpiles. In this study, we quantified chlortetracycline, monensin, and tylosin losses in runoff from beef manure stockpiles during two separate but consecutive experiments representing different weather conditions (i.e., temperature and precipitation amount and form). Concentrations of chlortetracycline, monensin, and tylosin in runoff were positively correlated with initial concentrations of antibiotics in manure. The highest concentrations of chlortetracycline, monensin, and tylosin in runoff were 210, 3175, and 2544 microg L(-1), respectively. Relative antibiotic losses were primarily a function of water losses. In the experiment that had higher runoff water losses, antibiotic losses ranged from 1.2 to 1.8% of total extractable antibiotics in manure. In the experiment with lower runoff water losses, antibiotic losses varied from 0.2 to 0.6% of the total extractable antibiotics in manure. Manure analysis over time suggests that in situ degradation is an important mechanism for antibiotic losses. Degradation losses during manure stockpiling may exceed cumulative losses from runoff events. Storing manure in protected (i.e., covered) facilities could reduce the risk of aquatic contamination associated with manure stockpiling and other outdoor manure management practices.     

Antibiotic degradation during manure composting

On-farm manure management practices, such as composting, may provide a practical and economical option for reducing antibiotic concentrations in manure before land application, thereby minimizing the potential for environmental contamination. The objective of this study was to quantify degradation of chlortetracycline, monensin, sulfamethazine, and tylosin in spiked turkey (Meleagris gallopavo) litter during composting. Three manure composting treatments were evaluated: a control treatment (manure pile with no disturbance or adjustments after initial mixing), a managed compost pile (weekly mixing and moisture content adjustments), and vessel composting. Despite significant differences in temperature, mass, and nutrient losses between the composting treatments and the control, there was no difference in antibiotic degradation among the treatments. Chlortetracycline concentrations declined rapidly during composting, whereas monensin and tylosin concentrations declined gradually in all three treatments. There was no degradation of sulfamethazine in any of treatments. At the conclusion of the composting period (22-35 d), there was >99% reduction in chlortetracycline, whereas monensin and tylosin reduction ranged from 54 to 76% in all three treatments. Assuming first-order decay, the half-lives for chlortetracycline, monensin, and tylosin were 1, 17, and 19 d, respectively. These data suggest that managed compositing in a manure pile or in a vessel is not better than the control treatment in degrading certain antibiotics in manure. Therefore, low-level manure management, such as stockpiling, after an initial adjustment of water content may be a practical and economical option for livestock producers in reducing antibiotic levels in manure before land application.     

Fate and behaviour of phenanthrene in the natural and artificial soils

For the assessment of contaminated soils ecotoxicological tests are used to estimate the bioavailability of contaminants in soil samples. Terrestrial tests reveal the habitat function of soils, and parameters applied in tests involving microorganisms include respiration activity and potential ammonium oxidation. For such tests, the threshold values needed to assess the results have already been established in guidelines ISO 17155 and ISO 15685. In this paper, we discuss about the respiration activity and potential ammonium oxidation results obtained from a wide variety of soils with different physico-chemical properties and levels of contamination. These results show that microbial respiration and potential ammonium oxidation have different sensitivities to various classes of contaminants. We demonstrated that both organic and inorganic contaminants influence potential ammonium oxidation, whereas microbial respiration is predominantly affected by biodegradable organic contaminants. These differences might be useful for more detailed assessments of soil contamination, leading to different recommended actions depending on which parameter is affected.     

An inexpensive light-scattering particle monitor: field validation

We have developed a small, light, passive, inexpensive, datalogging particle monitor called the "UCB" (University of California Berkeley particle monitor). Following previously published laboratory assessments, we present here results of tests of its performance in field settings at high particle concentrations. We demonstrate the mass sensitivity of the UCB in relation to gravimetric filter-based PM(2.5) mass estimates as well as commercial light-scattering instruments co-located in field chamber tests and in kitchens of wood-burning households. The coefficient of variation of the unadjusted UCB mass response in relation to gravimetric estimates was 15%. Although requiring adjustment for differences in sensitivity, inter-monitor performance was consistently high (r(2) > 0.99). Moreover, the UCB can consistently estimate PM(2.5) mass concentrations in wood-burning kitchens (Pearson r(2) = 0.89; N = 99), with good agreement between duplicate measures (Pearson r(2) = 0.94; N = 88). In addition, with appropriate cleaning of the sensing chamber, UCB mass sensitivity does not decrease with time when used intensively in open woodfire kitchens, demonstrating the significant potential of this monitor.