Changes in soil respiration across a chronosequence of tallgrass prairie reconstructions

Close relationships among climatic factors and soil respiration (R_s) are commonly reported. However, variation in R_s across the landscape is compounded by site-specific differences that impede the development of spatially explicit models. Among factors that influence R_s, the effect of ecosystem age is poorly documented. We hypothesized that R_s increases with grassland age and tested this hypothesis in a chronosequence of tallgrass prairie reconstructions in central Iowa, U.S.A. We also assessed changes in root biomass, root ingrowth, aboveground net primary productivity (ANPP), and the strength of soil temperature and moisture in predicting R_s. We found a significant increase in total growing season R_s with prairie age (R² = 0.79), ranging from 714 g C m^?2 in the youngest reconstruction (age 4) to 939 g C m^?2 in the oldest prairie (age 12). Soil temperature was a strong predictor of intra-seasonal R_s among prairies (R² = 0.78–0.87) but mean growing season soil temperature and moisture did not relate to total R_s. The increase in R_s with age was positively correlated with root biomass (r = 0.80) and ANPP (r = 0.87) but not with root ingrowth. Our findings suggest that growing season R_s increases with tallgrass prairie age, root biomass, and ANPP during young grassland development.     

Cross-species correlation between queen mating numbers and worker ovary sizes suggests kin conflict may influence ovary size evolution in honeybees

During social evolution, the ovary size of reproductively specialized honey bee queens has dramatically increased while their workers have evolved much smaller ovaries. However, worker division of labor and reproductive competition under queenless conditions are influenced by worker ovary size. Little comparative information on ovary size exists in the different honey bee species. Here, we report ovariole numbers of freshly dissected workers from six Apis species from two locations in Southeast Asia. The average number of worker ovarioles differs significantly among species. It is strongly correlated with the average mating number of queens, irrespective of body size. Apis dorsata, in particular, is characterized by numerous matings and very large worker ovaries. The relation between queen mating number and ovary size across the six species suggests that individual selection via reproductive competition plays a role in worker ovary size evolution. This indicates that genetic diversity, generated by multiple mating, may bear a fitness cost at the colony level.     

The first ceratopsian dinosaur from South Korea

In 2008, a new basal neoceratopsian was discovered in the Tando beds (Albian) of Tando Basin in South Korea. It represents the first ceratopsian dinosaur in the Korean peninsula and is assigned to Koreaceratops hwaseongensis gen. et sp. nov. Autapomorphies of Koreaceratops include very tall neural spines over five times higher than the associated centra in the distal caudals, and a unique astragalus divided into two fossae by a prominent craniocaudal ridge on the proximal surface. A phylogenetic analysis indicates that Koreaceratops is positioned between Archaeoceratops and all more derived neoceratopsians, and the elongation of caudal neural spines was an important derived character in non-ceratopsid neoceratopsians. The very tall caudal neural spines in Koreaceratops, Montanoceratops, Udanoceratops, Protoceratops, and Bagaceratops appear to be homoplasious, suggesting an independent adaptation, possibly for swimming. Skeletal evidence suggests that obligate quadrupedalism occurred gradually in neoceratopsians progressing from bipedal through facultative quadrupedalism, to complete quadrupedalism in Coronosauria.     

Modeling population effects of the Deepwater Horizon oil spill on a long-lived species

The 2010 Deepwater Horizon (DWH) oil spill exposed common bottlenose dolphins (Tursiops truncatus) in Barataria Bay, Louisiana to heavy oiling that caused increased mortality and chronic disease and impaired reproduction in surviving dolphins. We conducted photographic surveys and veterinary assessments in the decade following the spill. We assigned a prognostic score (good, fair, guarded, poor, or grave) for each dolphin to provide a single integrated indicator of overall health, and we examined temporal trends in prognostic scores. We used expert elicitation to quantify the implications of trends for the proportion of the dolphins that would recover within their lifetime. We integrated expert elicitation, along with other new information, in a population dynamics model to predict the effects of observed health trends on demography. We compared the resulting population trajectory with that predicted under baseline (no spill) conditions. Disease conditions persisted and have recently worsened in dolphins that were presumably exposed to DWH oil: 78% of those assessed in 2018 had a guarded, poor, or grave prognosis. Dolphins born after the spill were in better health. We estimated that the population declined by 45% (95% CI 14–74) relative to baseline and will take 35 years (95% CI 18–67) to recover to 95% of baseline numbers. The sum of annual differences between baseline and injured population sizes (i.e., the lost cetacean years) was 30,993 (95% CI 6607–94,148). The population is currently at a minimum point in its recovery trajectory and is vulnerable to emerging threats, including planned ecosystem restoration efforts that are likely to be detrimental to the dolphins’ survival. Our modeling framework demonstrates an approach for integrating different sources and types of data, highlights the utility of expert elicitation for indeterminable input parameters, and emphasizes the importance of considering and monitoring long-term health of long-lived species subject to environmental disasters. Article impact statement: Oil spills can have long-term consequences for the health of long-lived species; thus, effective restoration and monitoring are needed.     

Uncertainty quantification of steady and transient source term estimation in an urban environment

Environmental Fluid Mechanics - The growing concern of the effects of potential releases of chemical, biological or radiological materials in populated areas has led to an increase in urban...     

Dynamic risk assessment using failure assessment and Bayesian theory

To ensure the safety of a process system, engineers use different methods to identify the potential hazards that may cause severe consequences. One of the most popular methods used is quantitative risk assessment (QRA) which quantifies the risk associated with a particular process activity. One of QRA's major disadvantages is its inability to update risk during the life of a process. As the process operates, abnormal events will result in incidents and near misses. These events are often called accident precursors. A conventional QRA process is unable to use the accident precursor information to revise the risk profile. To overcome this, a methodology has been proposed based on the work of Meel and Seider (2006). Similar to Meel and Seider (2006) work, this methodology uses Bayesian theory to update the likelihood of the event occurrence and also failure probability of the safety system. In this paper the proposed methodology is outlined and its application is demonstrated using a simple case study. First, potential accident scenarios are identified and represented in terms of an event tree, next, using the event tree and available failure data end-state probabilities are estimated. Subsequently, using the available accident precursor data, safety system failure likelihood and event tree end-state probabilities are revised. The methodology has been simulated using deterministic (point value) as well as probabilistic approach. This Methodology is applied to a case study demonstrating a storage tank containing highly hazardous chemicals. The comparison between conventional QRA and the results from dynamic failure assessment approach shows the significant deviation in system failure frequency throughout the life time of the process unit.     

The impact of production type and region on polychlorinated biphenyl (PCB), polychlorinated dibenzo-p-dioxin and dibenzofuran (PCDD/F) concentrations in Canadian chicken egg yolks

Chicken eggs from five different production types (conventional, omega-3 enriched, free range, organic and free run) were collected, when available, from three regions (west, central and east) of Canada to determine persistent organic pollutant (POP) concentrations. Total polychlorinated biphenyl (PCB) concentrations (∑37 congeners) in yolks from the eggs ranged from 0.162 ng g⁻¹ lipid to 24.8 ng g⁻¹ lipid (median 1.25 ng g⁻¹ lipid) while the concentration of the sum of the 6 indicator PCBs ranged from 0.100 ng g⁻¹ lipid to 9.33 ng g⁻¹ lipid (median 0.495 ng g⁻¹ lipid). Total polychlorinated dibenzo-p-dioxin/dibenzofuran (PCDD/F) concentrations ranged from 2.37 pg g⁻¹ lipid to 382 pg g⁻¹ lipid (median 9.53 pg g⁻¹ lipid). The 2005 WHO toxic equivalency (TEQ) ranged from 0.089 pg TEQ_{PCDD/F+dioxin-like[DL]-PCB} g⁻¹ lipid to 12.8 pg TEQ_{PCDD/F+DL-PCB} g⁻¹ lipid (median 0.342 pg TEQ_{PCDD/F+DL-PCB} g⁻¹ lipid). PCB and PCDD/F concentrations were significantly different (p < 0.001) in egg yolks from different regions of collection. In contrast to observations in Europe, PCB and PCDD/F concentrations in Canadian egg yolks were not impacted solely by the production type (e.g., conventional, free range, organic, etc.) used to maintain the laying chickens. Additionally, only one Canadian free range yolk from western Canada (12.8 pg TEQ_{PCDD/F+DL-PCB} g⁻¹ lipid) exceeded the European toxic equivalent concentration limits for eggs (5 pg TEQ_{PCDD/F+DL-PCB} g⁻¹ lipid). This differs from observations in Europe where free range/home produced eggs frequently have higher POP concentrations than eggs from other production types. Median PCB dietary intake estimates based on consumption of eggs were less than 10 ng d⁻¹ while median PCDD/F intakes were less than 45 pg d⁻¹.     

Identifying the cause of toxicity in an algal whole effluent toxicity study - an unanticipated toxicant

Toxicity was observed in whole effluent toxicity (WET) studies with the freshwater alga, Pseudokirchneriella subcapitata, in three consecutive monthly studies, (NOEC = 50-75%). Toxicity was not observed to Ceriodaphnia dubia or the fathead minnow, Pimephales promelas in concurrent studies. Selected toxicity identification evaluation (TIE) tests were conducted in a tiered approach to eliminate possible toxicants and progressively identify the causative agent. Filtration following alkaline adjustment (pH 10 or 11) was effective in eliminating significant growth effects and also reduced phosphate concentration. The TIE studies confirmed that the observed effluent toxicity was caused by excess ortho-phosphate in the effluent not by overstimulation or related to unfavorable N:P ratios; but due to direct toxicity. The 96-h 25% inhibition concentration (IC25) of ortho-phosphate to P. subcapitata was 3.4 mg L⁻¹ while the maximum acceptable toxicant concentration was 4.8 mg L⁻¹. This study illustrates the value of multi-species testing and also provides an example of an effective TIE using algae identifying an unanticipated toxicant.     

A mixed methodology for evaluating use of evidence in conservation planning

Conservation practitioners widely recognize the importance of making decisions based on the best available evidence. However, the effectiveness of evidence use in conservation planning is rarely assessed, which limits opportunities to improve evidence-based practice. We devised a mixed methodology for empirically evaluating use of evidence that applies social science tools to systematically appraise what kinds of evidence are used in conservation planning, to what effect, and under what limitations. We applied our approach in a case study of the Nature Conservancy of Canada (NCC), a leading land conservation organization. We conducted qualitative and quantitative analyses of 65 NCC planning documents (n = 13 in-depth) to identify patterns in evidence use, and surveyed 35 conservation planners to examine experiences of and barriers to using evidence. Although claims in plans contained a wide range of evidence types, 26% of claims were not referenced or associated with an identifiable source. Lack of evidence use was particularly apparent in claims associated with direct threats, particularly those identified as low (71% coded as insufficient or lacking evidence) or medium (45%) threats. Survey participants described relying heavily on practitioner experience and highlighted capacity limitations and disciplinary gaps in expertise among planning teams as barriers to using evidence effectively. We found that although time-intensive, this approach yielded actionable recommendations for improving evidence use in NCC conservation plans. Similar mixed-method assessments may streamline the process by including interviews and refining the document analysis frames to target issues or sections of concern. We suggest our method provides an accessible and robust point of departure for conservation practitioners to evaluate whether the use of conservation planning reflects in-house standards and more broadly recognized best practices.     

Wild meat trade over the last 45 years in the Peruvian Amazon

The trade in wild meat is an important economic component of rural people's livelihoods, but it has been perceived to be among the main causes of the decline of wildlife species. Recently, the COVID-19 pandemic has brought to light an additional concern of wildlife markets as a major human-health challenge. We analyzed data from the largest longitudinal monitoring (1973–2018) of the most important urban wild-meat markets in Iquitos, Peru, to examine the trends in and impacts of these markets on people's livelihoods. Over the last 45 years, wild meat sales increased at a rate of 6.4 t/year (SD 2.17), paralleling urban population growth. Wild meat sales were highest in 2018 (442 t), contributing US$2.6 million (0.76%) to the regional gross domestic product. Five species of ungulates and rodents accounted for 88.5% of the amount of biomass traded. Vulnerable and Endangered species represented 7.0% and 0.4% of individuals sold, respectively. Despite growth in sales, the contribution of wild meat to overall urban diet was constant: 1–2%/year of total meat consumed. This result was due to greater availability and higher consumption of cheaper meats (e.g., in 2018, poultry was 45.8% cheaper and was the most consumed meat) coupled with the lack of economic incentives to harvest wild meat species in rural areas. Most wild meat was sold salted or smoked, reducing the likelihood of foodborne diseases. Community-based wildlife management plans and the continued trade bans on primates and threatened taxa may avoid biodiversity loss. Considering the recent COVID-19 pandemic, future management plans should include potential viral hosts and regulation and enforcement of hygiene practices in wild-meat markets.