Bridging the generation gap in plants: pollination, parental fecundity, and offspring demography

Despite extensive study of pollination and plant reproduction on the one hand, and of plant demography on the other, we know remarkably little about links between seed production in successive generations, and hence about long-term population consequences of variation in pollination success. We bridged this "generation gap" in Ipomopsis aggregata, a long-lived semelparous wildflower that is pollinator limited, by adding varying densities of seeds to natural populations and following resulting plants through their entire life histories. To determine whether pollen limitation of seed production constrains rate of population growth in this species, we sowed seeds into replicated plots at a density that mimics typical pollination success and spacing of flowering plants in nature, and at twice that density to mimic full pollination. Per capita offspring survival, flower production, and contribution to population increase (lambda) did not decline with sowing density in this experiment, suggesting that typical I. aggregata populations freed from pollen limitation will grow over the short term. In a second experiment we addressed whether density dependence would eventually erase the growth benefits of full pollination, by sowing a 10-fold range of seed densities that falls within extremes estimated for the natural "seed rain" that reaches the soil surface. Per capita survival to flowering and age at flowering were again unaffected by sowing density, but offspring size, per capita flower production, and lambda declined with density. Such density dependence complicates efforts to predict population dynamics over the longer term, because it changes components of the life history (in this case fecundity) as a population grows. A complete understanding of how constraints on seed production affect long-term population growth will hinge on following offspring fates at least through flowering of the first offspring generation, and doing so for a realistic range of population densities.     

State of the Estuaries in the Mid-Atlantic Region of the United States

The U.S. EPA has prepared a State of the Region Report for Mid-Atlantic Estuaries to increase knowledge of environmental condition for improved environmental management. Sources of information included the National Estuary Programs, the Chesapeake Bay Program, the state monitoring programs in Delaware, Maryland, and Virginia, Federal programs such as National Status & Trends, National Shellfish Register, National Wetlands Inventory, the Environmental Monitoring and Assessment Program, and other primary literature sources. The state of the estuarine environment was summarized using indicators for water and sediment quality, habitat change, condition of living resources, and aesthetic quality. Each indicator was briefly discussed relative to its importance in understanding estuarine condition. Wherever possible, data from multiple programs were used to depict condition. Finally, an overall evaluation of estuarine condition in the region was determined. The usefulness of monitoring programs that collect consistent information with a well-defined sampling design cannot be overemphasized.     

The unusual suspects? Perception of underlying causes of anthropogenic climate change in coastal communities in Cambodia and Tanzania

Public perception of the underlying causes of anthropogenic climate change is a complex and subjective issue that is critical to effective risk communication. This issue is important to scientists and policymakers because of the role of individual perceptions in influencing their protective behaviour towards risk (e.g., the adoption of climate risk reduction and mitigation strategies). This cross-sectional study elucidated people's perceptions of the underlying causes of human-induced climate change in coastal communities in Cambodia and Tanzania. The multinomial logistic regression model was based on a geographically and demographically stratified national sample of 3,706 individuals conducted between March and September 2013. The distribution of the fundamental causes of anthropogenic climate change in the pooled sample was deforestation (29%), overpopulation – births and immigration (18%), greenhouse gas emissions (12%), illegal resource extraction (14%), and God's will and transgressing cultural norms (26%). Few people in both countries believed that, the usual suspect, greenhouse gas emission was the fundamental cause of anthropogenic climate change. The number of poor rural residents who indicated that deforestation was the major underlying cause of climate change was approximately three times more than members of the same sub-group who noted that greenhouse gas emissions were the underlying cause of climate change. People who had tertiary education were less likely to consider God's will and transgressing cultural norms as the underlying cause of anthropogenic climate change rather than attributing it to greenhouse gas emissions. Therefore, it is imperative to mainstream climate change into educational curricula in both countries.     

Relationships between watershed emergy flow and coastal New England salt marsh structure, function, and condition

This study evaluated the link between watershed activities and salt marsh structure, function, and condition using spatial emergy flow density (areal empower density) in the watershed and field data from 10 tidal salt marshes in Narragansett Bay, RI, USA. The field-collected data were obtained during several years of vegetation, invertebrate, soil, and water quality sampling. The use of emergy as an accounting mechanism allowed disparate factors (e.g., the amount of building construction and the consumption of electricity) to be combined into a single landscape index while retaining a uniform quantitative definition of the intensity of landscape development. It expanded upon typical land use percentage studies by weighting each category for the intensity of development. At the RI salt marsh sites, an impact index (watershed emergy flow normalized for marsh area) showed significant correlations with mudflat infauna species richness, mussel density, plant species richness, the extent and density of dominant plant species, and denitrification potential within the high salt marsh. Over the 4-year period examined, a loading index (watershed emergy flow normalized for watershed area) showed significant correlations with nitrite and nitrate concentrations, as well as with the nitrogen to phosphorus ratios in stream discharge into the marshes. Both the emergy impact and loading indices were significantly correlated with a salt marsh condition index derived from intensive field-based assessments. Comparison of the emergy indices to calculated nitrogen loading estimates for each watershed also produced significant positive correlations. These results suggest that watershed emergy flow is a robust index of human disturbance and a potential tool for rapid assessment of coastal wetland condition.     

Environmental accounting of natural capital and ecosystem services for the US National Forest System

The National Forests of the United States encompass 192.7?million acres (78?million hectares) of land, which is nearly five percent of the total land area of the nation. These lands are managed by the US Forest Service (USFS) for multiple uses, including extraction of timber, production of fossil fuels and minerals, public recreation, and the preservation of biodiversity, clean air, water, and soils. The USFS is interested in valuing the natural capital within, and the ecosystem services provided by, their lands. This is in part to justify expenditures in a time of limited resources. We used emergy and an environmental accounting approach, to quantify the ecosystem services, the exported environmental goods and information provided by National Forest System (NFS) lands, and the natural capital residing on those lands. Environmental accounting using emergy provides a method to value these flows of services and storages of capital using a common biophysical unit, the solar emjoule and its monetary equivalent the emdollar. We compare emdollar values to economic values gleaned from the literature. In 2005, the ecosystem services provided by USFS lands were equivalent to 197?billion emdollars, and the value of NFS natural capital was 24.3?trillion emdollars. Our evaluation suggests that the Federal Government budget allocation for the NFS ($5.55E+09 in 2005) was well spent, protecting 24.3?trillion emdollars in natural capital and insuring annual ecosystem services totaling 197?billion emdollars. Monetary values for some natural capital and ecosystem services are similar to emergy-derived values (resources like fish, wildlife, water, and firewood extracted from forests), and others are widely different (biodiversity, fossil, and mineral resources). There is large uncertainty associated with computing the environment’s contributions to society whether using emergy or accepted economic techniques; yet, the magnitude of these emergy-derived estimates suggests that even with the uncertainty, the values are significant and monetary expenditures for the Forest Service are justified.     

Positive vs. false detection: A comparison of analytical methods and performance for analysis of cyclic volatile methylsiloxanes (cVMS) in environmental samples from remote regions

Contamination and analytical variation can significantly hinder trace analysis of cyclic methyl volatile siloxanes (cVMS); potentially resulting in the report of false positives at concentrations approaching detection limits. To assess detection and variation associated with trace cVMS analysis in environmental matrices, a co-operative laboratory comparison for the analysis of octametylcyclotetrasiloxane (D4), decamethylcylcopentasiloxane (D5), and dodecametylcyclohexasiloxane (D6) in sediment and biota from the Svalbard Archipelago was conducted. Two definitions of detection limits were evaluated in this study; method detection limits (MDL, matrix defined) and limits of detection (LOD, solvent defined). D5 was the only cVMS detected above both LOD (0.08–0.81 ng g⁻¹ ww) and MDL (0.47–2.36 ng g⁻¹ ww) within sediment by all laboratories where concentrations ranged from 0.55 to 3.91 ng g⁻¹ ww. The percentage of positive detects for D5 decreased by 80% when MDL was defined as the detection limit. D5 was also detected at the highest frequency among all laboratories in fish liver with concentrations ranging from 0.72 to 345 ng g⁻¹ ww. Similar to sediment, percentage of positive detects for D5 decreased by 60% across all laboratories for fish livers when using MDL (0.68–3.49 ng g⁻¹ ww). Similar observations were seen with both D4 and D6, indicating that sample matrix significantly contributes to analytical response variation. Despite differences in analytical methods used between laboratories, good agreement was obtained when using MDL to define detection limits. This study shows the importance of incorporating variation introduced by sample matrices into detection limit calculations to insure data accuracy of cVMS at low concentrations.     

Continuous automated imaging-in-flow cytometry for detection and early warning of Karenia brevis blooms in the Gulf of Mexico

Monitoring programs for harmful algal blooms (HABs) typically rely on time-consuming manual methods for identification and enumeration of phytoplankton, which make it difficult to obtain results with sufficient temporal resolution for early warning. Continuous automated imaging-in-flow by the Imaging FlowCytobot (IFCB) deployed at Port Aransas, TX has provided early warnings of six HAB events. Here we describe the progress in automating this early warning system for blooms of Karenia brevis. In 2009, manual inspection of IFCB images in mid-August 2009 provided early warning for a Karenia bloom that developed in mid-September. Images from 2009 were used to develop an automated classifier that was employed in 2011. Successful implementation of automated file downloading, processing and image classification allowed results to be available within 4 h after collection and to be sent to state agency representatives by email for early warning of HABs. No human illness (neurotoxic shellfish poisoning) has resulted from these events. In contrast to the common assumption that Karenia blooms are near monospecific, post-bloom analysis of the time series revealed that Karenia cells comprised at most 60–75 % of the total microplankton.     

Stainless Steel Anti-Smog Mufflers—Cut Air Pollution

An automatic process gas chromatograph has been developed for use on the recovery furnace stack of a Kraft pulp mill. The instrument analyzes for widely varying concentrations of H₂S, SO₂, CH₃SH and higher order sulfur compounds. It is insensitive to the fixed gases and water vapor, and performs its analysis in approximately ten minutes. The instrument features a microcoulometric detector giving it sensitivity to H₂S as low as 0.1 ppm, and SO₂ and CH₃SH as low as 0.5 ppm. The major limit to even higher sensitivity at this stage of development lies with two problems: the background noise level in the detector and the sulfur compound absorption in the Porapak Q chromatograph column. At the reported sensitivity, a 40-ml gas sample was used. The instrument also contains a data analysis system supplementary to the usual strip chart recorder. This system is made up of a digital voltmeter, a digital translator, and a teletype and hence allows the transfer of the output data to a digital computer for processing. The processed data are usually presented in the form of ppm quantities of the component gases in the stack gas. The instrument has worked successfully on small furnace effluent for periods of 25 hr but has not been tried on recovery furnace stacks. It has also run on prepared samples for periods of up to seven days with no maintenance or attendance necessary.     

Measurement of Ambient Ground-Level Concentrations of Hydrogen Fluoride

The use of published, accepted methods for measuring ambient levels of gaseous hydrogen fluoride (HF) with a double-tape sampler led to large errors. The major source of error was found to be scrubbing In the stainless steel intake, which was avoided by substituting Teflon for the stainless steel. To avoid this and other problems encountered in the measurement of HF, we revised the double-tape sampler method and modified the double-tape sampler. We designed and constructed an HF calibrator for use in testing the revised method and modified sampler In the field and laboratory.

The results of a round robin indicated that, in the laboratory, the revised method has a single-operator precision of 3 percent at 2.6 μg/m³ and a between-laboratory precision of 4 percent. The average bias at 2.6 μg/m³ was 0.02 μg/m³ and was not significantly different from zero. Comparable precision and accuracy were obtained in the field. The response was linear, at least to 10 μg/m³. The limit of detectability, which appears to be limited by the variability in measurements of blank tapes, is 0.07 μg/m³. The revised method appears both precise and accurate.