CHARACTERIZATION OF TOXIC CONDITIONS ABOVE WILSON'S CREEK NATIONAL BATTLEFIELD PARK,MISSOUR1

ABSTRACT: Wilson's Creek has an extensive history of toxicity from both point and nonpoint sources. Seven-day chronic daphnid (Ceriodaphnia dubia) bioassays identified one toxic site in the Wilson's Creek watershed. Procedures for the characterization phase of a Toxicity Identification Evaluation (TIE) were modified for chronic assessment and performed on four water samples from the toxic site. The characterization involved chemical/physical alterations of samples, combined with bioassays, to help in identification of the class(es) of toxicants; followed by chemical analyses. To help understand the additivity of mixtures, toxic units were derived. Successive samples contained concentrations of copper, cadmium, nickel and zinc that literature values describe as being chronically toxic to daphnids. Summed chronic toxic units for these values greatly exceeded ambient toxic units, and more than accounted for observed toxicity. Substantial fluctuations in water quality occurred over the five sampling periods of the characterization studies and a Test of Methods, June through August, 1991. This variability illustrates the difficulty in detecting and documenting nonpoint sources of pollution. Tests using living organisms, in conjunction with toxicity identification methods, on samples taken over time appear to be appropriate for detecting acute and chronic toxicity in areas impacted by intermittent point and nonpoint-source toxicity.     

A Bayesian mixture model for missing data in marine mammal growth analysis

Much of what is known about bottle nose dolphin (Tursiops truncatus) anatomy and physiology is based on necropsies from stranding events. Measurements of total body length, total body mass, and age are used to estimate growth. It is more feasible to retrieve and transport smaller animals for total body mass measurement than larger animals, introducing a systematic bias in sampling. Adverse weather events, volunteer availability, and other unforeseen circumstances also contribute to incomplete measurement. We have developed a Bayesian mixture model to describe growth in detected stranded animals using data from both those that are fully measured and those not fully measured. Our approach uses a shared random effect to link the missingness mechanism (i.e. full/partial measurement) to distinct growth curves in the fully and partially measured populations, thereby enabling drawing of strength for estimation. We use simulation to compare our model to complete case analysis and two common multiple imputation methods according to model mean square error. Results indicate that our mixture model provides better fit both when the two populations are present and when they are not. The feasibility and utility of our new method is demonstrated by application to South Carolina strandings data.     

The scope and severity of white-nose syndrome on hibernating bats in North America

Assessing the scope and severity of threats is necessary for evaluating impacts on populations to inform conservation planning. Quantitative threat assessment often requires monitoring programs that provide reliable data over relevant spatial and temporal scales, yet such programs can be difficult to justify until there is an apparent stressor. Leveraging efforts of wildlife management agencies to record winter counts of hibernating bats, we collated data for 5 species from over 200 sites across 27 U.S. states and 2 Canadian provinces from 1995 to 2018 to determine the impact of white-nose syndrome (WNS), a deadly disease of hibernating bats. We estimated declines of winter counts of bat colonies at sites where the invasive fungus that causes WNS (Pseudogymnoascus destructans) had been detected to assess the threat impact of WNS. Three species undergoing species status assessment by the U.S. Fish and Wildlife Service (Myotis septentrionalis, Myotis lucifugus, and Perimyotis subflavus) declined by more than 90%, which warrants classifying the severity of the WNS threat as extreme based on criteria used by NatureServe. The scope of the WNS threat as defined by NatureServe criteria was large (36% of Myotis lucifugus range) to pervasive (79% of Myotis septentrionalis range) for these species. Declines for 2 other species (Myotis sodalis and Eptesicus fuscus) were less severe but still qualified as moderate to serious based on NatureServe criteria. Data-sharing across jurisdictions provided a comprehensive evaluation of scope and severity of the threat of WNS and indicated regional differences that can inform response efforts at international, national, and state or provincial jurisdictions. We assessed the threat impact of an emerging infectious disease by uniting monitoring efforts across jurisdictional boundaries and demonstrated the importance of coordinated monitoring programs, such as the North American Bat Monitoring Program (NABat), for data-driven conservation assessments and planning.     

Impacts of ocean acidification on marine shelled molluscs

Over the next century, elevated quantities of atmospheric CO₂ are expected to penetrate into the oceans, causing a reduction in pH (?0.3/?0.4 pH unit in the surface ocean) and in the concentration of carbonate ions (so-called ocean acidification). Of growing concern are the impacts that this will have on marine and estuarine organisms and ecosystems. Marine shelled molluscs, which colonized a large latitudinal gradient and can be found from intertidal to deep-sea habitats, are economically and ecologically important species providing essential ecosystem services including habitat structure for benthic organisms, water purification and a food source for other organisms. The effects of ocean acidification on the growth and shell production by juvenile and adult shelled molluscs are variable among species and even within the same species, precluding the drawing of a general picture. This is, however, not the case for pteropods, with all species tested so far, being negatively impacted by ocean acidification. The blood of shelled molluscs may exhibit lower pH with consequences for several physiological processes (e.g. respiration, excretion, etc.) and, in some cases, increased mortality in the long term. While fertilization may remain unaffected by elevated pCO₂, embryonic and larval development will be highly sensitive with important reductions in size and decreased survival of larvae, increases in the number of abnormal larvae and an increase in the developmental time. There are big gaps in the current understanding of the biological consequences of an acidifying ocean on shelled molluscs. For instance, the natural variability of pH and the interactions of changes in the carbonate chemistry with changes in other environmental stressors such as increased temperature and changing salinity, the effects of species interactions, as well as the capacity of the organisms to acclimate and/or adapt to changing environmental conditions are poorly described.     

Low-level sedimentation modifies behaviour in juvenile Haliotis iris and may affect their vulnerability to predation

Sedimentation is an important stressor of coastal ecosystems; yet, there is little research into specific mechanisms by which populations are affected by additional sediment loads resulting from anthropogenic-driven processes. This study explored the potential impact of the proposed disposal of over 7 million m³ of dredge spoil on a nearby fishery for the blackfoot abalone Haliotis iris. The range of sediment deposition predicted by models to occur on reefs inhabited by H. iris as a result of the dispersal of sediment from the disposal site was used to design controlled experiments between July and September 2011 to test the likely effects of sedimentation on: (a) behaviour and mortality of juvenile H. iris and (b) photosynthetic vitality of crustose coralline algae (CCA) that form nursery habitats for H. iris obtained from Brinns Point (45, 40.3′S, 170, 39.4′E). We observed no direct effects on the health or mortality of H. iris juveniles or the photosynthetic vitality of habitat forming CCA. H. iris did, however, avoid sediments by moving from predation refugia beneath cobbles to vertical surfaces on cobble edges significantly more often in sediment treatments compared to sediment-free controls. Deposited sediments were also found to inhibit righting response, key behaviour in allowing H. iris to reattach to the substratum following dislodgement. Results of this study suggest that indirect mortality from reductions in available refugia from predation and inability to recover from dislodgement could be significant. These results highlight the importance of understanding indirect impacts of stressors on key ecological processes in order to predict ecological responses.     

On allegations of invasive species denialism

Science denialism retards evidenced-based policy and practice and should be challenged. It has been a particular concern for mitigating global environmental issues, such as anthropogenic climate change. But allegations of science denialism must also be well founded and evidential or they risk eroding public trust in science and scientists. Recently, 77 published works by scholars, scientists, and science writers were identified as containing invasive species denialism (ISD; i.e., rejection of well-supported facts about invasive species, particularly the global scientific consensus about their negative impacts). We reevaluated 75 of these works but could find no examples of refutation of scientific facts and only 5 articles with text perhaps consistent with one of the 5 characteristics of science denialism. We found, therefore, that allegations of ISD were misplaced. These accusations of science denialism may have arisen because invasion biology defines its subjects—invasive species—based on multiple subjective and normative judgments. Thus, more than other applied sciences its consensus is one of shared values as much as agreed knowledge. Criticisms of invasion biology have largely targeted those subjective and normative judgments and their global imposition, not the knowledge on which the discipline is based. Regrettably, a few invasion biologists have misinterpreted the critique of their values-based consensus as a denial of their science when it is not. To make invasion biology a more robust and widely accepted science and to avoid unnecessary misunderstandings and conflicts, invasion biologists could be more accepting of perspectives originating from other disciplines and more open to values-based critique from scholars and scientists outside their field. This recommendation applies to all conservation sciences, especially those addressing global challenges, because these sciences must serve and be relevant to communities with an extraordinary diversity of cultures and values.     

Widespread density-dependent seedling mortality promotes species coexistence in a highly diverse Amazonian rain forest

Negative density-dependent mortality can promote species coexistence through a spacing mechanism that prevents species from becoming too locally abundant. Negative density-dependent seedling mortality can be caused by interactions among seedlings or between seedlings and neighboring adults if the density of neighbors affects the strength of competition or facilitates the attack of natural enemies. We investigated the effects of seedling and adult neighborhoods on the survival of newly recruited seedlings for multiple cohorts of known age from 163 species in Yasuni National Park, Ecuador, an ever-wet, hyper-diverse lowland Amazonian rain forest. At local scales, we found a strong negative impact on first-year survival of conspecific seedling densities and adult abundance in multiple neighborhood sizes and a beneficial effect of a local tree neighborhood that is distantly related to the focal seedling. Once seedlings have survived their first year, they also benefit from a more phylogenetically dispersed seedling neighborhood. Across species, we did not find evidence that rare species have an advantage relative to more common species, or a community compensatory trend. These results suggest that the local biotic neighborhood is a strong influence on early seedling survival for species that range widely in their abundance and life history. These patterns in seedling survival demonstrate the role of density-dependent seedling dynamics in promoting and maintaining diversity in understory seedling assemblages. The assemblage-wide impacts of species abundance distributions may multiply with repeated cycles of recruitment and density-dependent seedling mortality and impact forest diversity or the abundance of individual species over longer time scales.     

Habitat quality and heterogeneity influence distribution and behavior in African buffalo (Syncerus caffer)

Top-down effects of predators on prey behavior and population dynamics have been extensively studied. However, some populations of very large herbivores appear to be regulated primarily from the bottom up. Given the importance of food resources to these large herbivores, it is reasonable to expect that forage heterogeneity (variation in quality and quantity) affects individual and group behaviors as well as distribution on the landscape. Forage heterogeneity is often strongly driven by underlying soils, so substrate characteristics may indirectly drive herbivore behavior and distribution. Forage heterogeneity may further interact with predation risk to influence prey behavior and distribution. Here we examine differences in spatial distribution, home range size, and grouping behaviors of African buffalo as they relate to geologic substrate (granite and basalt) and variation in food quality and quantity. In this study, we use satellite imagery, forage quantity data, and three years of radio-tracking data to assess how forage quality, quantity, and heterogeneity affect the distribution and individual and herd behavior of African buffalo. We found that buffalo in an overall poorer foraging environment keyed-in on exceptionally high-quality areas, whereas those foraging in a more uniform, higher-quality area used areas of below-average quality. Buffalo foraging in the poorer-quality environment had smaller home range sizes, were in smaller groups, and tended to be farther from water sources than those foraging in the higher-quality environment. These differences may be due to buffalo creating or maintaining nutrient hotspots (small, high-quality foraging areas) in otherwise low-quality foraging areas, and the location of these hotspots may in part be determined by patterns of predation risk.     

Trace-level measurement of complex combustion effluents and residues using multidimensional gas chromatography-mass spectrometry (MDGC-MS)

The identification and quantitation of non-method-specific target analytes have greater importance with respect to EPA's current combustion strategy. The risk associated with combustion process emissions must now be characterized. EPA has recently released draft guidance on procedures for the collection of emissions data to support and augment site-specific risk assessments (SSRAs) as part of the hazardous waste incineration permitting process. This guidance includes methodology for quantifying total organic (TO) emissions as a function of compound volatility. The ultimate intent is to compare the amount of organic material identified and quantified by target analyte-specific methodologies to organic emissions quantified by the TO methodology. The greater the amount accounted for by the target analyte-specific methodologies, the less uncertainty may be associated with the SSRAs. A limitation of this approach is that the target analyte-specific methodologies do not routinely quantify compounds of low toxicological interest; nor do they target products of incomplete combustion (PICs). Thus, the analysis can miss both toxic and non-toxic compounds. As a result, it is unknown whether the uncharacterized fraction of the TO emission possesses toxic properties. The hypothesis that we propose to test is that organic emissions and organics extracted from particulate matter (PM) are more complex than standard GC-MS-based instrumentation can currently measure. This complexity can affect quantitation for toxic compounds, thereby potentially affecting risk assessments. There is a pressing need to better characterize these organic emissions from hazardous waste incinerators and PM extracts from various other combustion sources. We will demonstrate that multidimensional gas chromatography-mass spectrometry (MDGC-MS) procedures significantly improve chromatographic separation for complex environmental samples. Sequential repetitive heart-cutting MDGC, with coupled mass spectrometry will be shown to be a complete analysis technique. The ability of this technique to disengage components from complex mixtures taken from hazardous and municipal waste incinerators will be shown.     

Prenatal diagnosis of congenital cytomegalovirus infection: False-negative amniocentesis at 20 weeks' gestation

Cytomegalovirus (CMV) is the most common cause of congenital infection. Recent studies show amniocentesis to be a 100 per cent sensitive and 100 per cent specific predictor of congenital infection, and recommend that it be offered in the at-risk pregnancy. However, these publications have focused on pregnancies at or beyond 22 weeks' gestation. Here, we report a case of maternal CMV hepatitis at 7–8 weeks' gestation, in which culture and polymerase chain reaction testing for CMV in amniotic fluid at 20 weeks' gestation were negative, but the infant had a positive CMV urine culture shortly after delivery. Implications for the prenatal diagnosis of CMV infection are discussed.