Different collector types for sampling deposition of polycyclic aromatic hydrocarbons--comparison of measurement results and their uncertainty

Different collector types, sample workup procedures and analysis methods to measure the deposition of polycyclic aromatic hydrocarbons (PAH) were tested and compared. Whilst sample workup and analysis methods did not influence the results of PAH deposition measurements, using different collector types changed the measured deposition rates of PAH significantly. The results obtained with a funnel-bottle collector showed the highest deposition rates and a low measurement uncertainty. The deposition rates obtained with the wet-only collectors were the lowest at industrial sites and under dry weather conditions. For the open-jar collectors the measurement uncertainty was high. Only at an industrial site with extremely high PAH deposition rates the results of open-jar collectors were comparable to those obtained with funnel-bottle collectors. Thus, if bulk deposition of PAH has to be measured, funnel-bottle combinations are proved to be the collectors of choice. These collectors were the only ones always fulfilling the requirements of European legislation.     

Verifying emission factors and national POPs emission inventories for the UK using measurements and modelling at two rural locations

Different approaches are used to verify the adequacy of emission factors (EFs) and their use in emission inventories of persistent organic pollutants (POPs). The applicability of EFs was tested using atmospheric dispersion modelling to predict atmospheric concentrations of polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), dibenzo-p-dioxins (PCDDs) and dibenzofurans (PCDFs) and resulting toxic equivalents (SigmaTEQ) and particulate matter <10 microm (PM(10)) in two rural locations in northern England (UK). The modelling was based on general assumptions of fuel composition, consumption and heating needs to simulate emissions of POPs from the domestic burning of coal and wood where ambient measurements were made in the winter of 1998. The model was used to derive the local contribution to ambient air concentrations, which were estimated independently based on comparative air measurements. The results support the hypothesis that in both villages, the majority of PAHs and the lower chlorinated PCDFs were locally released. The situation for PCBs and polychlorinated naphthalenes (PCNs) was different. While the EFs show the release of both compound groups from the domestic burning of coal and wood, the ambient levels of these "legacy POPs" in the villages were still clearly dominated by other sources. Rural areas relying mainly on fossil fuels can exceed the proposed UK ambient air quality standard for benzo[a]pyrene during winter. The measured EFs were then used to estimate the importance of the domestic burning of coal and wood to national emission inventories for these compound classes. Extrapolations to the UK suggest that the domestic burning of pure wood and coal were minor emitters for chlorinated POPs but contributed strongly to PAH and PM(10) levels in 2000. Finally, the UK's national POPs emission inventories based on source inventories and EF, as used here, were compared to estimates derived using the increase in atmospheric concentration of selected POPs.     

Distribution of the Lamellibrachia spp. (Siboglinidae,Annelida) and their trophosome endosymbiont phylotypes in the Mediterranean Sea

During the 2010/2011 Exploration vessel Nautilus expedition to the Mediterranean Sea, samples of Lamellibrachia (Siboglinidae, Annelida) were imaged in situ and collected from hydrothermal vent and methane “cold seeps.” An analysis of these Lamellibrachia and their endosymbiotic thioautotrophic gammaproteobacteria reveals two distinct endosymbiont phylotypes. Phylotype 1 was present in Lamellibrachia specimens from 947 m at the Eratosthenes seamount seep (a seep off Cyprus in the Eastern Mediterranean), and Phylotype 2 was found in siboglinids from 618 m at a hydrothermal vent within Palinuro volcanic complex in Tyrrhenian Sea. Both phylotypes coexist in siboglinids at 1,036 m from the Palmachim disturbance, a cold seep in the Eastern Mediterranean’s Levantine basin. Our results, combined with existing knowledge of siboglinid host and endosymbiotic bacteria biogeography, reveal that two major groups of endosymbionts coexist within lamellibranchids and escarpids. The phylogenetic clustering of these bacteria is primarily influenced by geographic location, rather than selection by the siboglinid host.     

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.     

Flux by fin: fish-mediated carbon and nutrient flux in the northeastern Gulf of Mexico

Seagrass meadows are among the most productive ecosystems in the marine environment. It has been speculated that much of this production is exported to adjacent ecosystems via the movements of organisms. Our study utilized stable isotopes to track seagrass-derived production into offshore food webs in the northeastern Gulf of Mexico. We found that gag grouper (Myctereoperca microlepis) on reefs as far as 90 km from the seagrass beds incorporate a significant portion of seagrass-derived biomass. The muscle tissue of gag grouper, a major fisheries species, was composed on average of 18.5–25% seagrass habitat-derived biomass. The timing of this annual seagrass subsidy appears to be important in fueling gag grouper egg production. The δ³⁴S values of gag grouper gonad tissues varied seasonally and were δ³⁴S depleted during the spawning season indicating that gag utilize the seagrass-derived biomass to support reproduction. If such large scale trophic subsidies are typical of temperate seagrass systems, then loss of seagrass production or habitat would result in a direct loss of offshore fisheries productivity.     

Econometric modeling of fisheries with complex life histories: Avoiding biological management failures

Economics of the fishery has focused on the wastefulness of common pool resource exploitation. Pure open access fisheries dissipate economic rents and degrade biological stocks. Biologically managed fisheries also dissipate rents but are thought to hold biological stocks at desired levels. We develop and estimate an empirical bioeconomic model of the Gulf of Mexico gag fishery that questions the presumptive success of biological management. Unlike previous bioeconomic life history studies, we provide a way to circumvent calibration problems by embedding our estimation routine directly in the dynamic bioeconomic model. We nest a standard biological management model that accounts for complex life history characteristics of the gag. Biological intuition suggests that a spawning season closure will reduce fishing pressure and increase stocks, and simulations of the biological management model confirm this finding. However, simulations of the empirical bioeconomic model suggest that these intended outcomes of the spawning closure do not materialize. The behavioral response to the closure appears to be so pronounced that it offsets the restriction in allowable fishing days. Our results indicate that failure to account for fishing behavior may play an important role in fishery management failures.     

Aging and demographic plasticity in response to experimental age structures in honeybees (<Emphasis Type="Italic">Apis mellifera</Emphasis> L)

Honeybee colonies are highly integrated functional units characterized by a pronounced division of labor. Division of labor among workers is mainly age-based, with younger individuals focusing on in-hive tasks and older workers performing the more hazardous foraging activities. Thus, experimental disruption of the age composition of the worker hive population is expected to have profound consequences for colony function. Adaptive demography theory predicts that the natural hive age composition represents a colony-level adaptation and thus results in optimal hive performance. Alternatively, the hive age composition may be an epiphenomenon, resulting from individual life history optimization. We addressed these predictions by comparing individual worker longevity and brood production in hives that were composed of a single-age cohort, two distinct age cohorts, and hives that had a continuous, natural age distribution. Four experimental replicates showed that colonies with a natural age composition did not consistently have a higher life expectancy and/or brood production than the single-cohort or double-cohort hives. Instead, a complex interplay of age structure, environmental conditions, colony size, brood production, and individual mortality emerged. A general tradeoff between worker life expectancy and colony productivity was apparent, and the transition from in-hive tasks to foraging was the most significant predictor of worker lifespan irrespective of the colony age structure. We conclude that the natural age structure of honeybee hives is not a colony-level adaptation. Furthermore, our results show that honeybees exhibit pronounced demographic plasticity in addition to behavioral plasticity to react to demographic disturbances of their societies.     

Impact of marine protected areas on temporal stability of fish species diversity

Preserving biodiversity over time is a pressing challenge for conservation science. A key goal of marine protected areas (MPAs) is to maintain stability in species composition, via reduced turnover, to support ecosystem function. Yet, this stability is rarely measured directly under different levels of protection. Rather, evaluations of MPA efficacy generally consist of static measures of abundance, species richness, and biomass, and rare measures of turnover are limited to short-term studies involving pairwise (beta diversity) comparisons. Zeta diversity is a recently developed metric of turnover that allows for measurement of compositional similarity across multiple assemblages and thus provides more comprehensive estimates of turnover. We evaluated the effectiveness of MPAs at preserving fish zeta diversity across a network of marine reserves over 10 years in Batemans Marine Park, Australia. Snorkel transect surveys were conducted across multiple replicated and spatially interspersed sites to record fish species occurrence through time. Protection provided by MPAs conferred greater stability in fish species turnover. Marine protected areas had significantly shallower decline in zeta diversity compared with partially protected and unprotected areas. The retention of harvested species was four to six times greater in MPAs compared with partially protected and unprotected areas, and the stabilizing effects of protection were observable within 4 years of park implementation. Conversely, partial protection offered little to no improvement in stability, compared with unprotected areas. These findings support the efficacy of MPAs for preserving temporal fish diversity stability. The implementation of MPAs helps stabilize fish diversity and may, therefore, support biodiversity resilience under ongoing environmental change.