Application of a Life Cycle Simulation Model to Evaluate Impacts of Water Management and Conservation Actions on an Endangered Population of Chinook Salmon

Fisheries and water resource managers are challenged to maintain stable or increasing populations of Chinook salmon in the face of increasing demand on the water resources and habitats that salmon depend on to complete their life cycle. Alternative management plans are often selected using professional opinion or piecemeal observations in place of integrated quantitative information that could reduce uncertainty in the effects of management plans on population dynamics. We developed a stochastic life cycle simulation model for an endangered population of winter-run Chinook salmon in the Sacramento River, California, USA with the goal of providing managers a tool for more effective decision making and demonstrating the utility of life cycle models for resource management. Sensitivity analysis revealed that the input parameters that influenced variation in salmon escapement were dependent on which age class was examined and their interactions with other inputs (egg mortality, Delta survival, ocean survival). Certain parameters (river migration survival, harvest) that were hypothesized to be important drivers of population dynamics were not identified in sensitivity analysis; however, there was a large amount of uncertainty in the value of these inputs and their error distributions. Thus, the model also was useful in identifying future research directions. Simulation of variation in environmental inputs indicated that escapement was significantly influenced by a 10% change in temperature whereas larger changes in other inputs would be required to influence escapement. The model presented provides an effective demonstration of the utility of life cycle simulation models for decision making and provides fisheries and water managers in the Sacramento system with a quantitative tool to compare the impact of different resource use scenarios.     

Long-term dynamic of forest vegetation after reduction of copper smelter emissions

The state of tree and ground vegetation layers in spruce-fir forests around the Middle Ural Copper Smelter (Revda, Sverdlovsk oblast) has been repeatedly evaluated in 25 permanent sampling plots at 5- to 10-year intervals (1989–2013). The results have been used to characterize the dynamics of plant communities in the period of reduction of emissions from the smelter. Although the annual amount of emissions has decreased from 150–225 × 10³ t in the 1980s to less than 5 × 10³ t after 2010, the vegetation in the impact zone (1 and 2 km from the smelter) remains severely suppressed: the trees continue to die off, and the diversity of ground vegetation layer is very low. In zones with low and moderate levels of industrial pollution (30 and 4–7 km from the smelter), natural factors associated with windfall disturbance after the 1995 windstorm with snow have played a more important role in the dynamics of forest communities than the reduction of emissions itself.     

Intracellular cyanobiont Richelia intracellularis: ultrastructure and immuno-localisation of phycoerythrin,nitrogenase, Rubisco and glutamine synthetase

In marine tropical or subtropical plankton the filamentous, heterocyst-forming cyanobacterium Richelia intracellularis forms a symbiosis with the diatom Rhizosolenia clevei. An ultrastructural analysis of the apex of Rhizosolenia clevei showed that the cytoplasm in that particular part of the cell was present only where the cyanobiont was located. The cyanobiont was, however, always outside the host cytoplasm. Vegetative cells as well as the heterocysts of the cyanobiont were devoid of gas vesicles and cyanophycin granules, while carboxysomes and large glycogen granules were common. The cyanobacterial cell wall apparently remained intact in both vegetative and heterocyst cells. In green excitation light the heterocysts and vegetative cells emitted a bright yellow fluorescence, indicating that both cell types possessed high concentrations of the pigment phycoerythrin (PE) commonly associated with photosystem (PS) II. The presence of this pigment in both cell types was verified by immunogold localisation. Using the same technique, the nitrogenase (dinitrogenase reductase) enzyme was shown to be exclusively present in the heterocysts, while Rubisco was localised primarily to the carboxy-somes, which were only detected in vegetative cells. Using an antiserum against the ammonia assimilating enzyme glutamine synthetase (GS), we could demonstrate very low levels of this enzyme, indicating repression of GS in the cyanobiont.     

Determining gestational age using genome methylation profile: A novel approach for fetal medicine

Gestational age determination by traditional tools (last menstrual period, ultrasonography measurements and Ballard Maturational Assessment in newborns) has major limitations and therefore there is a need to find different approaches. In this study, we looked for a molecular marker that can be used to determine the accurate gestational age of the newborn. To this end, we performed reduced representation bisulfite sequencing (RRBS) on 41 cord blood and matching placenta samples from women between 25 and 40 weeks of gestation and generated an epigenetic clock based on the methylation level at different loci in the genome. We identified a set of 332 differentially methylated regions (DMRs) that undergo demethylation in late gestational age in cord blood cells and can predict the gestational age (r = −.7, P = 2E-05). Once the set of 411 DMRs that undergo de novo methylation in late gestational age was used in combination with the first set, it generated a more accurate clock (R = .77, P = 1.87E-05). We have compared gestational age determined by Ballard score assessment with our epigenetic clock and found high concordance. Taken together, this study demonstrates that DNA methylation can accurately predict gestational age and thus may serve as a good clinical predictor.     

Three lessons conservation science can learn from the COVID-19 pandemic

Article impact statement: COVID-19 has demonstrated the need to optimize research activity, convey the gravity of loss, and reevaluate merit in conservation science.     

1,2,3,5,6,7-Hexachloronaphthalene and 1,2,3,4,6,7-hexachloronaphthalene - selective retention in rat liver and appearance in wildlife

The two isomers 1,2,3,5,6,7- and 1,2,3,4,6,7-hexachloronaphthalene are shown to be selectively retained in the liver of rats orally dosed with the commercial PCN product Halowax 1014. The retention was further studied by dosing rats orally with a mixture of the two compounds. The rats were sacrificed after 1, 10, 35 and 120 days, respectively. The two hexachloronaphthalenes were found to be strongly retained in the liver and the concentration ratios liver/adipose tissue were remarkably high. 1,2,3,5,6,7- And 1,2,3,4,6,7-hexachloronaphthalene were also found to be present in two environmental samples from the Swedish east coast, cod liver and guillemot egg.     

We're all in this together…except for you: The effects of workload,performance feedback,and racial distance on helping behavior in teams

We draw from social categorization theory and the actor–observer hypothesis to extend previous research regarding receiving high levels of help from team members. Specifically, we explore how a team member's performance feedback on how they handled a disproportionately heavy share of the team's workload and how their racial distance from the rest of their teammates affect the amount of helping that person receives from their teammates. Results from a laboratory study in which 79 teams worked on a computerized, decision‐making task demonstrated a three‐way interaction between workload, performance feedback, and the racial distance between the feedback recipient and the rest of their teammates. Racially distant negative feedback recipients who had a disproportionately heavy share of their team's workload received less help from teammates than their racially similar counterparts. Copyright © 2012 John Wiley & Sons, Ltd.     

Placental transfer of polychlorinated biphenyls, their hydroxylated metabolites and pentachlorophenol in pregnant women from eastern Slovakia

The aim of the present study was to understand the placental transfer of polychlorinated biphenyls (PCBs), specific hydroxylated PCB metabolites (OH-PCBs), and pentachlorophenol (PCP) in blood serum, in a birth cohort from eastern Slovakia. During the period 2002-2004, cord blood specimens were collected in parallel with maternal specimens from women delivering in the two eastern Slovak districts of Michalovce and Svidnik/Stropkov. A total of 92 pairs of mother-cord specimens at delivery were selected for this study. 4-OH-CB107, 3-OH-CB153, 4-OH-CB146, 3'-OH-CB138, 4-OH-CB187, and 4'-OH-CB172 were quantified. The median concentrations of Sigma(17)PCBs, Sigma(6)OH-PCBs, and PCP in cord serum were 0.92, 0.33, and 0.69 ng/g wet wt., respectively and highly correlated with the corresponding maternal serum levels (correlations were R(2)=0.61, 0.78, and 0.82, respectively). The median cord to mother ratios of the Sigma(17)PCBs, Sigma(6)OH-PCBs, and PCP were 0.18, 0.75, and 1.10, respectively. The median ratio of the Sigma(6)OH-PCBs to the Sigma(17) PCBs in the cord serum was 0.38 from wet weight based concentrations, which was about four times higher than the ratio of these compounds in maternal serum (0.09). PCP was more abundant than any PCB or OH-PCB congener measured in cord serum. The higher cord to maternal ratios of OH-PCB metabolites as compared with the parent compounds suggests either a higher placental transfer rate or greater metabolism in the fetus as compared with the maternal compartment. These findings are consistent with their preferential binding to TTR that can cross the placenta. The cord to maternal ratio varies by congener (e.g., 4-OH-CB107=0.58, 4-OH-CB146=0.74, 3'-OH-CB138=1.01).     

Evidence-Based Knowledge Versus Negotiated Indicators for Assessment of Ecological Sustainability: The Swedish Forest Stewardship Council Standard as a Case Study

Assessing ecological sustainability involves monitoring of indicators and comparison of their states with performance targets that are deemed sustainable. First, a normative model was developed centered on evidence-based knowledge about (a) forest composition, structure, and function at multiple scales, and (b) performance targets derived by quantifying the habitat amount in naturally dynamic forests, and as required for presence of populations of specialized focal species. Second, we compared the Forest Stewardship Council (FSC) certification standards’ ecological indicators from 1998 and 2010 in Sweden to the normative model using a Specific, Measurable, Accurate, Realistic, and Timebound (SMART) indicator approach. Indicator variables and targets for riparian and aquatic ecosystems were clearly under-represented compared to terrestrial ones. FSC’s ecological indicators expanded over time from composition and structure towards function, and from finer to coarser spatial scales. However, SMART indicators were few. Moreover, they poorly reflected quantitative evidence-based knowledge, a consequence of the fact that forest certification mirrors the outcome of a complex social negotiation process.     

Analysis of mono- to deca-brominated diphenyl ethers in chickens at the part per billion level

Polybrominated diphenyl ethers (PBDEs) are flame retardants which have been found to be increasing in the environment. Because of structural similarities to the polychlorinated biphenyls and concerns that PBDEs may be widespread, we have investigated their presence in a food source, namely chickens. A GC-MS method was developed to analyze mono- through deca-BDEs in chicken fat samples. The method utilized GC pressure programming and selected ion monitoring to quantitate PBDEs at the low part per billion level. Four 13C-labeled surrogates were used to determine recoveries; recoveries averaged from 76% to 114%. Thirteen chickens from the Southern US and a composite sample of chickens from North Dakota were analyzed by this method. The total concentrations of PBDEs on a whole weight basis ranged from 1.7 ppb in North Dakota chickens to 39.4 ppb in a chicken from Arkansas. On a lipid weight basis, these levels were lower than those generally found in fish and fish-eating mammals. The PBDE pattern was also different from other samples reported; penta-BDEs rather than tetra-BDEs were the most prominent congeners.