Demographic impact of introducing modern medicine to a subsistence-level agrarian population: A simulation

Typical of many peasant communities in the Third World, the highland Indian population of Nuñoa, Peru operates close to its capacity for providing members with adequate nutrition. High birth and mortality rates maintain population stability in groups such as this. The introduction of modern medical services could decrease mortality and stimulate population growth, thus upsetting stability of the population size.Development of Third World countries includes improving health of subsistence-level populations by providing modern medical services. However, such changes would have secondary effects which should be anticipated. Using the Nuñoa population as a representative data base, and making a number of simplifying assumptions to increase the generality of this case, a simulation model has been devised to explore some of the consequences of introducing modern medical services.The model predicts that decreased mortality would initiate population growth. Some growth would be supported by changes in individual consumption patterns. But unless decreases in birth rate stabilized the population, it would increase beyond the level sustainable by local resources. Starvation or emigration would cause the population to crash. The model identifies several strategies for reducing birth rate sufficiently to avoid a population crash. Despite these strategies, increased equilibrium size of population would reduce per capita consumption. Since the population lives at the subsistence level, hardship, hunger, and even starvation could result. Thus, introduction of modern medical services could involve a trade-off between short-term improvements in health and. long-term economic hardship for the population. The model suggests that improved well-being of the population would require not only modern medical services but also (a) reduced birth rates; and (b) the improved technology necessary to increase food production.     

Cell surface-expression of the phosphate-binding protein PstS: System development, characterization, and evaluation for phosphorus removal and recovery

Simultaneous overabundance and scarcity of inorganic phosphate(P_i) is a critical issue driving the development of innovative water/wastewater treatment technologies that not only facilitate Pi removal to prevent eutrophication,but also recover P_i for agricultural reuse.Here,a cell-surface expressed high-affinity phosphate binding protein(PstS) system was developed,and its P_i capture and release potential was evaluated.E.coli was genetically modified to express PstS on its outer membrane using the ice nucleation protein(INP)as an anchoring motif.Verification of protein expression and localization were performed utilizing SDS-polyacrylamide gel electrophoresis(SDS-PAGE),western blot,and outer membrane separation analyses.Cell surface characterization was investigated through acid-base titration,X-ray photoelectron spectroscopy(XPS),and Fourier transform infrared spectroscopy(FTIR).These tests provided information on the macromolecular structure and composition of the bacteria surface as well as the proton-exchange properties of the surface functional groups(i.e.,pKa values).Phosphate desorption and adsorption batch experiments were conducted to evaluate the effects of temperature,pH,and ionic strength on phosphate capture and release.The PstS surface-displayed cells demonstrated greater potential to release and capture phosphate compared to non-modified cells.Higher temperatures up to 40℃,basic pH conditions(pH=10.5),and higher ionic strength up to 1.0 mol/L KCl promoted 20%-50% higher phosphate release.     

Reproductive periodicity of the scleractinian coral Lophelia pertusa from the Trondheim Fjord, Norway

Between 2002 and 2008, samples of the cold-water scleractinian coral Lophelia pertusa were collected from the Trondheim Fjord in Norway to examine reproductive periodicity. Collections were made from three locations: Tautra, (63°35.36′N, 10°31.23′E at 40–70 m), Stokkbergneset (63°28.18′N, 09°54.73′E at 110–500 m), and Røberg (63°28.88′N, 09°59.50′E at 250 m). Populations of L. pertusa from the Trondheim Fjord initiated oogenesis in January and spawning occurred from late January to early March the following year. Gametogenic cycles of the female L. pertusa samples overlapped by approximately 2 months, with oogonia visible in January, but this was not evident in the males. This paper provides the most complete gametogenic cycle to date and spawning observations for this important structure-forming species. The results from fjord populations are compared with published and preliminary data from other regions and are discussed in the context of regional differences in physical and biological variables, particularly food supply. Differences in gametogenic cycles within a single species provide a rare opportunity (especially in deep-sea species) to examine potential drivers of reproduction.     

Leaf Litterbag Sampling for Larval Plethodontid Salamander Populations in Georgia

Survey techniques for larval salamanders vary in their effectiveness and efficiencies. In this study, the leaf litterbag sampling technique was employed to gather data on larval salamander populations in perennial streams of southern Georgia. Salamanders were collected monthly for 12 months to analyze capture counts and population size-class structure. Simultaneous dipnet sweep data were used to examine potential count data biases of the leaf litterbag sampling technique. In both leaf litterbag and dipnet sweep surveys, adult and larval Southern Two-lined Salamanders (Eurycea cirrigera) and larval Southern Red Salamanders (Pseudotriton ruber) were sampled. In leaf litterbags, larval E. cirrigera were captured most frequently, followed by adult E. cirrigera and larval P. ruber, respectively. However, the efficiency of collecting adult E. cirrigera and larval P. ruber could not be determined because of small sample sizes. Larval E. cirrigera counts detected from leaf litterbags were frequently lower than those associated with dipnet sweeps, suggesting that the former may underestimate larval salamander counts. Leaf litterbags successfully detected all E. cirrigera size-classes (i.e., first-year, second-year, and adult), further indicating that larvae in Georgia spend 2 years in the aquatic phase. Leaf litterbags are an effective method of sampling larval salamanders when used to assess species assemblage and age-class distribution.     

A case study of bats and white‐nose syndrome demonstrating how to model population viability with evolutionary effects

Ecological factors generally affect population viability on rapid time scales. Traditional population viability analyses (PVA) therefore focus on alleviating ecological pressures, discounting potential evolutionary impacts on individual phenotypes. Recent studies of evolutionary rescue (ER) focus on cases in which severe, environmentally induced population bottlenecks trigger a rapid evolutionary response that can potentially reverse demographic threats. ER models have focused on shifting genetics and resulting population recovery, but no one has explored how to incorporate those findings into PVA. We integrated ER into PVA to identify the critical decision interval for evolutionary rescue (DIER) under which targeted conservation action should be applied to buffer populations undergoing ER against extinction from stochastic events and to determine the most appropriate vital rate to target to promote population recovery. We applied this model to little brown bats (Myotis lucifugus) affected by white‐nose syndrome (WNS), a fungal disease causing massive declines in several North American bat populations. Under the ER scenario, the model predicted that the DIER period for little brown bats was within 11 years of initial WNS emergence, after which they stabilized at a positive growth rate (λ = 1.05). By comparing our model results with population trajectories of multiple infected hibernacula across the WNS range, we concluded that ER is a potential explanation of observed little brown bat population trajectories across multiple hibernacula within the affected range. Our approach provides a tool that can be used by all managers to provide testable hypotheses regarding the occurrence of ER in declining populations, suggest empirical studies to better parameterize the population genetics and conservation‐relevant vital rates, and identify the DIER period during which management strategies will be most effective for species conservation.     

Gametogenic periodicity in the chemosynthetic cold-seep mussel “<Emphasis Type="Italic">Bathymodiolus” childressi</Emphasis>

The gametogenic periodicity of the cold seep mussel “Bathymodiolus” childressi was analysed from a time series of samples from depths of ∼ 650 m surrounding the Brine Pool cold seep on the continental slope of the northern Gulf of Mexico. Occasional samples were retrieved from Bush Hill and GC 234 for comparison. At the Brine Pool, both females and males showed strong reproductive periodicity with the initiation of gametogenesis from December to March, followed by a period of gamete growth or proliferation and spawning from October to February. Gametogenesis was synchronized at all three sites. Gametogenic periodicity appears to be correlated with surface production that peaks during the winter months. Downward flux of detritus during this period may provide food for the planktotrophic larvae and also supplementary nutrition for the adult, which has chemosynthetic bacterial symbionts but is also capable of filter feeding. Individuals in all three populations carried parasites and these were especially common at Bush Hill and GC234, where it is suggested they have a major impact on reproductive output.     

Engineered containment systems: Identification of dominant ecological processes for long‐term performance assessment and monitoring

The infiltration of rainfall into contaminated soils and wastes provides the mechanism whereby hazardous chemical and radionuclide constituents of concern are leached and transported to underlying groundwater and potential human and ecological receptors. The application of engineered covers to reduce rainfall infiltration is an approach that is often selected for the remediation of contaminated sites. Evapotranspiration, or water‐balance, cover designs have been shown to be effective ways of preventing infiltration in arid and semiarid climates. This particular design relies on evaporation and vegetative transpiration to reduce potential infiltration to acceptable levels. In this article, we identify and examine the dominant ecological processes that affect the performance of evapotranspiration cover designs. © 2012 Wiley Periodicals, Inc.     

Gametogenesis, spawning behavior, and early development in the “iceworm”Hesiocaeca methanicola (Polychaeta: Hesionidae) from methane hydrates in the Gulf of Mexico

Gametogenesis, spawning behavior, and early development have been described in the methane-seep polychaete Hesiocaecamethanicola Desbruyères and Toulmond, 1998, the first documentation of the reproductive biology of any cold-seep polychaete species. The worms were collected at the Green Canyon site in the Gulf of Mexico (27°44.77N; 91°13.33W) in August 1997. The gonads are situated in the neuropodia in association with an intraepithelial capillary system. Oogenesis is intraovarian, with oocytes remaining in the ovary until late vitellogenesis when they are released into the coelom for final growth and differentiation. Vitellogenesis involves both autosynthetic and heterosynthetic processes and, along with ovarian structure, suggests a relatively slow process of egg formation. Sperm differentiation is intertesticular until early spermiogenesis, when spermatid tetrads complete development in the coelom. The mature spermatozoon is an ect-aquasperm consisting of a tapering, digitate acrosome, a spherical nucleus, a midpiece containing from six to eight mitochondria and glycogen stores, and two centrioles associated with the flagellum. Both sexes undergo broadcast spawning, but the males spawn exclusively through the anus, a behavior previously unknown in polychaetes. Artificial fertilization resulted in spiral cleavage and development to the trochophore stage. Oocyte size-frequency analysis of adult females indicates a wide range of oocyte sizes and vitellogenic stages, suggesting that asynchronous gametogenesis occurs. Received: 13 July 2000 / Accepted: 29 November 2000     

Sampling and Analysis of Volatile Organic Compounds Evolved During Thermal Processing of Acrylonitrile Butadiene Styrene Composite Resins

Abstract

The evaluation of emissions of volatile organic compounds (VOCs) during processing of resins is of interest to resin manufacturers and resin processors. An accurate estimate of the VOCs emitted from resin processing has been difficult due to the wide variation in processing facilities. This study was designed to estimate the emissions in terms of mass of emitted VOC per mass of resin processed.

A collection and analysis method was developed and validated for the determination of VOCs present in the emissions of thermally processed acrylonitrile butadiene styrene (ABS) resins. Four composite resins were blended from automotive, general molding, pipe, and refrigeration grade ABS resins obtained from the manufacturers. Emission samples were collected in evacuated 6-L Summa canisters and then analyzed using gas chromatography/flame ionization detection/mass selective detection (GC/FID/MSD). Levels were determined for nine target analytes detected in canister samples, and for total VOCs detected by an inline GC/FID. The emissions evolved from the extrusion of each composite resin were expressed in terms of mass of VOCs per mass of processed resin. Styrene was the principal volatile emission from all the composite resins. VOCs analyzed from the pipe resin sample contained the highest level of styrene at 402 μg/g. An additional collection and detection method was used to determine the presence of aerosols in the emissions. This method involved collecting particulates on glass fiber filters, extracting them with solvents, and analyzing them using gas chromatography/mass spectrometry (GC/MS). No significant levels of any of the target analytes were detected on the filters.