Gonad morphology, sexual development, and colony composition in the obligate coral-dwelling damselfish Dascyllus aruanus

Gonad morphology and colony composition support the existing supposition that the obligate coral-dwelling damselfish Dascyllus aruanus has a protogynous hermaphroditic sexual pattern. Adults had either an active ovary containing vitellogenic oocytes, an ovotestis, or a spermiated testis and were classified as adult female, hermaphrodite, or adult male, respectively. Among individuals having male function, the testis (or testis portion of the ovotestis) takes the form of an unrestricted spermatogonial lobular testis. Among hermaphrodites having an ovotestis, a small proportion of individuals had a gonad in which both the ovarian and testicular portions were inactive (inactive hermaphrodites), whereas the majority had a predominantly testicular ovotestis that contained spermatozoa (male-active hermaphrodites). The size range of individuals within gonadal classes indicates that all D. aruanus first develop an ovariform gonad. Some individuals then undergo ovarian maturation to become adult females while others develop testicular tissue to form an ovotestis and become male-active hermaphrodites. Subsequently, progressive loss of ovarian tissue results in the development of a secondary testis from an ovotestis with the retention of a residual, afunctional lumen among adult males. The wide size range of individuals having an ovotestis suggests that some hermaphrodites function as adult females before developing testicular tissue while other individuals do not pass through an adult female stage. If this is the case, D. aruanus exhibits a diandric protogynous hermaphroditic sexual pattern. The apparent prolonged retention of an ovotestis with both healthy oocytes and an ovarian-type lumen in a spermiated ovotestis, as well as a functional sex ratio of 1:1 for adult females:adult males plus male-active hermaphrodites also raises the possibility that D. aruanus may be capable of bidirectional sex change during the hermaphroditic stage. Such a capability would be highly adaptive for a species having limited mobility and unpredictable recruitment of new colony members resulting in unpredictable mating opportunities.     

Alphafetoprotein,cholinesterases and rapidly adhering cells in the prenatal diagnosis of neural tube defects

Amniotic fluid cholinesterases tested on polyacrylamide gel and rapidly adhering cell analysis were compared in their efficiency at diagnosing fetal neural tube defects in three cases where the alphafetoprotein results were equivocal. While rapidly adhering cells were also equivocal, the cholinesterases consistently gave a clear indication of fetal abnormality.     

Optimum macrobenthic sampling protocol for detecting pollution impacts in the Southern California Bight

The optimum macrobenthic sampling protocol [sampling unit, sieve mesh size, and sample size (n)] was determined for detecting ecologically important pollution impacts in the Southern California Bight, U.S.A. Cost, in laboratory processing time, was determined for samples obtained using fourteen sampling units (0.005–0.1 m² surface area) and two sieve mesh sizes (1.0 and 0.5 mm). Statistical power analyses for t-tests of means were performed to estimate the minimum sample size (n _min) needed to reliably (=0.05, 1–0.95) reject the null hypothesis of no difference between a reference and both a stimulated and a degraded station on twelve measures of community structure. The optimum sampling protocol for detecting impacts was determined as that with the lowest total cost ×n _min on most measures.Five replicate, 0.02 m²×5 cm deep, 1.0 mm mesh samples per station could reliably distinguish reference from impacted conditions on nine or ten measures of community structure at less than one quarter of the cost of the standard sampling protocol of 5 replicate, 0.1 m², 1.0 mm mesh samples per station. About 5 replicate, small (<0.1 m²), 1.0 mm mesh samples per station may often be optimal for detecting important structural changes in macrobenthic communities with naturally high species richness and abundance.     

Are followers satisfied with conscientious leaders? The moderating influence of leader role authenticity

Leadership scholars have yet to identify a clear and consistent relationship between leader conscientiousness and followers' satisfaction with a leader. Drawing from socioanalytic theory and related personality research, we argue that the underlying motives of leader conscientiousness can manifest in systematically different behaviors aimed at team task accomplishment, ranging from rigid and order‐driven to relatively more adaptable approaches. Importantly, we posit that the relationship between a leader's conscientiousness and adaptability is conditioned by role authenticity (i.e., the extent to which a leader believes a role permits expressions of her or his “true self”). Hence, we articulate a conditional indirect effects model whereby leader conscientiousness and leader role authenticity jointly predict leader adaptability and, in turn, increasing levels of leader adaptability are positively associated with followers' shared satisfaction with their leader. Data from a sample of fire and rescue crews provide partial support for the model. Post hoc analyses suggest that the conditioning influence of leader role authenticity on leader conscientiousness is more informative when subfacets of conscientiousness are considered.     

A Review of Techniques Available for Estimating Short-Term NO2 concentrations

The Environmental Protection Agency is reviewing the need for a short-term NO₂ standard based on an averaging time of three hours or less. State Implementation plans and New Source Reviews will require air quality simulation techniques capable of estimating ambient NO₂ concentrations. There is a need for multi-source (urban) models and for point source models.

A review of currently available techniques for the estimation of NO₂ concentrations resulting from NO_x point sources is presented. The available methods include simple screening techniques and refined reactive plume models. The screening techniques first use a standard gaussian dispersion model to estimate the maximum 1 hr NO_x concentration caused by the source. The second step involves estimating the fraction of this NO* concentration occurring as NO₂.

Reactive plume models numerically simulate the simultaneous effects of dispersion and chemistry on NO₂ concentrations. Organic as well as inorganic reactions are incorporated. Reactive plume models should be used, where screening techniques indicate the potential for violation of the NO₂ standard.

Current generation reactive plume models neglect the effect of turbulent concentration fluctuation on NO₂ formation and use inappropriately large dispersion coefficients to estimate plume concentrations. Approaches being developed to resolve these problems are discussed.     

Incorporating connectivity into conservation planning for the optimal representation of multiple species and ecosystem services

Conservation planning tends to focus on protecting species’ ranges or landscape connectivity but seldom both—particularly in the case of diverse taxonomic assemblages and multiple planning goals. Therefore, information on potential trade-offs between maintaining landscape connectivity and achieving other conservation objectives is lacking. We developed an optimization approach to prioritize the maximal protection of species’ ranges, ecosystem types, and forest carbon stocks, while also including habitat connectivity for range-shifting species and dispersal corridors to link protected area. We applied our approach to Sabah, Malaysia, where the state government mandated an increase in protected-area coverage of approximately 305,000 ha but did not specify where new protected areas should be. Compared with a conservation planning approach that did not incorporate the 2 connectivity features, our approach increased the protection of dispersal corridors and elevational connectivity by 13% and 21%, respectively. Coverage of vertebrate and plant species’ ranges and forest types were the same whether connectivity was included or excluded. Our approach protected 2% less forest carbon and 3% less butterfly range than when connectivity features were not included. Hence, the inclusion of connectivity into conservation planning can generate large increases in the protection of landscape connectivity with minimal loss of representation of other conservation targets.     

Fenvalerate concentrations in a mineral and an organic soil receiving multiple applications during the growing season

Abstract

Fenvalerate EC at 140 g AI/ha was applied 7 times at 2 wk intervals to duplicate plots of Plainfield sand and an organic soil contained in 2.2 x 0.9 m field microplots with and without an onion crop present in 1980 and 1981 respectively. Soil samples were taken immediately before and after each application and at 2, 4, and 6 wk after the last application in 1980. Additional samples were taken at 22 and 34 wk for the 1981 treatment. Concentrations of fenvalerate were determined by glc. In the crop‐free mineral soil, fenvalerate levels declined from. 0.07–0.11 ppm immediately after spraying to 0.01–0.03 ppm after 2 wk; in the organic soil the rate of addition of fenvalerate exceeded the rate of disappearance and the concentration in the soil gradually increased over the 14 wk treatment period to the 0.9–1.0 ppm range. This concentration decreased slowly over the next 10 wk to 0.7–0.8 ppm and was still 0.5–0.7 ppm the following spring. Results were similar for cropped soils. Concentrations in the top third of the 15 cm cores were 6x and 15x those in the middle third for sand and organic soil, respectively. Concentrations, in the onions at harvest were <0.01 ppm.     

The effect of multiple soil applications of disulfoton on enhanced microbial degradation in soil and subsequent uptake of insecticidal chemicals by potato plants

Abstract

Potatoes were grown during 1992 in 2 m² plots of loam which had received 1, 2 or 3 annual treatments of Di‐Syston 15G, equivalent to 3.36 kg AI/ha, in furrow at planting. The presence of enhanced degradative activity to the sulfoxide and sulfone metabolites of disulfoton in the soil treated in the previous two years was confirmed by laboratory tests prior to the 1992 treatments. Soil, seed potato and foliage from the three treatments were analyzed for disulfoton and its sulfoxide and sulfone metabolites for 12 wk following planting/treatment. Disulfoton was the major insecticidal component of the soil, a minor component of the seed piece and was not detected (<0.02 ppm) in potato foliage. Disulfoton concentrations in each of the three substrates sampled were similar for the three treatments. Disulfoton sulfoxide and sulfone were the major insecticidal components of the seed piece and foliage. Their maximum concentrations in 1st year soil, seed pieces and foliage were ca. 2x, 2x and 6x, respectively, those measured in the 2nd and 3rd year treatments. The results demonstrate that enhanced microbial degradation of relatively minor insecticidal compounds in the soil can profoundly affect insecticide levels in the plant when these compounds are the major insecticidal components accumulated. The broader implications for crop protection using soil‐applied systemic insecticides are discussed.     

Daily, monthly, seasonal, and annual ammonia emissions from Southern High Plains cattle feedyards

Ammonia emitted from beef cattle feedyards adds excess reactive N to the environment, contributes to degraded air quality as a precursor to secondary particulate matter, and represents a significant loss of N from beef cattle feedyards. We used open path laser spectroscopy and an inverse dispersion model to quantify daily, monthly, seasonal, and annual NH emissions during 2 yr from two commercial cattle feedyards in the Panhandle High Plains of Texas. Annual patterns of NH fluxes correlated with air temperature, with the greatest fluxes (>100 kg ha d) during the summer and the lowest fluxes (<15 kg ha d) during the winter. Mean monthly per capita emission rate (PCER) of NH-N at one feedyard ranged from 31 g NH-N head d (January) to 207 g NH-N head d (October), when increased dietary crude protein from wet distillers grains elevated emissions. Ammonia N emissions at the other feedyard ranged from 36 g NH-N head d (January) to 121 g NH-N head d (September). Monthly fractional NH-N loss ranged from a low of 19 to 24% to a high of 80 to 85% of fed N at the two feedyards. Seasonal PCER at the two feedyards averaged 60 to 71 g NH-N head d during winter and 103 to 158 g NH-N head d during summer. Annually, PCER was 115 and 80 g NH-N head d at the two feedyards, which represented 59 and 52% of N fed to the cattle. Detailed studies are needed to determine the effect of management and environmental variables such as diet, temperature, precipitation, and manure water content on NH emissions.     

Personality and parasites: sex-dependent associations between avian malaria infection and multiple behavioural traits

The evolution and ecology of consistent behavioural variation, or personality, is currently the focus of much attention in natural populations. Associations between personality traits and parasite infections are increasingly being reported, but the extent to which multiple behavioural traits might be associated with parasitism at the same time is largely unknown. Here, we use a population of great tits, Parus major, to examine whether infection by avian malaria (Plasmodium and Leucocytozoon) is associated with three behavioural traits assayed under standardized conditions. All of these traits are of broad ecological significance and two of them are repeatable or heritable in our population. Here, we show weak correlations between some but not all of these behavioural traits, and sex-dependent associations between all three behavioural traits and parasite infection. Infected males showed increased problem-solving performance whereas infected females showed reduced performance; furthermore, uninfected females were four times more likely to solve problems than uninfected males. Infected females were more exploratory than uninfected females, but infection had no effect on males. Finally, infected males were more risk-averse than uninfected males but females were unaffected. Our results demonstrate the potential for complex interactions between consistent personality variation and parasite infection, though we discuss the difficulty of attributing causality in these associations. Accounting for complex parasite-behaviour associations may prove essential in understanding the evolutionary ecology of behavioural variation and the dynamics of host–parasite interactions.