Quantitative and ultrastructural studies on the reproductive biology of the polychaete Pholoe minuta in Galway Bay

Previous works by the present authors have identified, in a qualitative fashion, the reproductive cycle of Pholoe minuta (Fabricius) in inner Galway (53°13.5N; 9°7W). This quantitative, histological study, carried out over the period late May 1981 to late April 1982, shows that P. minuta is polytelic (two to three annual spawnings in an individual's lifespan). Individuals become sexually mature for the first time when approaching 3 yr of age. Estimates were made of the size of the reproductively active population (47 to 49%), sex ratio (1:1), duration (10 to 11 mo) and pattern (unimodal) of gametogenesis and fecundity levels (210 198 eggs m^-2). Maturation (mean oocyte size=85 m) and spawning (for 1 wk during late March through early April) were shown to be synchronised. Throughout oogenesis, follicle cells play an important role in binding together oocyte clusters, and desmosomal contacts are evident between oocyte and follicle cell plasmalemmas. No evidence for the synthesis of yolk precursors in the follicle cell cytoplasm was discovered. Oocytes are rich in Golgi apparatuses (yolk synthesising) and nuclear pores are numerous. Rough endoplasmic reticulum is distended in nature. Egg envelope development does not appear to commence until after the onset of vitellogenesis. Mature spermatozoa are of the primitive bullet-shaped type, with an unmodified acrosome. A possible method of elevation membrane formation is described.     

Biodiversity versus emergencies: the impact of restocking on Animal Genetic Resources after disaster

Restocking is a favoured option in supporting livelihoods after a disaster. With the depletion of local livestock populations, the introduction of new species and breeds will clearly affect biodiversity. Nevertheless, the impact of restocking on Animal Genetic Resources has been largely ignored. The aim of this paper, therefore, is to examine the consequences of restocking on biodiversity via a simple model. Utilising a hypothetical project based on cattle, the model demonstrates that more than one-third of the population was related to the original restocked animals after three generations. Under conditions of random breed selection, the figure declined to 20 per cent. The tool was then applied to a donor-led restocking project implemented in Bosnia-Herzegovina. By restocking primarily with Simmental cattle, the model demonstrated that the implementation of a single restocking project is likely to have accelerated the decline of the indigenous Buşa breed by a further nine per cent. Thus, greater awareness of the long-term implications of restocking on biodiversity is required.     

A life according to nature: from ancient theoretical ideal to future sustainable practice

Recent developments in environmental education in the United States reveal a noticeable tendency toward the position that every institution of higher education should make the cultivation of ecological intelligence an essential part of every student??s learning experience. But a theoretical study of the history of the idea of sustainability in the Western philosophical tradition shows that this concept has been relatively neglected in favor of the notion of a human subjugation of nature. For the idea of a human life according to nature was cultivated by a few ancient thinkers but subverted by various modern notions of the hegemony of man over nature. In light of the clear fact that sustainability is a concern increasingly shared by industry, government, and academe, there is cogent empirical evidence that a life according to nature is an idea whose time has finally come. This paper seeks to act as a catalyst for environmental education by identifying primary sources, providing theoretical frameworks, and supplying practical counsels for determining viable approaches to sustainability useful to industrial actors, governmental policy-makers, and environmental professionals. Thus the paper aims to start a dialogue between various constituencies, especially industrialists and ecologists, about the theoretical foundations and practical implications of sustainability. In doing so, the paper presents elements applicable to the education and training of interested environmentalists at different levels and in different fields, be it formal or non-formal schooling of academics, specialized training or retraining of decision-makers, or common-ground communication to the general public. Finally, the paper suggests that not only the natural sciences, the social sciences, and the technical studies, but also the humanities disciplines can make indispensable contributions to sustainability studies, and that therefore the best practices in this area will inevitably be interdisciplinary.     

Emission study of a diesel engine fueled with higher alcohol-biodiesel blended fuels

This work examines the effect of butanol (higher alcohol) on the emission pattern of neat neem oil biodiesel (NBD100) fueled diesel engine. Single-cylinder, 4-stroke, research diesel engine was employed to conduct the trial. Blends comprising the mixture of biodiesel and higher alcohol were prepared by employing an ultrasonic agitator. Four test fuels such as neat neem oil biodiesel, diesel, and two blends of higher alcohol/neem oil biodiesel: 10% and 20% (by volume). Experimental result showed that increasing alcohol content to biodiesel brought down the various emissions such as Smoke, NO_x, HC, and CO by 6.8%, 10.4%, 8.6%, and 5.9%, respectively, at all loads. It was also concluded from the trail that a 20% higher alcohol/neem oil biodiesel blends show the promising signs in reducing all the emissions associated with biodiesel fuelled diesel engine.     

Demography of Pholoe minuta (Polychaeta: Sigalionidae) in Galway Bay,west coast of Ireland,with special reference to settlement and recruitment patterns

Pholoe minuta is a numerically dominant member of the Amphiura filiformis subcommunity in Galway Bay. A longterm (5 yr) assessment of its population structure highlighted the shortfall in information regarding juvenile stages in the post-spawning months. Additional remote and in situ sampling programmes (including the use of a Muus sampling device), covering two successive postspawning periods, were undertaken to provide information on the juvenile recruits. Estimates of density levels (130 to 680 m^-2), growth rates (doubling in size in 2 mo) and mortalities (80%) were calculated for the newly settled P. minuta. Mean monthly densities, seasonal population structure, recruitment levels (21.1%), growth (1 mm per annum) and survivorship patterns of the adult population were evaluated using the dorsal width of the fifth chaetiger, which is shown to be a suitable parameter of total body size. The success of grab sampling as a method for examining early settlement of P. minuta is critically reviewed, and a recommendation for future benthic population studies is proposed.     

Wetlands as an alternative stable state in desert streams

Historically, desert drainages of the American southwest supported productive riverine wetlands (ciénegas). Region-wide erosion of ciénegas during the late 19th and early 20th century dramatically reduced the abundance of these ecosystems, but recent reestablishment of wetlands in Sycamore Creek, Arizona, USA, provides an opportunity to evaluate the mechanisms underlying wetland development. A simple model demonstrates that density-dependent stabilization of channel substrate by vegetation results in the existence of alternative stable states in desert streams. A two-year (October 2004-September 2006) field survey of herbaceous cover and biomass at 26 sites located along Sycamore Creek is used to test the underlying assumption of this model that vegetation cover loss during floods is density dependent, as well as the prediction that the distribution of vegetation abundance should shift toward bimodality in response to floods. Observations of nonlinear, negative relationships between herbaceous biomass prior to flood events and the proportion of persistent vegetation cover were consistent with the alternative stable state model. In further support of the alternative-state hypothesis, vegetation cover diverged from an approximately normal distribution toward a distinctly bimodal distribution during the monsoon flood season of 2006. These results represent the first empirically supported example of alternative-state behavior in stream ecosystems. Identification of alternative stable states in desert streams supports recent hypotheses concerning the importance of strong abiotic-disturbance regimes and biogeomorphic mechanisms in multiple-state ecosystems.     

Cross-sectional biomonitoring study of pesticide exposures in Queensland,Australia, using pooled urine samples

A range of pesticides are available in Australia for use in agricultural and domestic settings to control pests, including organophosphate and pyrethroid insecticides, herbicides, and insect repellents, such as N,N-diethyl-meta-toluamide (DEET). The aim of this study was to provide a cost-effective preliminary assessment of background exposure to a range of pesticides among a convenience sample of Australian residents. De-identified urine specimens stratified by age and sex were obtained from a community-based pathology laboratory and pooled (n = 24 pools of 100 specimens). Concentrations of urinary pesticide biomarkers were quantified using solid-phase extraction coupled with isotope dilution high-performance liquid chromatography–tandem mass spectrometry. Geometric mean biomarker concentrations ranged from <0.1 to 36.8 ng/mL for organophosphate insecticides, <0.1 to 5.5 ng/mL for pyrethroid insecticides, and <0.1 to 8.51 ng/mL for all other biomarkers with the exception of the DEET metabolite 3-diethylcarbamoyl benzoic acid (4.23 to 850 ng/mL). We observed no association between age and concentration for most biomarkers measured but noted a “U-shaped” trend for five organophosphate metabolites, with the highest concentrations observed in the youngest and oldest age strata, perhaps related to age-specific differences in behavior or physiology. The fact that concentrations of specific and non-specific metabolites of the organophosphate insecticide chlorpyrifos were higher than reported in USA and Canada may relate to differences in registered applications among countries. Additional biomonitoring programs of the general population and focusing on vulnerable populations would improve the exposure assessment and the monitoring of temporal exposure trends as usage patterns of pesticide products in Australia change over time.     

Does The World Need U.S. Farmers Even If Americans Don’t?

We consider the implications of trends in the number of U.S. farmers and food imports on the question of what role U.S. farmers have in an increasingly global agrifood system. Our discussion stems from the argument some scholars have made that American consumers can import their food more cheaply from other countries than it can produce it. We consider the distinction between U.S. farmers and agriculture and the effect of the U.S. food footprint on developing nations to argue there might be an important role for U.S. farmers, even if it appears Americans don’t need them. For instance, we may need to protect U.S. farmland and, by implication, U.S. farmers, for future food security needs both domestic and international. We also explore the role of U.S. farmers by considering the question of whether food is a privilege or a right. Although Americans seem to accept that food is a privilege, many scholars and commentators argue that, at least on a global scale, food is a right, particularly for the world’s poor and hungry. If this is the case, then U.S. farmers might have a role in meeting the associated obligation to ensure that the poor of the world have enough food to eat. We look at the consequences of determining that food is a right versus a privilege and the implications of that decision for agricultural subsidies as well as U.S. agriculture and nutrition policies.     

Population dynamics and reproductive cycle of Pholoë minuta (Polychaeta: Sigalionidae) in Galway Bay

Pholoë minuta (Fabricius) is a prominent member of the Amphiura filiformis (O.F. Müller) subcommunity in Galway Bay, Ireland. The aim of the present investigation was to study the population dynamics and reproductive cycle of P. minuta in this area. Monthly sampling over a 2 yr period (November 1978–October 1980), at a permanent station (18 m) with a fine sand substrate, revealed a mean density of 96 individuals per 0.1 m². The width of the fifth elytron was correlated with total body length and was used as a basis for analysing population structure. Four distinct year classes were evident and estimates of recruitment levels and growth rates were calculated. P. minuta is polytelic and reproduces for the first time when approaching 3 yr of age. Spawning occurred in March—April and appeared to be associated with a seasonal low in bottom-water temperature.