Modeling inverted biomass pyramids and refuges in ecosystems

Although the existence of robust inverted biomass pyramids (IBPs) seems paradoxical, they are well known to exist in planktonic communities, and have recently been discovered in pristine coral reefs and in a reef off the North Carolina coast. Understanding the underlying mechanisms which produce inverted biomass pyramids provides new ecological insights. Some ecologists hypothesize that “the high growth rate of prey and low death rate of predators” causes IBPs. However, we show this is not always the case (see Sections 3.1 and 4). We devise predator–prey models to describe three mechanisms that can lead to IBPs: (1) well-mixed populations with large prey turn-over rate, (2) well-mixed populations with prey immigration, and (3) non-mixed populations where the prey can hide in refuges. The three models are motivated by the three ecosystems where IBPs have been observed. We also devise three refuge mediated models, with explicit refuge size, which incorporate different prey responses in the refuge, and we discuss how these lead to IBPs.     

Effects of landscape protection on farm management and farmers' income in Norway

Protected Landscapes (PLs) are increasingly used in Norway to conserve cultural (human modified) landscapes. In many cases the maintenance of agricultural activities in PLs is required to preserve landscape character. Whilst research exists on land conservation policies in general, the particular effects of PL on management and adjustment of the farms involved have not received attention in the literature. We present results from a questionnaire sent to owners of agricultural land within PLs in Norway. Whilst landowners were divided upon the effects of PLs on farm management, the economic situation of the farm was little affected. Furthermore, changes in farm management after the establishment of a PL did not seem to have been driven by the establishment of the PLs per se. Most importantly, farm management changes were related to potential options to develop the farm and its land. A statistical model showed that PL-farms did not differ significantly from farms outside PL in the development of their land use or animal husbandry. Our findings thus indicate that the establishment of PL played a minor role as a driving force of changes in farm management and farm income.     

Prenatally detected trisomy 4 and 6 mosaicism—cytogenetic results and clinical phenotype

We report on a live-born male with 46,XY/47,XY+4/47,XY,+6 mosaicism. Trisomy 4 mosaicism was detected by karyotyping chorionic villus samples (CVS) and was confirmed by the analysis of 16 metaphases obtained from cultured amniotic fluid cells. Eight metaphases were normal (46,XY), two had trisomy 4 (47,XY,+4), and two had trisomy 6 (47,XY,+6). Two postnatal chromosomal analyses of blood lymphocytes at birth and at the age of one week were normal. Chromosomal analysis of cultured skin fibroblasts from the right inguinal region at the age of 12 months revealed trisomy 4 (47,XY,+4) in 49 metaphases, trisomy 6 (47,XY,+6) in 2 metaphases, and a normal karyotype (46,XY) in 49 cells of the 100 analyzed metaphases, respectively. The main clinical findings consist of prenatal growth retardation, hypoplasia of the right side of the face, a dysplastic and posteriorly rotated right ear, a high vaulted palate, retrognathia, aplasia of the right thumb, hypoplasia of the fingernails, a deep sacral dimple, and patchy skin hypopigmentation of the right leg. When last seen at the age of 14 months, his development was nearly normal. Five patients with trisomy 4 mosaicism have been reported previously, but none with an additional trisomy 6 mosaicism. Copyright © 2003 John Wiley & Sons, Ltd.     

The effect of mixtures of organophosphate and carbamate pesticides on acetylcholinesterase and application of chemometrics to identify pesticides in mixtures

Organophosphate (OP) and carbamate (CP) pesticides act by the inhibition of acetylcholinesterase (AChE). This enables the use of this enzyme for the detection of these pesticides in the environment. While many studies have looked at the effect of single pesticides on AChE, the effect of mixtures of pesticides still requires extensive investigation. This is important to evaluate the cumulative risk in the case of simultaneous exposure to multiple pesticides. Therefore we examined the effect of five different pesticides (carbaryl, carbofuran, parathion, demeton-S-methyl, and aldicarb) on AChE activity to determine whether combinations had an additive, synergistic, or antagonistic inhibitory effect. Results indicated that the mixtures had an additive inhibitory effect on AChE activity. The data from the assays of the mixtures were used to develop and train an artificial neural network (ANN) which was then utilised successfully for the identification of pesticides and their concentrations in mixtures. This study is significant because it evaluated mixtures of OPs and CPs where previous studies focused on either OPs or CPs. Previous studies have only examined up to three pesticides while this study evaluated mixtures of five pesticides simultaneously. This is also the first study where an ANN was able to utilise data from the inhibition of a single enzyme to differentiate five different pesticides and their concentrations from mixtures.     

Understanding the role and influence of social norms: lessons for NRM

Much has been written about social norms in disciplines such as law and economics but they are less studied in the field of Natural Resource Management (NRM). Although norms are acknowledged to be an influence on decision–making, they are difficult to identify and measure in the field and their role is often implicit or not well understood or articulated. This paper addresses an important knowledge gap by combining social norms theory with the specifics of a particular case study. We examined the influence of social norms on landholder behaviour in a small rural community undergoing demographic change in Australia. Findings from interviews with landholders and government agency personnel indicate that established norms within the farming community are influencing incoming landholders; and that new norms and practices have also emerged as a result of government investment through the local Landcare group. We suggest that a better understanding of social norms in different contexts will give rise to strategies that make NRM interventions more effective.     

Ammonia emissions from surface flow and subsurface flow constructed wetlands treating dairy wastewater

Agricultural wastewater treatment is important for maintaining water quality, and constructed wetlands (CW) can be an effective treatment option. However, some of the N that is removed during treatment can be volatilized to the atmosphere as ammonia (NH(3)). This removal pathway is not preferred because it negatively impacts air quality. The objective of this study was to assess NH(3) volatilization from surface flow (SF) and subsurface flow (SSF) CWs. Six CWs (3 SF and 3 SSF; 6.6 m(2) each) were loaded with dairy wastewater ( approximately 300 mg L(-1) total ammoniacal nitrogen, TAN = NH(3)-N + NH(4)(+)-N) in Nova Scotia, Canada. From June through September 2006, volatilization of NH(3) during 12 or 24 h periods was measured using steady-state chambers. No differences (p > 0.1) between daytime and nighttime fluxes were observed, presumably due in part to the constant airflow inside the chambers. Changes in emission rates and variability within and between wetland types coincided with changes in the vegetative canopy (Typha latifolia L.) and temperature. In SSF wetlands, the headspace depth also appeared to affect emissions. Overall, NH(3) emissions from SF wetlands were significantly higher than from SSF wetlands. The maximum flux densities were 974 and 289 mg NH(3)-N m(-2) d(-1) for SF and SSF wetlands, respectively. Both wetland types had similar TAN mass removal. On average, volatilization contributed 9 to 44% of TAN removal in SF and 1 to 18% in SSF wetlands. Results suggest volatilization plays a larger role in N removal from SF wetlands.     

Perceptions of Wood in Rivers and Challenges for Stream Restoration in the United States

This article reports a study of the public perception of large wood in rivers and streams in the United States. Large wood is an element of freshwater aquatic ecosystems that has attracted much scientific interest in recent years because of its value in biological and geomorphological processes. At the heart of the issue is the nature of the relationship between scientific recognition of the ecological and geomorphological benefits of wood in rivers, management practices utilizing wood for river remediation progress, and public perceptions of in-channel wood. Surveys of students’ perceptions of riverscapes with and without large wood in the states of Colorado, Connecticut, Georgia, Illinois, Iowa, Missouri, Oregon, and Texas suggest that many individuals in the United States adhere to traditionally negative views of wood. Except for students in Oregon, most respondents considered photographs of riverscapes with wood to be less aesthetically pleasing and needing more improvement than rivers without wood. Analysis of reasons given for improvement needs suggest that Oregon students are concerned with improving channels without wood for fauna habitat, whereas respondents elsewhere focused on the need for cleaning wood-rich channels for flood risk management. These results underscore the importance of public education to increase awareness of the geomorphological and ecological significance of wood in stream systems. This awareness should foster more positive attitudes toward wood. An integrated program of research, education, and policy is advocated to bridge the gap between scientific knowledge and public perception for effective management and restoration of river systems with wood.     

Knowledge,agency and collective action as barriers to energy-saving behaviour

Energy saving is becoming a rising priority as a response to climate change and fossil fuel depletion in recent years. However, despite energy-related behaviour change being an important part of many environmental education initiatives, “energy literacy” among citizens remains patchy in both the USA and the UK, with evidence of strong positive attitudes but less consistent knowledge. Whilst it is clear that increasing knowledge does not automatically produce behaviour changes, potential questions must be asked about the logic of focusing solely on behaviour without simultaneously exploring and enhancing understanding of energy issues. This research, undertaken at a higher education institution with a strong focus on sustainability, illustrates the potential risks of targeting behaviour change and individual action at the expense of increasing knowledge, or encouraging collaborative and democratic endeavours. Results from an online survey indicate widespread misconceptions about energy which may reduce the effectiveness of energy-saving behaviours, alongside variable levels of motivation and engagement with energy issues. Respondents report a strong belief in the efficacy of personal changes, yet uncertainty about their capacity to influence business and government alongside a persistent faith in science to provide solutions to energy issues. The paper concludes by reflecting on the challenges arising from these findings for understanding agency and effectiveness in energy relationships.