Evaluation of the ecological impacts of beaver reintroduction on aquatic systems

The extent and quality of freshwater systems is declining globally. Combined with past drainage, straightening and flow regulation, current systems are often functional but not pristine. Conservation, creation and restoration of freshwater systems is common but requires significant planning, resources and active monitoring and may only be a short-term solution to the long-term problem of destruction and loss of riparian zones. Beavers (Castor spp.) have the ability to create physical and biological habitat heterogeneity through the construction of woody debris dams, thereby restoring lost natural discontinuities in freshwater systems. Beavers may thus offer a natural, more passive solution to the need for wetland restoration or creation and the problem of homogenisation of watercourses. As such, numerous beaver reintroductions and introductions have been undertaken based in part on restoring this lost natural heritage. However, it is crucial to be able to predict the potential effects on existing biota of physical modifications by beavers to ecosystems, especially in the light of further population expansion, whilst also disentangling these effects from other influences, namely herbivory. The impact of beavers on aquatic systems was studied using a combination of field-based surveys and experiments, using aquatic plants and macro-invertebrates as indicators of hydromorphological changes and to quantify the effects of direct foraging. The research presented in this thesis demonstrates beaver adaptive foraging behaviours between terrestrial and aquatic habitats, whilst feeding highly selectively, optimally and opportunistically, using the white water lily (Nymphaea alba) as a model species. The effects of beaver foraging on the aquatic plant resource and diversity was low over short time spans (e.g. 1 year), but when selective foraging was assessed over greater time scales (e.g. 10 years) the effects of foraging were distinct. Significant changes in aquatic plant height, biomass, richness, diversity and composition were observed over this time period due to selective grazing on large rhizomatous species (e.g. Menyanthes trifoliata). These direct effects occurred even though changes in water levels, which are commonly believed to be the main driver of beaver influence on aquatic vegetation, were negligible. In a separate study in Sweden where beavers commonly constructed dams, with ponds then forming upstream, the aquatic plant and coleoptera species richness and composition differed in comparison to adjacent non-beaver created wetlands. Therefore, having a range of wetland types in the environment increases physical and biological heterogeneity creating unique niches that are exploited by disparate taxa. The construction of a series of dams within a single reach of stream flowing through a Scottish agricultural landscape also increased physical habitat diversity. Distinctive macroinvertebrate assemblages and modified functional diversity were associated with each dominant habitat type in the stream, resulting in increased landscape scale richness. The findings of this thesis confirm that beaver engineering and foraging has the potential to create unique and highly heterogeneous wetland and stream habitats within landscapes that enhances richness and diversity for multiple species groups. This thesis also supports part of the rationale for the trial reintroduction of beaver to Scotland that beavers can restore degraded habitats

Give beavers permanent residence - we'd be dam stupid not to

First paragraph: Beavers have recently made a tentative return to Britain. Scotland has led the way, with an official trial population in Knapdale, a remote area of lochs and forest in the west of the country; and another in Tayside to the east, suspected to come from private-collection escapees and unlicensed releases. Further south, a small feral population in Devon in south-west England is currently being tolerated by officialdom and admired locally, while there are also plans for a trial in mid-Wales.https://theconversation.com/give-beavers-permanent-residence-wed-be-dam-stupid-not-to-5525

Loss Aversion and Ruinous Optimal Wagering in the Markowitz Model of Non-Expected Utility

The purpose in this note is to demonstrate that the non-expected utility model of Markowitz implies that agents can obtain maximum expected utility from wagering all of their wealth on actuarialy unfair high probability outcomes. In order to remove this property it is necessary to assume that loss aversion tends to infinity as stake size as a proportion of wealth approaches unity

Loss aversion and ruinous optimal wagers in cumulative prospect theory

We demonstrate that extant parametric specifications of Cumulative Prospect Theory exhibit counterfactual implications for optimal wagers at actuarially unfair odds. In particular they imply individuals may maximizes their utility, called value function in Cumulative Prospect Theory, by wagering all or large proportions of their wealth on actuarially unfair gambles. In order to eliminate this property it is necessary that loss aversion is unbounded and increases as stake size increases. We present new parametric specifications of the value function over losses that exhibit this feature and therefore eliminate the ruinous wagering property

Out of work, out of leisure, out of place: Moral regulation, citizenship and volunteering in the rural "Idyll"

This paper presents components of semi-structured interview exploratory research (n=25) carried out during 2003in NSW's far north coast rainbow region as preparation of a larger agenda which seeks to interrogate ways in which national policy that circumscribes citizenship, interacts with cultural practices of belonging in rural "idyllic" tourism regions subjected to rapid growth in immigration from urban environments in successive waves. The central thrust of our approach is to examine the way in which work-for-the-dole volunteering, with it's emphasis on producing the active citizen in the bodies of the unemployed, operates to inform cultural practices of place infused with diverse, contradictory, and intersecting meanings of idleness bound up in culturally mediated relationships between joblessness and leisure. Though barely scratching the surface of highly complex and fluid relations, the paper focuses on how obligatory volunteering operates to both subvert and support the extent to which work-for the-dole ameliorates social alienation as a condition of joblessness. What happens to the sense of belonging when layers of regional migrants are pushed together by the welfare syste

Análise Ecoepidemiológico da Leishmaniose Visceral Canina no Município de Foz do Iguaçu entre 2018 e 2019

Dissertação de mestrado apresentada ao Programa de Pós-Graduaçãoem Biociências, do Instituto Latino-Americano de Ciências da Vida e da Natureza, da Universidade Federal da Integração Latino-Americana, como requisito parcial à obtenção do título de Mestre em Ciências, área de concentração Biociências.As leishmanioses são consideradas doenças parasitárias zoonóticas e cosmopolitas, em processo de expansão em diversos continentes. A alta adaptabilidade do agente etiológico a um amplo espectro de hospedeiros mamíferos é observada na forma mais agressiva da doença, a leishmaniose visceral (LV) ou Calazar, causada pelo protozoário Leishmania infantum, e transmitida a seus hospedeiros vertebrados pelo flebotomíneo Lutzomia longipalpis. Com características ecoepidemiológicas singulares, embora possa se apresentar insidiosa em parte importante do seu curso natural, a LV é responsável por altas taxas de letalidade quando não tratada. A cidade de Foz do Iguaçu, fronteiriça com Ciudad del Este (Paraguai) e Puerto Iguazu (Argentina) apresenta um intenso fluxo de pessoas e animais, o que pode facilitar a circulação de diferentes espécies e cepas de Leishmania. Nos últimos anos, a casuística de LV vem aumentando de forma preocupante na população canina da cidade e o primeiro caso humano autóctone foi confirmado no ano de 2015. Atualmente, o Centro de Controle de Zoonozes (CCZ) e os laboratórios de referência estaduais utilizam testes rápidos e sorológicos de ELISA (Enzyme-Linked Immunosorbent Assay) para diagnosticar a enfermidade em cães do município e da região, procedimento indicado pelo Ministério da Saúde. Entretanto, número importante de casos, incluindo-se muitos subclínicos, necessita de confirmação por técnicas que apresentem maior sensibilidade e especificidade diagnósticas. Neste estudo foram averiguados os resultados através da análise de concordância por meio do Coeficiente de Cohen Kappa entre o teste rápido com a confirmação pelo teste de ELISA em relação ao teste molecular via PCR (polymerase chain reaction) em tempo real utilizando amostra de sangue total obtido pela demanda espontânea do CCZ, realizando-se um levantamento socioambiental dos tutores dos animais e correlacionando o com a situação epidemiológica desta enfermidade canina. O estudo também elaborou mapa de adequabilidade ambiental baseados nas condições climáticas e avaliou potencial área de ocorrência da zoonose. Através do modelo estatístico verificou-se que não houve concordância entre o teste molecular com os testes sorológicos resultando em um valor k=0,1675. Outro ponto analisado refletiu que a permanência do animal em área externa aumenta o risco em mais de cinco vezes de contraírem a doença. Em relação a adequabilidade ambiental, concluiu-se que a cidade apresenta um elevado potencial de ocorrência da leishmaniose visceral canina. O presente estudo visou contribuir com análises ecoepidemiológicas da região e auxiliar no melhor conhecimento sobre as características moleculares do parasita da LV circulante na Tríplice Fronteira, buscando incrementar e validar as opções diagnósticas disponíveis na região

Rewilding wetlands: beaver as agents of within-habitat heterogeneity and the responses of contrasting biota

Ecosystem engineers can increase biodiversity by creating novel habitat supporting species that would otherwise be absent. Their more routine activities further influence the biota occupying engineered habitats. Beavers are well-known for transforming ecosystems through dam building and are therefore increasingly being utilised for habitat restoration, adaptation to climate extremes, and in long term rewilding. Abandoned beaver ponds develop into meadows or forested wetlands that differ fundamentally from other terrestrial habitats and thus increase landscape diversity. Active beaver ponds, by contrast, are superficially similar to other non-engineered shallow wetlands, but ongoing use and maintenance might affect how beaver ponds contribute to aquatic biodiversity. We explored the 'within-habitat' effect of an ecosystem engineer by comparing active beaver ponds (BP) in southern Sweden with coexisting other wetlands (OW), using sedentary (plants) and mobile (water beetles) organisms as indicators. BP differed predictably from OW in environmental characteristics and were more heterogeneous. BP supported more plant species at plot (+15%) and site (+33%) scales, and plant beta diversity, based on turnover between plots, was 17% higher than in other wetlands (OW), contributing to a significantly larger species pool in BP (+17%). Beetles were not differentiated between BP and OW based on diversity measures but were 26% more abundant in BP. Independent of habitat creation beaver are thus significant agents of within-habitat heterogeneity that differentiates beaver ponds from other standing water habitat; as an integral component of the rewilding of wetlands re-establishing beaver should benefit aquatic biodiversity across multiple scales

Using ecosystem engineers as tools in habitat restoration and rewilding: beaver and wetlands

Potential for habitat restoration is increasingly used as an argument for reintroducing ecosystem engineers. Beaver have well known effects on hydromorphology through dam construction, but their scope to restore wetland biodiversity in areas degraded by agriculture is largely inferred. Our study presents the first formal monitoring of a planned beaver-assisted restoration, focussing on changes in vegetation over 12 years within an agriculturally-degraded fen following beaver release, based on repeated sampling of fixed plots. Effects are compared to ungrazed exclosures which allowed the wider influence of waterlogging to be separated from disturbance through tree felling and herbivory. After 12 years of beaver presence mean plant species richness had increased on average by 46% per plot, while the cumulative number of species recorded increased on average by 148%. Heterogeneity, measured by dissimilarity of plot composition, increased on average by 71%. Plants associated with high moisture and light conditions increased significantly in coverage, whereas species indicative of high nitrogen decreased. Areas exposed to both grazing and waterlogging generally showed the most pronounced change in composition, with effects of grazing seemingly additive, but secondary, to those of waterlogging.  Our study illustrates that a well-known ecosystem engineer, the beaver, can with time transform agricultural land into a comparatively species-rich and heterogeneous wetland environment, thus meeting common restoration objectives. This offers a passive but innovative solution to the problems of wetland habitat loss that complements the role of beavers in water or sediment storage and flow attenuation. The role of larger herbivores has been significantly overlooked in our understanding of freshwater ecosystem function; the use of such species may yet emerge as the missing ingredient in successful restoration

Identification of coherent patterns in gene expression data using an efficient biclustering algorithm and parallel coordinate visualization

<p>Abstract</p> <p>Background</p> <p>The DNA microarray technology allows the measurement of expression levels of thousands of genes under tens/hundreds of different conditions. In microarray data, genes with similar functions usually co-express under certain conditions only <abbrgrp><abbr bid="B1">1</abbr></abbrgrp>. Thus, biclustering which clusters genes and conditions simultaneously is preferred over the traditional clustering technique in discovering these coherent genes. Various biclustering algorithms have been developed using different bicluster formulations. Unfortunately, many useful formulations result in NP-complete problems. In this article, we investigate an efficient method for identifying a popular type of biclusters called additive model. Furthermore, parallel coordinate (PC) plots are used for bicluster visualization and analysis.</p> <p>Results</p> <p>We develop a novel and efficient biclustering algorithm which can be regarded as a greedy version of an existing algorithm known as pCluster algorithm. By relaxing the constraint in homogeneity, the proposed algorithm has polynomial-time complexity in the worst case instead of exponential-time complexity as in the pCluster algorithm. Experiments on artificial datasets verify that our algorithm can identify both additive-related and multiplicative-related biclusters in the presence of overlap and noise. Biologically significant biclusters have been validated on the yeast cell-cycle expression dataset using Gene Ontology annotations. Comparative study shows that the proposed approach outperforms several existing biclustering algorithms. We also provide an interactive exploratory tool based on PC plot visualization for determining the parameters of our biclustering algorithm.</p> <p>Conclusion</p> <p>We have proposed a novel biclustering algorithm which works with PC plots for an interactive exploratory analysis of gene expression data. Experiments show that the biclustering algorithm is efficient and is capable of detecting co-regulated genes. The interactive analysis enables an optimum parameter determination in the biclustering algorithm so as to achieve the best result. In future, we will modify the proposed algorithm for other bicluster models such as the coherent evolution model.</p