Unravelling the multiple interacting drivers of host–pathogen coexistence is crucial in understanding how an apparently stable state of endemism may shift towards an epidemic and lead to biodiversity ...loss. Here, we investigate the apparent coexistence of the global amphibian pathogen Batrachochytrium dendrobatidis (Bd) with Bombina variegata populations in The Netherlands over a 7-year period. We used a multi-season mark–recapture dataset and assessed potential drivers of coexistence (individual condition, environmental mediation and demographic compensation) at the individual and population levels. We show that even in a situation with a clear cost incurred by endemic Bd, population sizes remain largely stable. Current environmental conditions and an over-dispersed pathogen load probably stabilize disease dynamics, but as higher temperatures increase infection probability, changing environmental conditions, for example a climate-change-driven rise in temperature, could unbalance the current fragile host–pathogen equilibrium. Understanding the proximate mechanisms of such environmental mediation and of site-specific differences in infection dynamics can provide vital information for mitigation actions.
Is Reintroduction Biology an Effective Applied Science? Taylor, Gemma; Canessa, Stefano; Clarke, Rohan H. ...
Trends in ecology & evolution (Amsterdam),
November 2017, 2017-11-00, 20171101, Letnik:
32, Številka:
11
Journal Article
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Reintroduction biology is a field of scientific research that aims to inform translocations of endangered species. We review two decades of published literature to evaluate whether reintroduction ...science is evolving in its decision-support role, as called for by advocates of evidence-based conservation. Reintroduction research increasingly addresses a priori hypotheses, but remains largely focused on short-term population establishment. Similarly, studies that directly assist decisions by explicitly comparing alternative management actions remain a minority. A small set of case studies demonstrate full integration of research in the reintroduction decision process. We encourage the use of tools that embed research in decision-making, particularly the explicit consideration of multiple management alternatives because this is the crux of any management decisions.
Reintroductions are an increasingly popular tool for the conservation of threatened species. The number of peer-reviewed reintroduction-related studies continues to grow almost exponentially.
Reintroduction biology is an applied science that supports all forms of conservation translocations. Its purpose is to provide knowledge that facilitates decisions about which management strategies to use.
As an applied science, reintroduction biology should be driven by, and respond to, management needs. This involves testing a priori hypotheses relevant to management at multiple ecological levels, and explicitly predicting and comparing the outcomes of management alternatives.
Recently, a small but increasing number of studies have sought this integration by combining predictive modelling, analysis of experimental and monitoring data, and decision-support methods.
Abstract
Wildlife diseases are contributing to the current Earth’s sixth mass extinction; one disease, chytridiomycosis, has caused mass amphibian die-offs. While global spread of a hypervirulent ...lineage of the fungus
Batrachochytrium dendrobatidis
(
Bd
GPL) causes unprecedented loss of vertebrate diversity by decimating amphibian populations, its impact on amphibian communities is highly variable across regions. Here, we combine field data with in vitro and in vivo trials that demonstrate the presence of a markedly diverse variety of low virulence isolates of
Bd
GPL in northern European amphibian communities. Pre-exposure to some of these low virulence isolates protects against disease following subsequent exposure to highly virulent
Bd
GPL in midwife toads (
Alytes obstetricans
) and alters infection dynamics of its sister species
B. salamandrivorans
in newts (
Triturus marmoratus
), but not in salamanders (
Salamandra salamandra
). The key role of pathogen virulence in the complex host-pathogen-environment interaction supports efforts to limit pathogen pollution in a globalized world.
Captive breeding and reintroduction programs remain a powerful but divisive tool for management of threatened species, with a proven potential to avoid extinction, but low long-term success rates and ...high resource requirements. Monitoring the results of reintroductions is critical to be able to assess short- and long-term success, adjusting management decisions as new information becomes available. In this study, we assessed the first 15years of the captive breeding and restocking program for the European pond turtle Emys orbicularis in Liguria, northern Italy. We estimated survival of released turtles by modelling mark-recapture monitoring data. We then used those estimates to update our prior expectations about long-term outcomes, and to adjust management decisions about the age of individuals to release. Modelling results suggest released turtles had sufficiently high survival, matching prior expectations, such that local extinction has been averted in the short-term. Survival was similar among candidate age classes for releases, suggesting the release of younger individuals can provide positive outcomes while reducing management costs. On the other hand, survival varied among sites, indicating the need for ongoing in-situ habitat management to ensure long-term persistence. Moreover, the late onset of sexual maturity in the species means reproduction of released animals cannot yet be determined with certainty. Captive breeding and reintroduction programs normally require long-term efforts; therefore, focused monitoring that is clearly linked to decision-making is necessary to continually refine and adjust management strategies.
•We analyzed monitoring data for 7years of releases of captive-bred turtles.•Estimated survival was similar for 3–5year-old turtles, but varied among sites.•Initial uncertainty regarding the age class to release has been resolved.•Key uncertainty now shifts to site suitability and breeding in the wild.•Monitoring data should be collected with a clear link to management uncertainty.
The European Union (EU) committed to halt the loss of biodiversity in its 2020 Biodiversity Strategy. However, all reports show conservation efforts are falling short of their objectives and the ...status of biodiversity in the EU continues to decline. Here, we propose four key avenues for the next Strategy, currently under discussion, to make EU conservation efforts more effective. First, we suggest the next Biodiversity Strategy should ensure legal coverage for threatened species not listed in the EU Habitats and Birds Directives, which currently cover only 16.4% of all threatened species. Second, halting biodiversity loss requires threatened species to be adequately managed. To this end, the potential of the extant Natura 2000 should be fully released. Already designated protected areas (PAs) hold more species than currently declared as target for management, leaving an opportunity to further manage more threatened species. Third, to address dynamism associated to climate and land use change, conservation management should be expanded outside PAs, using the planned network of Green Infrastructure. Fourth, while more funding is required to properly implement the Biodiversity Strategy, the improvements we suggest can be made more cost-effective by using systematic planning approaches and better integration of conservation policy in other sectorial policies, such as the Common Agriculture Policy. While existing policy mechanisms can already be used to implement some of these recommendations, revised policies should seek better integration of conservation into other sectorial policies, as well as efficient allocation and use of funds to increase the efficiency of conservation efforts.
Summary
Applied ecologists continually advocate further research, under the assumption that obtaining more information will lead to better decisions. Value of information (VoI) analysis can be used ...to quantify how additional information may improve management outcomes: despite its potential, this method is still underused in environmental decision‐making. We provide a primer on how to calculate the VoI and assess whether reducing uncertainty will change a decision. Our aim is to facilitate the application of VoI by managers who are not familiar with decision‐analytic principles and notation, by increasing the technical accessibility of the tool.
Calculating the VoI requires explicit formulation of management objectives and actions. Uncertainty must be clearly structured and its effects on management outcomes evaluated. We present two measures of the VoI. The expected value of perfect information is a calculation of the expected improvement in management outcomes that would result from access to perfect knowledge. The expected value of sample information calculates the improvement in outcomes expected by collecting a given sample of new data.
We guide readers through the calculation of VoI using two case studies: (i) testing for disease when managing a frog species and (ii) learning about demographic rates for the reintroduction of an endangered turtle. We illustrate the use of Bayesian updating to incorporate new information.
The VoI depends on our current knowledge, the quality of the information collected and the expected outcomes of the available management actions. Collecting information can require significant investments of resources; VoI analysis assists managers in deciding whether these investments are justified.
Seasonal cycles have a demonstrated effect on the dynamics of human and animal diseases. However, their quantitative implications for disease mitigation in wildlife are less well studied. We ...quantitatively investigate the effect of seasonality on chytridiomycosis caused by Batrachochytrium salamandrivorans in European fire salamanders (Salamandra salamandra). Floquet theory is a mathematical tool that allows the analysis of periodic systems. In epidemiology, it can be used to study the fate of a un-/managed host population when confronted with a new pathogen. Based on this theory, we develop a novel metric that captures outbreak dynamics similarly to the non-seasonal basic reproduction number R0, but also accounts for seasonal cycles. We use this Floquet-R0 to determine the management needed to defend a susceptible host population from disease outbreaks. In the B. salamandrivorans case, we found a limited effect of seasonality on disease dynamics and mitigation for two hypothetical European fire salamander populations with different seasonal cycles. However, a general model analysis suggested that Floquet-R0 could deviate up to ±33% from the non-seasonal R0, thus leading to insufficient or unnecessary management if seasonality is ignored. We recommend considering seasonal cycles – especially activity cycles with two peaks – when planning mitigation for chytridiomycosis and other wildlife diseases, because they add a considerable layer of uncertainty to analysis and decision-making. The Floquet-R0 metric we present is an intuitive tool to quantitatively evaluate seasonality of disease and its influence on management. Keywords: Basic reproduction number, Floquet theory, Fire salamander, Management, Seasonal forcing, Time-varying coefficient
Integral chain management of wildlife diseases Martel, An; Vila‐Escale, Mireia; Fernández‐Giberteau, Daniel ...
Conservation letters,
March/April 2020, 2020-03-00, 20200301, 2020-03-01, Letnik:
13, Številka:
2
Journal Article
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The chytrid fungus Batrachochytrium dendrobatidis has caused the most prominent loss of vertebrate diversity ever recorded, which peaked in the 1980s. Recent incursion by its sister species B. ...salamandrivorans in Europe raised the alarm for a new wave of declines and extinctions in western Palearctic urodeles. The European Commission has responded by restricting amphibian trade. However, private amphibian collections, the main end consumers, were exempted from the European legislation. Here, we report how invasion by a released, exotic newt coincided with B. salamandrivorans invasion at over 1000 km from the nearest natural outbreak site, causing mass mortality in indigenous marbled newts (Triturus marmoratus), and posing an acute threat to the survival of nearby populations of the most critically endangered European newt species (Montseny brook newt, Calotriton arnoldi). Disease management was initiated shortly after detection in a close collaboration between policy and science and included drastic on site measures and intensive disease surveillance. Despite these efforts, the disease is considered temporarily contained but not eradicated and continued efforts will be necessary to minimize the probability of further pathogen dispersal. This precedent demonstrates the importance of tackling wildlife diseases at an early stage using an integrated approach, involving all stakeholders and closing loopholes in existing regulations.
Emerging Infectious Diseases (EIDs) are recognised as global extinction drivers of threatened species. Unfortunately, biodiversity managers have few tested solutions to manage them when often the ...desperate need for solutions necessitates a response. Here we test in situ biosecurity protocols to assess the efficacy of managing Psittacine beak and feather disease (PBFD), one of the most common and emergent viral diseases in wild parrots (Psittaciformes) that is currently affecting numerous threatened species globally. In response to an outbreak of PBFD in Mauritius "echo" parakeets (Psittacula eques), managers implemented a set of biosecurity protocols to limit transmission and impact of Beak and feather disease virus (BFDV). Here we used a reciprocal design experiment on the wild population to test whether BFDV management reduced viral prevalence and viral load, and improved nestling body condition and fledge success. Whilst management reduced the probability of nestling infection by approximately 11% there was no observed impact on BFDV load and nestling body condition. In contrast to expectations there was lower fledge success in nests with added BFDV biosecurity (83% in untreated vs. 79% in treated nests). Our results clearly illustrate that management for wildlife conservation should be critically evaluated through targeted monitoring and experimental manipulation, and this evaluation should always focus on the fundamental objective of conservation.
Urbanization affects streams by modifying hydrology, increasing pollution and disrupting in-stream and riparian conditions, leading to negative responses by biotic communities. Given the global trend ...of increasing urbanization, improved understanding of its direct and indirect effects at multiple scales is needed to assist management. The theory of stream ecology suggests that the riverscape and the surrounding landscape are inextricably linked, and watershed-scale processes will also affect in-stream conditions and communities. This is particularly true for species with semi-aquatic life cycles, such as amphibians, which transfer energy between streams and surrounding terrestrial areas. We related measures of urbanization at different scales to frog communities in streams along an urbanization gradient in Melbourne, Australia. We used boosted regression trees to determine the importance of predictors and the shape of species responses. We then used structural equation models to investigate possible indirect effects of watershed imperviousness on in-stream parameters. The proportion of riparian vegetation and road density surrounding the site at the reach scale (500-m radius) had positive and negative effects, respectively, on species richness and on the occurrence of the two most common species in the area (Criniasignifera and Limnodynastesdumerilii). Road density and local aquatic vegetation interacted in influencing species richness, suggesting that isolation of a site can prevent colonization, in spite of apparently good local habitat. Attenuated imperviousness at the catchment scale had a negative effect on local aquatic vegetation, indicating possible indirect effects on frog species not revealed by single-level models. Processes at the landscape scale, particularly related to individual ranging distances, can affect frog species directly and indirectly. Catchment imperviousness might not affect adult frogs directly, but by modifying hydrology it can disrupt local vegetation and prove indirectly detrimental. Integrating multiple-scale management actions may help to meet conservation targets for streams in the face of urbanization.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
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