20,614 research outputs found

    Great Bay Estuary Restoration Compendium

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    Single species approaches to natural resource conservation and management are now viewed as antiquated and oversimplified for dealing with complex systems. Scientists and managers who work in estuaries and other marine systems have urged adoption of ecosystem based approaches to management for nearly a decade, yet practitioners are still struggling to translate the ideas into practice. Similarly, ecological restoration projects in coastal systems have typically addressed one species or habitat. In recent years, efforts to focus on multiple species and habitats have increased. Our project developed an integrated ecosystem approach to identify multi-habitat restoration opportunities in the Great Bay estuary, New Hampshire. We created a conceptual site selection model based on a comparison of historic and modern distribution and abundance data, current environmental conditions, and expert review. Restoration targets included oysters and softshell clams, salt marshes, eelgrass beds, and seven diadromous fish species. Spatial data showing the historical and present day distributions for multiple species and habitats were compiled and integrated into a geographic information system. A matrix of habitat interactions was developed to identify potential for synergy and subsequent restoration efficiency. Output from the site selection models was considered within this framework to identify ecosystem restoration landscapes. The final products of these efforts include a series of maps detailing multi-habitat restoration opportunities extending from upland freshwater fish habitat down to the bay bottom. A companion guidance document was created to present project methods and a review of restoration methods. The authors hope that this work will help to stimulate and inform new restoration projects within the Great Bay estuarine system, and that it will serve as a foundation to be updated and improved as more information is collected

    Ecological models at fish community and species level to support effective river restoration

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    RESUMEN Los peces nativos son indicadores de la salud de los ecosistemas acuáticos, y se han convertido en un elemento de calidad clave para evaluar el estado ecológico de los ríos. La comprensión de los factores que afectan a las especies nativas de peces es importante para la gestión y conservación de los ecosistemas acuáticos. El objetivo general de esta tesis es analizar las relaciones entre variables biológicas y de hábitat (incluyendo la conectividad) a través de una variedad de escalas espaciales en los ríos Mediterráneos, con el desarrollo de herramientas de modelación para apoyar la toma de decisiones en la restauración de ríos. Esta tesis se compone de cuatro artículos. El primero tiene como objetivos modelar la relación entre un conjunto de variables ambientales y la riqueza de especies nativas (NFSR), y evaluar la eficacia de potenciales acciones de restauración para mejorar la NFSR en la cuenca del río Júcar. Para ello se aplicó un enfoque de modelación de red neuronal artificial (ANN), utilizando en la fase de entrenamiento el algoritmo Levenberg-Marquardt. Se aplicó el método de las derivadas parciales para determinar la importancia relativa de las variables ambientales. Según los resultados, el modelo de ANN combina variables que describen la calidad de ribera, la calidad del agua y el hábitat físico, y ayudó a identificar los principales factores que condicionan el patrón de distribución de la NFSR en los ríos Mediterráneos. En la segunda parte del estudio, el modelo fue utilizado para evaluar la eficacia de dos acciones de restauración en el río Júcar: la eliminación de dos azudes abandonados, con el consiguiente incremento de la proporción de corrientes. Estas simulaciones indican que la riqueza aumenta con el incremento de la longitud libre de barreras artificiales y la proporción del mesohabitat de corriente, y demostró la utilidad de las ANN como una poderosa herramienta para apoyar la toma de decisiones en el manejo y restauración ecológica de los ríos Mediterráneos. El segundo artículo tiene como objetivo determinar la importancia relativa de los dos principales factores que controlan la reducción de la riqueza de peces (NFSR), es decir, las interacciones entre las especies acuáticas, variables del hábitat (incluyendo la conectividad fluvial) y biológicas (incluidas las especies invasoras) en los ríos Júcar, Cabriel y Turia. Con este fin, tres modelos de ANN fueron analizados: el primero fue construido solamente con variables biológicas, el segundo se construyó únicamente con variables de hábitat y el tercero con la combinación de estos dos grupos de variables. Los resultados muestran que las variables de hábitat son los ¿drivers¿ más importantes para la distribución de NFSR, y demuestran la importancia ecológica de los modelos desarrollados. Los resultados de este estudio destacan la necesidad de proponer medidas de mitigación relacionadas con la mejora del hábitat (incluyendo la variabilidad de caudales en el río) como medida para conservar y restaurar los ríos Mediterráneos. El tercer artículo busca comparar la fiabilidad y relevancia ecológica de dos modelos predictivos de NFSR, basados en redes neuronales artificiales (ANN) y random forests (RF). La relevancia de las variables seleccionadas por cada modelo se evaluó a partir del conocimiento ecológico y apoyado por otras investigaciones. Los dos modelos fueron desarrollados utilizando validación cruzada k-fold y su desempeño fue evaluado a través de tres índices: el coeficiente de determinación (R2 ), el error cuadrático medio (MSE) y el coeficiente de determinación ajustado (R2 adj). Según los resultados, RF obtuvo el mejor desempeño en entrenamiento. Pero, el procedimiento de validación cruzada reveló que ambas técnicas generaron resultados similares (R2 = 68% para RF y R2 = 66% para ANN). La comparación de diferentes métodos de machine learning es muy útil para el análisis crítico de los resultados obtenidos a través de los modelos. El cuarto artículo tiene como objetivo evaluar la capacidad de las ANN para identificar los factores que afectan a la densidad y la presencia/ausencia de Luciobarbus guiraonis en la demarcación hidrográfica del Júcar. Se utilizó una red neuronal artificial multicapa de tipo feedforward (ANN) para representar relaciones no lineales entre descriptores de L. guiraonis con variables biológicas y de hábitat. El poder predictivo de los modelos se evaluó con base en el índice Kappa (k), la proporción de casos correctamente clasificados (CCI) y el área bajo la curva (AUC) característica operativa del receptor (ROC). La presencia/ausencia de L. guiraonis fue bien predicha por el modelo ANN (CCI = 87%, AUC = 0.85 y k = 0.66). La predicción de la densidad fue moderada (CCI = 62%, AUC = 0.71 y k = 0.43). Las variables más importantes que describen la presencia/ausencia fueron: radiación solar, área de drenaje y la proporción de especies exóticas de peces con un peso relativo del 27.8%, 24.53% y 13.60% respectivamente. En el modelo de densidad, las variables más importantes fueron el coeficiente de variación de los caudales medios anuales con una importancia relativa del 50.5% y la proporción de especies exóticas de peces con el 24.4%. Los modelos proporcionan información importante acerca de la relación de L. guiraonis con variables bióticas y de hábitat, este nuevo conocimiento podría utilizarse para apoyar futuros estudios y para contribuir en la toma de decisiones para la conservación y manejo de especies en los en los ríos Júcar, Cabriel y Turia.Olaya Marín, EJ. (2013). Ecological models at fish community and species level to support effective river restoration [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/28853TESI

    Anthropogenic Habitats Facilitate Dispersal of an Early Successional Obligate: Implications for Restoration of an Endangered Ecosystem

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    Landscape modification and habitat fragmentation disrupt the connectivity of natural landscapes, with major consequences for biodiversity. Species that require patchily distributed habitats, such as those that specialize on early successional ecosystems, must disperse through a landscape matrix with unsuitable habitat types. We evaluated landscape effects on dispersal of an early successional obligate, the New England cottontail (Sylvilagus transitionalis). Using a landscape genetics approach, we identified barriers and facilitators of gene flow and connectivity corridors for a population of cottontails in the northeastern United States. We modeled dispersal in relation to landscape structure and composition and tested hypotheses about the influence of habitat fragmentation on gene flow. Anthropogenic and natural shrubland habitats facilitated gene flow, while the remainder of the matrix, particularly development and forest, impeded gene flow. The relative influence of matrix habitats differed between study areas in relation to a fragmentation gradient. Barrier features had higher explanatory power in the more fragmented site, while facilitating features were important in the less fragmented site. Landscape models that included a simultaneous barrier and facilitating effect of roads had higher explanatory power than models that considered either effect separately, supporting the hypothesis that roads act as both barriers and facilitators at all spatial scales. The inclusion of LiDAR-identified shrubland habitat improved the fit of our facilitator models. Corridor analyses using circuit and least cost path approaches revealed the importance of anthropogenic, linear features for restoring connectivity between the study areas. In fragmented landscapes, human-modified habitats may enhance functional connectivity by providing suitable dispersal conduits for early successional specialists

    Ontogeny influences sensitivity to climate change stressors in an endangered fish.

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    Coastal ecosystems are among the most human-impacted habitats globally, and their management is often critically linked to recovery of declining native species. In the San Francisco Estuary, the Delta Smelt (Hypomesus transpacificus) is an endemic, endangered fish strongly tied to Californian conservation planning. The complex life history of Delta Smelt combined with dynamic seasonal and spatial abiotic conditions result in dissimilar environments experienced among ontogenetic stages, which may yield stage-specific susceptibility to abiotic stressors. Climate change is forecasted to increase San Francisco Estuary water temperature and salinity; therefore, understanding the influences of ontogeny and phenotypic plasticity on tolerance to these critical environmental parameters is particularly important for Delta Smelt and other San Francisco Estuary fishes. We assessed thermal and salinity limits in several ontogenetic stages and acclimation states of Delta Smelt, and paired these data with environmental data to evaluate sensitivity to climate-change stressors. Thermal tolerance decreased among successive stages, with larval fish exhibiting the highest tolerance and post-spawning adults having the lowest. Delta Smelt had limited capacity to increase tolerance through thermal acclimation, and comparisons with field temperature data revealed that juvenile tolerance limits are the closest to current environmental conditions, which may make this stage especially susceptible to future climate warming. Maximal water temperatures observed in situ exceeded tolerance limits of juveniles and adults. Although these temperature events are currently rare, if they increase in frequency as predicted, it could result in habitat loss at these locations despite other favourable conditions for Delta Smelt. In contrast, Delta Smelt tolerated salinities spanning the range of expected environmental conditions for each ontogenetic stage, but salinity did impact survival in juvenile and adult stages in exposures over acute time scales. Our results underscore the importance of considering ontogeny and phenotypic plasticity in assessing the impacts of climate change, particularly for species adapted to spatially and temporally heterogeneous environments

    Ecoengineering with Ecohydrology: Successes and failures in estuarine restoration

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    © 2016 Elsevier Ltd. Ecological Engineering (or Ecoengineering) is increasingly used in estuaries to re-create and restore ecosystems degraded by human activities, including reduced water flow or land poldered for agricultural use. Here we focus on ecosystem recolonization by the biota and their functioning and we separate Type A Ecoengineering where the physico-chemical structure is modified on the basis that ecological structure and functioning will then follow, and Type B Ecoengineering where the biota are engineered directly such as through restocking or replanting. Modifying the physical system to create and restore natural processes and habitats relies on successfully applying Ecohydrology, where suitable physical conditions, especially hydrography and sedimentology, are created to recover estuarine ecology by natural or human-mediated colonisation of primary producers and consumers, or habitat creation. This successional process then allows wading birds and fish to reoccupy the rehabilitated areas, thus restoring the natural food web and recreating nursery areas for aquatic biota. We describe Ecohydrology principles applied during Ecoengineering restoration projects in Europe, Australia, Asia, South Africa and North America. These show some successful and sustainable approaches but also others that were less than successful and not sustainable despite the best of intentions (and which may even have harmed the ecology). Some schemes may be 'good for the ecologists', as conservationists consider it successful that at least some habitat was created, albeit in the short-term, but arguably did little for the overall ecology of the area in space or time. We indicate the trade-offs between the short- and long-term value of restored and created ecosystems, the success at developing natural structure and functioning in disturbed estuaries, the role of this in estuarine and wetland management, and the costs and benefits of Ecoengineering to the socio-ecological system. These global case studies provide important lessons for both the science and management of estuaries, including that successful estuarine restoration is a complex and often difficult process, and that Ecoengineering with Ecohydrology aims to control and/or simulate natural ecosystem processes

    Habitat Benefit Assessment and Decisionmaking: A Report to the National Marine Fisheries Service

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    Habitats and the services they provide are part of our nation’s portfolio of natural capital assets. As for many components of this portfolio, it is difficult to assess the value of their services, and this complicates regulators’ investment decisions, especially when the alternative use is measurable. The principal objective of this report is to suggest possible strategies for the National Marine Fisheries Service (NMFS) as it applies economic analyses and arguments in support of the agency’s trustee responsibilities. Many approaches are possible, and as we discuss, the “right” strategy will depend on the questions asked, the resources available, and the agency’s role in the consultation process. We discuss in detail bioeconomic modeling and ecosystem indicator approaches to habitat value assessment. Although the approaches are discussed independently, multiple tools could be used simultaneously across different regions or within the same region on different aspects of one consultation.Bioeconomic, ecological indicators, ecosystem services

    Hampton-Seabrook Estuary Habitat Restoration Compendium

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    The goal of this report is to identify restoration opportunities within the watershed derived from data on habitat change. Many other factors exist that are important in the identification and selection of restoration projects, including water quality and non-point source pollution, water withdrawal, harbor maintenance, recreational impacts, human history, and socioeconomic factors, among others. Although information regarding these factors is not explicitly included in this analysis, these factors must be considered and addressed as they may limit the potential for success in specific restoration effort

    Information and communication on the designation and management of Natura2000 sites. Main Report 3: Towards Integrated Management

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    Following the selection of Special Protection Areas (SPA) and Sites of Community Importance (SCI) according to the Birds and the Habitats Directives, most European Member States are now in process of formally designating SPAs and SCIs as Special Areas of Conservation (SAC) or Natura2000 sites. These protected areas collectively form the European Union’s Natura2000 network. Member States are also selecting and implementing adequate management approaches and instruments to maintain and restore the favourable conservation status of protected species and habitat types and to prevent damage to the integrity of the sites. Both actions follow Articles 6.1 and 6.2 of the Habitats Directive. To help the Member States, the European Commission wishes to improve the knowledge and exchange of information and good practice both on the designation process of SPAs and SACs and on the establishment of conservation measures and instruments for these areas. Furthermore, the Commission wants to stress the importance of the sites and their management by involving a wider group of stakeholders in the development of so-called integrated management, in accordance with Article 2 of the Habitats Directive. The project ‘PREPARATORY ACTIONS- Lot 2: Information and communication on the designation and management of sites’ (tender ENV.B.2/SER/2007/0076) is intended to help the Commission to achieve these objectives. In this report we will elaborate on the concept of integrated management as an option for managing the sites. In the first part the meaning of integrated management will be explored. In a second part we give some examples of management approaches that we think illustrate best the concept of integrated management and its potential to achieve the Natura2000 goals

    Hampton-Seabrook Estuary Restoration Compendium

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    The Hampton-Seabrook Estuary Habitat Restoration Compendium (HSEHRC) is a compilation of information on the historic and current distributions of salt marsh and sand dune habitats and diadromous fishes within the Hampton-Seabrook Estuary watershed. These habitats and species groups were selected due to the important ecological role they play within the watershed and with effective restoration and conservation efforts, will continue to play. Other ecologically important habitats and species, such as avifauna, shellfish and eelgrass beds, currently are or historically were present within the watershed. Shellfish and seagrass are recognized as important habitats within the Estuary, but were not included in the current report because a different analytical approach may be required for such dynamic and/or short-lived species. A recent report by the New Hampshire (NH) Audubon Society details modern bird use of the Hampton-Seabrook Estuary (McKinley and Hunt 2008). Restoration opportunities have been identified within the watershed by evaluating habitat loss and changes in land use over time. Restoration opportunities are not prioritized in order to allow the goals and objectives of each restoration practitioner to govern project selection. However, in accordance with an ecosystem-based approach to restoration, areas containing multi-habitat restoration opportunities are considered to be of the highest priority. Furthermore, restoration efforts should ensure processes critical for the support of restored components are maintained or reestablished. The goal of this report is to identify restoration opportunities within the watershed derived from data on habitat change. Many other factors exist that are important in the identification and selection of restoration projects, including water quality and non-point source pollution, water withdrawal, harbor maintenance, recreational impacts, human history, and socioeconomic factors, among others. Although information regarding these factors is not explicitly included in this analysis, these factors must be considered and addressed as they may limit the potential for success in specific restoration efforts We present a series of maps detailing changes in the extent of sand dune and salt marsh habitats over time, the current and historic distribution of seven diadromous fish species, and restoration opportunities within the Hampton-Seabrook Estuary and watershed. A narrative describes the methods used, the results of analyses and examples of prominent restoration projects. Each major section concludes with references used in the narrative and maps. The maps are available for viewing as portable document format (.pdf) files. For those with GIS capabilities, the ArcMap 9.2 project files, associated data files and metadata are included on the compact disc as well. The underlying concept and methods for the HSEHRC stem from a previous project conducted within the Great Bay Estuary, the Great Bay Estuary Restoration Compendium (Odell et al. 2006)
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