154 research outputs found

    Development, Evaluation, and Implementation of a Standardized Fish Community-Based Index of Biotic Integrity for Evaluating the Ecological Health of Boreal Plains Streams and Rivers in Saskatchewan, Canada

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    Freshwater ecosystems face increasing threats from anthropogenic influences and multiple stressors, necessitating effective management techniques to assess, conserve, and restore aquatic health. Fish-based Index of Biotic Integrity (IBI) tools play a crucial role in assessing and monitoring the health of freshwater ecosystems. Despite a prosperous, significant fishery and ample aquatic habitats, Saskatchewan (SK), and much of Canada’s boreal region, currently lack a fish-based IBI framework, and the development and evaluation of such a tool could complement existing monitoring programs and provide a novel approach to fisheries and aquatic resource management within SK, and more broadly, northern Canada. This study developed and evaluated a fish-based IBI framework for streams and rivers of the Beaver River watershed in the Boreal Plain ecozone of SK. This watershed exhibits a gradient of human disturbance, ranging from agriculture in the south to relatively unimpacted forest landscapes in the north, making it an ideal location to study the potential effects of human stressors on fish and aquatic ecosystems and evaluate the IBI in a relatively homogenous area with multiple land-use stressors. By assessing various measures of land use and fish habitat, I classified minimally disturbed (or low-stress) conditions, established a gradient of stream and river health throughout the Beaver River watershed at 18 sites, and then determined fish community response to known stressors. A potential limitation of fish-biomonitoring studies is the effect of seasonality and timing of sampling on the interpretation of results, especially in northern regions where temperature extremes likely influence fish reproduction and mobility. Therefore, I revisited five of the sites annually over a three-year period to test the sensitivity of the IBI to interannual variability. I identified nine metrics, selected across the major metric categories, that showed the highest responsiveness to human disturbance. As expected, IBI scores decreased with increasing stress, but a depauperate and tolerant fish community, confounded by high interannual variability in environmental conditions and the fish community, created difficulties in developing the IBI and limited my ability to attribute variations to natural trends through time or anthropogenic influence. My results reinforce the importance of long-term monitoring to decipher trends in natural variation of fish communities from variation created by anthropological stressors and can inform fisheries and aquatic ecosystem health management and decision making in SK as well as other Boreal Plains’ watersheds throughout Canada

    Climate effects on fish in Sweden : Species-Climate Information Sheets for 32 key taxa in marine and coastal waters

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    The purpose of this publication is to summarize the state of knowledge on the effects of environmental variability and climate change for individual species and stocks based on literature review, giving species-climate information for 32 key taxa in Swedish marine and coastal waters. The report is written in English. The extent and scale of recent changes in climate due to global warming is unprecedented and causes increasing effects on ecosystems. In oceans, ongoing warming leads to, for example, increased water temperatures, decreased ice cover and effects on hydrology and water circulation patterns that can in turn influence salinity. The environmental alterations affect species distribution, biology, and hence also the delivery of marine ecosystem services and human well-being. The results of this review on the effects of environmental variability and climate change on marine taxa are presented as species-climate information sheets designed in a user-friendly format aimed to enhance accessibility for professionals spanning different fields and roles, including e.g. scientific experts, NGOs affiliates and managers. The species-climate information sheets presented here cover 32 key taxa selected among the economically and ecologically most important coastal and marine fish and crustacean species in Swedish waters. The species-wise evaluations show that climate change leads to a wide range of effects on fish, reflecting variations in their biology and physiological tolerances. The review also highlights important data and knowledge gaps for each species and life stage. Despite the high variability and prevailing uncertainties, some general patterns appeared. On a general level, most fish species in Swedish marine and coastal waters are not expected to benefit from climate change, and many risks are identified to their potential for recruitment, growth and development. Boreal, marine and cold-adapted species would be disadvantaged at Swedish latitudes. However, fish of freshwater origin adapted to warmer temperature regimes could benefit to some extent in the Baltic Sea under a warming climate. Freshwater fish could also be benefitted under further decreasing salinity in the surface water in the Baltic Sea. The resulting effects on species will not only depend on the physiological responses, but also on how the feeding conditions for fish, prey availability, the quality of essential fish habitats and many other factors will develop. A wide range of ecological factors decisive for the development of fish communities are also affected by climate change but have not been explored here, where we focused on the direct effects of warming. The sensitivity and resilience of the fish species to climate change will also depend on their present and future health and biological status. Populations exposed to prolonged and intense fishing exploitation, or affected by environmental deterioration will most likely have a lower capacity to cope with climate change effects over time. For both the Baltic Sea and the North Sea, it is important to ensure continued work to update and improve the species-climate information sheets as results from new research become available. It can also be expected that new important and relevant biological information and improved climate scenarios will emerge continuously. Continued work is therefore important to update and refine the species-climate information sheets, help filling in currently identified knowledge gaps, and extend to other species not included here. Moreover, there is need to integrate this type of species-level information into analyses of the effects of climate change at the level of communities and ecosystems to support timely mitigation and adaptation responses to the challenges of the climate change

    Natural or anthropogenic variability? A long-term pattern of the zooplankton communities in an ever-changing transitional ecosystem

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    The Venice Lagoon is an important site belonging to the Italian Long-Term Ecological Research Network (LTER). Alongside with the increasing trend of water temperature and the relevant morphological changes, in recent years, the resident zooplankton populations have also continued to cope with the colonization by alien species, particularly the strong competitor Mnemiopsis leidyi. In this work, we compared the dynamics of the lagoon zooplankton over a period of 20 years. The physical and biological signals are analyzed and compared to evaluate the hypothesis that a slow shift in the environmental balance of the site, such as temperature increase, sea level rise (hereafter called “marinization”), and competition between species, is contributing to trigger a drift in the internal equilibrium of the resident core zooplankton. Though the copepod community does not seem to have changed its state, some important modifications of structure and assembly mechanisms have already been observed. The extension of the marine influence within the lagoon has compressed the spatial gradients of the habitat and created a greater segregation of the niches available to some typically estuarine taxa and broadened and strengthened the interactions between marine species

    Otimização da gestão territorial das florestas mistas de sobreiro e pinheiro-manso: ocupação potencial e produtividade

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    Frente a los diferentes fenómenos ligados al cambio global se hace necesario explorar alternativas de resiliencia y sostenibilidad para los bosques mediterráneos, como lo pueden ser las masas mixtas de Pinus pinea y Quercus suber, una combinación con posibilidad de ampliar los servicios del ecosistema en comparación con la tradicional gestión forestal monoespecífica. Así pues, este trabajo consiste en la creación de modelos de distribución potencial, basados en GLM y Random Forests, para el pino piñonero y el alcornoque, lo que permitirá concretar qué áreas son aptas para este tipo de bosques gestionados. La calibración de los modelos se ha realizado en la mitad sur del país, para, una vez validados, ser aplicados al resto del país. En este sentido, los modelos se centran solamente en la parte abiótica de la distribución y constatan la gran perturbación antrópica de la ocupación actual, sobre la que se basa la modelación de la distribución potencial. Los resultados muestran que, de las variables edafoclimáticas, una de las más significativas para ambas especies es la textura del suelo, concretamente el % de arena; mientras que la temperatura máxima media y la continentalidad tienen más relevancia en los modelos del pino piñonero, siendo la precipitación la que más tiene para el alcornoque. Existe poco consenso científico sobre los determinantes de la distribución de estas dos especies, lo que hace necesario conocer mejor el impacto de las variables sobre ambas para aumentar el poder explicativo de los modelos en nuestra región.As florestas mistas de Pinheiro-manso e Sobreiro têm vindo a ganhar o interesse de gestores e proprietários florestais porque permitem aliar uma maior rentabilização da exploração florestal, através da produção mista de cortiça e pinha. Uma floresta mista será, em teoria, mais resiliente a um clima em mudança, aos desafios de uma economia global e com um papel importante na melhoria das funções do ecossistema de regulação hídrica, sequestro de carbono e manutenção da biodiversidade. O investimento na floresta comporta algumas incertezas. O sucesso das plantações está estreitamente ligado à aptidão ecológica do local, o que é determinado pelas condições climáticas, edáficas e orográficas. Porém, no território, existem também constrangimentos económicos e políticos. Reconhecer estes locais é fundamental para garantir a manutenção das espécies e a sustentabilidade na produção. Este trabalho pretende responder a este desafio e apoiar o gestor florestal numa tomada de decisão consciente e informada. Para tal criaram-se modelos probabilísticos de distribuição de espécies (Species Distribition Model - SDM, em inglês) que têm como objetivo, por um lado, permitir: i) identificar a influência de cada variável explicativa na distribuição das espécies; e, por outro, ii) estimar a aptidão do território continental de Portugal para a eventual presença das duas espécies em conjunto. Os modelos de ocupação potencial têm uma resolução de 500m e basearam-se na distribuição geográfica de a) presenças / ausências atuais da variável dependente — a existência de povoamentos de Pinheiro-manso, Sobreiro ou mistos— e b) os valores das variáveis explicativas. Aplicaram-se dois algoritmos inovadores na literatura científica (Pechi et al., 2019; Santini et al. 2021), pertencentes a duas famílias diferentes, com a finalidade de explorar as suas potencialidades: Generalized Linear Model (GLM) e Random Forests (RF). A informação geográfica utilizada para conhecer a atual distribuição de ambas as espécies, como variável dependente, provém do 6º Inventário Florestal Nacional (ICNF, 2015), enquanto que as variáveis explicativas foram extraídas de diferentes fontes: • Os indicadores climáticos — alguns deles relativos à categorização BIOCLIM — foram calculados com dados de precipitação e temperaturas média, mínima e máxima dos últimos 30 anos provenientes da base de dados interpolada IBERIA01 para o período 1971-2015 (Herrera et al., 2019). As variáveis selecionadas foram: o número de dias de geada no ano (T. mín. < 0ºC), a temperatura máxima média m ºC, a continentalidade em ºC (BIO 07) e a média das precipitações acumuladas anuais em mm (BIO 12). • As propriedades físico-químicas dos solos, foram compiladas da base de dados INFOSOLO 1966-2014 (Ramos et al., 2017). As variáveis seleccionadas foram o pH e a textura dos solos, mais concretamente a percentagem de areia. • A Carta de Ocupação de Solos 2018 (DGT) foi usada como variável de perturbação antrópica utilizando camadas booleanas de exclusão associadas a determinados usos humanos do território: construção, agricultura e pastagens. Criou-se, adicionalmente, outra camada de exclusão associada a reservatórios de água temporários e permanentes: albufeiras, rios e sapais. Os modelos foram calibrados para a área de estudo, criada a partir das NUTS III da região sul do país, e incluem as regiões do Ribatejo, Alentejo e Algarve. Posteriormente, são validados com curvas ROC (Receiver Operating Characteristics), utilizando-se o valor AUC (Area Under the Curve) para comparar o rendimento de cada algoritmo. Contudo, apesar de RF obter melhores resultados do que GLM o processo de validação —ligeiramente para o pinheiro-manso e massas mixtas e bastante para o sobreiro—, decidiu-se a aplicação dos dois algoritmos para fora da área de estudo (resto área de Portugal continental), pelo facto dos modelos de aprendizagem automática poderem estar sobre-calibrados (Jiménez-Valverde et al., 2008). No que diz respeito aos resultados estatísticos, as variáveis que mais contribuem para a modelação da ocupação de Pinus pinea foram a textura arenosa dos solos e a temperatura máxima média; enquanto que para Quercus suber, as variáveis mais significativas foram a percentagem da areia e a precipitação anual. A relação nos três primeiros casos, respetivamente para cada espécie, é positiva, mas no último caso a relação é negativa, sendo o intervalo mais estável para precipitações entre os 600 e 700 mm. No que se refere à aplicação dos modelos fora da área de estudo e no caso do pinheiro-manso, a representação cartográfica para RF sugere áreas de expansão que o modelo GLM descarta totalmente: regiões do alto Mondego e o Pinhal de Leiria. Já no caso dos modelos para o sobreiro mostram resultados muito parecidos entre si, sugerindo a idoneidade da expansão desta espécie nas regiões da Beira Alta e Trásos-Montes. Finalmente, a aplicação dos modelos criados com as ocorrências de povoamentos mistos mostra probabilidades muito baixas de ocorrência utilizando ambos os algoritmos, não sendo possível definir áreas de distribuição potencial neste caso. Consideramos que a forte influência antropogénica na distribuição atual dos povoamentos de pinheiro-manso e sobreiro constitui um forte constrangimento à distribuição potencial modelada deste tipo de floresta mista. Destaca-se também o pouco consenso científico em relação às variáveis abióticas que determinam a distribuição do Pinus pinea e de Quercus suber. Existem grandes discrepâncias nos modelos criados para estas duas espécies na atualidade, o que mostra a necessidade de continuar a trabalhar interdisciplinarmente de forma melhorar o valor explicativo dos modelos de distribuição de espécies na região mediterrânica. Só assim será possível obter resultados de modelação com a aplicação prática necessária para os diferentes agentes territoriais trabalharem com o mínimo de incerteza possível

    Relationship between synoptic circulations and the spatial distributions of rainfall in Zimbabwe

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    This study examines how the atmospheric circulation patterns in Africa south of the equator govern the spatial distribution of precipitation in Zimbabwe. The moisture circulation patterns are designated by an ample set of eight classified circulation types (CTs). Here it is shown that all wet CTs over Zimbabwe features enhanced cyclonic/convective activity in the southwest Indian Ocean. Therefore, enhanced moisture availability in the southwest Indian Ocean is necessary for rainfall formation in parts of Zimbabwe. The wettest CT in Zimbabwe is characterized by a ridging South Atlantic Ocean high-pressure, south of South Africa, driving an abundance of southeast moisture fluxes, from the southwest Indian Ocean into Zimbabwe. Due to the proximity of Zimbabwe to the Agulhas and Mozambique warm current, the activity of the ridging South Atlantic Ocean anticyclone is a dominant synoptic feature that favors above-average rainfall in Zimbabwe. Also, coupled with a weaker state of the Mascarene high, it is shown that a ridging South Atlantic Ocean high-pressure, south of South Africa, can be favorable for the southwest movement of tropical cyclones into the eastern coastal landmasses resulting in above-average rainfall in Zimbabwe. The driest CT is characterized by the northward track of the Southern Hemisphere mid-latitude cyclones leading to enhanced westerly fluxes in the southwest Indian Ocean, limiting moist southeast winds into Zimbabwe

    New Trends in Environmental Engineering, Agriculture, Food Production, and Analysis

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    This Special Issue presents the latest advances in agriculture, aquaculture, food technology and environmental protection and engineering, discussing, among others, the following issues: new technologies in water, stormwater and wastewater treatment; water saving, lake restoration; new sludge and waste management systems; biodiesel production from animal fat waste; the microbiological quality of compound fish feeds for aquaculture; the role of technological processes to improve food quality and safety; new trends in the analysis of food and food components including in vitro, in vivo, and in silico analyses; and functional and structural aspects of bioactivities of food molecules

    Modularity Facilitates Flexible Tuning of Plastic and Evolutionary Gene Expression Responses during Early Divergence

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    Gene expression changes have been recognized as important drivers of adaptation to changing environmental conditions. Little is known about the relative roles of plastic and evolutionary responses in complex gene expression networks during the early stages of divergence. Large gene expression data sets coupled with in silico methods for identifying coexpressed modules now enable systems genetics approaches also in nonmodel species for better understanding of gene expression responses during early divergence. Here, we combined gene coexpression analyses with population genetics to separate plastic and population (evolutionary) effects in expression networks using small salmonid populations as a model system. We show that plastic and population effects were highly variable among the six identified modules and that the plastic effects explained larger proportion of the total eigengene expression than population effects. A more detailed analysis of the population effects using a Q(ST)-F-ST comparison across 16,622 annotated transcripts revealed that gene expression followed neutral expectations within modules and at the global level. Furthermore, two modules showed enrichment for genes coding for early developmental traits that have been previously identified as important phenotypic traits in thermal responses in the same model system indicating that coexpression analysis can capture expression patterns underlying ecologically important traits. We suggest that module-specific responses may facilitate the flexible tuning of expression levels to local thermal conditions. Overall, our study indicates that plasticity and neutral evolution are the main drivers of gene expression variance in the early stages of thermal adaptation in this system

    Biology and Control of Invasive Fishes

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    This book is a collection of 12 peer-reviewed articles on freshwater invasive fish and is the first on this topic. It focuses on real-world lessons learned from managing common carp, bigheaded carp, sea lamprey, northern pike, and lake trout in different parts of the world. Articles also discuss damage caused by invasive fish, environmental DNA as means to measure spawning carp, and CO2 as a fish deterrent. Detailed critical evaluations of the possibility of using koi herpes virus to control common carp, market-driven fishing (invasivorism), as well as changes in lock and dam operating protocols to control bigheaded carps are also presented. Several important commonalities are noted between successful management efforts, including the simultaneous use of multiple integrated strategies, a focus on suppressing reproduction, and a deep local knowledge in an introductory article that provides context for the discipline
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