Multiple stressors effects on community stability

Las actividades antropogénicas ejercen una presión constante sobre los sistemas naturales, amenazando la diversidad, la estabilidad y el funcionamiento de estos en todo el planeta. Además, existe un gran número de factores de estrés antropogénico, como son la eutrofización, la contaminación química y los eventos extremos, que actúan de manera simultánea. En esta tesis se evalúan e implementan nuevos enfoques para comprender los efectos individuales y combinados de los factores de estrés antropogénico sobre la estabilidad de las comunidades y ecosistemas de agua dulce. Esto se hace, en un primer lugar, revisando la literatura disponible sobre los efectos combinados de las olas de calor y los contaminantes químicos, destacando los vacíos de conocimiento y sugiriendo formas eficientes de integrar los eventos extremos en la evaluación del impacto ambiental de los factores de estrés múltiple. Esta tesis se basa también en grandes experimentos de mesocosmos al aire libre para investigar los efectos de los factores de estrés múltiple sobre las comunidades y ecosistemas dulceacuícolas. En estos trabajos se analizan los efectos de tres estresores agrícolas (dos pesticidas y la contaminación por nutrientes) a nivel de población, comunidad y ecosistema, y se estudian sus impactos sobre la estabilidad del ecosistema y la dimensionalidad entre los parámetros que describen dicha estabilidad. Además, se explora el potencial de las redes tróficas para dilucidar los mecanismos que impulsan la disimilitud composicional de las comunidades acuáticas después de la aplicación de una perturbación puntual, y se evalúan los mecanismos que influyen en la aparición de interacciones entre los factores de estrés en el largo plazo. Finalmente, este trabajo analiza los efectos de los eventos extremos, como las olas de calor, sobre la complejidad de los ecosistemas de agua dulce utilizando métricas topológicas y cuantitativas de redes tróficas. En ese sentido, los cambios en la complejidad de la red trófica fueron vinculados con los cuatro componentes que definen la estabilidad del sistema, y que caracterizan la estabilidad funcional, estructural y de los flujos de energía entre las especies que forman la red trófica. En general, esta tesis propone un enfoque general para dilucidar los efectos del cambio global sobre la estabilidad de los ecosistemas, brindando información útil para preservar la estructura y funcionalidad de éstos en condiciones ambientales cambiantes

Food web rewiring drives long-term compositional differences and late-disturbance interactions at the community level

Ecological communities are constantly exposed to multiple natural and anthropogenic disturbances. Multivariate composition (if recovered) has been found to need significantly more time to be regained after pulsed disturbance compared to univariate diversity metrics and functional endpoints. However, the mechanisms driving the different recovery times of communities to single and multiple disturbances remain unexplored. Here, we apply quantitative ecological network analyses to try to elucidate the mechanisms driving long-term community-composition dissimilarity and late-stage disturbance interactions at the community level. For this, we evaluate the effects of two pesticides, nutrient enrichment, and their interactions in outdoor mesocosms containing a complex freshwater community. We found changes in interactions strength to be strongly related to compositional changes and identified postdisturbance interactionstrength rewiring to be responsible for most of the observed compositional changes. Additionally, we found pesticide interactions to be significant in the long term only when both interaction strength and food-web architecture are reshaped by the disturbances. We suggest that quantitative network analysis has the potential to unveil ecological processes that prevent long-term community recovery.Fil: Polazzo, Francesco. Instituto Madrileño de Estudios Avanzados; EspañaFil: Marina, Tomas Ignacio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Austral de Investigaciones Científicas; ArgentinaFil: Crettaz Minaglia, Melina Celeste. Instituto Madrileño de Estudios Avanzados; España. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Rico, Andreu. Instituto Madrileño de Estudios Avanzados; España. Universidad de Valencia; Españ

Food web rewiring drives long-term compositional differences and late-disturbance interactions at the community level

Ecological communities are constantly exposed to multiple natural and anthropogenic disturbances. Multivariate composition (if recovered) has been found to need significantly more time to be regained after pulsed disturbance compared to univariate diversity metrics and functional endpoints. However, the mechanisms driving the different recovery times of communities to single and multiple disturbances remain unexplored. Here, we apply quantitative ecological network analyses to try to elucidate the mechanisms driving long-term community-composition dissimilarity and late-stage disturbance interactions at the community level. For this, we evaluate the effects of two pesticides, nutrient enrichment, and their interactions in outdoor mesocosms containing a complex freshwater community. We found changes in interactions strength to be strongly related to compositional changes and identified postdisturbance interactionstrength rewiring to be responsible for most of the observed compositional changes. Additionally, we found pesticide interactions to be significant in the long term only when both interaction strength and food-web architecture are reshaped by the disturbances. We suggest that quantitative network analysis has the potential to unveil ecological processes that prevent long-term community recovery.Fil: Polazzo, Francesco. Instituto Madrileño de Estudios Avanzados; EspañaFil: Marina, Tomas Ignacio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Austral de Investigaciones Científicas; ArgentinaFil: Crettaz Minaglia, Melina Celeste. Instituto Madrileño de Estudios Avanzados; España. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Rico, Andreu. Instituto Madrileño de Estudios Avanzados; España. Universidad de Valencia; Españ

Environmental variability in aquatic ecosystems: Avenues for future multifactorial experiments

The relevance of considering environmental variability for understanding and predicting biological responses to environmental changes has resulted in a recent surge in variability-focused ecological research. However, integration of findings that emerge across studies and identification of remaining knowledge gaps in aquatic ecosystems remain critical. Here, we address these aspects by: (1) summarizing relevant terms of variability research including the components (characteristics) of variability and key interactions when considering multiple environmental factors; (2) identifying conceptual frameworks for understanding the consequences of environmental variability in single and multifactorial scenarios; (3) highlighting challenges for bridging theoretical and experimental studies involving transitioning from simple to more complex scenarios; (4) proposing improved approaches to overcome current mismatches between theoretical predictions and experimental observations; and (5) providing a guide for designing integrated experiments across multiple scales, degrees of control, and complexity in light of their specific strengths and limitations

ECORISK2050: An Innovative Training Network for predicting the effects of global change on the emission, fate, effects, and risks of chemicals in aquatic ecosystems

By 2050, the global population is predicted to reach nine billion, with almost three quarters living in cities. The road to 2050 will be marked by changes in land use, climate, and the management of water and food across the world. These global changes (GCs) will likely affect the emissions, transport, and fate of chemicals, and thus the exposure of the natural environment to chemicals. ECORISK2050 is a Marie Skłodowska-Curie Innovative Training Network that brings together an interdisciplinary consortium of academic, industry and governmental partners to deliver a new generation of scientists, with the skills required to study and manage the effects of GCs on chemical risks to the aquatic environment. The research and training goals are to: (1) assess how inputs and behaviour of chemicals from agriculture and urban environments are affected by different environmental conditions, and how different GC scenarios will drive changes in chemical risks to human and ecosystem health; (2) identify short-to-medium term adaptation and mitigation strategies, to abate unacceptable increases to risks, and (3) develop tools for use by industry and policymakers for the assessment and management of the impacts of GC-related drivers on chemical risks. This project will deliver the next generation of scientists, consultants, and industry and governmental decision-makers who have the knowledge and skillsets required to address the changing pressures associated with chemicals emitted by agricultural and urban activities, on aquatic systems on the path to 2050 and beyond

Laghi alpini, indicatori dei cambiamenti globali: due esempi dalle Alpi Italiane

I laghi alpini sono ecosistemi estremi, situati in aree remote e popolati da flora e fauna con caratteristiche peculiari. Essendo posti in aree remote, lontani da fonti dirette d\u2019inquinamento, i laghi alpini vengono considerati come luoghi incontaminati. Tuttavia, a partire dagli anni Ottanta, questi ecosistemi si sono rivelati affetti dal trasporto a lunga distanza degli inquinanti provenienti dalle zone industriali delle pianure e dall\u2019introduzione di specie alloctone. A causa del ristretto numero di specie autoctone, questi laghi (originariamente privi di pesci) hanno una bassa resilienza alle modificazioni e possono essere estremamente sensibili alle introduzioni di pesci. L\u2019intensit\ue0 delle pressioni antropiche che insistono sui laghi alpini richiede quindi una valutazione quantitativa delle possibili modificazioni. Poich\ue9 risulta impossibile estendere l\u2019attivit\ue0 di ricerca a tutti i laghi delle Alpi, sono stati selezionati due ambienti sulla base: a) della collocazione geografica dei gruppi di ricerca coinvolti nel progetto; b) della geomorfologia dei siti, considerando soprattutto la loro accessibilit\ue0, essendo collocati in aree spesso raggiungibili solo a piedi. Alla luce di queste considerazioni, sono stati selezionati il Lago Dimon (Friuli - Venezia Giulia, Alpi Carniche) e il Lago sottano della Balma (Piemonte, Alpi Cozie). Durante luglio e ottobre 2017, sono state effettuate due campagne di campionamento in ogni lago tramite elettropesca (Lago Dimon) e reti multimaglia branchiali (Lago della Balma) per ottenere informazioni qualitative relative alle popolazioni ittiche introdotte e al loro stato sanitario. Nel Lago Dimon sono stati campionati esemplari di scazzone (Cottus gobio) e di sanguinerola (Phoxinus phoxinus). Invece, presso il Lago della Balma, sono stati campionati solo esemplari di salmerino di fonte (Salvelinus fontinalis). Per quanto riguarda le analisi batteriologiche, nel Lago Dimon \ue8 stato isolato Aeromonas sobria, un batterio ampiamente diffuso nell\u2019ambiente acquatico che, in condizioni particolari pu\uf2 diventare opportunista. Nel Lago della Balma invece, sono stati isolati Plesiomonas shigelloides (anche esso ampiamente diffuso nell\u2019ambiente acquatico) e Yersinia ruckeri. Quest\u2019ultimo \ue8 un patogeno primario che normalmente viene isolato in salmonidi allevati in impianti ittiogenici. Tale ritrovamento ci permette di sottolineare il ruolo delle specie aliene nell\u2019introduzione di nuovi patogeni, anche in ambienti incontaminati. Dall\u2019analisi istologica abbiamo ottenuto risultati interessanti. Infatti, gli esemplari di C. gobio mostrano vacuolizzazione citoplasmatica degli epatociti da moderata a severa, con localizzazione da multifocale a diffusa. Queste alterazioni non sono mai state descritte in esemplari di scazzone selvatico o mantenuto in ambiente controllato; per questo motivo, ulteriori indagini sono in corso per chiarire meglio questa segnalazione. Concludendo, \ue8 possibile affermare che l\u2019uomo impatta questi ecosistemi in molteplici modi. Queste modificazioni danneggiano la fauna autoctona ed in generale la biodiversit\ue0 acquatica. Si rendono quindi necessari ulteriori studi al fine di valutare l\u2019impatto delle specie ittiche aliene sulla fauna terrestre, ed in particolare sugli anfibi

Combined effects of heatwaves and micropollutants on freshwater ecosystems: towards an integrated assessment of extreme events in multiple stressors research

Freshwater ecosystems are strongly influenced by weather extremes such as heatwaves (HWs), which are predicted to increase in frequency and magnitude in the future. In addition to these climate extremes, the freshwater realm is impacted by the exposure to various classes of chemicals emitted by anthropogenic activities. Currently, there is limited knowledge on how the combined exposure to HWs and chemicals affects the structure and functioning of freshwater ecosystems. Here, we review the available literature describing the single and combined effects of HWs and chemicals on different levels of biological organization, to obtain a holistic view of their potential interactive effects. We only found a few studies (13 out of the 61 studies included in this review) that investigated the biological effects of HWs in combination with chemical pollution. The reported interactive effects of HWs and chemicals varied largely not only within the different trophic levels but also depending on the studied endpoints for populations or individuals. Hence, owing also to the little number of studies available, no consistent interactive effects could be highlighted at any level of biological organization. Moreover, we found an imbalance towards single species and population experiments, with only five studies using a multitrophic approach. This results in a knowledge gap for relevant community and ecosystem level endpoints, which prevents the exploration of important indirect effects that can compromise food web stability. Moreover, this knowledge gap impairs the validity of chemical risk assessments and our ability to protect ecosystems. Finally, we highlight the urgency of integrating extreme events into multiple stressors studies and provide specific recommendations to guide further experimental research in this regard

Environmental variability in aquatic ecosystems: Avenues for future multifactorial experiments

International audienceThe relevance of considering environmental variability for understanding and predicting biological responses to environmental changes has resulted in a recent surge in variability-focused ecological research. However, integration of findings that emerge across studies and identification of remaining knowledge gaps in aquatic ecosystems remain critical. Here, we address these aspects by: (1) summarizing relevant terms of variability research including the components (characteristics) of variability and key interactions when considering multiple environmental factors; (2) identifying conceptual frameworks for understanding the consequences of environmental variability in single and multifactorial scenarios; (3) highlighting challenges for bridging theoretical and experimental studies involving transitioning from simple to more complex scenarios; (4) proposing improved approaches to overcome current mismatches between theoretical predictions and experimental observations; and (5) providing a guide for designing integrated experiments across multiple scales, degrees of control, and complexity in light of their specific strengths and limitations

Environmental variability in aquatic ecosystems: Avenues for future multifactorial experiments

Abstract The relevance of considering environmental variability for understanding and predicting biological responses to environmental changes has resulted in a recent surge in variability‐focused ecological research. However, integration of findings that emerge across studies and identification of remaining knowledge gaps in aquatic ecosystems remain critical. Here, we address these aspects by: (1) summarizing relevant terms of variability research including the components (characteristics) of variability and key interactions when considering multiple environmental factors; (2) identifying conceptual frameworks for understanding the consequences of environmental variability in single and multifactorial scenarios; (3) highlighting challenges for bridging theoretical and experimental studies involving transitioning from simple to more complex scenarios; (4) proposing improved approaches to overcome current mismatches between theoretical predictions and experimental observations; and (5) providing a guide for designing integrated experiments across multiple scales, degrees of control, and complexity in light of their specific strengths and limitations

Environmental variability in aquatic ecosystems : Avenues for future multifactorial experiments

The relevance of considering environmental variability for understanding and predicting biological responses to environmental changes has resulted in a recent surge in variability-focused ecological research. However, integration of findings that emerge across studies and identification of remaining knowledge gaps in aquatic ecosystems remain critical. Here, we address these aspects by: (1) summarizing relevant terms of variability research including the components (characteristics) of variability and key interactions when considering multiple environmental factors; (2) identifying conceptual frameworks for understanding the consequences of environmental variability in single and multifactorial scenarios; (3) highlighting challenges for bridging theoretical and experimental studies involving transitioning from simple to more complex scenarios; (4) proposing improved approaches to overcome current mismatches between theoretical predictions and experimental observations; and (5) providing a guide for designing integrated experiments across multiple scales, degrees of control, and complexity in light of their specific strengths and limitations