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The proximity of freshwater ecosystems to anthropogenic activities makes them one of the most threatened environments by plastic pollution in the form of microplastics (MPs). Therefore, it is crucial to identify the primary drivers of MP dynamics in rivers to enhance their management. This work analyzed the concentration of MPs in water and sediments and evaluated the influence of land use and its relationship with the main biotic indices employed to assess the water quality of rivers. This research was carried out in four different catchments, with three sampling points established in each river basin. The results revealed that MPs were ubiquitous across all locations, with concentrations ranging from 0.10 to 35.22 items m−3 in waters and from 26 to 643 items Kg−1 in sediments. The highest concentration of MPs both in water and sediments were found in the Lagares River (35.22 items m−3 and 643 items Kg−1), while the lowest concentrations were found in the Miñor River for water (0.10 items m−3) and Tea River for sediments (138 items Kg−1). Urbanization degree was identified as the primary driver of MP pollution in water, whereas population density correlated with sediment pollution levels. These findings explain the elevated MPs abundance in the more urbanized and populated Gafos and Lagares rivers compared to the relatively pristine Miñor and Tea rivers. Furthermore, the presence of MPs in sediments was found to negatively impact the most sensitive benthic macroinvertebrate taxa, as evidenced by lower values of the IASPT and EPT indices at sampling points with higher sediment MPs concentrations (Gafos and Lagares). [ABSTRACT FROM AUTHOR]

India boasts of a vast freshwater resource network (rivers, wetlands, and groundwater), which has unique ecological, social and economic values associated with it. Despite their importance for both people and biodiversity, its freshwater ecosystems (FWEs) are heavily impacted through multiple factors such as pollution, overexploitation, habitat loss/modification and climate change. India is also among the hotspots of water resource overuse that has caused a serious decline in freshwater availability.Given that healthy FWEs lie at the centre for supporting the country's ecology, health, economy, livelihoods and ultimately achieving multiple policy goals, it is crucial that holistic and focused efforts are made to protect, conserve, and restore all types of FWEs.We call for an urgent and a greater focus on implementing conservation actions for FWEs in India and suggest the following strategy to enhance focus on their conservation: (1) establishing a shared freshwater conservation vision at a national scale, (2) developing and including national freshwater conservation goals within global efforts, (3) conducting simultaneous conservation action planning at regional scales and (4) bridge planning to implementation gap by strengthening key enabling conditions: i) mainstream FWE conservation within key existing governance instruments, ii) secure sustainable conservation funding, iii) improve data access and knowledge translation; iv) create national awareness around importance of FWEs; v) facilitate collaboration among key actors. [ABSTRACT FROM AUTHOR]

Climate change may lead to range shifts, and barriers to such displacements may result in extirpations from previously suitable habitats. This may be particularly important in freshwater ecosystems that are highly fragmented by anthropogenic obstacles, such as dams and other smaller in‐stream barriers. Conservation planning in freshwaters should consider the dynamic effects of climate change and the ability of species to cope with it. In this study, we developed a framework for incorporating climate‐driven dispersal barriers into conservation planning taking into account the medium and long‐term impacts of climate change and species with obligatory interactions. Given that freshwater mussels (Bivalvia: Unionida) are a group of highly threatened organisms dependent on fish hosts to complete their larval development and dispersal, we used Marxan to prioritize areas for their joint conservation in the Iberian Peninsula as a case study. We tested two connectivity scenarios between current and future habitats, (i) unlimited dispersal capacity and (ii) dispersal constrained by artificial barriers, and also identified priority translocation areas for species that were unable to disperse. Accounting for the effects of climate change on species distributions allowed the identification of long‐term conservation areas, but disregarding artificial barriers to dispersal may lead to unrealistic solutions. Integrating the location of barriers allowed the identification of priority areas that are more likely to be colonized in the future following climatic shifts, although this resulted in an additional loss of six to eight features (~5%–7%) compared to solutions without dispersal constraints. Between 173 and 357 artificial barriers (~1.6%–3.3%) will potentially block species dispersal to irreplaceable planning units. Where removal of artificial barriers is unfeasible, conservation translocations may additionally cover up to eight additional features that do not meet conservation targets due to dispersal constraints. This study highlights the challenge of identifying protected areas to safeguard biodiversity under climate change. [ABSTRACT FROM AUTHOR]

Mediterranean spring ecosystems are unique habitats at the interface between surface water and groundwater. These ecosystems support a remarkable array of biodiversity and provide important ecological functions and ecosystem services. Spring ecosystems are influenced by abiotic, biotic, and anthropogenic factors such as the lithology of their draining aquifers, their climate, and the land use of their recharge area, all of which affect the water chemistry of the aquifer and the spring discharges. One of the most relevant characteristics of spring ecosystems is the temporal stability of environmental conditions, including physicochemical features of the spring water, across seasons and years. This stability allows a wide range of species to benefit from these ecosystems (particularly during dry periods), fostering an unusually high number of endemic species. However, global change poses important threats to these freshwater ecosystems. Changes in temperature, evapotranspiration, and precipitation patterns can alter the water balance and chemistry of spring water. Eutrophication due to agricultural practices and emergent pollutants, such as pharmaceuticals, personal care products, and pesticides, is also a growing concern for the preservation of spring biodiversity. Here, we provide a synthesis of the main characteristics and functioning of Mediterranean spring ecosystems. We then describe their ecological value and biodiversity patterns and highlight the main risks these ecosystems face. Moreover, we identify existing knowledge gaps to guide future research in order to fully uncover the hidden biodiversity within these habitats and understand the main drivers that govern them. Finally, we provide a brief summary of recommended actions that should be taken to effectively manage and preserve Mediterranean spring ecosystems for future generations. Even though studies on Mediterranean spring ecosystems are still scarce, our review shows there are sufficient data to conclude that their future viability as functional ecosystems is under severe threat. [ABSTRACT FROM AUTHOR]

Fungal biodiversity is still mostly unknown and their presence in particular ecosystems such as freshwater habitats is often underestimated. The ecological role that these fungi play in freshwater environments mainly concerns their activity as decomposers of litter and plant material. At present, it is estimated that 3870 species belong to the ecological group of freshwater fungi (13 phyla and 45 classes). In this survey, we provide an overview of the Italian freshwater fungal diversity on the basis of the field and literature data. In the literature, data on freshwater fungi are fragmentary and not updated, focusing mainly on northern Italy where the most important lakes and rivers are present, while data from central and southern Italy (including Sicily and Sardinia) are almost completely ineffective. In particular, Ascomycota are reported in only 14 publications, most of which concern the freshwater environments of Lombardia, Piemonte, and Veneto. Only one publication explores the biodiversity of freshwater Basidiomycota in the wetlands of the Cansiglio forest (Veneto). The field observation allowed for us to identify 38 species of Basidiomycota growing in riparian forest of Italy. However, the number of fungi in freshwater habitats of Italy is strongly underestimated and many species are still completely unknown. [ABSTRACT FROM AUTHOR]

Assessment, maintenance, and implementation of environmental flow (hereafter e-flow) in rivers and wetlands have been recognized as a vital tool for sustaining freshwater ecosystems in several countries including India. In this view, the paper intends to review the current understanding of e-flow concept in India. This can be accomplished by reviewing case studies reported for different river basins across India and documented literature, legislative and water policy reports, minutes of meetings, workshops, and conferences. with the aim, On the other hand, its aims to briefly trace the history of e-flow assessment studies as well as the progress that has been achieved so far since 1998s. Role of enabling factors and constraints for e-flow implementation in India at a macro scale is also highlighted, which shows e-flow understanding has received considerable attention over the past two decades for the conservation of freshwater ecosystems and is still evolving. This paper also concludes with identifying a range of actions and gives some directions for future research that requires for e-flow implementation in a river basin. [ABSTRACT FROM AUTHOR]

Land‐use and land‐cover transitions can affect biodiversity and ecosystem functioning in a myriad of ways, including how energy is transferred within food‐webs. Size spectra (i.e. relationships between body size and biomass or abundance) provide a means to assess how food‐webs respond to environmental stressors by depicting how energy is transferred from small to larger organisms. Here, we investigated changes in the size spectrum of aquatic macroinvertebrates along a broad land‐use intensification gradient (from Atlantic Forest to mechanized agriculture) in 30 Brazilian streams. We expected to find a steeper size spectrum slope and lower total biomass in more disturbed streams due to higher energetic expenditure in physiologically stressful conditions, which has a disproportionate impact on large individuals. As expected, we found that more disturbed streams had fewer small organisms than pristine forest streams, but, surprisingly, they had shallower size spectrum slopes, which indicates that energy might be transferred more efficiently in disturbed streams. Disturbed streams were also less taxonomically diverse, suggesting that the potentially higher energy transfer in these webs might be channelled via a few efficient trophic links. However, because total biomass was higher in pristine streams, these sites still supported a greater number of larger organisms and longer food chains (i.e. larger size range). Our results indicate that land‐use intensification decreases ecosystem stability and enhances vulnerability to population extinctions by reducing the possible energetic pathways while enhancing efficiency between the remaining food‐web linkages. Our study represents a step forward in understanding how land‐use intensification affects trophic interactions and ecosystem functioning in aquatic systems. [ABSTRACT FROM AUTHOR]

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Macroinvertebrates are used as bioindicators worldwide, but the high diversity of macroinvertebrate species and endemism in Latin America (LA) requires greater knowledge of this group to increase the effectiveness of biomonitoring. We examined some of the primary taxonomic and ecological studies on macroinvertebrates in the region, quantified the number of papers that used foreign and local indices, examined alternative approaches to bioassessment that may be more relevant for the region, and explored freshwater ecosystem management in LA. Here, we highlight the need to increase taxonomic knowledge and the number of specialists in local fauna, establish and maintain taxonomic collections in public institutions, and make online databases on the biodiversity in each country available. However, we also demonstrate that taxonomy specialists of different nationalities do collaborate on the generation of fundamental information about biodiversity in LA. We found that 57% of the 215 reviewed scientific articles from LA used foreign but locally adapted indices for biomonitoring aquatic ecosystems. Only 21% of these articles presented local indices developed in LA. New technologies, such as environmental DNA, offer substantial potential for bioassessment but only in regions where sufficient taxonomic knowledge exists and where species-level stressor–response relationships are well described. In the absence of more complete taxonomic records, there could be some value in developing biological trait and multimetric indices, and occupancy models could be developed to analyze the relationship between taxa and stress factors. These tools could be adopted by researchers to generate more accurate biotic indices based on local taxa. Finally, in LA, bioindicators are used to support scientific research more often than as environmental monitoring tools. Environmental laws and regulations that support the biomonitoring of LA freshwaters and unified criteria for evaluating and monitoring aquatic ecosystems are essential to face regional and global challenges. [ABSTRACT FROM AUTHOR]

Microbiota play essential roles in nitrogen (N) cycling in freshwater river ecosystems. However, our understanding of microbial functional groups associated with N cycling (especially denitrification) in freshwater rivers under anthropogenic disturbance is still poor. Here, we studied the impacts of different land‐use types on denitrification‐related microbiota in the Weihe River, Hanjiang River, and their tributaries, in the Qinling Mountains, China. The major land‐use types in the three river areas were divided into natural (forest, shrub, grassland, and open water) and anthropogenic (agricultural and urbanized land) types. A landscape survey of microbiota in the river water and sediment was carried out with extensive sample sources based on deep 16S rRNA gene sequencing, which yielded operational taxonomic units for predicting functional groups. With increases in proportions of agricultural and urbanized land areas, electrical conductivity, total N, ammonium‐N, and nitrate‐N all increased in water samples. Conversely, microbial diversity exhibited a decreasing trend in water samples, whereas the relative abundance of denitrification‐related functional groups increased, with increases in the proportions of agricultural and urbanized land areas. The relative abundances of denitrification‐ and human‐related microbial functional groups in sediment samples were distinctively higher in Weihe River (mainly under agriculture and urbanization), when compared with those of Hanjiang River and Qinling tributaries (dominated by forests). The results indicate that anthropogenic land‐use types, such as agricultural and urbanized land, result in simple microbial community structure and stimulate microbe‐mediated denitrification in freshwater rivers. [ABSTRACT FROM AUTHOR]

Micro(nano)plastics (MNPs) are pervasive pollutants posing significant environmental and health risks. Selecting appropriate sentinel species to assess MNPs in terrestrial and aquatic environments involves considering factors such as species behavior, habitat, exposure pathways, and the feasibility of sampling. For these reasons, it was imperative to launch a virtual special issue (VSI) in Ecological Indicators. This editorial summarizes the contributions submitted to the VSI, which invited research on bioindicators of MNPs, including sampling protocols, monitoring strategies, and analytical methods, to advance our understanding and management of plastic pollution. The VSI received a total of 12 contributions from four countries, with a significant majority originating from Italy. To present the contributions, we have organized the sections into original articles and reviews. The original articles are further divided into sections on the occurrence of MNPs in biotic and abiotic compartments, the selection of bioindicators, and the effects and risk assessment of MPs. The reviews are categorized based on their focus on aquatic and terrestrial ecosystems. Future ecotoxicology studies should select bioindicators based on exposure to MNPs, conservation status, ecological roles, and human consumption. [ABSTRACT FROM AUTHOR]

The present study reports a potentially toxic cyanobacterial species, Woronichinia naegeliana, which was observed along with a continuous bloom of Microcystis from a freshwater pond while monitoring cyanobacterial blooms along central Kerala, south India. Woronichinia is a toxic cyanobacterium usually found in freshwater ecosystems associated with other harmful cyanobacterial blooms. The monitoring was carried out from 2019 to 2020, and the high cell density of Woronichinia was observed in March 2020 (8.4 × 104 cells L−1). Hydrographic parameters studied revealed that the abundance of Woronichinia species was favoured by higher temperature (29 °C) with comparatively low nutrient values (NO3: 10.5 μmol L−1; PO4: 2.3 μmol L−1) while Microcystis desired a higher temperature (31 °C) with increased nutrient values (NO3: 96.78 μmol L−1; PO4: 5.88 μmol L−1). [ABSTRACT FROM AUTHOR]

In the modern era, due to urbanization, industrialization, and anthropogenic activities in the catchment, greenhouse gas (GHG; CO2, CH4, and N2O) emissions from freshwater ecosystems received scientific attention because of global warming and future climate impacts. A developing country such as India contributes a huge share (4% of global) of GHGs from its freshwater ecosystems (e.g., rivers, lakes, reservoirs) to the atmosphere. This is the first comprehensive review dealing with the GHG emissions from Indian freshwater bodies. Literature reveals that the majority of GHG from India is emitted from its inland water, with 19% of CH4 flux and 56% of CO2 flux. A large part of India's gross domestic product (GDP) is manipulated by its rivers. As a matter of fact, 117.8 Tg CO2 year−1 of CO2 is released from its major riverine waters. The potential of GHG emissions from hydropower reservoirs varies between 11–52.9% (mainly CH4 and CO2) because of spatio-temporal variability in the GHG emissions. A significant contribution was also reported from urban lakes, wetlands, and other inland waters. Being a subtropical country, India is one of the global GHG hotspots, having the highest ratio (GHG: GDP) of 1301.79. However, a large portion of India's freshwater has not been considered yet, and there is a need to account for precise regional carbon budgets. Therefore, in this review, GHG emissions from India's freshwater bodies, drivers behind GHG emissions (e.g., pH, mean depth, dissolved oxygen, and nutrients), and long-term climatic risks are thoroughly reviewed. Besides research gaps, future directions and mitigation measures are being suggested to provide useful insight into the carbon dynamics (sink/source) and control of GHG emissions. [ABSTRACT FROM AUTHOR]

Non-indigenous species may pose a threat to native ecosystems worldwide. In aquatic environments, invasives may have a negative impact on human food security and livelihoods. Several water fleas (Crustacea: Branchiopoda: Cladocera) are notorious invasive alien species influencing large freshwater lake systems and even inland seas. In the current review, we discuss the state of knowledge regarding non-indigenous species in the Cladocera and their invasiveness potential in different continents. We argue that the potential impacts and occurrence of cladoceran exotics may be higher than generally assumed. We critically review 79 cases from literature sources, involving 61 cladoceran taxa where records outside of their natural distribution ranges were previously interpreted as invasions. We assessed the probability of natural range expansions versus human-mediated introductions and we discuss several major corridors of invasion. We estimate human-mediated transportations for at least 43 taxa (out of 61; ca 70%), while other cases can be seen as natural expansions of their distribution ranges (not necessarily/not likely human-mediated) and/or taxonomical confusion. We confirm non-indigenous presence in recipient regions for at least 41 cladoceran taxa, of which several are true invasives (i.e., with negative impacts on native ecosystems). The majority are zooplankters with effects on pelagic freshwater ecosystems, yet we also report on introductions by littoral taxa. We argue that cryptic introductions of cladocerans are taking place on a global scale, yet they remain under the radar. We highlight several striking case studies, such as the Ponto–Caspian onychopods that have invaded the Baltic Sea and the Laurentian Great Lakes, and several clones of the anomopod genera Daphnia and Bosmina that have successfully colonised new environments, causing equilibria shifts in native aquatic worlds. At the same time, we dispel some myths about taxa that were misconstrued as invasive in certain localities. Based on our review, the first of its kind for freshwater zooplankton, future environmental monitoring tools including molecular techniques and detailed surveys with rigorous and critical taxonomical assessments may help to provide a clearer picture on the extent of invasiveness of cladocerans. [ABSTRACT FROM AUTHOR]

The article describes how Big Data, such as geospatial and Earth Observation data, combined with advanced technologies, open opportunities for new ways of producing environment statistics. As an example of the use of Big Data, the article broadly presents SDG indicator 6.6.1 "Change in the extent of water-related ecosystems over time", from the development of the methodology to the creation of datasets and their use by policy makers. The article also discusses the challenges of using geospatial and Earth Observation data both on a global scale and on a specific example of SDG indicator 6.6.1. [ABSTRACT FROM AUTHOR]

Investigating the influence of biodiversity on ecosystem functioning over environmental gradients is needed to anticipate ecosystem responses to global change. However, our understanding of the functional role of freshwater biodiversity, especially for microbes, is mainly based on manipulative experiments, where biodiversity and environmental variability are minimized. Here, we combined observational and manipulative experiments to analyse how fungal biodiversity responds to and mediates the impacts of drying on two key ecosystem processes: organic matter decomposition and fungal biomass accrual. Our observational data set consists of fungal biodiversity and ecosystem processes from 15 streams spanning a natural gradient of flow intermittence. Our manipulative design evaluates the responses of ecosystem processes to two fungal richness levels crossed with three levels of drying. For the observational experiment, we found that increasing the duration of drying reduced fungal species richness and caused compositional changes. Changes in species composition were driven by species turnover, suggesting resistance mechanisms to cope with drying. We also found that fungal richness had a positive effect on organic matter decomposition and fungal biomass accrual. Positive effects of fungal biodiversity were consistent when controlling for the effects of drying duration on richness by means of structural equation modelling. In addition, our results for the manipulative experiment showed that the positive effects of higher richness on both ecosystem processes were evident even when exposed to short or long simulated drying. Overall, our study suggests that maintaining high levels of biodiversity is crucial for maintaining functional freshwater ecosystems in response to ongoing and future environmental changes. [ABSTRACT FROM AUTHOR]

Freshwater ecosystems are important sources of freshwater and essential resources for the development of different economic activities. Monitoring the water quality of these systems is important for their preservation and to prevent risks to human health. The present work addresses the main aspects reported in the literature related to the monitoring of water quality in superficial freshwater ecosystems. Examples of research carried out in different parts of the world are analyzed, illustrating the aspects to be taken into account during water quality monitoring, particularly the case of the Almendares River (Havana, Cuba), which has been evaluated for a period of more than 15 years. [ABSTRACT FROM AUTHOR]

Water crises in Latin America are more a consequence of poor management than resource scarcity. Addressing water management issues through better coordination, identification of problems and solutions, and agreement on common objectives to operationalize integrated water resources management (IWRM) could greatly improve water governance in the region. Composite indices have great potential to help overcome capacity and information challenges while supporting better IWRM. We applied one such index, the Freshwater Health Index (FHI) in three river basins in Latin America (Alto Mayo, Perú; Bogotá, Colombia; and Guandu, Brazil) to assess freshwater ecosystem vitality, ecosystem services, and the water governance system in place. The approach included convening management agencies, water utilities, planning authorities, local NGOs and industries, community groups and researchers to co-implement the FHI. The results provide detailed information on the ecological integrity of each basin and the sustainability of the ecosystem services being provided. All three basins show very low scores for governance and stakeholder engagement, thus improving both in the region should be a priority. The results also shed light on how the FHI framework can help inform decision-making to improve IWRM implementation by facilitating stakeholder engagement while contributing to coordination, identification of problems and solutions as well as agreement on common objectives. Because implementation of IWRM is part of the solution for the United Nations Sustainable Development Goal (SDG) 6.5 ("By 2030, implement IWRM at all levels, including through transboundary cooperation as appropriate"), our case studies can serve as examples to other Latin American countries to achieve SDG 6.5. [ABSTRACT FROM AUTHOR]

Biofilms are matrix‐enclosed communities that represent the most dominant and active mode of microbial life on Earth. Because biofilms are inherently more productive than any equivalent planktonic community, they are of great relevance to all environments they inhabit. However, their existence and importance are still poorly known by the general public, conservation practitioners and environmental policymakers.Most micro‐organisms of multicellular organisms (including humans, animals and plants) occur in the form of true biofilms or biofilm‐like structures that play vital roles in their development, physiology and immunity. Conversely, some biofilms can have a negative effect on host health.Biofilms growing on non‐biological surfaces are essential components of many terrestrial and marine ecosystems: they form the basis of food webs and ensure nutrient cycling and bioremediation in natural systems. However, environmental biofilms can promote the persistence of human pathogens, produce harmful toxins, foul and corrode surfaces in natural and man‐made settings; all of which can have significant health and economic implications.There is a knowledge gap about the roles of biofilms in the epidemiology of wildlife emerging infectious diseases, yet these pose a major threat to public health, biodiversity and sustainability. The drivers of global environmental change all affect biofilm structure and functions. The consequences for host and ecosystem health are, however, poorly understood. While the concept of a healthy microbiome (as opposed to dysbiosis) is emerging in medicine and conservation biology, the concept of a healthy biofilm remains to be defined in environmental sciences.Here, we use an integrative approach to (a) review current knowledge on the roles of biofilms growing on biological and non‐biological interfaces for the health of multicellular organisms and ecosystems, and (b) provide future research directions to address identified knowledge gaps. Giving the biofilm life‐form its full importance will help understand the effects of global environmental change on these communities and, in turn, on human, animal, plant and ecosystem health. [ABSTRACT FROM AUTHOR]

The increasing use of artificial light at night has led to ecosystem exposure to light pollution worldwide. Aquatic ecosystems are particularly exposed, since lit road networks, urban development and industrial infrastructure are frequently located along river, lake, and sea shores. Although the negative effects of night‐time lighting on the physiology, behaviour, and life‐history traits of animals have been largely documented, there is a large knowledge gap about the responses of plants, especially regarding leaf functioning and resource‐management strategies. Some authors have proposed contrasting hypotheses of mechanistic responses to dim light at night in plants, but empirical results are still lacking.Based on field measurements of nocturnal irradiance in freshwater ecosystems located in peri‐urban areas, we performed a mesocosm experiment using three species of submerged aquatic plants. After 5 months of exposure to realistic dim light at night, four functional traits related to the resource management at the leaf level were measured.Artificial light at night had significant effects on the leaf physiology or chemistry, affecting their resource acquisition rate, but with different response intensities depending on the species. No effect was found on morphological or biomechanical traits for any of the studied species.These results support the hypothesis that plants could interpret dim light at night as a shaded environment and respond accordingly.We demonstrated that the effects of light at night on plants may have been underestimated in previous work. By modifying biotic interactions (e.g., competition and herbivory), these responses can have profound effects on community structure and ecosystem functioning. [ABSTRACT FROM AUTHOR]

Aim: Ecological relationships between species richness and biomass production are increasingly thought to be pervasive across the globe. Yet, diversity–production relationships have not been explored extensively for freshwater fish communities even though fisheries production provides key services to humans. Our aim was to evaluate the diversity–production relationship of fish communities inhabiting freshwater streams across the Appalachian Mountain range and examine how diversity–production relationships varied across streams possessing different thermal signatures. Location: Our study area included 25 freshwater stream ecosystems spanning from Vermont to North Carolina in the United States. Twenty sites were located in Maryland south to Tennessee and North Carolina, while five additional higher latitude sites were sampled in Massachusetts and Vermont. Methods: We sampled the 25 study streams from June to September 2012 and collected fish population information to calculate biomass, species richness, the Shannon diversity index and annual production for each fish community. Linear mixed effects models were used to analyse the relationship between diversity indices and total community production. We also compared diversity and production relationships across other taxa. Results: Across all streams, community fish production, biomass and P/B ratios ranged from 0.15–6.79 g m−2 y−1, 0.61–0.73 g m−2 and 0.21–1.07 y−1, respectively. Species richness had a significant positive effect (p =.012) on community fish production, while accounting for the thermal signature of the streams as a random effect and other habitat covariates. The Shannon diversity index did not have a significant effect (p =.101) on community production. Main conclusions: The diversity–production relationship observed for stream fish communities was similar to other studies but demonstrated one of the highest slopes. Our results demonstrate that effects of biodiversity resonate to influence the production of fishes; thus, management of fisheries is more closely coupled to biodiversity than previously thought. [ABSTRACT FROM AUTHOR]

While future climate scenarios predict declines in precipitations in many regions of the world, little is known of the mechanisms underlying community resilience to prolonged dry seasons, especially in 'naïve' Neotropical rainforests. Predictions of community resilience to intensifying drought are complicated by the fact that the underlying mechanisms are mediated by species' tolerance and resistance traits, as well as rescue through dispersal from source patches.We examined the contribution of in situ tolerance‐resistance and immigration to community resilience, following drought events that ranged from the ambient norm to IPCC scenarios and extreme events.We used rainshelters above rainwater‐filled bromeliads of French Guiana to emulate a gradient of drought intensity (from 1 to 3.6 times the current number of consecutive days without rainfall), and we analysed the post‐drought dynamics of the taxonomic and functional community structure of aquatic invertebrates to these treatments when immigration is excluded (by netting bromeliads) or permitted (no nets).Drought intensity negatively affected invertebrate community resistance, but had a positive influence on community recovery during the post‐drought phase. After droughts of 1 to 1.4 times the current intensities, the overall invertebrate abundance recovered within invertebrate life cycle durations (up to 2 months). Shifts in taxonomic composition were more important after longer droughts, but overall, community composition showed recovery towards baseline states. The non‐random patterns of changes in functional community structure indicated that deterministic processes like environmental filtering of traits drive community re‐assembly patterns after a drought event. Community resilience mostly relied on in situ tolerance‐resistance traits. A rescue effect of immigration after a drought event was weak and mostly apparent under extreme droughts.Under climate change scenarios of drought intensification in Neotropical regions, community and ecosystem resilience could primarily depend on the persistence of suitable habitats and on the resistance traits of species, while metacommunity dynamics could make a minor contribution to ecosystem recovery. Climate change adaptation should thus aim at identifying and preserving local conditions that foster in situ resistance and the buffering effects of habitat features. [ABSTRACT FROM AUTHOR]

The role of multitrophic diversity in sustaining multiple functions simultaneously (multifunctionality) is still poorly understood in natural communities, especially in highly diverse aquatic ecosystems. Existing studies have focused on the effect of single trophic group on ecosystem function and on individual ecosystem functions, neglecting the fact that multiple trophic groups are needed to maintain ecosystem multifunctionality.Here, using a 16‐year database from tropical shallow lakes, we combined species richness of nine single trophic group into a unique measurement of multitrophic richness. We then investigated the influence of the richness within separate single trophic group and in a multitrophic context on ecosystem multifunctionality. We also investigated how removal of any single trophic group influence the effect of the multitrophic richness on multifunctionality; and how the interactions among multiple single trophic group affect multifunctionality.We showed that the multitrophic richness had a stronger positive effect on multifunctionality than the richness of single trophic group. The removal of each single trophic group decreased the effect of the multitrophic richness on multifunctionality. The larger predatory vertebrates and primary producers had stronger positive effects on multifunctionality, but the richness of basal trophic groups fuelled the large‐sized predators, thus indirectly contributing to increase multifunctionality.Our study highlights the need for preserving multiple trophic groups to sustain multifunctionality in highly diverse aquatic ecosystems; thus, trophic degradation of the ecosystems should strongly impair their functioning. A free Plain Language Summary can be found within the Supporting Information of this article. [ABSTRACT FROM AUTHOR]

In aquatic systems, biological invasions can result in adverse ecological effects. Management techniques available for non-native fish removal programs (including eradication and population size control) vary widely, but include chemicals, harvest regimes, physical removal, or biological control. For management agencies, deciding on what non-native fish removal program to use has been challenging because there is little reliable information about the relative effectiveness of these measures in controlling or eradicating non-native fish. We conducted a systematic review, including a critical appraisal of study validity, to assess the effectiveness of different non-native fish removal methods and to identify the factors that influence the overall success rate of each type of method. We found 95 relevant studies, generating 158 data sets. The evidence base was dominated by poorly documented studies with inadequate experimental designs (76% of removal projects). When the management goal was non-native fish eradication, chemical treatments were relatively successful (antimycin 89%; rotenone 75%) compared with other interventions. Electrofishing and passive removal measure studies indicated successful eradication was possible (58% each) but required intensive effort and multiple treatments over a number of years. Of these studies with sufficient information, electrofishing had the highest success for population size control (56% of data sets). Overall, inadequate data quality and completeness severely limited our ability to make strong conclusions about the relationships between non-native fish abundance and different methods of eradication and population control and the factors influencing the overall success rate of each method. Our review highlights that there is considerable scope for improving our evaluations of non-native fish removal methods. It is recommended that programs should have explicitly stated objectives, better data reporting, and study designs that (when possible and appropriate) incorporate replicated and controlled investigations with rigorous, long-term quantitative monitoring. Future research on the effectiveness of non-native fish removal methods should focus on: (i) the efficacy of existing or potentially new removal measures in larger, more complex environments; (ii) a broader range of removal measures in general; and (iii) phenotypic characteristics of individual fish within a population that fail to be eradicated or controlled. Key words: alien invasive species, restoration, nonindigenous species, invasive species, invasion biology, evidence-based policy. Dans les systemes aquatiques, les invasions biologiques peuvent entrainer des effets ecologiques defavorables. Les techniques de gestion disponibles pour les programmes de retrait de poissons non indigenes (incluant l'eradication et le controle de taille de population) varient enormement, mais incluent les produits chimiques, les regimes de peche, le retrait physique ou le controle biologique. Pour les agences de gestion, le choix du programme de retrait de poissons non indigenes a utiliser est complique parce qu'il y a peu d'informations fiables sur l'efficacite relative de ces mesures au niveau du controle ou de l'eradication du poisson non indigene. Nous avons fait une revue systematique, y compris une evaluation critique de validite des conclusions d'etude, afin d'evaluer l'efficacite des differentes methodes de retrait de poissons non indigenes et d'etablir les facteurs qui influent sur le taux de reussite global de chaque type de methodes. Nous avons trouve 95 etudes pertinentes, donnant 158 ensembles de donnees. L'assise factuelle comprenait une preponderance d'etudes mal documentees avec des conceptions experimentales inadequates (76 % de projets de retrait). Quand le but de gestion etait l'eradication de poissons non indigenes, les traitements chimiques avaient une reussite relativement bonne (antimycine 89 %; rotenone 75 %) comparativement a d'autres interventions. Les etudes de mesure de peche a l'electricite et de retrait passif ont indique que l'eradication reussie etait possible (58 % chacun) mais elle exigeait un effort intense et des traitements multiples au cours d'un certain nombre d'annees. De ces etudes ayant des informations suffisantes, la peche a l'electricite avait le plus haut taux de succes en matiere de controle de taille de population (56 % des ensembles de donnees). En general, la qualite inadequate et l'aspect incomplet des donnees ont severement limite notre capacite de tirer des conclusions probantes des relations entre l'abondance de poissons non indigenes et les differentes methodes d'eradication et de regulation des populations et les facteurs influant sur le taux de reussite global de chaque methode. Les points culminants de notre revue mettent en lumiere qu'il y a une marge considerable pour ameliorer nos evaluations de methodes de retrait de poissons non indigenes. On recommande que les programmes aient des objectifs explicites clairement formules, une meilleure communication des donnees et des modeles d'etude qui (lorsque possible et approprie) incorporent des examens reproduits et controles au moyen de surveillance quantitative rigoureuse a long terme. La recherche future sur l'efficacite des methodes de retrait de poissons non indigenes devrait etre centree sur : (i) l'efficacite des mesures de retrait existantes ou potentiellement nouvelles dans des environnements plus grands, plus complexes; (ii) une gamme plus large de mesures de retrait en general et (iii) les caracteristiques phenotypiques de poisson individuel dans une population qui echappe a la suppression ou au controle. Mots-cles: especes envahissantes exotiques, restauration, especes non indigenes, especes envahissantes, biologie de l'invasion, politique fondee sur les faits., Introduction In aquatic systems, biological invasions can result in adverse ecological effects (Gozlan et al. 2009; Ricciardi and Maclsaac 2010). Invasive species threaten biodiversity (Vitousek et al. 1997; Sala et [...]

Our understanding of how the phylogenetic tree of fishes might be affected by the ongoing extinction risk is poor. This is due to the unavailability of comprehensive DNA data, especially for many African lineages. In addition, the ongoing taxonomic confusion within some lineages, e.g., Cyprinidae, makes it difficult to contribute to the debate on how the fish tree of life might be shaped by extinction. Here, we combine COI sequences and taxonomic information to assemble a fully sampled phylogeny of the African Cyprinidae and investigate whether we might lose more phylogenetic diversity (PD) than expected if currently threatened species go extinct. We found evidence for phylogenetic signal in extinction risk, suggesting that some lineages might be at higher risk than others. Based on simulated extinctions, we found that the loss of all threatened species, which approximates 37% of total PD, would lead to a greater loss of PD than expected, although highly evolutionarily distinct species are not particularly at risk. Pending the reconstruction of an improved multi-gene phylogeny, our results suggest that prioritizing high-EDGE species (evolutionary distinct and globally endangered species) in conservation programmes, particularly in some geographic regions, would contribute significantly to safeguarding the tree of life of the African Cyprinidae. Key words: African freshwater ecosystems, conservation, DNA barcoding, EDGE, IUCN Red List. L'impact possible de l'extinction en cours sur l'arbre phylogenetique des poissons est mal connu. Cela decoule de l'indisponibilite de donnees d'ADN completes, particulierement chez des groupes africains. De plus, la confusion qui persiste au sein de certains groupes, p. ex. les Cyprinidae, rend difficile les contributions au debat sur la facon dont l'arbre des poissons pourrait etre affecte par l'extinction. Dans ce travail, les auteurs ont combine les sequences COI et les informations taxonomiques pour assembler une phylogenie bien echantillonnee des Cyprinidae africains et pour etudier si la disparition des especes presentement menacees pourrait entrainer une perte de diversite phylogenetique (DP) plus grande qu'attendue. Les auteurs ont trouve des evidences d'un signal phylogenetique en matiere de risque d'extinction, ce qui suggere que certains groupes seraient plus a risque que d'autres. Sur la base d'extinctions simulees, les auteurs ont trouve que l'extinction de toutes les especes menacees, soit environ 37 % de la DP, menerait a une perte de DP plus grande qu'attendue, tandis que les especes tres distinctes sur le plan evolutif ne seraient pas particulierement a risque. En attendant la reconstruction d'une phylogenie multigenique amelioree, les resultats suggerent qu'il faudrait prioriser les especes EDGE (<< Evolutionary Distinct and Globally Endangered >>) dans les programmes de conservation, particulierement au sein de certaines regions geographiques, afin de contribuer de maniere importante a la sauvegarde de la diversite phylogenetique chez les Cyprinidae africains. [Traduit par la Redaction] Mots-cles : ecosystemes d'eau douce africains, conservation, codage a barres de l'ADN, EDGE, liste rouge de l'IUCN., Introduction Evidence that we are losing biodiversity at an unprecedented rate is now piling up (Vamosi and Vamosi 2008; Barnosky et al. 2011; Ceballos et al. 2015). For example, one-fifth [...]

An approach to complex assessment of permissible pollutant loads for aquatic and terrestrial ecosystems has been proposed. The approach is based on evaluation of the contaminant removal (assimilation) or inflow rate on the basis of the difference between the mass flow rates at the lower and upper gauging stations of the selected river section. The removal (assimilation) or inflow rate is considered to be the current pollutant load on the river ecosystem (CLR). The maximum permissible pollutant inflow between the stations calculated on the basis of its maximum permissible concentration (MPC) is the maximum permissible load (MPLR). The difference between the MPLR and the CLR is considered the remainder of the pollution limit of the river ecosystem or the permissible load. The atmospheric deposition rate of the pollutant is considered its current load on the whole geosystem (CLG). The sum of the pollutant removal rate due to forest felling and the pollutant assimilation/inflow rate in the river, divided by the area of the drained portion of the water catchment area, is considered the maximum permissible load on the geosystems (MPLG). The difference between the MPLG and CLG is considered the remainder of the pollution limit of the terrestrial ecosystem or the permissible load. [ABSTRACT FROM AUTHOR]

Unicellular eukaryotes have pivotal ecological roles in aquatic ecosystems by participating in biogeochemical processes and structuring microbial food webs. However, revealing their biogeographical patterns remains challenging, as it is reflected in the rather limited available knowledge. In this study, two central patterns, the taxa–area and the distance–decay relationships, were tested for freshwater unicellular eukaryotes. Sampling was performed in 31 mountainous freshwater ecosystems in Thessaly (Greece). Sampling sites had different geohydromorphological characteristics (altitude, 124–704 m; depth, 0.3–1 m; surface area, 188–123 000 m2; geographical distances, 0.03–48.4 km). Unicellular eukaryote diversity was assessed by 18S rRNA gene diversity with high-throughput sequencing. Five supergroups (Stramenopiles, Alveolata, Rhizaria, Archaeplastida and Opisthokonta) were found with the most abundant taxa being Stramenopiles and Alveolata. Aquatic unicellular eukaryotes showed statistically significant but weak DDR and TAR. This can be attributed to the large proportion of specialists (91.9% of operational taxonomic units according to Levin's index). These results indicate that although mountainous pools and ponds can host high diversity of unicellular eukaryotes, the shaping of their communities is mainly regulated by niche-specific processes and environmental filtering and to a lesser extent by species dispersion processes. [ABSTRACT FROM AUTHOR]

Abstract Urban growth is a key process affecting the functioning of natural ecosystems, and consequently the global land-surface process. This work aimed at establishing the link between land cover changes around Harare Metropolitan city and the proliferation of aquatic hyacinth (Eichhornia crassipes) in Lake Chivero. Remotely sensed Landsat series acquired in the year 1973, 1981, 1994, 1998, 2008, 2009 and 2014 was used. Image classification was implemented to map the associated changes over time using discriminant analysis algorithm. Derived thematic land cover maps showed that agricultural land increased from 2% in 1973 to a 5% in 1981 reaching up to 30% in 2014, whereas the city's land area significantly (p < 0.05) increased between 1973 and 1994. However, water hyacinth constantly increased over time. The spatial and temporal resolution of Landsat images detected land cover changes and the proliferation of aquatic hyacinth (Eichhornia crassipes) in the Lake Chivero over time. Highlights • Fast urban expansion is a key factor affecting global climate change. • Remote sensing shows the potential in monitoring and understanding complex urban land use and land cover changes. • Post hoc test showed that water hyacinth can be accurately be discriminated from other land cover types. • Band 4, 5, 6 and 7 of the Landsat series data can be used to successfully map land cover changes. [ABSTRACT FROM AUTHOR]

Over the last few years, several of the world’s national park networks have implemented ecological integrity monitoring programs. These programs are based on a series of indicators to detect changes in ecosystem integrity. There are many scientific and logistical challenges in developing these programs due to limits in both our knowledge of ecosystems functioning and the resources for implementing such programs. Thus, the relatively quick and simple implementation of many monitoring programs has been to the detriment of their scientific validity. Few studies have focused on evaluating an entire monitoring program. This project presents an approach to evaluate the ecological and statistical relevance of ecosystem integrity indicators measured within a program with the goal of iterative optimization. The approach is based on three complementary elements: (1) spatial characterization of park ecosystems based on the classification of satellite imagery, (2) ecological validation of indicators based on ecosystem conceptual models and (3) statistical validation of indicators based on analyses of statistical power. This innovative approach allows a systematic, quantified, reproducible and generalizable review of the indicators of an ecological integrity monitoring program. It provides managers with an overview of the spatial representativeness of indicators, their ecological and statistical relevance according to different parameters such as the period monitored, the amount of change to be detected, and the degree of significance. Thus, the approach identifies monitoring gaps and offers various alternatives for improving sampling. The approach was developed and tested in the network of Quebec national parks, more specifically in the Frontenac, Jacques-Cartier and Bic national parks. The results clearly identify the strengths and weaknesses of the current program in place and possible improvements are proposed for these parks. This approach is a relevant tool for park networks, particularly for those that have limited resources for monitoring ecological integrity. [ABSTRACT FROM AUTHOR]

Abstract: Nutrient over‐enrichment increasingly threatens global water resources. Stressor‐response studies specifically designed to identify levels of nutrients strongly associated with undesirable ecological conditions are needed to inform numeric nutrient criteria that protect inland waters. Diatoms are important components of aquatic life, which support higher trophic levels and are sensitive to nutrient enrichment. We tested a framework that relies on stressor‐response modelling of phosphorus (P) enrichment and stream diatom assemblages across many field locations, multiple years and seasons within years, and under controlled experimental conditions to inform nutrient criteria development. Diatom species composition was nonlinearly correlated with total phosphorus (TP) throughout the 2‐year field study. This occurred despite temporal shifts in species composition between two hydrologically distinct years and over eight seasons. Species assemblages on rocks transplanted from a low P stream to mesocosms representing a P enrichment gradient (8, 20 and 100 μg/L) shifted into two groups over time. Species composition on rocks in low (20 μg/L) and high (100 μg/L) P mesocosms was consistent with assemblages at P‐enriched field sites, whereas rocks in control (8 μg/L) mesocosms had significantly different species composition, consistent with low P field sites. Species composition on rocks transplanted from high P streams did not shift as dramatically and were not significantly different after exposure to different P treatments in mesocosms. Threshold Indicator Taxa Analysis identified synchronous declines in several diatom species that culminated in assemblage thresholds associated with TP concentrations >20 and 25 μg/L for 2006 and 2007 respectively. Synthesis and applications. Diatom assemblages show consistent responses to nutrient enrichment despite temporal shifts associated with confounding factors common in stream ecosystems. Regulators should include diatom assemblage responses when developing numeric nutrient criteria. We present a framework that includes spatial, temporal and experimental components, and has broad applicability for use in different ecological settings to evaluate ecological endpoints and set limits for a variety of contaminants threatening freshwater ecosystems throughout the world. [ABSTRACT FROM AUTHOR]

Studies of the fate and toxicity of nanoparticles, including nanosilver (AgNPs), have been primarily conducted using bench scale studies over relatively short periods of time. To better understand the fate of AgNPs in natural aquatic ecosystems over longer time scales and ecological settings, we released suspensions of AgNPs (30–50 nm, capped with polyvinylpyrrolidone) into a boreal lake at the Experimental Lakes Area in Canada. Approximately 9 kg of silver was added from a shoreline point source from June to October 2014, which resulted in total Ag (TAg) concentrations of about 10 μg L-1 or less. In addition, dissolved Ag concentrations (DAg) were typically very low. Using single particle inductively coupled plasma mass spectrometry (sp-ICP-MS) analysis of grab samples, we found that the nanoparticles typically ranged in the 40–60 nm size class and were widely distributed throughout the lake, while larger aggregates (i.e. >100 nm) were infrequently detected. The highest occurrence of aggregates was found near the addition site; however, size distributions did not vary significantly among spatial locations or time suggesting rapid dispersal upon entry into the lake. Lake stratification at the thermocline was not a barrier to mobility of the AgNPs, as the particles were also detected in the hypolimnion. Environmental factors influenced Ag size distributions over sampling locations and time. Total dissolved phosphorus, bacterioplankton chlorophyll-a, and sampling time strongly correlated with aggregation and dissolution dynamics. AgNPs thus appear to be relatively mobile and persistent over the growing season in lake ecosystems. [ABSTRACT FROM AUTHOR]

Abstract: Globally, offset schemes have emerged in many statutory frameworks relating to development activities, with the aim of balancing biodiversity conservation and development. Although the theory and use of biodiversity offsets in terrestrial environments is broadly documented, little attention has been paid to offsets in stream ecosystems. Here we examine the application of offset schemes to stream ecosystems and explore whether they suffer similar shortcomings to those of offset schemes focused on terrestrial biodiversity. To challenge the applicability of offsets further, we discuss typical trajectories of urban expansion and their cascading physical, chemical and biological impacts on stream ecosystems. We argue that the highly connected nature of stream ecosystems and urban drainage networks can transfer impacts of urbanization across wide areas, complicating the notion of like‐for‐like exchange and the prospect of effectively mitigating biodiversity loss. Instead, we identify in‐catchment options for stormwater control, which can avoid or minimize the impacts of development on downstream ecosystems, while presenting additional public and private benefits. We describe the underlying principles of these alternatives, some of the challenges associated with their uptake, and policy initiatives being trialed to facilitate adoption. In conclusion, we argue that stronger policies to avoid and minimize the impacts of urbanization provide better prospects for protecting downstream ecosystems, and can additionally, stimulate economic opportunities and improve urban liveability. [ABSTRACT FROM AUTHOR]

Abstract: Today's river systems have been extensively modified, requiring us to rethink how we approach the management of these important ecosystems. We evaluated the effects of removing 6 weirs in River Villestrup (Jutland, Denmark) on the smolt run of brown trout (Salmo trutta) over the course of 12 years. During 5 of these years, we evaluated the number, size, and timing of smolts during their downstream migration. We found an increase in smolt output following the weir removals, along with a decrease in average length and indications of an earlier peak migration. Our results suggest that barrier removal has led to an increase in spawning success by adults, fry survival, recruitment, and smolt migration success. Weir removal is therefore a viable management approach to restore connectivity in freshwater streams and rivers, which promotes the passage of smolts as they migrate to marine environments. [ABSTRACT FROM AUTHOR]

This paper presents the results of research into pathways leading to the production of methane (CH4) and carbon dioxide (CO2) in sediments of two eutrophic reservoirs (Maziarnia and Nielisz), located in south-eastern Poland. In seeking to identify the pathways in question, use was made of analysis of stable carbon isotopes in CH4 and CO2 dissolved in pore water. This determined that CH4 is mainly produced through acetate fermentation, though the hydrogenotrophic methanogenic process may also be of importance, especially in deeper layers of sediments. Both the presence of autochthonous organic matter and increased pH values are shown to favour acetate fermentation. In turn, methanogenesis in sediments is assessed as capable of accounting for the generation of a considerable amount of CO2. Indeed, the role of methanogenesis in CO2 production is increasingly important further down in the layers of sediment, where allochthonous organic matter is predominant. [ABSTRACT FROM AUTHOR]

Phytoplankton is an important microbial component in many ecosystems, and thus, knowing the predictive variables of its distribution is very valuable. In this study, we evaluated the roles of niche-based and spatial processes on phytoplankton communities of nine lakes in southern Brazil (spatial distance covered of 220 km). Variation partitioning analysis was employed to determine the relative contributions of environmental and spatial variables on the distribution of prokaryotic (PRP) and eukaryotic (EUP) components of phytoplankton at multispatial extents. C-score analysis was carried out, at intra- and interlake scales, to examine whether phytoplankton species coexist less or more than expected by chance (taxa segregation and aggregation, respectively). Our results showed that, at broader spatial scales, both PRP and EUP distributions are mainly influenced by pure space, while at finer spatial scales, the two groups are mainly influenced by pure environment. PRP distribution at broader spatial scales was also significantly influenced by spatially structured environment, and was in general more affected by spatial variables than by EUP. Finally, a taxa segregation pattern was observed at the interlake scale. In general, our results suggest that niche-based processes are more important in structuring phytoplankton on the local scale while spatial processes on the regional scale. [ABSTRACT FROM AUTHOR]

The waste of commonly used medicines is known to contaminate freshwater ecosystems. Pharmaceuticals can be toxic, mutagenic, or modifying to freshwater organisms even at low concentrations if consider their permanent presence in the environment. Chemotherapeutics used to treat cancer, and in particular alkylating agents, contribute significantly to this form of pollution, the latter introducing cytotoxic and/or mutagenic lesions to the DNA and RNA of organisms which can be disruptive to their cells. The aim of the present study was to investigate the influence of the alkylating anticancer agent cyclophosphamide (CP) on Daphnia magna clones. We evaluated the life history parameters and protein profiles of this crustacean following exposure to environmentally relevant CP concentration of 10 ng L-1. Even at this low concentration, the alkylating agent caused modification of the life history parameters and proteome profile of the Daphnia. These changes were clone-specific and involved growth rate, age at first reproduction, neonate number, and proteins related to cell cycle and redox state regulation. The disturbance caused by pharmaceuticals contaminating freshwater ecosystem is probably weaker and unlikely to be cytotoxic in character due to the high dilution of these substances in the water. However, our results indicate that prolonged exposure of organisms to these toxins may lead to modifications on the organismal and molecular levels with unpredictable significance for the entire ecosystem. [ABSTRACT FROM AUTHOR]

Large protected areas have been created in Brazilian Amazon intending to safeguard as much of its biodiversity as possible. Despite these intentions, such megareserves were created predominantly focusing on terrestrial organisms and ecosystems. Here, we assessed the ability of the current Brazilian Amazon protected areas network to efficiently safeguard its stream-dwelling fish fauna. Ecological niche models were built for 138 stream fish species using MaxEnt software. We performed a gap analysis and spatial prioritization under three different Amazon protected areas scenarios: (1) strictly protected areas (SPAs) only; (2) SPA plus sustainable use areas (SPA + SUA); and (3) SPA + SUA plus indigenous territories (SPA + SUA + IT). The species were classified according to their distribution range size and required representation targets. Widespread species usually had lower area under the curve (AUC) and true skill statistics (TSS) values, which would be expected for large and heterogeneous areas such as the Amazon. Only partial gap species were found, with 20% to 90% of required representation targets included in PAs, which was not enough for a complete protection. Most of the officially protected areas in the Brazilian Amazon do not correspond to areas with high direct conservation values for stream fishes, once the priority areas for these species conservation were outside the PAs, leaving a high portion of the regional vertebrate fauna inadequately protected. We conclude that fishes and other freshwater organisms and habitats should be explicitly included during systematic conservation planning in order to thoroughly protect the Brazilian Amazon biodiversity. [ABSTRACT FROM AUTHOR]

Many natural habitats have been modified to accommodate for the presence of humans and their needs. Infrastructures – such as hydroelectric dams, weirs, culverts and bridges – are now a common occurrence in streams and rivers across the world. As a result, freshwater ecosystems have been altered extensively, affecting both biological and geomorphological components of the habitats. Many fish species rely on these freshwater ecosystems to complete their lifecycles, and the presence of barriers has been shown to reduce their ability to migrate and sustain healthy populations. In the long run, barriers may have severe repercussions on population densities and dynamics of aquatic animal species. There is currently an urgent need to address these issues with adequate conservation approaches. Adaptive management provides a relevant approach to managing barriers in freshwater ecosystems as it addresses the uncertainties of dealing with natural systems, and accommodates for future unexpected events, though this approach may not be suitable in all instances. A literature search on this subject yielded virtually no output. Hence, we propose a step-by-step guide for implementing adaptive management, which could be used to manage freshwater barriers. [ABSTRACT FROM AUTHOR]

More recently, the number of studies on the impacts of microplastics (MPs) on plants has drawn attention considerably. However, many of these studies focused on terrestrial plants, with vascular plants from freshwater ecosystems being little studied. Thus, we aimed to evaluate the possible effects of exposure of Salvinia auriculata , for 28 days, to different concentrations of polyethylene MPs (PE MPs – diameter: 35.46 ± 18.17 µm) (2.7 ×108 and 8.1 ×108 particles/m3), using different biomarkers. Our data indicated that exposure to PE MPs caused alterations in plant growth/development (inferred by the lower floating frond number, "root" length, and the number of "roots"), as well as lower dispersion of individuals in the experimental units. Plants exposed to PE MPs also showed lower epidermal thickness (abaxial leaf face) and a longer length of the central leaf vein and vascular bundle area. Ultrastructural analyses of S. auriculata exposed to MPs revealed rupture of some epidermal cells and trichomes on the adaxial and abaxial, leaf necrosis, and chlorosis. In the "roots", we observed dehydrated filamentous structures with evident deformations in plants exposed to the pollutants. Both on the abaxial leaf face and on the "roots", the adherence of PE MPs was observed. Furthermore, exposure to PE MPs induced lower chlorophyll content, cell membrane damage, and redox imbalance, marked by reduced catalase and superoxide dismutase activity and increased production of reactive oxygen and nitrogen species as well as malondialdehyde. However, in general, we did not observe the dose-response effect for the evaluated biomarkers. The values of the integrated biomarker response index, the principal component analysis (PCA) results and the hierarchical clustering analysis confirmed the similarity between the responses of plants exposed to different PE MPs concentrations. Therefore, our study sheds light on how PE MPs can affect S. auriculata and reinforces that putting these pollutants in freshwater environments might be hazardous from an ecotoxicological point of view. [Display omitted] • Exposure to PE MPs affects the growth and development of Salvinia auriculata. • Histomorphological changes are induced by exposure to PE MPs in S. auriculata. • Antioxidant activity is reduced in S. auriculata exposed to PE MPs. • PE MPs induces oxidative and nitrosative stress in S. auriculata. • PE MPs adheres to leaf and root structures of S. auriculata. [ABSTRACT FROM AUTHOR]

We present a comprehensive analysis of estimation of fisheries Maximum Sustainable Yield (MSY) reference points using an ecosystem model built for Mille Lacs Lake, the second largest lake within Minnesota, USA. Data from single-species modelling output, extensive annual sampling for species abundances, annual catch-survey, stomach-content analysis for predatory-prey interactions, and expert opinions were brought together within the framework of an Ecopath with Ecosim (EwE) ecosystem model. An increase in the lake water temperature was observed in the last few decades; therefore, we also incorporated a temperature forcing function in the EwE model to capture the influences of changing temperature on the species composition and food web. The EwE model was fitted to abundance and catch time-series for the period 1985 to 2006. Using the ecosystem model, we estimated reference points for most of the fished species in the lake at single-species as well as ecosystem levels with and without considering the influence of temperature change; therefore, our analysis investigated the trophic and temperature effects on the reference points. The paper concludes that reference points such as MSY are not stationary, but change when (1) environmental conditions alter species productivity and (2) fishing on predators alters the compensatory response of their prey. Thus, it is necessary for the management to re-estimate or re-evaluate the reference points when changes in environmental conditions and/or major shifts in species abundance or community structure are observed. [ABSTRACT FROM AUTHOR]

Succession in bloom-forming cyanobacteria belonging to distant functional groups in freshwater ecosystems is currently an undescribed phenomenon. However in the Hammam Debagh reservoir (Algeria), P. rubescens and Microcystis sp. co-occur and sometimes proliferate. With the aim of identifying the main factors and processes involved in this unusual cohabitation, water samples were collected monthly from February 2013 to June 2015 at the subsurface at four sampling stations and along the entire water column at one sampling station. In addition, the composition of the cyanobacterial communities was estimated by Illumina sequencing of a 16S rRNA gene fragment from samples collected over one year (October 2013-November 2014). This molecular approach showed that the Hammam Debagh reservoir displays high species richness (89 species) but very low diversity due to the high dominance of Microcystis in this community. Furthermore, it appears that Planktothrix rubescens and Microcystis sp. coexisted (from September to January) but proliferated alternately (Spring 2015 for P. rubescens and Spring 2014 and Autumn 2014/2015 for Microcystis). The main factors and processes explaining these changes in bloom-forming species seem to be related to the variation in the depth of the lake during the mixing period and to the water temperatures during the winter prior to the bloom season in spring. [ABSTRACT FROM AUTHOR]

Diatoms, combined with a multiproxy study of lake sediments (organic matter, N, δ15N, δ13C, biogenic silica, grain size, Cladocera and chironomids, Alnus pollen) from Lone Spruce Pond, Alaska detail the late-glacial to Holocene history of the lake and its response to regional climate and landscape change over the last 14.5 cal ka BP. We show that the immigration of alder (Alnus viridis) in the early Holocene marks the rise of available reactive nitrogen (Nr) in the lake as well as the establishment of a primarily planktonic diatom community. The later establishment of diatom Discostella stelligera is coupled to a rise of sedimentary δ15N, indicating diminished competition for this nutrient. This terrestrial-aquatic linkage demonstrates how profoundly vegetation may affect soil geochemistry, lake development, and lake ecology over millennial timescales. Furthermore, the response of the diatom community to strengthened stratification and N levels in the past confirms the sensitivity of planktonic diatom communities to changing thermal and nutrient regimes. These past ecosystem dynamics serve as an analogue for the nature of threshold-type ecological responses to current climate change and atmospheric nitrogen (Nr) deposition, but also for the larger changes we should anticipate under future climate, pollution, and vegetation succession scenarios in high-latitude and high-elevation regions. [ABSTRACT FROM AUTHOR]

Poyang Lake is suffering from persistent eutrophication, which is degrading the local ecosystem. A better understanding of the mechanisms that drive eutrophication in lake systems is essential to fight the ongoing deterioration. In this study, hydraulic residence time (HRT) was used to evaluate Poyang Lake’s trophic state. A hydrology and ecosystem forced model was constructed to simulate long-term changes in algae and aquatic plant biomass and total phosphorous (TP). A comparison analysis revealed that between 1812 and 1828 (i.e., a consistent-change stage), climate and hydrology were the main driving forces, while algae and aquatic plant biomass contributed only 20.9% to the trophic changes in Poyang Lake. However, between 1844 and 1860 the biomass predominated contributing 63.6%. This could be attributed to nutrient absorption by algae and aquatic plants. A correlation analysis of the water TP and algae and aquatic plant biomass revealed a strong positive relationship. However, the algae and aquatic plant growth rate tended to decline after the biomass reached half of the maximum. This research reconstructs the long-term trophic evolution of Poyang Lake and provides a better understanding of the relationship between climatic and hydrological changes and lake ecosystems. [ABSTRACT FROM AUTHOR]

• We develop an integrated method for assessing lake ecosystem health. • Lake ecosystem degradation shows clear spatial heterogeneity patterns in East China. • Identifying the nonlinear contribution of multiple stressors to lake degradation. • Lake ecosystem health is significantly influenced by its distance from the city. Freshwater lake ecosystems face unprecedented challenges with escalating anthropogenic pressure worldwide. An improved understanding of how environmental and socioeconomic factors impact lake health is crucial for strategic conservation and management. Here, we compiled data from 85 lakes from China's most densely populated regions and proposed an integrated index to examine spatial patterns of lake ecosystem health. We further evaluated how 16 socioeconomic drivers and environmental conditions drive these changes by using the Bayesian hierarchical model and Gradient boosting decision tree models. Our results suggest the integrated index can provide a comprehensive picture of lake ecosystem quality from a systems perspective combining water bodies and lakeshore zones. We find that lake degradation shows clear spatial heterogeneity patterns given the common forcings associated with climate factors and land-use practices within this region. We further reveal the non-linear relationships between the social and economic factors (distance, population, food production, gross domestic product [GDP], etc.) and lake ecology, and find that distance of the lake from the city center was the predominant factor that influenced the lake system health among these multiple drivers. This study contributes to the understanding of the differences and driving mechanisms of lake ecological degradation in areas of high human activity as a basis for further identifying environmental conflicts and recommendations to improve the state of lake ecosystems. [ABSTRACT FROM AUTHOR]

The plastisphere has been widely studied in the oceans; however, there is little information on how living organisms interact with the plastisphere in freshwater ecosystems, and particularly on how this interaction changes over time. We have characterized, over one year, the evolution of the eukaryotic and bacterial communities colonizing four everyday plastic items deployed in two sites of the same river with different anthropogenic impact. α-diversity analyses showed that site had a significant role in bacterial and eukaryotic diversity, with the most impacted site having higher values of the Shannon diversity index. β-diversity analyses showed that site explained most of the sample variation followed by substrate type (i.e., plastic item) and time since first colonization. In this regard, core microbiomes/biomes in each plastic at 1, 3, 6 and 12 months could be identified at genus level, giving a global overview of the evolution of the plastisphere over time. The measured concentration of antibiotics in the river water positively correlated with the abundance of antibiotic resistance genes (ARGs) on the plastics. These results provide relevant information on the temporal dynamics of the plastisphere in freshwater ecosystems and emphasize the potential contribution of plastic items to the global spread of antibiotic resistance. [Display omitted] • The evolution of microbial communities in the plastisphere was studied for one year. • Site, substrate, and colonization time were relevant in shaping the plastisphere. • Core microbiome/biomes could be identified in each plastic item along time. • Everyday plastic items can be considered reservoirs of antibiotic resistance genes. [ABSTRACT FROM AUTHOR]

• Bacterial succession affects biodegrading BPs and non-BPs within freshwaters. • Plastic type potentially influences plastisphere succession. • Biodegrading plastisphere reached faster to mature phase. • BPs have the ability to gather the potentially degradable microorganisms. Plastics in the environment provide a new and unique habitat for microorganisms - known as the plastisphere. The microbial succession within the plastisphere and their potentials for plastic degradation in freshwater ecosystems is still not clear. Here, we investigated variation of microbial communities in plastisphere and their capacity to biodegrade non-biodegradable plastics (non-BPs), i.e., polypropylene (PP) and polyethylene (PE), and biodegradable plastics (BPs), i.e., polylactic acid+polybutylene adipate-co-terephthalate (PLA+PBAT) for four-time periods (15, 30, 45, and 80 days) in three freshwaters. Results showed that the aging degree of plastics increased with succession of plastisphere, with higher degradation rates of BP blends than those of non-BPs. High-throughput sequencing from 112 biofilm samples revealed that bacterial and fungal community structure of the plastisphere were potentially affected by plastic types and gradually converge during biofilm succession. The plastisphere of BPs reached the mature phase more quickly than those of non-BPs and increased co-exclusion to complete for resources. Furthermore, ecological networks involving plastic aging indices, environmental factors and bacterial and fungal operational taxonomic units were established. Ecological networks revealed that BPs may pose the ability to attract and retain key microorganisms (of the orders Bacillales, Myxococcales and Xanthomonadales) that significantly influence community composition such that biodegradative functions were increased in freshwaters. [Display omitted] [ABSTRACT FROM AUTHOR]

Global change is transforming freshwater ecosystems, mainly through changes in basin flow dynamics. This study assessed how the combination of climate change and human management of river flow impacts metabolism of the Ebro River (the largest river basin in Spain, 86,100 km 2 ), assessed as gross primary production—GPP—and ecosystem respiration—ER. In order to investigate the influence of global change on freshwater ecosystems, an analysis of trends and frequencies from 25 sampling sites of the Ebro river basin was conducted. For this purpose, we examined the effect of anthropogenic flow control on river metabolism with a Granger causality study; simultaneously, took into account the effects of climate change, a period of extraordinary drought (largest in past 140 years). We identified periods of sudden flow changes resulting from both human management and global climate effects. From 1998 to 2012, the Ebro River basin was trending toward a more autotrophic condition indicated by P/R ratio. Particularly, the results show that floods that occurred after long periods of low flows had a dramatic impact on the respiration (i.e., mineralization) capacity of the river. This approach allowed for a detailed characterization of the relationships between river metabolism and drought impacts at the watershed level. These findings may allow for a better understanding of the ecological impacts provoked by flow management, thus contributing to maintain the health of freshwater communities and ecosystem services that rely on their integrity. [ABSTRACT FROM AUTHOR]

Freshwater ecosystems and associated habitats harbor incredible biodiversity. They offer various ecosystem services and sustain human livelihoods. However, due to increasing developmental pressure and rising water demand, these systems are under huge threat. As a result, many aquatic species are feared to become extinct in near future. Quantifying the patterns of aquatic species diversity and composition of river systems is urgently required. With this interest, we studied four river systems in the Western Ghats region, documenting the pattern of fish diversity and identifying the factors that influence fish species richness. Maintaining undisturbed streams and river basins, especially headwater regions is crucial for sustaining freshwater biodiversity in the tropical river ecosystems. [ABSTRACT FROM AUTHOR]

The McMurdo Dry Valleys constitute the largest ice free area of Antarctica. The area is a polar desert with an annual precipitation of ∼ 3 cm water equivalent, but contains several lakes fed by glacial melt water streams that flow from four to twelve weeks of the year. Over the past ∼20 years, data have been collected on the lakes located in Taylor Valley, Antarctica as part of the McMurdo Dry Valley Long-Term Ecological Research program (MCM-LTER). This work aims to understand the impact of climate variations on the biological processes in all the ecosystem types within Taylor Valley, including the lakes. These lakes are stratified, closed-basin systems and are perennially covered with ice. Each lake contains a variety of planktonic and benthic algae that require nutrients for photosynthesis and growth. The work presented here focuses on Lake Fryxell, one of the three main lakes of Taylor Valley; it is fed by thirteen melt-water streams. We use a functional regression approach to link the physical, chemical, and biological processes within the stream-lake system to evaluate the input of water and nutrients on the biological processes in the lakes. The technique has been shown previously to provide important insights into these Antarctic lacustrine systems where data acquisition is not temporally coherent. We use data on primary production (PPR) and chlorophyll-A (CHL)from Lake Fryxell as well as discharge observations from two streams flowing into the lake. Our findings show an association between both PPR, CHL and stream input. [ABSTRACT FROM AUTHOR]