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We used biological and physical responses at 71 shallow waterbodies with contrasting nutrient levels undergoing recovery from eutrophication to predict potential changes in waterbird species abundance, an important component of lake ecosystems. These general predictions were tested using 28 years of breeding waterbird data from three Danish shallow eutrophic lakes, comparing species-specific responses to improved nutrient and water transparency in two lakes with a third where conditions remained constantly suitable for breeding waterbirds. We predicted positive responses to improved water quality from pursuit diving predators (three grebe species), a specialist zooplankton feeder (northern shoveler Anas clypeata) and waterbirds feeding on (common pochard Aythya ferina) or within (tufted duck A. fuligula) submerged macrophyte underwater canopies. These species were characterised by positive waterbird community composition changes (using Principal Components Analysis) associated with decreasing nutrient loading and increasing water transparency at two lakes, with no change in breeding waterbird community at the third. Secchi depth explained 73–95% of variance in both PC axes at both restored lakes, but not at the third, suggesting water transparency was the major factor driving waterbird community composition. These examples show predicting waterbird species-specific responses to management can usefully direct the use of breeding waterbirds as indicator species. [ABSTRACT FROM AUTHOR]

Summary Affecting biodiversity, plants with larger genome sizes (GS) may be restricted in nutrient‐poor conditions. This pattern has been attributed to their greater cellular nitrogen (N) and phosphorus (P) investments and hypothesized nutrient–investment tradeoffs between cell synthesis and physiological attributes associated with growth. However, the influence of GS on cell size and functioning may also contribute to GS‐dependent growth responses to nutrients. To test whether and how GS is associated with cellular nutrient, stomata, and/or physiological attributes, we examined > 500 forbs and grasses from seven grassland sites conducting a long‐term N and P fertilization experiment. Larger GS plants had increased cellular nutrient contents and larger, but fewer stomata than smaller GS plants. Larger GS grasses (but not forbs) also had lower photosynthetic rates and water‐use efficiencies. However, nutrients had no direct effect on GS‐dependent physiological attributes and GS‐dependent physiological changes likely arise from how GS influences cells. At the driest sites, large GS grasses displayed high water‐use efficiency mostly because transpiration was reduced relative to photosynthesis in these conditions. We suggest that climatic conditions and GS‐associated cell traits that modify physiological responses, rather than resource–investment tradeoffs, largely explain GS‐dependent growth responses to nutrients (especially for grasses). [ABSTRACT FROM AUTHOR]

This study investigates the impact of environmental factors on benthic Chlorophyll-a (Chl-a) concentrations in river ecosystems, focusing on the Jhelum River Basin (JRB). It assesses the influence of hydro-chemical variables on Chl-a levels and trophic status across 59 sites spanning upstream, midstream, and downstream sections. The trophic status based on the mean and maximum concentration of Chl-a at various sites reveals the oligotrophic (76%) to mesotrophic (24%) nature of the JRB. Whereas, the concentration of total phosphorus (TP) revealed the mesotrophic (42%) to eutrophic (58%) nature of the JRB. Hierarchical cluster analysis (HCA) of data sets resulted in the formation of three distinct clusters. Cluster I was dominated by upstream sites (72%), cluster II was dominated by mid and downstream sites (71%), while cluster III was represented by main river and downstream sites (84%). Multiple linear regression (MLR) model (p˂0.05) revealed TP (30-554 µg/l) and dissolved oxygen (DO) (5–13 mg/l) as major parameters influencing Chl-a content. MLR also highlighted that ammoniacal nitrogen (NH3–N), nitrite nitrogen (NO2-N), electrical conductivity (EC), current velocity (V), discharge (D) and water temperature have significant relation (p˂0.05) with Chl-a concentration but differ seasonally. Water quality index (WQI) on the basis of NH3-N, TP, DO, Chl-a and Faecal Coliform (FC) highlighted excellent to good for majority of upstream sites and poor to water unsuitable for all downstream sites respectively. The study offers clear signs of nutrient enrichment and increasing algal biomass downstream of JRB. [ABSTRACT FROM AUTHOR]

We conducted a study to investigate the potential effects of nutrients released from a fish farm, which fell within the typical range found in oligotrophic offshore waters of the Aegean Sea, on phytoplankton growth. We designed an in situ bioassay experiment at a fish farm and incubated natural phytoplankton assemblages inside dialysis membrane bags for six days. Changes in phytoplankton growth in samples of ambient seawater collected throughout the experiment served as controls and were considered indicative of the net population change rates. Half of the bags were filled with seawater filtered through a 150-µm mesh, while the other half contained unfiltered seawater. The growth rates, estimated based on chlorophyll a concentrations and phytoplankton cell numbers inside the filtered and unfiltered bags, showed no significant differences. While no detectable net phytoplankton growth occurred in the ambient seawater, there was an exponential increase in chlorophyll a content and cell numbers within the bags. Moreover, the species richness within the bags gradually declined throughout the experiment. The findings of the study confirm that continuous nutrient releases from fish farms can promote high population growth rates in oligotrophic environments, provided that phytoplankton losses due to grazing, advection, and sinking are minimized or eliminated. [ABSTRACT FROM AUTHOR]

The poultry industry in developing countries is challenged by the high cost of conventional protein and energy feed ingredients. This problem has burdened researchers to use cheap and readily non-conventional feed ingredients such as tropical leaf meals (TLMs) to reduce the cost of feed. Tropical leaf meals are high in nutrients and important bioactive compounds, such as flavonoids and polyphenols. These important bioactive compounds in TLMs are responsible for their health promoting effects in animals. Research has shown that inclusion of moderate quantities of TLMs in livestock feed improves chicken performance and health. However, the inclusion of high levels of TLMs in poultry diets reduced chicken performance, which may be attributed to low palatability, high fibre content, poor digestibility, and the presence of antinational factors (ANFs) in TLMs. The potential of fermentation to enhance the nutrient content of feedstuffs high in fibre has been reported. Therefore, the objective of this research was to review the current knowledge on the effect of fermentation on nutritional and functional properties of TLMs and their feeding value on broiler chicken and laying hen performance. [ABSTRACT FROM AUTHOR]

In this study, 7500 Anabas testudineus (climbing perch) larvae were fed different diets, including vitamin E-enriched Moina micrura and egg custard-based inert diet, to study their growth, survival and physio-metabolic responses over a 30-day rearing period. The study comprised two control groups: C1, which received 100% vitamin E-enriched Moina for 30 days, and C2, which received a 100% egg custard-based inert diet for 30 days. Additionally, three treatment groups were included, which were fed with varying levels of enriched Moina and egg custard in different ratios and for different durations through co-feeding regimens. The egg custard-based inert diet had 40.98% crude protein and 6.69% ether extract. The results of the present study indicated that final body weight, weight gain, and specific growth rate were significantly (p ˂ 0.05) higher in T3 group, in which larvae fed with 75% enriched Moina + 25% egg custard for first 15 days, 50% enriched Moina + 50% egg custard for next 5 days, 25% enriched Moina + 75% egg custard for next 5 days; 0% enriched Moina + 100% egg custard for next 5 days. In addition, significantly (p ˂ 0.05) higher survival was obtained in C1 followed by T3 group. The appropriate co-feeding strategy based on digestive enzyme activity was observed in T3 and T2 groups. In terms of glucose, cortisol, superoxide dismutase (SOD), and catalase (CAT) levels, no significant difference (p ˃ 0.05) was observed between C1 and T3 groups. Moreover, significantly (p ˂ 0.05) higher levels of glutathione peroxidase (GPx) activity were observed in C1 and T3 groups. The activity of metabolic enzymes was also significantly affected by the co-feeding strategy. Overall, the T3 group showed improved growth and enzyme activity compared to other treatments. Thus, the present study establishes a co-feeding strategy by using vitamin E-enriched M. micrura and egg custard-based inert diet at levels as followed for the T3 group to boost the growth performance and physio-metabolic activity in A. testudineus larvae. [ABSTRACT FROM AUTHOR]

Preserved biological communities can provide baseline data about the historical ecosystems and environmental conditions that preceded recent anthropogenic alteration. Freshwater mussel shells show particularly good preservation, and the shell assemblages commonly found during archaeological excavations can offer insights into past ecosystems. We studied assemblages of Unio pictorum mussel shells from palaeochannel silts associated with the Late Bronze Age site of Must Farm in eastern England (c. 850 BC), on an ancient tributary of the modern‐day River Nene. We compared archaeological shells from two sediment horizons (broadly 1300–700 BC) to live individuals collected from two analogous sites on the present‐day Nene. Size and growth rate, interannual growth variability and stable isotope (δ18O and δ13C) composition were compared between the populations. Size and the von Bertalanffy growth parameter L∞ differed among all four populations. Mean lengths and L∞ were higher in the two modern populations (mean lengths 77.3 ± SE 0.8 and 73.8 ± SE 1.1 mm, L∞ 91.8 ± 5.4 and 79.0 ± 8.1 mm) than the ancient populations (mean lengths 58.1 ± SE 1.6 mm and 68.4 ± SE 0.9 mm; L∞ 71.5 ± 16.9 and 76.8 ± 6.2 mm). Modern individuals also showed greater variation in age‐corrected year‐to‐year growth. δ13C was lower in modern shells (−11.8‰ for modern shells, −9.03‰ and −9.02‰ for ancient shell populations), potentially reflecting altered hydrological and nutrient regimes. δ18O and δ13C were positively correlated for all but one sampled ancient shell, but not modern shells. These results reflect changes in local environmental conditions, particularly the transition from a shallow, slow‐flowing tributary to a deeper, canalised river with faster flow, as well as effects of anthropogenic nutrient enrichment. The findings demonstrate the importance of long‐term data in studying anthropogenic ecosystem alteration and avoiding shifting baseline syndrome in conservation planning. [ABSTRACT FROM AUTHOR]

Nitrogen (N) addition can stimulate tree growth; however, the strength of this growth effect usually changes over time and the factors underlying these responses are not fully understood. Based on a decade‐long N addition experiment (by adding 0, 20, 50, and 100 kg N ha−1 yr−1) in a boreal forest, we studied responses of tree growth to N addition over time and explored the potential role of temporal precipitation variation and plant stoichiometric changes in mediating this. We found positive growth responses to N addition but this effect changed nonlinearly over time. Annual precipitation was positively related to growth under high‐level N addition; hence, a hump‐shape temporal pattern in precipitation contributed to the nonlinear tree growth responses. After precipitation effects were accounted for, the positive growth responses to N addition peaked in the seventh year and then declined for all levels of N. Later reductions in growth responses could partly be attributed to increased leaf N:phosphorus (P) ratio over time, especially at higher N addition rates. We also found an increase in soil acid phosphatase, the ratio of labile to occluded soil P fraction, and a decreased ratio in leaf N to P resorption efficiency with increasing N addition rates during the late stage of this experiment, suggesting increased P demand. Collectively, our results imply that changes in plant nutrient stoichiometry with cumulative N input may limit the N stimulation on tree growth over time, while temporal precipitation variation appears unlikely to modulate this effect under the atmospheric N deposition. Plain Language Summary: Tree growth can be limited by the availability of nitrogen (N), while the stimulation effects of increased N input on growth can change over time due to constraints by the availability of either water or other nutrients such as phosphorus (P). We investigated the temporal dynamics of tree growth to decade‐long N addition in a boreal forest and assessed how growth was mediated by temporal precipitation variation and plant tissue N:P. The rate of tree growth was enhanced by N addition, but the positive effect first increased but then decreased over time. Annual precipitation variation mediated the growth response to the highest N addition (100 kg N ha−1 yr−1) only, whereas an increase in leaf N:P ratio over time under N addition explained the changes in tree growth response to N addition. We also found evidence for the acceleration of ecosystem P cycling. Our findings suggest that the relative P limitation may constrain tree growth responses to increased N availability over time, and these should be considered in predicting forest carbon sequestration with N deposition. Key Points: Effects of N addition on tree growth changed nonlinearly over timeInterannual precipitation enhanced the stimulation effect of N addition on tree growth under the highest N level onlyThe increase in leaf N:P ratio over time mediated the temporal dynamics of tree growth responses to N addition [ABSTRACT FROM AUTHOR]

Introduction: Nitrogen (N) and phosphorus (P) enrichment due to anthropogenic activities can significantly affect soil N transformations in forest ecosystems. However, the effects of N and P additions on nitrification and denitrification processes in Metasequoia glyptostroboides plantations, and economically important forest type in China, remain poorly understood. Methods: This study investigated the responses of soil nitrification and denitrification rates, as well as the abundances of nitrifiers and denitrifiers, to different levels of N and P additions in a 6-year nutrient addition experiment in a M. glyptostroboides plantation. Results: Stepwisemultiple regression analysis was used to identify the main predictors of nitrification and denitrification rates. The results showed that moderate N addition (N2 treatment, 2.4 mol·m-2) stimulated nitrification rates and abundances of ammonia-oxidizing archaea (AOA) and bacteria (AOB), while excessive N and P additions inhibited denitrification rates and reduced the abundance of nirS-type denitrifiers. AOB abundance was the main predictor of nitrification rates under N additions, whereas microbial biomass carbon and nirS gene abundance were the key factors controlling denitrification rates. Under P additions, tree growth parameters (diameter at breast height and crown base height) and AOB abundance were the primary predictors of nitrification and denitrification rates. Discussion: Our study reveals complex interactions among nutrient inputs, plant growth, soil properties, and microbial communities in regulating soil N transformations in plantation forests. This study also offers valuable insights for formulating effective nutrient management strategies to enhance the growth and health of M. glyptostroboides plantations under scenarios of increasing elevated nutrient deposition. [ABSTRACT FROM AUTHOR]

Mangroves offer many important ecosystem services including carbon sequestration, serving as nursery grounds to many organisms, and acting as barriers where land and sea converge. Mangroves exhibit environmental flexibility and resilience and frequently occur in nutrient-limited systems. Despite existing research on mangrove microbiomes, the effects of nutrient additions on microbial community structure, composition, and function in intertidal and landward zones of mangrove ecosystems remain unclear. We utilized a long-term nutrient amendment study in Exmouth Gulf, Western Australia conducted in two zones, the intertidal fringe and supralittoral scrub forests, dominated by Avicennia marina. Root samples were fractionated into rhizosphere, rhizoplane and endosphere compartments and analyzed by 16S rRNA gene amplicon sequencing to determine the effects of nutrient stress on community structure and function. Our data showed species richness and evenness were significantly higher in the scrub forest zone. PERMANOVA analysis revealed a significant effect of nutrient enrichment on beta diversity (p = 0.022, R2 = 0.012) in the fringe forest zone only. Cylindrospermopsis, which has been associated with harmful algal blooms, was found to be significantly enriched in fringe phosphatefertilized plots and nitrogen-fixing Hyphomicrobiales were significantly depleted in the scrub nitrogen-fertilized plots. Meanwhile, root compartments and forest zone had a greater effect on beta diversity (p = 0.001, R2 = 0.186; p = 0.001, R2 = 0.055, respectively) than nutrient enrichment, with a significant interaction between forest zone and root compartment (p = 0.001, R2 = 0.025). This interaction was further observed in the distinct divergence identified in degradative processes of the rhizosphere compartment between the two forest zones. Degradation of aromatic compounds were significantly enriched in the fringe rhizosphere, in contrast to the scrub rhizosphere, where degradation of carbohydrates was most significant. Despite the highly significant effect of forest zone and root compartments, the long-term effect of nutrient enrichment impacted community structure and function, and potentially compromised overall mangrove health and ecosystem stability. [ABSTRACT FROM AUTHOR]

Arbuscular mycorrhizal fungi (AMF) facilitate ecosystem functioning through provision of plant hosts with phosphorus (P), especially where soil P is limiting. Changes in soil nutrient regimes are expected to impact AMF, but the direction of the impact may depend on context. We predicted that nitrogen (N)‐only enrichment promotes plant invasions and exacerbates their P limitation, increasing the utility of AMF and promoting AMF diversity. We expected that enrichment with N, P and other nutrients similarly promotes plant invasions, but decreases the benefit and diversity of AMF because P is readily available for both native and exotic plants.We tested these hypotheses in eucalypt woodlands of south‐western Australia, that occur on soils naturally low in P. We evaluated AMF communities within three modified ground‐layer states representing different types of nutrient enrichment and associated plant invasions. We compared these modified states to near‐natural reference woodlands.AMF richness varied across ground‐layer states. The moderately invaded/N‐enriched state showed the highest AMF richness, while the highly invaded/NP‐enriched state showed the lowest AMF richness. The reference state and the weakly invaded/enriched state were intermediate. AMF richness and colonisation were higher in roots of exotic than native plant species.AMF community composition differed among ground‐layer states, with the highly invaded/NP‐enriched state being most distinct. Distinctions among states were often driven by family‐level patterns. Reference and moderately invaded/N‐enriched states each supported distinct groups of zero‐radius operational taxonomic units (zOTUs) in Acaulosporaceae, Gigasporaceae and Glomeraceae, whereas Gigasporaceae and Glomeraceae were nearly absent from the highly invaded/NP‐enriched state. Further, Diversisporaceae and Glomeraceae were most diverse in the moderately invaded/N‐enriched state.Synthesis. Both the nature of soil nutrient enrichment and plant provenance matter for AMF. N‐only enrichment of low‐P soils increased AMF richness, likely due to the introduction of AMF‐dependent exotic plant species and exacerbation of their P limitation. In contrast, multi‐nutrient enrichment, decreased AMF richness potentially due to a decrease in host dependence on AMF, regardless of host provenance. The changes in AMF community composition with nutrient enrichment and plant invasion warrant further research into predicting the functional implications of these changes. [ABSTRACT FROM AUTHOR]

Symbiotic microorganisms in reef-building corals, including algae, bacteria, archaea, fungi, and viruses, play critical roles in the adaptation of coral hosts to adverse environmental conditions. However, their adaptation and functional relationships in nutrient-rich environments have yet to be fully explored. This study investigated Duncanopsammia peltata and the surrounding seawater and sediments from protected and non-protected areas in the summer and winter in Dongshan Bay. High-throughput sequencing was used to characterize community changes, co-occurrence patterns, and factors influencing symbiotic coral microorganisms (zooxanthellae, bacteria, and archaea) in different environments. The results showed that nutrient enrichment in the protected and non-protected areas was the greatest in December, followed by the non-protected area in August. In contrast, the August protected area had the lowest nutrient enrichment. Significant differences were found in the composition of the bacterial and archaeal communities in seawater and sediments from different regions. Among the coral symbiotic microorganisms, the main dominant species of zooxanthellae is the C1 subspecies (42.22–56.35%). The dominant phyla of bacteria were Proteobacteria, Cyanobacteria, Firmicutes, and Bacteroidota. Only in the August protected area did a large number (41.98%) of SAR324_cladeMarine_group_B exist. The August protected and non-protected areas and December protected and non-protected areas contained beneficial bacteria as biomarkers. They were Nisaea, Spiroplasma, Endozoicomonas, and Bacillus. No pathogenic bacteria appeared in the protected area in August. The dominant phylum in Archaea was Crenarchaeota. These symbiotic coral microorganisms' relative abundances and compositions vary with environmental changes. The enrichment of dissolved inorganic nitrogen in environmental media is a key factor affecting the composition of coral microbial communities. Co-occurrence analysis showed that nutrient enrichment under anthropogenic disturbances enhanced the interactions between coral symbiotic microorganisms. These findings improve our understanding of the adaptations of coral holobionts to various nutritional environments. [ABSTRACT FROM AUTHOR]

Simultaneous exposure to multiple stressors complicates the challenge of predicting ecological responses to global environmental change. Here, we show that the contributions of individual species and functional groups to the overall stability of ecosystems can be modified by the presence of different stressors, both individually and in combination. By disturbing natural rocky shore communities with nutrients and sediments and simulating extinction of predatory whelks and grazers, we also found that consumers can simultaneously stabilise and destabilise communities along different stability dimensions, irrespective of their trophic position. Our results suggest that our experimental disturbances influenced consumer contributions to stability indirectly by modifying the interactions between consumers and macroalgae in different ways. These findings merit further exploration in different systems exposed to a range of different stressors to better understand how perturbations of different kinds can modify the multifaceted contributions of species to the overall stability of ecosystems. [ABSTRACT FROM AUTHOR]

This comprehensive review explores the escalating challenge of nutrient enrichment in aquatic ecosystems, spotlighting the dire ecological threats posed by harmful algal blooms (HABs) and excessive particulate organic matter (POM). Investigating recent advancements in water treatment technologies and management strategies, the study emphasizes the critical need for a multifaceted approach that incorporates physical, chemical, and biological methods to effectively address these issues. By conducting detailed comparative analyses across diverse aquatic environments, it highlights the complexities of mitigating HABs and underscores the importance of environment-specific strategies. The paper advocates for sustainable, innovative solutions and international cooperation to enhance global water quality and ecosystem health. It calls for ongoing advancement, regular monitoring, and comprehensive research to adapt to emerging challenges, thus ensuring the preservation of aquatic biodiversity and the protection of communities reliant on these vital resources. The necessity of integrating technological innovation, ecological understanding, and global cooperation to safeguard aquatic ecosystems for future generations is paramount. [ABSTRACT FROM AUTHOR]

Community weighted mean trait, i.e., functional composition, has been extensively used for upscaling of individual traits to the community functional attributes and ecosystem functioning in recent years. Yet, the importance of intraspecific trait variation relative to species turnover in determining changes in CWM still remains unclear, especially under nutrient enrichment scenarios. In this study, we conducted a global data synthesis analysis and three nutrient addition experiments in two sites of alpine grassland to reveal the extent to which species turnover and ITV contribute to shift in CWM in response to nutrient enrichment. The results consistently show that the importance of ITV relative to species turnover in regulating CWM in response to nutrient enrichment strongly depends on trait attributes rather than on environmental factors (fertilization type, climatic factors, soil properties, and light transmittance). For whole plant traits (height) and leaf morphological traits, species turnover is generally more important than ITV in determining CWM following most treatments of nutrient addition. However, for leaf nutrient traits, ITV outweighed species turnover in determining shifts in CWM in response to almost all treatments of nutrient addition, regardless of types and gradients of the nutrient addition. Thus, our study not only provides robust evidence for trait-dependent importance of ITV in mediating community functional composition, but also highlights the need to consider the nature of functional traits in linking ITV to community assembly and ecosystem functioning under global nutrient enrichment scenarios. [ABSTRACT FROM AUTHOR]

Aim: Understanding the distance–decay relationship (DDR) has been considered important because it reflects a combination of several ecological processes such as dispersal limitation and environmental sorting. However, effects of human disturbances on DDR are poorly known, especially in freshwater lakes. This study is aimed to examine how anthropogenic eutrophication modified the relationships between three facets (taxonomic, functional and phylogenetic) of macroinvertebrate beta diversity and geographic and environmental distances across 30 freshwater lakes. Location: The Yangtze River floodplain, China. Methods: We used Mantel tests to examine the relationships between multiple facets of assemblage dissimilarities (overall beta diversity, replacement and richness difference components) and geographic and environmental distances. Distance‐based redundancy analysis (dbRDA) and associated variation partitioning procedures were applied to explore the relative contributions of environmental and spatial factors on the three facets of beta diversity. Results: We found that none of the three beta diversity facets was related to geographic distance, but all were significantly related to environmental distance, mainly mirroring eutrophication‐related variables. Based on the variation partitioning approach, the macroinvertebrate assemblages examined were almost exclusively structured by environmental factors associated with eutrophication, while spatial variables had a negligible effect. Nevertheless, the different facets of beta diversity did not decrease (i.e., no homogenization trend) in lake groups showing the highest eutrophication levels, implying complex influences of anthropogenic disturbances in driving homogenization or differentiation in assemblage compositional dissimilarity. Main Conclusions: Our findings suggested that the high degrees of eutrophication acted as an environmental filter to significantly modify the spatial distance–decay relationships, possibly via decreasing the importance of dispersal limitation in shaping macroinvertebrate assemblages in the studied lakes. Given the sensitivity of beta diversity patterns to eutrophication we found in this study, we recommend that the role of anthropogenic disturbances should be incorporated into research on general ecological patterns like the DDR. [ABSTRACT FROM AUTHOR]

We studied the effects of varying levels of nitrogen (N), phosphorus (P), and nitrogen and phosphorus mixture (NP) enrichment on the hatching of resting eggs to determine whether nutrient enrichment levels affect the emergence of zooplankton from resting eggs. We treated resting eggs with six different nutrient concentrations and returned them to the in situ water environment to simulate the restoration of a favourable environment after eutrophication. Low nutrient concentrations had a lesser impact on egg hatching compared with high concentrations, and P had a lesser impact on egg hatching than N and NP. Resting eggs were able to maintain their vitality even in unfavourable environments during the enrichment phase, and they hatched in large numbers when favourable conditions arose. High concentrations of N and NP had a significant effect on the community structure of hatched zooplankton, mainly affecting the emergence of copepod nauplii from resting eggs. The findings suggest that levels of nutrient enrichment determine the emergence of zooplankton from resting egg banks. This study provides a reference for the potential replenishment of active populations by resting egg banks in eutrophic river environments. [ABSTRACT FROM AUTHOR]

The timing and causes of lake eutrophication are often obscured when multiple anthropogenic disturbances coincide in space and time. This issue is particularly problematic for shallow lakes in arid regions that experience strong climatic forcing which alters lake hydrology and water levels, and further conflates causal drivers.We used Utah Lake (Utah, U.S.A.) as a model system to examine how natural hydrological variability and anthropogenic forcing influence ecosystem structure of large shallow lakes in arid climates. Paleolimnological analyses of sedimentary biogeochemistry, pigments, DNA, and morphological fossils were used to identify shifts in primary production and evaluate the relative influence of regional climate‐driven hydrological variability and of humans on ecosystem structure.Sediment cores revealed that the phase prior to non‐indigenous settlement included numerous macrophyte and gastropod remains, sedimentary DNA from plants, low organic matter, and low algal production. An abrupt transition occurred in the late 19th century concomitant with agricultural and urban expansion and the introduction of common carp, which was characterised by a loss of macrophytes and an increase in phytoplankton abundance as indicated by sedimentary DNA and pigment concentrations. A further shift to increased cyanobacteria occurred c. 1950 when exponential population growth increased wastewater influx, as recorded by sedimentary δ15N values.Taken together, our data demonstrate that the current eutrophic state of Utah Lake is a function of anthropogenic forcing rather than natural climate‐driven hydrological fluctuations. Furthermore, large lakes in arid regions can exhibit similar patterns of abrupt ecosystem change between alternate states as those observed in northern temperate/boreal and subtropical ecosystems. [ABSTRACT FROM AUTHOR]

Aquatic ecosystems are often impacted by several human‐derived pressures simultaneously. A key challenge for ecologists is to develop mechanistic understanding of the cumulative effects of multiple stressors on freshwater biodiversity.We established an outdoor mesocosm experiment to examine the individual and combined effects of two key stressors on lake ecosystems globally—nutrient enrichment and amplified water‐level fluctuations—on benthic algal and macroinvertebrate assemblages along a gradient in littoral water depth.We found that nutrient enrichment and water‐level fluctuations not only altered the structure of littoral communities when acting individually, but also interacted to dynamically alter biomass and community structure in different ways at different depths. As expected, enrichment increased benthic algal biomass significantly in very shallow waters. Yet, when enrichment co‐occurred with water‐level fluctuations, this pattern was reversed, with algal biomass increasing significantly in deeper waters, but not in the shallows that were exposed to fluctuating water levels. This pattern occurred across all algal groups that we examined except for green algae. Green algae biomass increased with nutrient enrichment, was greatest in the shallows, and remained unaffected by fluctuating water levels.Water‐level fluctuations modified the functional feeding group structure of benthic macroinvertebrate communities, reducing relative densities of collector‐gatherers and increasing those of predators. However, these changes occurred only in the shallow‐most regions exposed directly to fluctuating water levels.Our results reveal how two globally important stressors of standing water systems can interact in different ways in different ecological contexts and show how stressors can combine to have unanticipated impacts that vary in space. Our findings underscore the potentially highly multifaceted and complex nature of stressor combinations that present a major and growing challenge to ecosystem management, particularly in light of accelerating global environmental change. [ABSTRACT FROM AUTHOR]

Mangroves offer many important ecosystem services including carbon sequestration, serving as nursery grounds to many organisms, and acting as barriers where land and sea converge. Mangroves exhibit environmental flexibility and resilience and frequently occur in nutrient-limited systems. Despite existing research on mangrove microbiomes, the effects of nutrient additions on microbial community structure, composition, and function in intertidal and landward zones of mangrove ecosystems remain unclear. We utilized a long-term nutrient amendment study in Exmouth Gulf, Western Australia conducted in two zones, the intertidal fringe and supralittoral scrub forests, dominated by Avicennia marina. Root samples were fractionated into rhizosphere, rhizoplane and endosphere compartments and analyzed by 16S rRNA gene amplicon sequencing to determine the effects of nutrient stress on community structure and function. Our data showed species richness and evenness were significantly higher in the scrub forest zone. PERMANOVA analysis revealed a significant effect of nutrient enrichment on beta diversity (p = 0.022, R2 = 0.012) in the fringe forest zone only. Cylindrospermopsis, which has been associated with harmful algal blooms, was found to be significantly enriched in fringe phosphate-fertilized plots and nitrogen-fixing Hyphomicrobiales were significantly depleted in the scrub nitrogen-fertilized plots. Meanwhile, root compartments and forest zone had a greater effect on beta diversity (p = 0.001, R2 = 0.186; p = 0.001, R2 = 0.055, respectively) than nutrient enrichment, with a significant interaction between forest zone and root compartment (p = 0.001, R2 = 0.025). This interaction was further observed in the distinct divergence identified in degradative processes of the rhizosphere compartment between the two forest zones. Degradation of aromatic compounds were significantly enriched in the fringe rhizosphere, in contrast to the scrub rhizosphere, where degradation of carbohydrates was most significant. Despite the highly significant effect of forest zone and root compartments, the long-term effect of nutrient enrichment impacted community structure and function, and potentially compromised overall mangrove health and ecosystem stability.

Background: Amalgamation of metal-tolerant plant growth promoting rhizobacteria (PGPR) with biochar is a promising direction for the development of chemical-free biofertilizers that can mitigate environmental risks, enhance crop productivity and their biological value. The main objective of the work includes the evaluation of the influence of prepared bacterial biofertilizer (BF) on biometric growth parameters as well as physiological and biochemical characteristics of rapeseed (Brassica napus L.) at copper action. Methods: The prepared BF was based on novel metal tolerant strain of PGPR Buttiauxella sp. EA20 isolated from the rhizosphere of orchid Epipactis atrorubens and birch wood biochar (BC). The pot-scale experiments included six treatments: peat-containing control substrate (CS); CS + 200Cu (200 mg Cu/kg of soil); CS + 5% BC (v/v); CS + 5% BC + 200Cu; CS + 5% BF (v/v); CS + 5% BF + 200Cu. Results: Single Cu treatment caused the decrease in rapeseed leaf area, shoot and root length, fresh and dry biomass, as well as an increase in water saturation deficit, possibly due to damage of cell membranes by lipid peroxidation. Addition of BF or BC alone mitigated these harmful effects of copper. Application of BF, regardless of Cu addition, increased the rapeseed leaf area (1.6 times on average), plant fresh and dry biomass (2.5 times on average), and photosynthetic pigment content (1.8 times on average). In addition, BF treatment along with Cu enhanced the antioxidant activity of B. napus due to the accumulation of non-enzymatic antioxidants such as carotenoids, free proline and soluble phenolic compounds, including flavonoids. Moreover, plant enrichment with copper and essential macronutrients such as nitrogen, phosphorus and potassium was observed. Conclusions: The study concludes that application of complex biofertilizer based on metal tolerant PGPR strain Buttiauxella sp. EA20 and birch wood biochar mitigated the harmful effects of copper, enhanced the rapeseed growth and increased its biological value. Future perspective includes evaluation of the potential for using the resulting biofertilizer to improve the growth and biofortification of other crop species.

Natural landscapes are increasingly impacted by nitrogen enrichment from aquatic and airborne pollution sources. Nitrogen enrichment in the environment can eliminate the net benefits that plants gain from nitrogen-fixing microbes such as rhizobia, potentially altering host-mediated selection on nitrogen fixation. However, we know little about the long-term effects of nitrogen enrichment on this critical microbial service. Here, we sampled populations of the legume Acmispon strigosus and its associated soil microbial communities from sites spanning an anthropogenic nitrogen deposition gradient. We measured the net growth benefits plants obtained from their local soil microbial communities and quantified plant investment into nodules that house nitrogen-fixing rhizobia. We found that plant growth benefits from sympatric soil microbes did not vary in response to local soil nitrogen levels, and instead varied mainly among plant lines. Soil nitrogen levels positively predicted the number of nodules formed on sympatric plant hosts, although this was likely due to plant genotypic variation in nodule formation, rather than variation among soil microbial communities. The capacity of all the tested soil microbial communities to improve plant growth is consistent with plant populations imposing strong selection on rhizobial nitrogen fixation despite elevated soil nitrogen levels, suggesting that host control traits in A. strigosus are stable under long-term nutrient enrichment.

Insights into ecological drivers of alien plant invasions can be gained through comparative studies of growth and fecundity of invasive alien plants versus those of co‐occurring non‐invasive alien plants and native plants across environmental conditions in common garden settings. Habitats that harbour alien plant species in many ecosystems globally are presently experiencing light pollution resulting from artificial light at night (ALAN) and increased rates of nutrient enrichment of the soil. However, the potential interactive effects of ALAN and nutrient enrichment on invasiveness of alien plant species remain unknown.Here, we performed a common‐garden experiment to test the interactive effects of ALAN and soil nutrient enrichment on the growth of a random set of ten alien (five invasive and five non‐invasive naturalized) and seven co‐occurring native ornamental plant species that are commonly cultivated within urban and peri‐urban areas of Nairobi city in Kenya. We predicted that a simultaneous increase in photoperiod via ALAN and nutrient enrichment will favour growth of invasive alien plant species over that of non‐invasive alien and native plant species. We grew the 17 plant species under natural daylight (ALAN−) versus natural daylight followed by ALAN (ALAN+) and fully crossed with two levels of nutrient enrichment (low vs. high) and competition (competition vs. no‐competition against a native plant Ocimum gratissimum) treatments.Under simultaneous high‐nutrient and no‐competition treatments, ALAN enhanced mean total biomass of invasive and non‐invasive naturalized alien species by 61.1% and 131.4%, respectively but decreased that of native plant species by 34%. In contrast, under simultaneous high‐nutrient and competition treatments, ALAN enhanced mean total biomass of invasive alien plant species by 68.6% and that of non‐invasive naturalized alien species by 51.9% and native species by 35.4%. High‐nutrient treatment enhanced flower formation more strongly in invasive and non‐invasive naturalized alien plants than in native plants. The invasive and non‐invasive naturalized alien species grew taller than native species across the light, nutrient, and competition treatments.Synthesis: The present findings suggest that light pollution and nutrient enrichment may jointly confer growth advantage to invasive alien plant species over that of co‐occurring native plant species and enhance invasiveness of alien plant species. [ABSTRACT FROM AUTHOR]

In Benin, most of urban wastewaters are discharged into rivers without any prior treatment. The objective of this study was to assess the effects of urban wastewater on the macroinvertebrate communities of the upper Ouémé River in Benin. To address this question, 30 stations located on five rivers were monitored in the dry and the wet seasons. For each station and each season, 12 samples of macroinvertebrates following standardized French multi-habitat sampling protocol were collected and physico-chemical parameters were recorded. Three types of stations were chosen on each river: two control stations located upstream of the wastewater discharge points, two stations impacted in the urban area and receiving urban wastewaters, and two stations downstream of the wastewater discharge points to measure the resilience of a set of river characteristics. Urban wastewater impacted the water quality by mainly increasing electrical conductivity and the nutrient concentrations. Wastewaters also deeply impacted the diversity and the composition of the invertebrate community. The Indval index highlighted three indicator taxa for the control stations (Caenidae, Baetidae and Ephemerellidae), one for the impacted stations (Chironomidae), and two for the downstream stations (Libellulidae and Lestidae). We also observed ecosystem resilience a few hundred meters downstream of the discharge points. These results challenge managers on the degradation of river water quality in the upper Ouémé River, but also reveal good self-purification capacities of the watercourses likely to promote the resilience of these ecosystems. This study focuses on the effects of urban wastewater on macroinvertebrate communities in the upper Ouémé basin in Benin. We found similar responses in African invertebrates to those observed in other parts of the world. However, we unexpectedly observed a stronger impact during the wet season than during the dry season. Furthermore, community resilience did not depend primarily on the distance downstream of the wastewater input, but rather on a combination of several factors. [ABSTRACT FROM AUTHOR]

The mutualistic relationship between plants and arbuscular mycorrhizal (AM) fungi is essential for optimal plant nutrition, enabling plants to better withstand biotic and abiotic stressors and enhancing survival, reproduction, and colonization of new environments. Activities, such as soil enrichment or compaction, may decrease the benefits of AM fungi for plants, potentially reducing interactions in urban environments. Here, we examine this prediction by studying how urbanization alters AM interactions with the invasive herb Ruellia nudiflora (Acanthaceae).We collected soil and plants from deep urban sites (DUS; e.g., sidewalks), open urban sites (OUS; parks), and rural sites (RS) to analyse soil nutrient content, plant morphology, AM colonization rates, spore density, richness, and diversity.Contrary to predicted, DUS had the lowest soil nutrient concentration, except for phosphorus, reducing AM colonization. This supports the prediction of reduced AM interactions in urban environments. We also found that potassium affects the AM association. Urban plants had smaller and more compact root systems compared to their rural counterparts, but there were no discernible differences in AM fungi communities between urban and rural environments.Phosphorus enrichment in sidewalks is the main driver of reductionof R. nudiflora‐AM fungi interactions in Mérida. More studies are needed to gain a better understanding of how AM fungi contribute to plant colonization in urban environments. [ABSTRACT FROM AUTHOR]

Ecosystems are connected by flows of nutrients and organisms. Changes to connectivity and nutrient enrichment may destabilise ecosystem dynamics far from the nutrient source.We used gradostats to examine the effects of trophic connectivity (movement of consumers and producers) versus nutrient‐only connectivity on the dynamics of Daphnia pulex (consumers) and algae (resources) in two metaecosystem configurations (linear vs. dendritic).We found that Daphnia peak population size and instability (coefficient of variation; CV) increased as distance from the nutrient input increased, but these effects were lower in metaecosystems connected by all trophic levels compared with nutrient‐only connected systems and/or in dendritic compared with linear systems.We examined the effects of trophic connectivity (i.e. both trophic levels move rather than one or the other) using a generic model to qualitatively assess whether the expectations align with the ecosystem dynamics we observed.Analysis of our model shows that increased Daphnia population sizes and fluctuations in consumer‐resource dynamics are expected with nutrient connectivity, with this pattern being more pronounced in linear rather than dendritic systems.These results confirm that connectivity may propagate and even amplify instability over a metaecosystem to communities distant from the source disturbance, and suggest a direction for future experiments, that recreate conditions closer to those found in natural systems. Read the free Plain Language Summary for this article on the Journal blog. [ABSTRACT FROM AUTHOR]

Nutrients are important determinants of diatom growth in lakes, and diatoms are considered reliable indicators of changing lake nutrient concentrations and eutrophication. However, diatom ecologies are not static, nor are they linked to single environmental variables, leading to imprecise diatom nutrient inferences. Anthropogenic nutrient enrichment is the principal issue facing New Zealand's lakes. Thus, knowledge of diatom responses to nutrients in New Zealand lakes will be important for understanding contemporary and past changes in nutrient availability. Using a nutrient amendment experiment and diatom communities from dune lakes, here we show that the response of specific diatom species is not universal among lakes and is partly determined by lake nutrient concentrations and limitation status. The response of focal diatom species to nutrient additions differed from previously reported nutrient requirements, and did not align with published, assigned trophic statuses. This study highlights that the response of diatoms to nutrient enrichment is context-dependent, and that intraspecific generalisations of diatom ecologies between geographic locations or through time should be made with caution. To apply diatoms to making nutrient inferences, more work focusing on how physiochemical and biological factors influence diatom nutrient requirements is required. [ABSTRACT FROM AUTHOR]

Symbiotic microorganisms in reef-building corals, including algae, bacteria, archaea, fungi, and viruses, play critical roles in the adaptation of coral hosts to adverse environmental conditions. However, their adaptation and functional relationships in nutrient-rich environments have yet to be fully explored. This study investigated Duncanopsammia peltata and the surrounding seawater and sediments from protected and non-protected areas in the summer and winter in Dongshan Bay. High-throughput sequencing was used to characterize community changes, co-occurrence patterns, and factors influencing symbiotic coral microorganisms (zooxanthellae, bacteria, and archaea) in different environments. The results showed that nutrient enrichment in the protected and non-protected areas was the greatest in December, followed by the non-protected area in August. In contrast, the August protected area had the lowest nutrient enrichment. Significant differences were found in the composition of the bacterial and archaeal communities in seawater and sediments from different regions. Among the coral symbiotic microorganisms, the main dominant species of zooxanthellae is the C1 subspecies (42.22–56.35%). The dominant phyla of bacteria were Proteobacteria, Cyanobacteria, Firmicutes, and Bacteroidota. Only in the August protected area did a large number (41.98%) of SAR324_cladeMarine_group_B exist. The August protected and non-protected areas and December protected and non-protected areas contained beneficial bacteria as biomarkers. They were Nisaea, Spiroplasma, Endozoicomonas, and Bacillus. No pathogenic bacteria appeared in the protected area in August. The dominant phylum in Archaea was Crenarchaeota. These symbiotic coral microorganisms’ relative abundances and compositions vary with environmental changes. The enrichment of dissolved inorganic nitrogen in environmental media is a key factor affecting the composition of coral microbial communities. Co-occurrence analysis showed that nutrient enrichment under anthropogenic disturbances enhanced the interactions between coral symbiotic microorganisms. These findings improve our understanding of the adaptations of coral holobionts to various nutritional environments.

The article discusses the interaction between climate change and anthropogenic pressures in the eutrophication process. Eutrophication, which is the excessive supply of nutrients to estuarine and coastal regions, poses a significant threat to ecosystems worldwide. The article explores the complex link between climate change and eutrophication, highlighting the potential exacerbation of eutrophication and its negative impacts due to climate-driven factors such as temperature changes, wind patterns, and sea level rise. The research topic also covers various themes related to eutrophication assessment, biogeochemical consequences, anthropogenic pressures, climate variability, ecosystem comparisons, and the effects of eutrophication on ecosystem services. The volume includes six papers contributed by scientists from different countries, providing insights into the effects of different factors on marine ecosystems. [Extracted from the article]

We explored patterns of benthic diatom composition across sixty-two high-elevation alpine lakes spanning a wide range of nitrogen (N) concentrations due to atmospheric deposition and background variation in lake and watershed characteristics. Our goals were to (1) assess the effect of lake water N concentration on benthic diatom composition during late summer or fall conditions and (2) identify policy-relevant response thresholds. The analyses were carried out on a large set of diatom and water chemistry data, integrated with new data. Multivariate and correlation analyses revealed associations between pH, N concentration, and benthic diatom composition, but the effects of pH and N were confounded. However, partial correlation analysis allowed us to identify “N-responsive diatoms”; that is, diatom taxa with nonspurious associations with N. Focusing on these taxa, we detected a decline in the abundance of taxa preferring low N concentrations and an increase in the abundance of taxa preferring high N concentrations starting at NO3 concentrations of approximately 5 µmol L−1. We interpreted this shift as an effect of watershed N saturation due to atmospheric deposition. Based on the results, we suggest a late-summer or fall concentration threshold of 5 µmol NO3 L−1 to prevent change in benthic diatoms in high-elevation alpine lakes.

Wastewater from agricultural source carries excess nitrogen and phosphorous into wetlands and causes eutrophication in waterbody. Enrichment of nitrogen and phosphorous affects the natural nutrient removal and plant growth in wetlands. We conducted a greenhouse experience to explore the effects of excess N and P on the growth of Carex schmidtii, so as to provide evidence for wetland phytoremediation. The results showed that high concentration of N had negative effects on the plant height and growth rate of C. schmidtii. Excess N and P significantly reduced the leaf morphology and mass per plant or leaf but increased the length and the ratio of withered leaf. Furthermore, the chlorophyll content and lid peroxidation indicated that high concentrations of N and P exerted much injury to the blades of C. schmidtii. These results help in understanding the responses of C. schmidtii to agricultural wastewater and suggest the limited capacity of C. schmidtii tussock for the phytoremediation of agricultural wastewater in wetlands. [ABSTRACT FROM AUTHOR]

In this study, we have shown that nutrient input in aquatic ecosystems has different impacts on the various facets of phytoplankton and zooplankton diversity. We designed an experiment with eleven levels of nutrient addition replicated four times. Alpha, beta, and gamma taxonomic and functional diversity indices were calculated based on organisms' occurrences and abundances in each microcosm, among microcosms of the same treatment and for the set microcosms of a same treatment. There was an increase in species richness and a decrease in equitability along the gradient for both groups. Taxonomic beta diversity based on occurrences was positively related to nutrient gradient, but a hump-shaped relationship between nutrient enrichment and beta diversity was observed when abundance data were considered, showing greater variation in species composition at intermediate levels of nutrient. Alpha functional richness increased for both groups, whereas alpha and gamma RaoQ, and gamma functional divergence decreased, indicating that nutrient enrichment promotes functional trait richness, but also the dominance of species. At small spatial scale and at a short period of time, we showed that taxonomic and functional diversities respond in similar ways to nutrient enrichment. We conclude that nutrient input may modify community composition and affect ecological processes overtime. [ABSTRACT FROM AUTHOR]

Intra‐annual (i.e. seasonal) temporal niche partitioning is essential to the maintenance of biodiversity in many plant communities. However, understanding of how climate and global change drivers such as eutrophication influence seasonal niche partitioning in plant assemblages remains limited.We used early‐season and late‐season compositional data collected from 10 grassland sites around the world to explore relationships between climate variability and intra‐annual species segregation (i.e. seasonal β‐diversity) and to assess how nutrient enrichment alters seasonal β‐diversity in plant communities. We then assessed whether changes in seasonal β‐diversity in response to nutrient enrichment are underpinned by species turnover or nestedness and determined how specific functional groups (i.e. annual forbs, perennial forbs, C3 and C4 graminoids and legumes) respond to eutrophication within and across early and late sampling dates.We found a positive relationship between intra‐annual temperature variability and seasonal β‐diversity but observed no relationship between intra‐annual precipitation variability and seasonal β‐diversity. Nutrient enrichment increased seasonal β‐diversity and increased turnover of species between early‐ and late‐season communities. Nutrient enrichment reduced the abundance of C4 graminoids and legumes within and across sampling timepoints and eliminated intra‐annual differences in these groups. In contrast, nutrient enrichment resulted in seasonal differences in C3 graminoids, which were not observed in control conditions and increased abundance of C3 graminoids and annual forbs within and across early and late sampling dates.Synthesis: Our understanding of how grasslands respond to various components of global change is primarily based on studies that document community changes at inter‐annual scales. Using early‐season and late‐season compositional data from 10 grassland sites around the world, we show that nutrient enrichment increases seasonal β‐diversity and alters intra‐annual dynamics of specific functional groups in unique ways. [ABSTRACT FROM AUTHOR]

The impact of growth conditions on the nitrogen, protein, colour and amino acid profiles of Palmaria palmata (from 2 locations) were investigated. Laboratory cultures of P. palmata were grown over a period of 18 days with and without nutrient addition, i.e., with culture medium (F/2) and urea (0.05 or 0.10 g L−1). The total nitrogen (TN) content of cultured P. palmata originating from longlines harvested from Cork increased with the addition of culture medium (F/2) and urea (0.05 g L−1) in comparison to the initial sample (4.15 ± 0.05 vs 1.73 ± 0.03%) while biomass from Galway increased with addition of culture medium (F/2) and urea (0.10 g L−1) in comparison to the initial sample (3.72 ± 0.05 vs 2.43 ± 0.06%). The protein nitrogen (PN) and non-protein nitrogen (NPN) of cultured P. palmata originating from Galway also increased when grown with the addition of nutrients. Nutrient enrichment during growth influenced the colour characteristics (lightness L*, redness a*, yellowness b* and colour difference ΔE) and the electrophoretic protein profile. Correlations between TN and ΔE (r = 0.945) for Cork originated sample, PN and ΔE (r =-0.944) and NPN and ΔE (r = 0.734) for Galway originated sample were observed. In-gel digestion followed by UPLC-MS/MS demonstrated that RuBiSCo, phycoerythrin and allophycocyanin expression in P. palmata was enhanced with nutrient addition. Amino acid profile and score analysis showed variation as a function of nutrient addition. Overall, nutrient inclusion in the growth medium provides a strategy for the enhanced production of high-quality protein by P. palmata. [ABSTRACT FROM AUTHOR]

Since the Green Revolution, the management of agrochemicals has become a cornerstone of agriculture, allowing it to expand over terrestrial ecosystems previously deemed unsuitable for cultivation. Such expansion altered the connectedness of aquatic habitats to organisms with complex life cycles by increasing the number of temporary ponds in interfluves. Here, we investigate how spatial isolation and intensification in the use of agrochemicals can interact to increase or decrease the permeability of agricultural fields to these organisms by affecting community structure in temporary ponds.We carried out a field experiment that simulates realistic scenarios of agrochemical contamination at different levels of spatial isolation. We constructed 45 1200‐L artificial ponds in a Savanna landscape in Brazil at three distances from a source wetland (30, 120, and 480 m). The ponds were spontaneously colonized by aquatic insects and amphibians and treated with no agrochemicals (control), fertilizers (as in managed pastures) or fertilizers and a single pulse of the insecticide fipronil and the herbicide 2,4‐D (as in sugarcane fields) following realistic dosages and application schedules.Communities treated only with fertilizers generally exhibited a higher abundance of aquatic insects at the peak of the rainy season, suggesting that fertilization caused bottom‐up effects. However, because low spatial isolation and fertilization favoured different predatory taxa, their insect prey eventually became less abundant in less isolated fertilized ponds. Communities treated with fertilizers and pesticides diverged strongly from other treatments after the application of the insecticide, when a decrease in insect abundance indirectly benefitted amphibian populations. In this case, spatial isolation delayed the recovery of the abundance of several herbivore and detritivore insects in isolated ponds.Synthesis and applications. These results have direct consequences for the emergence of insects and amphibians, possibly affecting important ecosystem services. Such consequences can be controlled by avoiding agrochemical contamination at the peak of most taxa reproductive season or through changes in spatial isolation by deliberately constructing wetlands in interfluves. In all cases, the effects of agrochemicals and isolation must be addressed jointly for a successful management of biodiversity in agricultural landscapes. [ABSTRACT FROM AUTHOR]