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Abstract

There is an urgent need to track how natural systems are responding to global change in order to better guide management efforts. Traditionally, taxonomically based metrics have been used as indicators of ecosystem integrity and conservation status. However, functional approaches offer promising advantages that can improve bioassessment performance. In this study, we aim to test the applicability of functional redundancy (FR), a functional feature related to the stability, resistance and resilience of ecosystems, as a tool for bioassessment, looking at woody riparian communities in particular. We used linear mixed-effect models to investigate the response of FR and other traditional biomonitoring indices to natural (drought duration) and anthropogenic stress gradients (flow regulation and agriculture) in a Mediterranean basin. Such indices include species richness, a taxonomic index, and the Riparian Quality Index, which is an index of ecological status. Then, we explored the ability of FR and the other indices to discriminate between different intensities of human alteration. FR showed higher explanatory capacity in response to multiple stressors, although we found significant negative relationships between all the biological indices (taxonomic, functional and ecological quality) and stress gradients. In addition, FR was the most accurate index to discriminate among different categories of human alteration in both perennial and intermittent river reaches, which allowed us to set threshold values to identify undisturbed (reference condition), moderately disturbed and highly disturbed reaches in the two types of river. Using these thresholds and the best-fitting model, we generated a map of human impact on the functional redundancy of riparian communities for all the stretches of the river network. Our results demonstrate that FR presents clear advantages over traditional methods, which suggests that it should be part of the biomonitoring toolbox used for environmental management so as to obtain better predictions of ecosystem response to environmental changes.
... 4.7.2 Riparian plant communities as biomonitors of Mediterranean IRES: a case study Bruno et al. (2016a) investigated the use of riparian vegetation as bioindicators in Mediterranean-climate perennial rivers and IRES using taxonomic and functional community metrics. Riparian species richness and quality (Riparian Quality Index, González del Tánago and García de Jalón, 2011) were reduced by land-use intensification, flow regulation and natural flow intermittence. ...
... 18;Bruno et al., 2016a). ...
... 18 Spatial patterns of human impact levels based on predicted values of the functional redundancy of riparian vegetation communities in IRES (thin lines) and perennial rivers (thick lines) in a basin in south-east Spain.Bruno et al. (2016a) provide further details.FromBruno et al. (2016a). ...
... Further, they can serve as a food source for other invertebrates, fishes, and birds (Wallace & Webster, 1996;Buss et al., 2015). From this perspective, FD helps to understand the relationships between the community structure and the functioning of aquatic ecosystems (Bruno et al., 2016). Thus, FD is indicated by the diversity of characteristics of taxa in ecosystems (Schleuter et al., 2010), i.e., biological or ecological (e.g., related to habitat preferences, like pH and temperature tolerances, tolerance to organic pollution, biogeographic distribution, etc.) traits. ...
... Biological traits of macroinvertebrates, such as maximum body size, breathing patterns, morphological specialisations for anchoring to substrate, types of osmoregulatory organs, and feeding habits (among others), provide information about local environmental conditions, i.e., these categories of traits are sets of biological responses to stressors (Reynaga et al., 2020). Hence, relevant studies have been carried out on benthic macroinvertebrates and their FD through biological traits (Bruno et al., 2016;Forio, 2017;Forio et al., 2018;Arenas-Sánchez et al., 2021;Paz et al., 2022). Thus, as in the case of the taxonomical approach, the FD can be summarised using indices. ...
Thesis
Water is a valuable and finite resource on earth, and water quality (WQ) is becoming a sensitive issue in many countries. WQ is influenced by natural (e.g., changes in precipitation trends, erosion) and anthropogenic (e.g., urban, industrial, agricultural activities) factors whose influence changes with time and space and affects water use. Thus, a monitoring program that will provide empirical evidence to support decision-making on surface WQ issues is vital. Scientists face the challenge of providing stakeholders with accurate indicators of surface WQ monitoring that help guide the water management decision process. This PhD study uses different statistical approaches to solving questions linked to surface WQ of the Paute river basin (PRB) (south of Ecuador). As such, an extensive database collected in the PRB throughout a 5-year monitoring program (the year 2008 and period 2010-2013) was analysed. Statistical approaches involve hierarchical and non-hierarchical cluster methods, non-parametric classification algorithms, mathematical optimisation techniques, measures of similarity of clustering outputs, ordination methods, and regression models. The overall research goal of this doctoral project was to mine relevant information about the different components of surface WQ in the PRB streams using adequate statistical procedures. Firstly, a spatial WQ characterisation of the studied basin was performed using only chemical and microbiological information. As a result, two WQ classes were established, representing low and high pollution levels. Further, the key chemical and microbiological parameters that most explain these groups and their spatial variability were identified. Then, the biotic/ecological component (i.e., benthic macroinvertebrates) was used as a biological response variable regarding descriptive parameters (i.e., physical, chemical, microbiological, geomorphological and integrity habitat quality parameters). Different statistical algorithms were implemented using the macroinvertebrate community's taxonomic/biotic and functional approaches to find the most accurate indices/metrics that best discriminated among less, moderately and highly polluted sites in the PRB streams. Also, the relevant descriptive variables to explain the spatial variability of both taxonomical/biotic and functional macroinvertebrates aspects were identified. Likewise, using the benthic macroinvertebrates, questions about using fine (i.e., genera) or coarse (i.e., families) taxonomic resolutions were answered, giving a new perspective on using these bioindicators in the PRB. This research showed degraded streams are characterised by high levels of faecal coliforms, electric conductivity, chlorides, total hardness, nitrogen, total alkalinity, biochemical oxygen demand, turbidity, water temperature, low levels of oxygen and poor macroinvertebrate functional and taxonomic attributes, as well as fluvial habitat degradation. Contrarily, clean sites are associated with good land use plans, adequate habitat conditions (i.e., riparian vegetation and streambed heterogeneity), and high levels of taxonomic/biotic and functional diversity of macroinvertebrates. These ecological integrity features were congruent with permissible records of chemical and microbiological WQ parameters. Also, the geomorphological parameters such as elevation, slope and river order were relevant to explain the macroinvertebrate's responses. The results show that these outputs of different surface WQ components can vary in magnitude regarding the sub-basins of the PRB hydrological system, and one of the primary factors that affect their trends is land use. The macroinvertebrate community and their taxonomic and functional mechanisms are affected by stress linked with anthropization. Thus, a remarkable result of the current research is that these mechanisms were reasonably parameterised to help assess the impact of stress on the macroinvertebrate community, providing validated tools for future WQ monitoring in the PRB.
... Among other functions, they act in nutrient cycling and energy flow within food webs and may serve as a food source for other invertebrates, fish, and birds (Wallace & Webster, 1996;Buss et al., 2015). In the past two decades, interest in the functional diversity (FD) of benthic macroinvertebrates, has increased because FD helps to understand the relationships between community structure and the functioning of aquatic ecosystems facing various types of disturbance (Bruno et al., 2016). FD is indicated by the diversity of taxa's traits in ecosystems (Schleuter et al., 2010). ...
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Functional diversity (FD) is useful for the evaluation of freshwater ecosystems. The FD of macroinvertebrate families for river water quality (WQ) assessment in the Paute River Basin (PRB), Ecuador, was investigated. Macroinvertebrate samples and data about 26 physical, chemical, microbiological and hydro-geomorphological variables were available. Literature-based biological traits were allocated as scores to the macroinvertebrates data through fuzzy coding. The Generalised Additive Mixed Model (GAMM) was used to assess the performance of six FD indices using the referred 26 WQ descriptive variables. The best performing GAMM led to selecting the index based on functional dendrograms including the species community pool (wFDc) as the most suitable to characterise FD in the PRB. The sub-basins of the PRB were grouped in three classes applying Average Linkage Clustering (ALC) and using wFDc. The Random Forest (RF) algorithm was used with a global efficiency of 89% to assess the ALC clusters consistency and pre-identify the significant WQ descriptive variables, explaining most of the FD variability. The Kruskal-Wallis test was then applied to refine the outcomes of the previous analysis. Twelve WQ descriptive variables were finally identified as the best discriminant predictors for FD, including the riparian vegetation, electric conductivity, dissolved oxygen, total hardness, faecal coliforms and pH. It is believed that the implemented approach successfully assessed the stream WQ status of the PRB upon selecting a suitable macroinvertebrate FD index; as such, it could be applied to other tropical basins for WQ assessment.
... In this context, a higher redundancy could ensure the ecosystem's resilience capacity after a decline in species diversity promoted by a perturbation due to several species with similar functional attributes/roles (Mouillot et al., 2014;Rosenfeld, 2002). Functional redundancy is a crucial tool in prioritization decisions by managers once it indicates "the lowest threshold" necessary to maintain the integrity of the ecosystem (Bruno et al., 2016;Moreno-García and Baiser, 2021;Rosenfeld, 2002). Therefore, it is crucial to integrate all components of vulnerability for an accurate measure in ecosystems (Markovic et al., 2017;Weißhuhn et al., 2018). ...
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Ecosystem vulnerability is crucial information for conservation managers. We assessed the sensitivity and resilience (vulnerability components) patterns of fish and phytoplankton assemblages in French lakes (natural and artificial). We measured resilience (functional redundancy) and sensitivity, an index considering three characteristics of rarity for species. We hypothesized that geographically close lakes have similar resilience and sensitivity for fish assemblages (H1). Then, we tested the correlation between environmental gradients and resilience and sensitivity components, assuming that fish and phytoplankton do not respond similarly to environmental factors and that, consequently, there is no congruence between sensitivity and resilience patterns between of two groups. Also, we tested the hypotheses that species-rich assemblages show higher resilience and sensitivity in French lakes (H2); the highest values of resilience and sensitivity are related to phytoplankton (H3); and assemblages from natural lakes have higher resilience and sensitivity level (H4). We found similar resilience levels in spatially close fish assemblages due to fish dispersal limitations that contributed to create regional patterns in functional structure. Besides, acidity and eutrophication processes are good indicators of sensitivity level for fish. There is a mismatch in resilience and sensitivity levels between fish and phytoplankton, reinforcing importance of using a multi-taxa approach. Also, the components were positively related to taxonomic richness in assemblages showing importance of conserving biodiversity. Finally, we observed higher values of resilience and sensitivity for phytoplankton, as expected for a highly diverse group. Additionally, phytoplankton assemblages in natural lakes showed higher resilience levels than artificial environments, confirming the importance of preserving natural systems to conserve ecosystem functionality.
... De la Riva et al. (2017) and Fu et al. (2015) found FRic advantageous to FEve and FDiv for identifying functional diversity change affected by climate gradient. While Bruno et al. (2016b) concluded that FRic's predictive capacity exceeded by FR when assessing environmental stress on riparian woodlands. The question is which of the functional diversity indices can best predict the functioning of the ecosystem: the mechanism based on a single trait level weighted by abundance CWM, or alternatively that based on the complementarity of multiple trait levels non-weighted (FRic) or weighted by abundance (FEve, FDiv, FDis, Q). ...
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Invasive alien species (IAS) poses a significant threat to plant biodiversity globally and even considered one of the largest threats to biodiversity, second to habitat loss. They behave as pioneer species in different landscapes, tolerant to disturbances, climatic conditions, high competitive potential and generalists in distribution. Their superior competitive ability results in the loss of native flora leading to extinction. The success of IAS generally attributed to differences in functional traits compared to less successful aliens as well as to native species. Several studies envisaged that the impacts of plant invasions are not universal and depend on the trait diversity of both, the introduced species and the resident community. Functional traits best describe the alien's success over natives , and they seem to be important attributes to conservation biology and ecosystem management. Moreover, their ecological impacts remain poorly understood due to lack of quantitative studies. In the present paper, we adopted the systematic literature review approach for collecting and analysing the scientific data. A total of 212 critical research papers and grey literature for last three decades were found meeting the aims, were collected from relevant sources. Present review emphasizes the differences in key functional traits between invasive alien plants and the native species which aid them to alter ecosystem functioning by modifying habitat according to their needs. We also focus on potential habitats for invasion based on a conceptual framework concerning response-effect traits. Review provides a quantitative assessment of invading species for their ecological performance , emerging problems and possible solution.
... Functional space quality was assessed by selecting the most relevant functional axes given the optimal number of dimensions (Maire et al., 2015). Functional redundancy, a metric that indicates the average representation of organisms playing similar functional roles in the ecosystem, was calculated by classifying the species into functional groups ( Figure S2) by means of clustering approaches based on a trait dissimilarity matrix (Bruno et al., 2016;Laliberté et al., 2010). ...
Article
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Uptake and elimination rate constants were positively correlated among species, but only when effects of body size and phylogeny were incorporated in the analysis. Together, uptake and elimination rates predicted dramatic Cd bioaccumulation differences among species that agreed with field-based measurements. We discovered a potential tradeoff between the ability to eliminate Cd and the ability to detoxify it across species, particularly mayflies. The best-fit regression models were driven by phylogenetic parameters (especially differences among families) rather than functional traits, suggesting that it may eventually be possible to predict a taxon's physiological performance based on its phylogenetic position, provided adequate physiological information is available for close relatives. There appears to be great potential for evolutionary physiological approaches to augment our understanding of insect responses to environmental stressors in nature. comparative methods evolutionary physiology bioaccumulation phylogeny tradeoff W ith 6,500 species described to date in North America (1), aquatic insects are a diverse and ecologically important group (2), particularly in rivers and streams. For example, the orders Ephemeroptera, Plecoptera, and Trichoptera (EPT taxa) include 58 recognized families and 2,700 species (1). Among these many lineages, great diversity exists in morphology, life history characteristics, and physiology stemming from a long and complex evolutionary history. Although the origins of the Ephemeroptera are unknown (3), a general paradigm of the terrestrial ancestry of aquatic insects is widely accepted, with numerous invasions of freshwater habitats hypothesized throughout evolutionary history (4). Many of these invasions have entailed adaptive ''solutions'' that involve complex suites of traits that in combination determine the range of environmental conditions that a given taxon can tolerate. Some traits that arose in response to past environmental challenges may now render certain species relatively more susceptible to modern anthropogenic pollutants. These pollutants may be either entirely novel (e.g., organophosphate insecticides) (see ref. 5) or were historically present at much lower concentrations in natural environments than they are in many ecosystems today (e.g., trace metals) (6). This variation in susceptibility has practical implications, because the ecological structure of aquatic insect communities is often used to indicate the ecological conditions in freshwater systems (7-9). Differences among species' responses to environmental stressors can be profound, but it is uncertain whether the cause is related to functional ecology [usually the assumption (10, 11)] or physiological traits (5, 12-14), which have received considerably less attention. To the degree that either is involved, their link to phylogeny and evolutionary history remains poorly understood. Here, we ask whether the tendency for related species to be similar (i.e., phylogenetic signal) (15, 16) extends to physiological traits that contribute to sensitivity to the stressor: cadmium. Generalizations about phylogenetic linkages to stress responses have been hindered to date by the limited number of species that can be studied. We overcome this hurdle by using highly developed methodologies for efficiently quantifying critical processes that control sensitivity to dissolved cadmium (see refs. 13, 17, and 18) (Fig. 1). These physiological processes have previously been considered in a conceptual model of metal toxicity (19) that explicitly assumes that chronic toxicity in nature is the manifestation of metal accumulation at target sites (i.e., metal-sensitive sites) that ensues when the rate of metal influx exceeds the combined rates of metal excretion and detoxification. In practice, the model can be tested by combining bioaccumulation kinetics (see ref. 17) and subcellular fractionation (e.g., refs. 18 and 20). We have used this integrated approach to reconcile apparent discrepancies between insect responses to trace metals in toxicity assays and in nature (13), to infer Cd sensitivity differences among predaceous stoneflies (14), and to understand the mechanisms underlying the metal tolerance of a caddis fly (21). We used phylogenetic analyses (22-30) to explore physiological processes related to dissolved Cd susceptibility in 21 field-collected aquatic insect species representing eight EPT families [supporting information (SI) Table S1]. We tested for correlations and possible trade-offs among traits and used traits in combination to predict the more emergent property (sensitivity) in each of these species. We asked whether phylogenetic approaches (15, 16, 22-30) are potentially more powerful than traditional functional guild approaches (e.g., ref. 31) for predicting sensitivity differences among species. We compared statistical models that include body weight, feeding strategy, and lineage as independent variables by using both conventional and
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Human-driven ecosystem simplification has highlighted questions about how the number of species in an ecosystem influences its functioning. Although biodiversity is now known to affect ecosystem productivity, its effects on stability are debated. Here we present a long-term experimental field test of the diversity–stability hypothesis. During a decade of data collection in an experiment that directly controlled the number of perennial prairie species, growing-season climate varied considerably, causing year-to-year variation in abundances of plant species and in ecosystem productivity. We found that greater numbers of plant species led to greater temporal stability of ecosystem annual aboveground plant production. In particular, the decadal temporal stability of the ecosystem, whether measured with intervals of two, five or ten years, was significantly greater at higher plant diversity and tended to increase as plots matured. Ecosystem stability was also positively dependent on root mass, which is a measure of perenniating biomass. Temporal stability of the ecosystem increased with diversity, despite a lower temporal stability of individual species, because of both portfolio (statistical averaging) and overyielding effects. However, we found no evidence of a covariance effect. Our results indicate that the reliable, efficient and sustainable supply of some foods (for example, livestock fodder), biofuels and ecosystem services can be enhanced by the use of biodiversity.
Chapter
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