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Boxplots highlighting differences in biomonitoring index values between each hydrological class and drying pattern. a) BMWP; b) Ntaxa; c) ASPT; d) Family LIFE. Boxes show the 25th, 50th and 75th percentiles, whiskers indicate the minimum and maximum values within 1.5 times of the interquartile range.
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p>Temporary rivers comprise a significant proportion of river networks globally and their prevalence is expected to increase as a result of future climate change and anthropogenic water resource pressures. Despite this, the influence of drying events on freshwater biomonitoring tools within temporary rivers has received limited research attention w...
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Context 1
... influence of FP on biomonitoring indices was examined within separate mixed-effect models due to an uneven number of samples within FP categories for each DP, which precluded a FP × DP interaction from being reliably tested. BMWP and Ntaxa were modelled using a Poisson distribution via 'generalized linear mixed-ef- fect models' (GLMMs), while ASPT and Family LIFE were modelled with a Gaussian distribution using linear mixed-effect models (LMMs); these were conducted using 'glmer' and 'lmer' functions (respectively) within the 'lme4′ package (Bates et al., 2017). The identity of each watercourse and sampling season were used as random effects in all models to ac- count for any potential lack of spatial or temporal independence be- tween macroinvertebrate samples. ...
Context 2
... no biomonitoring indices were significantly affected by the individual influence of DP (see Table 1). Perennial sites typically obtained higher BMWP scores and Ntaxa values compared with temporary reaches along rivers which dried long- itudinally from the headwaters, but overlapped more so within rivers that dried from the mid-reaches (see Fig. 2a and b). ASPT and Family LIFE scores displayed less marked differences between each HC for both DPs, although marginally increased within perennial sites at streams drying longitudinally from the headwaters and slightly decreased at perennial sites positioned along watercourses which dried within the mid-reaches (see Fig. 2c and d). The amount ...
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... the mid-reaches (see Fig. 2a and b). ASPT and Family LIFE scores displayed less marked differences between each HC for both DPs, although marginally increased within perennial sites at streams drying longitudinally from the headwaters and slightly decreased at perennial sites positioned along watercourses which dried within the mid-reaches (see Fig. 2c and d). The amount of statistical variance explained by each biomonitoring index was always lower when con- sidering HC (maximum R 2 m = 0.25) compared to FP (maximum Fig. 1. The location of the studied rivers within the United Kingdom. R 2 m = 0.41; see Table 1). All biomonitoring indices differed sig- nificantly between FP groups, with ...
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... In the last years, freshwater research has encouraged efforts in the development of tools to evaluate the health of non-perennial rivers during the dry phase (Steward et al., 2011(Steward et al., , 2018Wilding et al., 2018). While intermittent rivers can be at some point assessed during the flow phase, ephemeral streams (and dry rivers), lacking water most of the time, are still devoid of ecosystem health indicators. ...
... Among the biotic indices tested for macroinvertebrates, only family richness, OCH and EPT/EPT + OCH varied significantly along the PCA axis of anthropogenic impact (PC1_local or PC1_regional) but did not show significant differences across the natural impact gradient (PC2_local and/or PC2_regional). This is supported by previous studies in temporary rivers showing higher correspondence of the value of these indices with anthropogenic gradient (Prat et al., 2014;Soria et al., 2020;Wilding et al., 2018). The decline in EPT/EPT + OCH ratio in response to anthropogenic predictors can be explained by the replacement of the lotic taxa (e.g., EPT) by the lentic (e.g., OCH) taxa adapted to dominant environmental conditions in disconnected pools such as increased ...
Temporary rivers, forming the majority of river networks worldwide, are key biodiversity hotspots. Despite their great value for maintaining biodiversity and ecosystem functioning, they are often neglected in biomonitoring programs due to several challenges, such as their variable hydromorphology and the difficulty of establishing reference conditions given their dynamic nature, resulting in highly variable communities. Disconnected pools often form in temporary rivers when flow ceases, providing refuge for aquatic taxa. Given their importance for biodiversity conservation, revising and adapting biotic indices are needed. Here, we evaluate the performance of current biological indices designed for perennial rivers (macroinvertebrates, diatoms) and functional metrics (macroinvertebrates) in assessing biological quality of disconnected pools. We sampled 55 disconnected pools in Catalonia, NE Spain, covering local (e.g., physico-chemical variables, water chemistry) and regional (e.g., human influence, hydrological variables at the water body level) natural and anthropogenic gradients. Only a few macroinvertebrate biotic indices (e.g., family richness, EPT/EPT + OCH and OCH) showed strong responses to anthropogenic predictors and were unaffected by natural predictors at both local and regional scales, making them suitable for biomonitoring. Of the newly adopted functional metrics of macroinvertebrate communities tested, only two (i.e., functional redundancy of predators and response diversity based on the total community) responded strongly to anthropogenic predictors. The rest showed varying responses to the interactive effect of anthropogenic and natural predictors, requiring calibration efforts. Models assessing these metrics explained <40 % of the total variation, likely due to the interplay of colonization/extinction dynamics and density-dependent trophic interactions governing community assemblages in disconnected pools. Although some existing biological metrics could potentially be used to monitor the ecological status of disconnected pools, we call for further development of biomonitoring tools specifically designed for these habitats since they will become more widespread with global change.
... Significant intensity and severity events of drought can have complex consequences, including reducing hydrological connectivity, enhancing siltation, changing the structure of aquatic vegetation, altering channel shape, increasing water temperature, decreasing dissolved oxygen availability, affecting water chemistry, and altering nutrient cycles (Ledger et al., 2011;Chessman, 2015). Also, drought has been noted for various characterizations used to describe its consequences in intermittent and regular systems, such as drying patterns (Wilding et al., 2018), extremely low flow levels (White et al., 2022), watershed water scarcity (Karaouzas et al., 2018), permanent drying (Carey et al., 2021), and others. In Mediterranean climate zones, intermittent watercourses denote a temporary or reduced flow in specific locations and periods (Banegas-Medina et al., 2021). ...
... There are numerous publications about field and controlled laboratory analyses for disentangling the effects of drought on abiotic and biotic changes in different freshwater systems. The study of macroinvertebrates has been more frequent in Mediterranean and temperate zones, both field-based and experimental approaches (Wilding et al., 2018). Using macroinvertebrate-based studies in field or controlled experiments involves primarily modeling the effects of anthropogenic pressures (Menbohan et al., 2022). ...
Drought significantly impacts freshwater ecosystems, disrupting all biological levels. In particular, freshwater macroinvertebrates undergo significant changes in taxonomic and functional diversity bioassessments. The effects often synergize with other stressors, such as pollution that drought can exacerbate. Several techniques have been well-developed (traditional) or have the potential (innovative) to address this issue. This review provides a comprehensive description of the impact of drought as a primary stressor on macroinvertebrate diversity. An overview of the research and projections are presented. Three conceptual pillars drive this study: taxonomic-functional responses, simultaneous pressure dynamics, and innovative techniques. Few studies have been conducted on lentic water bodies, arid and semi-arid systems, and on multiple continents. Common research keywords across continents are observed less frequently in experimental than in field studies. Most analyzed studies examine community structure, which is more common in field-based than experimental studies. Agricultural land use effect, urbanization, and invasive species are the stressors most associated with drought. Integrating traditional with advanced/innovative techniques that have hardly been applied makes it challenging to understand ecological responses comprehensively. If innovative techniques are employed to consider the dynamics of multiple stressors and to consistently estimate taxonomic and functional diversity, promising avenues for future research could be uncovered.
... Makroinvertebrata adalah salah satu kelompok indikator biomonitoring peraiaran yang paling banyak digunakan secara global, dengan sejumlah besar indeks biotik dan alat yang tersedia berdasarkan toleransi fauna dan preferensi dalam kaitannya dengan stressor tertentu [5]. Di Eropa, sebagian besar indeks biomonitoring makroinvertebrata yang digunakan dalam implementasi Water Framework Directive, sebagian besar didasarkan pada sensitivitas taksa terhadap pengayaan nutrisi [5]. ...
... Makroinvertebrata adalah salah satu kelompok indikator biomonitoring peraiaran yang paling banyak digunakan secara global, dengan sejumlah besar indeks biotik dan alat yang tersedia berdasarkan toleransi fauna dan preferensi dalam kaitannya dengan stressor tertentu [5]. Di Eropa, sebagian besar indeks biomonitoring makroinvertebrata yang digunakan dalam implementasi Water Framework Directive, sebagian besar didasarkan pada sensitivitas taksa terhadap pengayaan nutrisi [5]. Sensitivitas makroinvertebrata terhadap pengayaan nutrisi telah mendukung indeks biotik yang digunakan untuk mengkarakterisasi kesehatan ekologis dan status lingkungan perairan [6]. ...
Rivers various benefits for human's necessities for life, but most of the rivers are heavily polluted. Surabaya is the capital city of East Java that uses the river as a source of raw water for drinking water. Monitoring water quality by identifying aquatic biota live in rivers can provide information about categories of water pollution. The objective of this study was to determine the level of water quality pollution in Menur Pumpungan River using the biolytic method. The research was conducted in Kali Menur Pumpungan. Determination of research stations was completed by purposive sampling method. The results denoted that three macroinvertebrate families classified as tolerant, namely Parathelpipusidae-B, Thiaridae-B, Viviparidae and one family classified as very tolerant, namely Tubificidae. Family Ephemeroptera, Plecoptera, and Tricoptera (EPT) were not found in Kali Menur Pumpungan. The average value of the water quality of Menur Pumpungan River is 1.2 that is included in the heavily polluted category. Methods for assessing water quality using the biolytic method can be used as environmental education materials for the community to protect rivers from pollution. PENDAHULUAN Surabaya merupakan Ibu kota Jawa Timur [1] yang memiliki sungai sebagai sumber air baku untuk air minum. Daerah Kota Surabaya yang dilewati oleh sungai seperti Kali Mas, Kali Jagir, Kali Branjangan, dan Kali Greges) memiliki banyak kegiatan masyarakat, industri dan pariwisata di sepanjang sungai. Kegiatan tersebut dapat berdampak pada meningkatnya pencemaran (organik, anorganik, logam berat, sampah plastik) di lingkungan, terutama di perairan [1][2][3][4]. Metode pengukuran untuk mengetahui kualitas perarairan telah banyak dilakukan.
... Intermittent rivers may account for more than 50% of all the world's rivers and make up a large proportion of headwater rivers . In recent years, they have been the subject of growing interest, especially in their ecological functioning (Datry et al., 2011 ;Wilding et al., 2018). They are involved in the upstream-to-downstream transport of sediment and organic matter required for feeding fish and other aquatic species (Reid et Ziemer, 1994 ;Stubbington et al., 2019), regulation of floods (Morin et al., 2009), water quality processes (Dodds and Oakes, 2008), and in the share of greenhouse gas emissions . ...
Les cours d’eau intermittents sont des cours d’eau qui cessent de couler à un moment donné dans l’espace et le temps. Cependant, la compréhension de la variabilité spatio-temporelle des cours d’eau intermittents ainsi que leur localisation précise dans le réseau hydrographique reste limitée en raison d’un manque de données (hydrométriques, hydrographiques, etc.…). Ces difficultés sont accentuées dans les régions à données limitées comme l’Afrique et cette thèse vise principalement à développer des approches méthodologiques qui s'appuient sur des modèles de forêts aléatoires (Random Forest) ainsi que des analyses statistiques pour caractériser la distribution spatiale des cours d’eau intermittents et mieux appréhender les mécanismes de contrôle de l’intermittence en Afrique afin de pallier les lacunes d’observations. D’abord, cette thèse s’est focalisée à l’échelle régionale au Burkina Faso où 49 stations de jaugeage des cours d’eau avec au minimum quatre ans de données sur la période 1955-1985 ont été examinées. Le nombre moyen de mois à débit nul par an ((Ndry) ̅) a été utilisé pour définir quatre classes croissantes d'intermittence du débit à savoir : permanent (0-1 mois à débit nul), faiblement intermittent (2-4), fortement intermittent (5-7), éphémère (8-12). Une analyse en composante principale (ACP) réalisée sur les 49 stations de jaugeages a montré que, bien que l’ordre de Strahler et la précipitation moyenne annuelle influencent la répartition géographique des différentes classes d’intermittence au Burkina Faso, la perméabilité moyenne et la surface amont des bassins versants expliquent principalement cette répartition. Cette étude suggère que la saisonnalité de la précipitation au Burkina Faso rend également saisonnier l’écoulement des cours d’eau à moins que les processus hydrogéologiques ne soient impliqués, notamment à travers la contribution des aquifères au débit de base pendant les périodes d’étiage. L’approche de prédiction par Random Forest a permis d’estimer sur le réseau hydrographique LCS que 83% de la longueur totale des cours d’eau au Burkina Faso sont intermittents contre 98% dans le réseau hydrographique nationale de référence (IGB-BNDT). Ensuite, à l’échelle de l’Afrique, 1125 stations de jaugeage avec au moins 4 ans de données sont examinées sur la période 1958-1991. Plusieurs modèles Random Forest ont été entrainés à relier les classes d’intermittence observée au droit des stations de jaugeage aux valeurs caractéristiques de 15 variables environnementales clés identifiées. L’indice d’aridité (P/ETP), la surface amont des bassins versants et l’évapotranspiration potentielle moyenne annuelle ont été identifiés comme les facteurs de contrôle les plus importants de l’intermittence à l’échelle continentale de l’Afrique. Cela se confirme d’autant plus que la majorité des stations classées intermittentes dans l’échantillon analysé ont des valeurs d’évapotranspiration potentielle moyenne annuelle qui sont supérieures à la précipitation moyenne annuelle (c.-à-d. indice d’aridité < 1). Cette étude prédit sur le réseau hydrographique LCS qu’en Afrique 44 % en longueur des cours d’eau sont permanents tandis que 56 % sont intermittents (9 % faiblement intermittents, 31 % fortement intermittents, 16 % éphémères). Les prédictions du modèle capturent en général la distribution spatiale de l’intermittence dans les réseaux hydrographiques nationaux de référence de l’Afrique du Sud, du Bénin, de Madagascar, du Mali et un peu moins au Burkina Faso. Enfin, cette thèse s’est appesantie sur les difficultés des réseaux hydrographiques globaux et continentaux à reproduire la variabilité spatiale de la densité de drainage observée sur les réseaux hydrographiques nationaux de référence des différents pays en Afrique. Une méthode simple pour extraire les cours d’eau des MNT (Modèle Numérique de Terrain) à partir de surface contributive (Amin) variable spatialement a été développée.
... They include the Lotic-invertebrate Index for Flow Evaluation (LIFE) (Extence et al., 1999), the Canadian Ecological Flow Index (CEFI) (Armanini, Horrigan, Monk, Peters, & Baird, 2011), the New Zealand version of LIFE (LIFE-NZ) (Greenwood, Booker, Smith, & Winterbourn, 2016), the Drought Effect of Habitat Loss on Invertebrates (DEHLI) index , the Monitoring Intermittent Streams (MIS) index , the Biodrought Index (Straka et al., 2019), the Hellenic Flow Index (ELF) (Theodoropoulos, Karaouzas, Vourka, & Skoulikidis, 2020) and the Costa Rican version of LIFE (Quesada-Alvarado, Umaña-Villalobos, Springer, & Picado-Barboza, 2021). Collectively, these indices have served diverse applications: assessing ecological responses to channel modification (Dunbar et al., 2010), flow regulation (Almeida, Merino-Aguirre, & Angeler, 2013;Armanini et al., 2014), water extraction (Bradley, Streetly, Farren, Cadman, & Banham, 2014;Streetly et al., 2014), drought (Monk, Wood, Hannah, & Wilson, 2008;White et al., 2019), stream drying Wilding, White, Chadd, House, & Wood, 2017) and environmental flows (Gillespie, Kay, & Brown, 2020); differentiating effects of pollution from those of hydrological variation (Clews & Ormerod, 2009;Theodoropoulos et al., 2020); indicating stream perenniality or intermittence (Straka et al., 2019(Straka et al., , 2021; identifying those streamflow characteristics that appear to most influence macroinvertebrate assemblages (Monk et al., 2006;Worrall et al., 2014) and licensing water abstractions (Wilding et al., 2017). ...
... They include the Lotic-invertebrate Index for Flow Evaluation (LIFE) (Extence et al., 1999), the Canadian Ecological Flow Index (CEFI) (Armanini, Horrigan, Monk, Peters, & Baird, 2011), the New Zealand version of LIFE (LIFE-NZ) (Greenwood, Booker, Smith, & Winterbourn, 2016), the Drought Effect of Habitat Loss on Invertebrates (DEHLI) index , the Monitoring Intermittent Streams (MIS) index , the Biodrought Index (Straka et al., 2019), the Hellenic Flow Index (ELF) (Theodoropoulos, Karaouzas, Vourka, & Skoulikidis, 2020) and the Costa Rican version of LIFE (Quesada-Alvarado, Umaña-Villalobos, Springer, & Picado-Barboza, 2021). Collectively, these indices have served diverse applications: assessing ecological responses to channel modification (Dunbar et al., 2010), flow regulation (Almeida, Merino-Aguirre, & Angeler, 2013;Armanini et al., 2014), water extraction (Bradley, Streetly, Farren, Cadman, & Banham, 2014;Streetly et al., 2014), drought (Monk, Wood, Hannah, & Wilson, 2008;White et al., 2019), stream drying Wilding, White, Chadd, House, & Wood, 2017) and environmental flows (Gillespie, Kay, & Brown, 2020); differentiating effects of pollution from those of hydrological variation (Clews & Ormerod, 2009;Theodoropoulos et al., 2020); indicating stream perenniality or intermittence (Straka et al., 2019(Straka et al., , 2021; identifying those streamflow characteristics that appear to most influence macroinvertebrate assemblages (Monk et al., 2006;Worrall et al., 2014) and licensing water abstractions (Wilding et al., 2017). ...
Hydrologically sensitive macroinvertebrate indices have been developed in Europe, the Americas and New Zealand to serve many purposes such as monitoring ecological responses to drought, flow regulation, water extraction and the provision of environmental flows. We created an Australian Macroinvertebrate Flow Index (AMFI) based on relative current‐velocity preferences of numerous Australian invertebrate families and genera, derived from a large dataset composited from past biomonitoring programs. We tested the new index with datasets independent from those used for its derivation, showing that it correlated strongly with current velocity and responded mostly as expected to discharge fluctuations downstream of a large dam. A genus‐level version was more responsive than a family‐level version, but the sensitivity of the family‐level version was improved by the incorporation of weighting based on taxon abundance. We suggest possible uses of the new index and recommend further development and testing, particularly in relation to intermittent streams and environmental flows.
... Intermittent rivers and ephemeral streams, hereafter IRES, are defined as every rivers and streams that cease to flow and/or dry at some points in space and time . Many authors have questioned the suitability of current biomonitoring approaches in IRES (Mazor et al., 2014;Munné and Prat, 2011;Prat et al., 2014;Reyjol et al., 2014;Steward et al., 2018;Stubbington et al., 2018;Wilding et al., 2018). However, only a few studies tested the applicability of the current macroinvertebrate-based biomonitoring approaches for intermittent rivers. ...
Intermittent rivers and ephemeral streams (IRES) represent the majority of the global river network, support high biodiversity and provide multiple ecosystem services. However, they are being degraded at alarming rates, and it may be questioned whether current invertebrate-based biomonitoring protocols, which were designed for rivers and streams that flow all year round, are also appropriate for assessing the ecological status of IRES. Here, we test for the first time the efficiency of the French invertebrate-based biomonitoring indicators to assess the ecological status of intermittent rivers downstream six sewage treatment plants along a gradient of flow intermittence (i.e., the percentage of a year without flow at a given site). We found that the effects of drying confounded with that of sewage and in most cases, current biomonitoring metrics did not distinguish between the effect of sewage and those of drying. Except for the taxonomic richness of invertebrates resistant to drying, all metrics decreased linearly with increasing flow intermittence. In addition, the efficiency for detecting sewage effects was lower at intermittent reaches compared to perennial reaches. Last, we identified biological traits responding to flow intermittence, but not to sewage effluents, and we further discuss the implication for traits-based monitoring. If current biomonitoring protocols calibrated for perennial rivers could still be applied to reaches prone to weak flow intermittence, alternatives are urgently needed for integrating intermittent rivers into current biomonitoring national programs.
... climatic aridity; Piggott et al., 2015; Figure 1). In contrast to index totals, 'average score per taxon' (ASPT) indices describe community sensitivity to impacts independent of taxonomic richness, and may thus experience less pronounced decreases in response to stressors (Wilding et al., 2018;Figure 1b). However, research is needed to inform the development of metrics that respond independently to impacts and natural stressors (Gutiérrez-Cánovas et al., 2015), and thus to enable effective biomonitoring in ecosystems responding to environmental change (Nõges et al., 2016). ...
... As such, we found limited support for our second hypothesis, that decreases would be less pronounced for richness-independent ASPT indices, although in the all-region model, impacts explained more variance than drying in WHPT-ASPT but not the index total. ASPT indices assess assemblages based on the impact sensitivities of their constituent families independently of taxonomic richness, thus facilitating impact discrimination in both temporary rivers (Wilding et al., 2018) and perennial rivers that experience seasonal flow variability (Álvarez-Cabria et al., 2010). ...
Rivers are dynamic ecosystems in which both human impacts and climate‐driven drying events are increasingly common. These anthropogenic and natural stressors interact to influence the biodiversity and functioning of river ecosystems. Disentangling ecological responses to these interacting stressors is necessary to guide management actions that support ecosystems adapting to global change.
We analysed the independent and interactive effects of human impacts and natural drying on aquatic invertebrate communities—a key biotic group used to assess the health of European freshwaters. We calculated biological response metrics representing communities from 406 rivers in eight European countries: taxonomic richness, functional richness and redundancy, and biomonitoring indices that indicate ecological status. We analysed metrics based on the whole community and a group of taxa with traits promoting resistance and/or resilience (‘high RR’) to drying. We also examined how responses vary across Europe in relation to climatic aridity.
Most community metrics decreased independently in response to impacts and drying. A richness‐independent biomonitoring index (the average score per taxon; ASPT) showed particular potential for use in biomonitoring, and should be considered alongside new metrics representing high RR diversity, to promote accurate assessment of ecological status.
High RR taxonomic richness responded only to impacts, not drying. However, these predictors explained little variance in richness and other high RR metrics, potentially due to low taxonomic richness. Metric responsiveness could thus be enhanced by developing region‐specific high RR groups comprising sufficient taxa with sufficiently variable impact sensitivities to indicate ecological status.
Synthesis and applications. Metrics are needed to assess the ecological status of dynamic river ecosystems—including those that sometimes dry—and thus to identify priority sites requiring action to tackle the causes of environmental degradation. Our results inform recommendations guiding the development of such metrics. We propose concurrent use of richness‐independent ‘average score per taxon’ indices and metrics that characterize the richness of resistant and resilient taxa. We observed interactions between aridity, impacts and drying, highlighting that these new metrics should be region specific, river type specific and adaptable, promoting their ability to inform management actions that protect biodiversity in river ecosystems responding to climate change.
... Compared to perennial sites, BMWP-type biomonitoring indices including WHPT naturally have lower values at temporary sites, and their values decrease further as dry phase durations increase, and are more variable over time both within and between years (Wilding et al. 2018;White et al. 2019). A major, national (and indeed global) research priority is thus to determine the index values indicative of unimpacted reference conditions and varying severity of human impacts-at sites representing the full range of different temporary river types (Stubbington et al. 2018). ...
We analysed the aquatic macroinvertebrate communities at two sites with contrasting temporary flow regimes in the River Thames headwaters: Ewen, which typically dries for six months each year, and Somerford Keynes, which stops flowing in late summer and dries only for a few weeks. The dataset spanned 2018, a typical hydrological year, and 2019, in which a wetter summer maintained flow. We characterized spatial and temporal variability in the communities and species, to inform effective biomonitoring in temporary streams.
... As a result, hydrological variability (i.e. temporal changes in river discharge, potentially including frequent, extreme discharge fluctuations and flow intermittence) significantly affects current biomonitoring tools (Wilding et al., 2018), which cannot distinguish between biological responses to natural hydrological variability and to human-induced hydrological alteration and degradation, resulting in misclassification of ecological status (Buffagni et al., 2020). ...
River biomonitoring uses biotic indices that assess human-induced degradation, including pollution, by comparison with type-specific static biological reference conditions. However, index scores that indicate pollution may reflect biological responses to natural hydrological variability associated with low flows and drying, leading biomonitoring schemes to misclassify sites as degraded. To address this, dynamic, site-specific adjustments of static biological reference conditions have been proposed, but current biomonitoring tools cannot facilitate implementation of these adjustments. We analyzed 329 samples from mediterranean-climate rivers in Greece, to evaluate the use of six stressor-specific macroinvertebrate-based indices of hydrological variability (CEFI, DEHLI, ELF, LIFE, LIFENZ, MIS-index) as tools to facilitate dynamic adjustments of static biological reference conditions. We examined macroinvertebrate assemblage responses to physicochemical and land use drivers in relation to each sample's hydrological conditions, as assessed by the six indices. We evaluated index performance beyond the region of development by exploring correlations among indices, including correlations with the region-specific Greek ELF index, for which 100% of taxa were represented. We also examined the influence of inorganic nutrient pollution on index performance by comparing index scores from samples with and without nutrient pollution. Season, water temperature, agricultural land use and nutrient pollution were major drivers of macroinvertebrate assemblage composition. Indices were positively correlated but correlation strength varied considerably, driven primarily by taxonomic representation (the proportion of sampled taxa included in each index's calculation), and potentially also by differences in river types, taxonomic resolution and sampling strategies. All indices identified site-specific hydrological conditions both in the presence and absence of nutrient pollution. We recommend the development of region-specific biotic indices of hydrological variability, or regional adaptation of existing indices, to represent 100% of the regional taxa pool and thus to enable acceptable performance beyond their region of development. Such indices could inform dynamic adaptation of static biological reference conditions by assessing site-specific hydrological conditions based on a macroinvertebrate assemblage, without the collection of additional, abiotic field data. Application of our proposed approach could prevent misclassification of ecological status, thus avoiding time-demanding and costly mismanagement of rivers and streams.
