Article
To read the full-text of this research, you can request a copy directly from the authors.

No full-text available

Request Full-text Paper PDF

To read the full-text of this research,
you can request a copy directly from the authors.

... Ecología Austral 32: [957][958][959][960][961][962][963][964][965][966][967][968][969][970][971] I����������� Agricultural practices can modify the overall health of the aquatic ecosystem through organic pollution and eutrophication (Yang et al. 2008;Matthaei et al. 2010) and negatively affect nontarget species such as macroinvertebrates, that inhabit agricultural streams (Barmentlo et al. 2019). Agricultural streams receive the nutrient load after fertilization, as well as suspended material and other components that drain from the fields (Schäfer et al. 2011;Stefanidis et al. 2015). Pesticides can also reach surface waters through atmospheric drift after their application, by surface runoff or by seepage of contaminated groundwater (Phillips and Bode 2004;Gärdenäs et al. 2006;Loewy et al. 2011). ...
... Therefore, multiple stressors, which rarely operate in isolation, can alter an entire ecosystem's functioning, and the combined effects of these stressors are complex and difficult to predict (Matthaei et al. 2010;Côté et al. 2016; Barmentlo et al. 2019). Moreover, these stress factors can modify the physicochemical and biological properties of water, whilst also contributing to other stress factors that modify the structure of macroinvertebrate assemblages, reducing species richness (Zacharia 2011;Stefanidis et al. 2015;Zhang et al. 2021). ...
... In contrast, at lower nutrient content levels and higher dissolved oxygen concentrations, the associated groups were some of the most susceptible. Consistent with this, Paisley et al. (2011), Stefanidis et al. (2015 and Zhang et al. (2018) reported that the most susceptible groups (Ephemeroptera, Plecoptera, Trichoptera) and those most tolerant to nutrient enrichment (Annelida, Mollusca, Diptera) were strongly associated with the sites which showed the lowest and highest levels of nutrient loading (NO 3 -, NH 4 + and, PRS), respectively. ...
... For the Pinios Catchment, nitrate and DO concentrations acted additively on ASPT, and nitrate was the dominant stressor. These results agree with the findings from previous studies (Stefanidis et al. 2016a(Stefanidis et al. , 2018 in which ASPT was associated with nutrients and DO, reflecting the ability of ASPT to capture changes in the abiotic environment related to nutrient and organic pollution (e.g., anoxic conditions). The role of nutrients, mainly nitrogen, on the occurrence of benthic invertebrate taxa has been documented in numerous studies performed elsewhere in Europe and the rest of the world Hering 2009, Villeneuve et al. 2015). ...
... The role of nutrients, mainly nitrogen, on the occurrence of benthic invertebrate taxa has been documented in numerous studies performed elsewhere in Europe and the rest of the world Hering 2009, Villeneuve et al. 2015). For instance, several studies have reported important relationships between nitrogen (TN, NH 4 -N) and macroinvertebrate communities (Wang et al. 2007, Ashton et al. 2014, Stefanidis et al. 2016a, confirming that nitrogen is a key predictor of the ASPT metric. However, these relationships indicate an indirect effect of eutrophication on macroinvertebrate communities, although direct toxic effects of nitrate on specific invertebrates are possible given high enough concentrations or exposure time (Camargo et al. 2005). ...
... Thus, future climate change is expected to impact DO indirectly through changes in the hydrologic regime and increased nutrient pollution but also directly through warming. These effects have been discussed by Stefanidis et al. (2016aStefanidis et al. ( , 2018, who examined the impact of hydrologic alteration and nutrient enrichment on oxygen and nitrate levels, confirming that these stressors are key predictors of benthic invertebrate indices, including ASPT, in the Pinios Catchment. However, the form of the effect may be expected to vary along the stressor gradient. ...
Article
Interactions between stressors in freshwater ecosystems, including those associated with climate change and nutrient enrichment, are currently difficult to detect and manage. Our understanding of the forms and frequency of occurrence of such interactions is limited; assessments using field data have been constrained as a result of varying data forms and quality. To address this issue, we demonstrate a statistical approach capable of assessing multiple stressor interactions using contrasting data forms in 3 European catchments (Loch Leven Catchment, UK: assessment of phytoplankton response in a single lake with time series data; Pinios Catchment, Greece: macroinvertebrate response across multiple rivers using spatial data; and Lepsämänjoki Catchment, Finland: phytoplankton response across multiple rivers using spatiotemporal data). Statistical models were developed to predict the relative and interactive effects of climate change and nutrient enrichment sensitive indicators (stressors) on indicators of ecological quality (ecological responses) within the framework of linear mixed effects models. In all catchments, indicators of nutrient enrichment were identified as the primary stressor, with climate change-sensitive indicators causing secondary effects (Loch Leven: additive, total phosphorus [TP] × precipitation; Pinios: additive, nitrate × dissolved oxygen; Lepsämänjoki: synergistic, TP × summer water temperature), the intensity of which varied between catchments and along the nutrient stressor gradient. Simple stressor change scenarios were constructed for each catchment and used in combination with mechanistic models to explore potential management responses. This approach can be used to explore the need for multiple stressor management in freshwaters, helping practitioners navigate a complex world of environmental change.
... There are various sources of information and environmental data for Pinios basin such as previous projects, published and unpublished studies as well as the RBMP of the Thessaly RBD, within which, Pinios basin is entirely located. In this study we take advantage of our previous extensive work on collecting and/or deriving the necessary datasets for the basin (Panagopoulos et al., 2013(Panagopoulos et al., , 2014Stefanidis et al., 2016). ...
... The merged dataset contains semiquantitative community information at family level from a total of 142 samples collected from different sites across the catchment of river Pinios (Fig. 1). This dataset also contains physicochemical data of water collected from the same sampling sites such as nutrient concentration in water (phosphate, nitrate, nitrite and ammonium) as well as BOD, surface dissolved oxygen (DO), saturation %, pH, conductivity, total suspended solids (TSS) and water discharge (Stefanidis et al., 2016). ...
... Based on the available macroinvertebrate community data we have calculated several candidate metrics to be used as response variables to nutrient and hydrologic parameters predicted by SWAT (Stefanidis et al., 2016). Specifically, we calculated the BMWP (Biological Monitoring Working Party) and the ASPT (Average Score Per Taxon) score according to the BMWP system (Armitage et al., 1983). ...
Article
Streams and rivers are among the most threatened ecosystems in Europe due to the combined effects of multiple pressures related to anthropogenic activities. Particularly in the Mediterranean region, changes in hydromorphology along with increased nutrient loadings are known to affect the ecological functions and ecosystem services of streams and rivers with the anticipated climate change being likely to further impair their functionality and structure. In this study, we investigated the combined effects of agricultural driven stressors on the ecology and delivered services of the Pinios river basin in Greece under three future world scenarios developed within the EU funded MARS project. Scenarios are based on combinations of Representative Concentration Pathways and Shared Socioeconomic Pathways and refer to early century (2030) and mid-century (2060) representing future climate worlds with particular socioeconomic characteristics. To assess the responses of ecological and ecosystem service indicators to the scenarios we first simulated hydrology and water quality in Pinios with a process-based model. Simulated abiotic stressor parameters (predictors) were linked to two biotic indicators, the macroinvertebrate indicators ASPT and EPT, with empirical modelling based on boosted regression trees and general linear models. Our results showed that the techno world scenario driven by fast economic growth and intensive exploitation of energy resources had the largest impact on both the abiotic status (nutrient loads and concentrations in water) and the biotic indicators. In contrast, the predicted changes under the other two future worlds, consensus and fragmented, were more diverse and were mostly dictated by the projected climate. This work showed that the future scenarios, especially the mid-century ones, had significant impact on both abiotic status and biotic responses underpinning the need for implementing catchment management practices able to mitigate the ecological threat on waters in the long-term.
... The vulnerability of rivers is reinforced by the strong link that these systems maintain with their drainage basin. Agricultural activities have serious ecological repercussions for rivers and profoundly alter their ecological health (Stefanidis et al. 2016;Taylor et al. 2016). ...
... The presence of Oligochaeta indicates that the sediments are rich in organic matter and filamentous bacteria (Odountan and Abou 2015). Agricultural activities may further affect the structure and ecological functioning of aquatic ecosystems (Stefanidis et al. 2016). Increased sedimentation due to cultivation practices and the drainage of pesticides into a river system also affect benthic communities (Steinman and Rosen 2000;Hepp et al. 2010 index and the Evenness index. ...
Article
Full-text available
The Alibori River, which flows through Benin’s cotton crop regions, receives surface water from much of the cultivated land that is situated along its banks. Chemical pollution in surface runoff from this land use threatens the ecological quality of the river. This study aimed to characterise the ecological status of the Alibori River under such agricultural pressures using biological indices and macroinvertebrate metrics. Water and macroinvertebrate samples were taken monthly from fifteen sites along the river between June 2015 and May 2016. The measured physico-chemical parameters and biological indices were subjected to descriptive statistics, bivariate correlations and partial least squares regression (PLSR). Taxonomic richness decreased from the upstream to the downstream reaches of the river. Sampling sites with high mineral content and organic load were home to more pollutiontolerant taxa, such as Chironomidae and Oligochaeta, with a high abundance of Thiaridae. Diversity indices reveal an unbalanced community and macroinvertebrate distribution characterised by the development of opportunistic taxa such as the gastropod Melanoides tuberculata. Decreases in taxonomic composition and community organisation between the upstream and downstream reaches of the river appear to be linked to less stable environmental conditions at the downstream sampling sites, and were compounded with a gradual increase in stress for organisms from the upper to lower reaches of the river. The composition, distribution and diversity characteristics of taxa collected is an indication that the ecological status of the Alibori River is under pressure, as a result of the agricultural activities along its banks.
... This contrasting pattern with lower loads of nitrogen and higher loads of phosphorus in the dry than the wet period is noted by several other studies. There is a general consensus that higher loads of nitrogen during the wet season usually reflects the effect of autumn and winter runoff of nitrate from agricultural land [41][42][43]. Concerning phosphorus, higher concentrations during the summer than the winter is often attributed to a dilution effect of the overall catchment phosphorus load [41]. Thus phosphate load is affected more by in stream processes and base flow and less by surface runoff explaining the observed pattern [36]. ...
... Simple linear regression analysis combined with mapping of nutrient loads and land uses in catchments showed that inorganic nitrogen loads are largely driven by the presence of agriculture (Figure 8). These results corroborate the findings of other studies from around the world [22,43,46,47] highlighting once again the role of agriculture as main source of diffuse pollution. However, local specific factors such as urban land uses in some catchments may also shape the spatial and temporal variability of phosphorus loads. ...
Article
Full-text available
Reduction of nutrient loadings is often prioritized among other management measures for improving the water quality of freshwaters within the catchment. However, urban point sources and agriculture still thrive as the main drivers of nitrogen and phosphorus pollution in European rivers. With this article we present a nationwide assessment of nitrogen and phosphorus loads that 18 large rivers in Greece receive with the purpose to assess variability among seasons, catchments, and river types and distinguish relationships between loads and land uses of the catchment. We employed an extensive dataset of 636 field measurements of nutrient concentrations and river discharges to calculate nitrogen and phosphorus loads. Descriptive statistics and a cluster analysis were conducted to identify commonalties and differences among catchments and seasons. In addition a network analysis was conducted and its modularity feature was used to detect commonalities among rivers and sampling sites with regard to their nutrient loads. A correlation analysis was used to identify major possible connections between types of land uses and nutrient loads. The results indicated that the rivers Alfeios, Strymonas, and Aliakmonas receive the highest inorganic nitrogen loads while the highest inorganic phosphorus loads were calculated for the rivers Strymonas, Aliakmonas, and Axios. Concerning the temporal variation of loads, inorganic nitrogen presented a peak on March and gradually declined until October when the dry period typically ends for most regions of Greece. Inorganic phosphorus loads had the highest average value in August and the lowest in October. Thus, our findings confirmed the presence of a typical seasonal variation in nitrogen loads that follows the seasonality in hydrology where high surface runoff during the wet months contribute to higher river discharges and higher nitrogen loads from the catchment. On the contrary, high phosphorus loads persisted during dry months that could be attributed to a dilution effect. Furthermore, the results imply a clear connection between agriculture and both nitrogen and phosphorus. Overall, this work presents extensive information on the nitrogen and phosphorus loads that major rivers in Greece receive that can largely aid water managers to adapt and revise basin management plans in accordance with agricultural management (e.g., which months farmers should reduce the use of fertilizers) with the purpose of meeting the environmental targets defined by the Water Framework Directive (WFD).
... According to Li et al. (2016), any alteration in the community structure and diversity corresponds to the change in the environmental conditions. There are various biotic and diversity indices used for water quality assessment (Alvial et al. 2012;Luo et al. 2018;Jacobsen and Marín, 2008;Bieger et al. 2010;Stefanidis et al. 2016). Diversity indices viz. ...
... TKN showed a strong association with Simpson's diversity index, whereas Clshowed a strong negative association with BMWP (R 2 = 0.63) and ASPT (R 2 = 0.72). The relationship between TKN and Simpson's diversity index indicated the indirect effect of eutrophication and the presence of nitrogen species on the macroinvertebrate community structure (Stefanidis et al. 2016). ...
... Based on Reference [18], till the early 2000s, approximately 35% of the total Greek runoff that enters the sea from river basins had unknown hydrological and hydrochemical regimes. Unfortunately, due to a lack of data, especially for small and medium catchments, the majority of the studies that deals with the water quality and the hydromorphological variability are only focused at catchment scale [15,[19][20][21][22][23][24][25]. Until recently, there was no large-scale water quality and hydromorphological data assemblage for all river and catchment sizes, highlighting a knowledge gap and the importance of the Greek rivers monitoring program that is based on the WFD implementation. ...
... Agricultural, industrial and urban effluents are considered the main sources of river pollution worldwide [34,35]. Particularly for Greece, there is a significant amount of research that has underpinned the impacts of agriculture in the water chemistry of running waters [21,23], as many anthropogenic pressures are linked with the agricultural activity. Catchment model simulations have demonstrated that the use of fertilizers in heavily agricultural catchments results in increased concentrations of nitrates and phosphates under various scenarios of future climate and management [36]. ...
Article
Full-text available
European rivers are under ecological threat by a variety of stressors. Nutrient pollution, soil erosion, and alteration in hydrology are considered the most common problems that riverine ecosystems are facing today. Not surprisingly, river monitoring activities in Europe have been intensified during the last few years to fulfil the Water Framework Directive (WFD) requirements. With this article, we present a nationwide assessment of the water quality and hydromorphological variability in Greek Rivers based on the results of the national monitoring program under the WFD. Water quality and hydromorphological data from 352 sites belonging to 221 rivers were explored with principal component analysis (PCA) to identify main environmental gradients and the variables that contribute the most to the total variance. Nitrate, phosphate, ammonium and electrical conductivity were identified as the most important water chemistry parameters, and typical vector-based spatial data analysis was applied to map their spatial distribution at sub-basin scale. In addition, we conducted simple linear models between the aforementioned parameters and the share of land uses within the basin of each sampling site in order to identify significant relationships. Agriculture was the most important land use affecting the nitrate and electrical conductivity, while artificial surfaces were the best predictor for phosphate and ammonium. Concerning the hydromorphological variability, fine types of substrate and discharge were the variables with the highest contribution to the total variance. Overall, the results of this article can be used for the preliminary assessment of susceptible areas/rivers to high levels of nutrient pollution that can aid water managers to formulate recommendations for improvement of further monitoring activities. Furthermore, our findings implicate the need for enhancement of agri-environmental measures and reduction of point-source pollution in disturbed areas to avert the risk of further environmental degradation under the anticipated global change.
... For instance, climate warning and water abstraction may reduce oxygen concentration in freshwaters and have a negative effect on species richness affecting, in consequence, community structure indicator parameters (Pardo and García 2016;Haubrock et al. 2020) that may consequently deteriorate the ecological status of the water bodies in question. In contrast, improving agricultural practices-e.g. the combined practice of deficit irrigation and fertilization reduction-improved water quality and had a significantly effect on indicator parameters, positively affecting macroinvertebrate communities (Stefanidis et al. 2016), and potentially improve the ecological status. In the case of species introduction, there are some general patterns in their impact. ...
Article
Full-text available
Ecological status classification systems based on biological elements (e.g., macroinvertebrate communities) are dependent on their response to different pressures. However, there is a need to determine if invasive species should be incorporated to indicator parameters (i.e. metrics based on measurements of richness and diversity) or as a pressure affecting such parameters. Moreover, because ecosystem classification systems are lacking for northwestern Iberian estuaries, there is even the possibility to develop a new metric penalizing presence or abundance of invasive species. To increase our understanding on this topic, we analyze the taxonomic and functional responses of benthic macroinvertebrates to Corbicula invasion along the environmental gradient of 12 northwestern Iberian estuaries. Macroinvertebrate assemblages were described and compared between invaded and uninvaded sections. Additionally, to assess differences in community structure, macroinvertebrate assemblages’ similarity was examined between two distinct estuarine sections (freshwater and oligohaline vs transitional water and mesohaline) and among water body types, including and excluding Corbicula from the analysis. The salinity gradient was the main driver explaining changes in macroinvertebrate assemblages and in functional group distribution. Freshwater and transitional water sections clearly differed in macroinvertebrate assemblages and functional groups composition. In addition, differences among river types in macroinvertebrate composition were found. Corbicula inclusion or exclusion from multivariate community analysis significantly affected the results in functional feeding group composition in the Cantabric-Atlantic siliceous river axis type. Nevertheless, considering Corbicula as a pressure at the regional scale did not provide different results in diversity indices calculation. Hence, we argue that because Corbicula eradication is virtually impossible, it should be included as an additional metric evidencing its presence as a negative indication, or be included within other indicator metrics used in the assessment of the ecological status, for instance in invertebrate abundance metrics were its dominance should be indicative of invasion impairment.
... Physical alterations affecting river hydromorphology as well as diffuse-source pollution are shown to be the key challenges in WFD implementation [41]. With nutrients and hydromorphological alterations being common stressors in many rivers of Greece [42,43] that act in concert, we cannot exclude the possibility of synergistic effects that offset the implemented measures. For example, Smeti et al. [44] showed that co-occurring stressors of flow intermittency and nutrient pollution had a significant effect on biodiversity of invertebrates and diatoms and related ecosystem functions in a Greek intermittent river. ...
Article
Full-text available
Regardless of the efforts of the European Union, freshwaters are in a state of environmental crisis. The Water Framework Directive has established a basis for the protection and restoration of European inland and coastal waters. In parallel, the Birds and Habitats Directives protect, maintain or restore, at favourable conservation status, selected species and habitats under a representative network of protected areas. Hence, the interplay between the EU regulations is of high scientific interest and practical relevance. In this article, Greece is used as a case study to explore whether anticipated synergies between the Water Framework Directive and the Nature Directives result in a better ecological status in the protected areas than in the non-protected ones. We investigated whether the ecological qualities that are defined by three biological quality elements (BQEs) differ between the WFD monitoring sites that are located within the Natura 2000 protected areas and those that are not. We identified a total of 148 river monitoring sites that are located within the Natura 2000 network, which corresponds to 30% of the WFD monitoring network. By employing ordered logit models for each BQE, we found that the ecological quality has the same likelihood to fail the WFD target of “good” quality for sites that are located within and outside the Natura 2000 protected areas. Our results confirmed our hypothesis that the EU directives have little synergy when it comes to restoration of ecological status of Greek running waters, according to the WFD.
... These activities lead to nitrogen leaching and flow alteration (Soviti et al., 2003;Ju et al., 2009), suggesting why these variables played critical roles in determining macroinvertebrate community distribution in the Kat River. Additionally, agricultural intensification can alter soil condition and increase run-off, which increases the nitrogen loads in rivers (Stefanidis et al., 2016). Lassaletta et al. (2009) found that agricultural cover explained 82% of the nutrient input in the Ebro River Basin of the Mediterranean catchment. ...
Thesis
Full-text available
Agricultural land-use is a leading cause of water quality deterioration, biodiversity loss and impairment of stream functionality. Understanding the mechanisms by which agricultural land-use impair stream ecosystems is important for their effective management, especially in Africa. In this study, a combination of analytical tools, including macroinvertebrate taxonomic- and trait-based community analysis, functional indices, functional feeding groups and stable isotopes were used to investigate the effects of an increasing gradient of agricultural disturbance on the community composition, functional diversity, and food web of aquatic macroinvertebrates in the Kat River. Eight sites grouped into four site categories that represent a decreasing gradient of agricultural pollution (LUC 1< LUC 2 < LUC 3 and LUC 4) were selected. Macroinvertebrates and physiochemical variables and aquatic and terrestrial basal food sources were sampled from the eight sites over four sampling occasions; dry (winter and spring) and wet (summer and autumn) periods using the SASS 5 protocols. The taxonomy-based analysis showed different responses of macroinvertebrates to agricultural disturbance, with taxa such as Lymnaea spp., L. columella, Appasus spp. Biomphalaria spp., Trithemis spp. and Oligochaeta identified as potentially tolerant indicators of agricultural pollution. These taxa were positively correlated with the highly disturbed LUC 1 sites, and increasing levels of NH4-N, NO2-N, temperature and TDS. Conversely, Caenis spp., Afroptilum spp., Pseudocloeon piscis, Pseudocloeon spp., Baeti harrisoni, and Potamonautes spp. were sensitive to agricultural pollution, indicating strong negative associations with LUC 1 sites and NH4-N, NO2-N, salinity, temperature and TDS. Further, a multimetric index (MMI) was developed, validated and applied to assess agricultural disturbance in the Kat catchment. Of the 29 metrics that satisfactorily discriminated the LUC 4 site from the LUC 1, 2 and 3 sites, only eight metrics were non-redundant and integrated into Kat River MMI. The metrics integrated into the final MMI were Decapoda abundance, EPT/Chironomidae abundance, %EPT abundance, %Ephemeroptera abundance, %Caenidae abundance, %Hydropsychidae abundance, %Oligochaeta+chironomidae abundance and Shannon index. The developed MMI proved effective as a biomonitoring tool for assessing the ecological health of agricultural pollution in the Kat River. The trait-based analysis showed that traits such as haemoglobin, spiracle, adult aquatic life stage, active swimming and predatory lifestyle were positively correlated with LUC 1 sites, and were deemed tolerant-trait indicators of agricultural pollution. Shredding, medium body size (>10–20 mm), crawling and a preference for macrophytes were negatively correlated with LUC 1 sites, and were deemed sensitive-trait indicators of agricultural pollution in the Kat River. Functional diversity responded predictably to agricultural pollution, as functional indices such as functional richness, significantly declining along disturbance gradient during the dry and wet periods. The functional feeding group results revealed that gatherers and scrapers dominated in the Kat River, and together represented 0.27–0.43 of the invertebrate composition. Shredders were the lowest represented in the Kat River, with a relative abundance of 0.18. The FFG results showed that filter-feeders and predators increased in abundance along increasing environmental stress gradient, whereas shredders’ abundance decreased along the environmental stress gradient. Analysis of stable carbon (δ13C) and nitrogen (δ15N) isotopes were used to estimate the contributions of aquatic and terrestrial resources to consumers across the four LUC and periods. Carbon contributions, determined using mixing models (Stable Isotope Analysis in R), revealed that consumers assimilated mainly aquatic sources (filamentous algae, macrophytes and biofilms), and this assimilation increased as agricultural disturbance increased across the two seasons. Terrestrial-derived food sources did not show evident variations among the LUCs, but C4 grasses changed along an increasing gradient of agricultural pollution during the two seasons. Further, there was enriched 15N of consumers, especially scrapers, predators and filter-feeders, along the disturbance gradient, whereas that of shredders declined along an agricultural disturbance gradient. NH4-N was the variable that affected consumers δ15N values, indicating a significant positive correlation with δ15N values for the majority of the consumers, especially gatherers, shredders and scrapers. The results of the study highlight the strength of a complementary approach to biomonitoring agricultural pollution in riverine systems. For example, the taxonomic analysis indicated changes in community composition, and the trait-based approach provided insights into the key stressors associated with agricultural pollution as a cause of water quality deterioration. The study contributes significantly to our understanding of riverine ecology in South Africa and, in particular the Kat River, in the context of agricultural pollution, which remains one of the leading causes of pollution of riverine ecosystems.
... The importance of nitrogen as a variable is not surprising as the agriculture in our area uses lot of (1,200,000 t per year) mineral fertilizers (GuGić et al., 2014), which causes an amount of nitrogen leaching to the waterbodies. Intensification of agriculture can lead to soil condition alteration and increase runoff of minerals, which can increase nitrogen amounts in waters (steFaniDis et al., 2016). The study of LassaLetta et al.(2009) concluded that agricultural cover explained 82% of the variation in nitrite concentration in streams in Ebro River Basin. ...
Article
The aim of this paper is to make a comparative analysis of benthic macroinvertebrate compositions in streams and rivers in Croatia with relation to different physical-chemical factors, especially nutrients. Samples were collected according to the AQEM method. At all the sites, 20 taxa were recorded of which Turbellaria, Gastropoda, Bivalvia, Oligochaeta, Hirudinea, Crustacea, Ephemeroptera, Odonata, Plecoptera, Heteroptera, Trichoptera, Coleoptera and Diptera were included in the present study. Water temperature mostly affected the composition of benthic macroinvertebrates to which it was inversely proportional. Nutrient enrichment, i.e., higher concentrations of ammonium, nitrates, nitrites, total nitrogen, orthophosphates and total phosphorus mostly affected Ephemeroptera, Plecoptera, Trichoptera and Diptera, by decreasing their diversity.
... Mediterranean rivers have a long history of human disturbances at basin and corridor scales (Cooper et al., 2013;Klausmeyer and Shaw, 2009;Stella et al., 2013). Nutrient pollution, habitat fragmentation and alteration in hydrology are perhaps the most common issues that Mediterranean lotic systems are facing today (Filipe et al., 2013;López-Doval et al., 2013;Stefanidis et al., 2016a;Stefanidis et al., 2018;Vörösmarty et al., 2010). Specifically, changes in riverine hydromorphology along with increased nutrient loadings are known to heavily influence both the ecological integrity and the aquatic biodiversity of these systems (Bonada and Resh, 2013;Filipe et al., 2013;Gasith and Resh, 1999;Hershkovitz and Gasith, 2013;Stefanidis et al., 2016b). ...
Article
Aquatic and riparian plants play a crucial role in the functioning of riverine ecosystems. Hence, analyzing multiple facets of plant diversity could be extremely useful for assessing the ecological integrity of lotic ecosystems. The main objective of this study was to investigate the response of multiple facets of aquatic plant diversity, such as species richness, taxonomic distinctness and compositional dissimilarity, to environmental factors (i.e. nutrient pollution and hydromorphological alteration) in 72 stream reaches of mainland Greece. We employed Generalized Additive Models to identify the variables with the highest influence and examine the response of species richness and taxonomic distinctness to environmental gradients. The relationship between compositional dissimilarity and the environment was examined with Generalized Dissimilarity Modelling. Our results supported our hypothesis that human disturbances play a considerable role in shaping macrophyte assemblages. In particular, phosphates and hydromorphological modification were significant predictors of species richness, whereas taxonomic distinctness was unaffected by indicators of anthropogenic stress but it was influenced mostly by elevation, water temperature and pH. Concerning the compositional dissimilarity, geographic distance, elevation, temperature and total inorganic nitrogen were the most important environmental parameters. Our findings suggest that human stressors, such as hydromorphological modification and nutrient enrichment, affect the plant species richness at stream reach scale, but when considering community composition or taxonomic distinctness, environmental factors associated with the natural variability (e.g. elevation, temperature and geographic distance) are of higher importance. Overall, our results emphasize the advantage of examining multiple aspects of diversity when designing conservation schemes and management plans for riparian areas.
... Gabellone et al. (2005) determined that higher nutrient concentrations (phosphorus and nitrogen) occurred in the Upper Salado basin which drains an intensively cropped region, than downstream where the river goes through a lowland area where pasture is the main land use, in Buenos Aires, Argentina. Stefanidis et al. (2016) and Gerth et al. (2017) suggested that streams draining cropped basins contain higher nutrient contents, conductivity and suspended matter than streams draining least disturbed areas. Present evidence suggests that the high nutrient concentrations in cropland streams are due to increased non-point loads from the fertilizer applications to the adjacent crops. ...
Article
In recent decades agriculture has intensified in the Argentine Pampa, and pesticide application has also increased. Livestock fields, although being progressively replaced by crops, are still commonly interspersed with crop fields. The objective of the present work is to assess the effects of land use on the benthic invertebrate assemblages of streams in the main Argentine agricultural region. Two areas were sampled during the 2011/12 growing season (November–March): Arrecifes, a homogeneous intensively cultivated area, and La Plata, a heterogeneous area of mixed livestock pasture, cropland and biological reserve. Nutrient concentrations in water were significantly higher in the streams surrounded by cropland. Measured pesticides in stream sediments were those most commonly used in crop production: chlorpyrifos, cypermethrin, lambda-cyhalothrin, endosulfan and its degradation product endosulfan sulfate. Detection frequency and pesticide concentrations were generally higher in streams surrounded by cropland than in streams surrounded by pasture or reserve. Macroinvertebrate assemblages were significantly different in streams with different land uses. Palaemonidae (Decapoda) and Caenidae (Ephemeroptera) were the taxa best represented in the reserve. Hyalellidae (Amphipoda) and Hirudinea were dominant at the streams surrounded by livestock fields. Within the streams surrounded by croplands, Oligochaeta and Hirudinea were best represented in La Plata while Chironomidae, Gastropoda and Oligochaeta were dominant at Arrecifes. Present evidence suggests that agrochemical applications contribute, in combination with other environmental variables, to the observed differences in macroinvertebrate assemblages in streams of different land use.
... The Soil and Water Assessment Tool (SWAT) has been proposed as a means to help quantify ES in watersheds [11]. It is a prominent process-based model, which has been widely used for agricultural management simulation (e.g., [12,13]), while it has also been applied for simulating agricultural pressures on biological quality elements [14] and further for the evaluation of management actions towards the implementation of Water Framework Directive (WFD) [15]. Reviewing the past literature, many studies have focused on provisioning ES as the water yield, crop production, food processing [16], by regulating ES as sedimentation, water quality, nutrient loading, and groundwater flow [11,17]. ...
Article
Full-text available
Lake Karla (Thessaly, Greece) drainage and morphological alterations affected all water-related ecosystem services (ES). The lake is restored as a multipurpose reservoir, whose inflows are boosted with pumping from Pinios River. The Soil and Water Assessment Tool (SWAT) simulated the watershed’s hydrology and the reservoir’s function, under a climate change scenario to assess water related ES. Official timeseries were used for five different scenarios with simulation period until 2100. The results suggest that the reservoir’s water quality is impacted by summer irrigation and by the water volume from the Pinios during winter. As for the selected ES, in almost all scenarios, they seem negatively affected.
... Cualquier cambio en el medio provoca alteraciones en la estructura y la diversidad biológica (Bilotta & Brazier, 2008;Collins et al., 2011;Li et al., 2016) donde se recomienda de manera puntual, realizarse evaluaciones con determinados índices de calidad del agua (Stefanidis et al., 2016;Luo et al., 2018) o aplicarse algún programa del agua para el control de la contaminación. ...
Article
Full-text available
Pollution of the Lake Titicaca's interior bay is one of the environmental concerns about this ecosystem where the search for new assessments for decision-making is a scientific challenge. The purpose of the study was to evaluate the stationary quality of water according to the relative sustainable environmental cost with aggregation of biomarkers: Puno Bay, Lake Titicaca, Peru. In the area of proximity to the effluents discharge by the Espinar oxidation lagoon of (15°51.073 / 69"59.729 at a depth of 1.8 m) dissolved oxygen, pH, total dissolved solids, electrical conductivity, Cu+, Zn+, Pb+, Fe+, Cd+, Al+, Cl-, NO3 - and NO2 - was measured. Likewise, the mean lethal concentration (LC50) in the species Gambusia punctata (Poey, 1854) was also evaluated. With all the measurements, the relative sustainable environmental cost with biomarker aggregation (COASORbiom) was determined. Dissolved oxygen or dissolved total solids were the physical-chemical parameters that did not meet the maximum permissible limit together with Cu+, Zn+, Cd+ and Al+ according to Supreme Decree No. 004-2017-MINAM. It was observed, lethal toxic sensitivity at low concentrations and in a short period of time (5:00 h) in G. punctata. The COASORbiom estimated was 0.54 meaning to be classified in the relative unsustainable resource category. It was concluded that the sampling area next the Espinar oxidation lagoon in the Puno Bay showed pollution of the water column, with high probability of negative environmental effects requiring, the efficient treatment of the discharged effluents.
... SWAT is a central component of some of the most advanced integrated frameworks and modeling studies for assessing the propagation of external forcings (climate, land use) through catchment systems and their impacts on hydraulic conditions within the channel and on riverine biota (Guse et al., 2015;Jä hnig et al., 2012;Papadaki et al., 2016). Over the past few years, several authors have used SWAT to evaluate the in-stream habitat of macroinvertebrates and fish and analyze how land use and climate change can adversely affect aquatic species (Casper et al., 2011;Chambers et al., 2017;Daneshvar et al., 2016;Fan et al., 2018;O'Keeffe et al., 2018;Stefanidis et al., 2016;Whittaker, 2005). Recognizing the applied nature of ecohydrology, and especially the interactions or the 'dual regulation' of the waterbiota interplay, watershed modelling can simulate desired ecosystem properties and can be used as a tool to manage environmental problems, such as reduce nonpoint source pollution, improve water retention capacity, and close nutrient and carbon budgets under current and future conditions. ...
Article
The ecohydrological model SWAT is an open-source tool used globally and applied to diverse catchments to gain insights into hydrology-driven ecological processes. In the last decades, the SWAT model has become increasingly popular to specifically address anthropogenic challenges related to hydrology, nutrients and sediment transport, and crop growth in diverse climatic, physiographic, and socioeconomic settings. This special issue reflects the importance SWAT has for simulating processes that are relevant for ecohydrology and hydrobiology.
... These models are capable of predicting future conditions outside the range of data-driven empirical models, projecting the effects of climate, land use, or population changes to inform future-proof mitigation measures (e.g., Wright et al., 2017). The model outputs primarily encompass hydrological or water quality variables, with biological receptors often being linked through empirical modeling (e.g., Stefanidis et al., 2016;Cremona et al., 2017). ...
Chapter
Freshwater ecosystems are among the most imperiled on earth, with rivers being particularly susceptible to anthropogenic stress. Environmental monitoring across Europe reveals that 45% of rivers are affected by more than one human-driven pressure. Detecting and quantifying the impact of multiple stressors exerted from these pressures thus represent important scientific tasks in support of aquatic ecosystem management. This chapter reviews the scientific literature on experimental and field-based observational studies investigating into multistressor effects. Forty experimental and 48 field-based observational studies were covered, dealing with 72 and 151 paired stressor combinations, respectively. Morphological stress paired with either nutrient or hydrological stress was most frequently addressed in both study types. While experiments focused on a broad range of receptor organisms including phytobenthos, benthic invertebrates, fish, microorganisms (e.g., bacteria and fungi) and related processes (e.g., leaf decomposition), field studies mainly investigated the effects on benthic invertebrates and fish. Stressor interactions were more relevant in the experimental studies, with almost 50% of phytobenthos receptor metrics featuring interactions, as compared to the field studies, where stressor interactions were often not specified. Unknown stressor interactions challenge aquatic ecosystem management by posing risks of unwanted “ecological surprises.” Future scientific efforts need to concentrate on classifying the relevance and strength of interactive effects across types of stressors, receptors, and existing ecosystems, considering the specific local conditions of the water bodies to be managed. River basin management will benefit from ecosystem modeling to diagnose the causes of detrimental ecological effects, or to predict the benefits and trade-offs of management strategies in multistressor contexts.
... The importance of this variable is not surprising, as the agriculture in the area uses 550-600 kg of N fertilizer per hectare annually, leading to a significant amount of N leaching to the waterbodies in the basin (Ju et al., 2009). Actually, agricultural intensification can alter soil condition and increase runoff, which will increase the nitrogen loads in the waters (Robertson and Vitousek, 2009;Stefanidis et al., 2016). Lassaletta et al. (2009) found that agricultural cover explained 82% of the variation in nitrate concentrations of stream waters in Ebro River Basin, a large Mediterranean catchment. ...
Article
Rapid agricultural development has induced severe environmental problems to freshwater ecosystems. In this study, we aimed to examine the structure and environmental determinants of macroinvertebrate assemblages in an agriculture dominated Lake Chaohu Basin, China. A cluster analysis of the macroinvertebrate communities identified four groups of sites that were characterized by significantly different macroinvertebrate species. These four groups of sites had concentric spatial distribution patterns that followed the variation in the environmental conditions from the less anthropogenically disturbed headwaters towards the more anthropogenically disturbed lower reaches of the rivers and the Lake Chaohu. Moreover, taxa richness decreased from the headwaters towards the Lake Chaohu. The increasing practice of agriculture has reduced the abundances and richness of pollution sensitive species while opposite effects on pollution tolerant species. The study identified substrate heterogeneity and nutrient concentrations as the key environmental factors regulating the changes in the macroinvertebrate communities. We propose that particular attentions should be paid to reduce the nutrient enrichment and habitat degradation in the Lake Chaohu Basin and similar agriculture dominated basins.
... Rivers that drain agricultural catchments are characterized by high levels of conductivity, nutrients, and suspended solids (Gerth et al., 2017;Stefanidis et al., 2015). Prior research found these associations in the presently assessed exotic forest plantation catchments (Fierro et al., 2016). ...
Article
Land-use change is a principal factor affecting riparian vegetation and river biodiversity. In Chile, land-use change has drastically intensified over the last decade, with native forests converted to exotic forest plantations and agricultural land. However, the effects thereof on aquatic ecosystems are not well understood. Closing this knowledge gap first requires understanding how human perturbations affect riparian and stream biota. Identified biological indicators could then be applied to determine the health of fluvial ecosystems. Therefore, this study investigated the effects of land-use change on the health of riparian and aquatic ecosystems by assessing riparian vegetation, water quality, benthic macroinvertebrate assemblages, and functional feeding groups. Twenty-one sites in catchment areas with different land-uses (i.e. pristine forests, native forests, exotic forest plantations, and agricultural land) were selected and sampled during the 2010 to 2012 dry seasons. Riparian vegetation quality was highest in pristine forests. Per the modified Macroinvertebrate Family Biotic Index for Chilean species, the best conditions existed in native forests and the worst in agricultural catchments. Water quality and macroinvertebrate assemblages significantly varied across land-use areas, with forest plantations and agricultural land having high nutrient concentrations, conductivity, suspended solids, and apparent color. Macroinvertebrate assemblage diversity was lowest for agricultural and exotic forest plantation catchments, with notable non-insect representation. Collector-gatherers were the most abundant functional feeding group, suggesting importance independent of land-use. Land-use areas showed no significant differences in functional feeding groups. In conclusion, anthropogenic land-use changes were detectable through riparian quality, water quality, and macroinvertebrate assemblages, but not through functional feeding groups. These data, particularly the riparian vegetation and macroinvertebrate assemblage parameters, could be applied towards the conservation and management of riparian ecosystems through land-use change studies.
... Macroinvertebrate based multivariate techniques have been applied widely in developed countries since the 1980s (Diego et al., 2016). However, the number of applications has increased markedly in the last 5 years; In Amazon ( Dedieu et al., 2015), in Atlantic (Tomi et al., 2016), and Central America (Stefanidis et al., 2016). ...
Article
Diversity of macroinvertebrates as well as Physico-chemical parameters were investigated in six sampling sites of Kano River between June 2014 to May 2015. The pattern of association between measured Physico-chemical parameters were significantly correlated using Pearson Product Moment Correlation and revealed high positive correlation between Total Nitrate and Total Phosphate at site A (.811) and negative correlation between Dissolved Oxygen and pH at site E (-.261). Eigen value of the three variables namely; Temperature, pH and Electrical Conductivity was satisfactory, explaining 73.64% and 70.79% of the total variance in dry season and wet season respectively, other components explained 26.36% and 29.06% noise. Kaiser-Meyer-Olkin in dry season value showed 0.700 degree of common variance is middling bordering meritorious adequacy value while wet season showed miserable degree of common variance value of 0.500. Bartletts' Test of Sphericity showed no difference in wet and dry season with the significant value of p < 0.001. Macroinvertebrates species group frequency distribution of homogeneous set at N 2271 showed Chironomidae subset-7 with the significance of 1.00 highest in harmonic mean value and Planariidae in subset-1 has 0.59 lowest in the value. Generalized Linear Model further revealed the pattern in seasonal variation in the macroinvertebrates data set. The findings were discussed and recommendations made. Key words: Dendrites, Diversity, Eigen value, Macroinvertebrates, Multivariate, River Kano.
... In order to assess the relations between the E-flow components and ecological indicators we used a large dataset of macroinvertebrate community data provided by the Greek National Monitoring program and published sources (For more details see Stefanidis et al. 2015). We used these data in order to calculate a series of macroinvertebrate metrics such as the BMWP (Biological Monitoring Working Party), the ASPT (Average Score Per Taxon) scores, the number of Ephemeroptera, Plecoptera and Trichoptera families (EPT), the relative abundance of Gastropoda, Oligochaeta and Diptera families subtracted from 1 (1-GOLD), the Log transformed abundance of selected families of Ephemeroptera, Plecoptera, Trichoptera and Diptera (Log10(SelEPTD + 1), the total number of taxa, the Shannon diversity index and the species evenness index. ...
Article
The ecological integrity of the Hassar Stream (suburban of Casablanca city, Morocco) is monitored using aquatic indicators (macroinvertebrates). In this study, monitoring water physicochemical quality reveals a high level of organic pollution and nutrients in this stream, mainly due to allochthonous inputs from Mediouna treated wastewater and greywater and solid waste from riparian settlements. In parallel, a total of 85 macrobenthic taxa belonging to three major faunistic groups (annelids, molluscs, and arthropods) were identified in this hydrosystem. The species richness and faunistic diversity increase progressively from upstream to downstream according to the organic and nutrients loads, and the mineralisation of waters. The assessment of the biological quality of the water using index methods (Belgian Biotic Index “BBI”, Family Biotic Index “FBI”, Iberian Biological Monitoring Working Party “IBMWP” and Iberian Average Score Per Taxon “IASPT”) indicates average or acceptable quality levels. Compared to its previous bioecological condition, the improvement of the faunal diversity and the biological quality of Hassar Stream water indicates a progressive recovery of the macroinvertebrates community and its resilience despite the chronic disturbance linked to the discharge of treated water from the Mediouna wastewater treatment plant. Finally, this study shows that biotic indices can constitute a complementary approach to the taxonomic richness and faunal diversity metrics to appreciate the resilience degree of a Mediterranean disturbed stream.
Article
The Alibori River, which flows through Benin’s cotton crop regions, receives surface water from much of the cultivated land that is situated along its banks. Chemical pollution in surface runoff from this land use threatens the ecological quality of the river. This study aimed to characterise the ecological status of the Alibori River under such agricultural pressures using biological indices and macroinvertebrate metrics. Water and macroinvertebrate samples were taken monthly from fifteen sites along the river between June 2015 and May 2016. The measured physico-chemical parameters and biological indices were subjected to descriptive statistics, bivariate correlations and partial least squares regression (PLSR). Taxonomic richness decreased from the upstream to the downstream reaches of the river. Sampling sites with high mineral content and organic load were home to more pollutiontolerant taxa, such as Chironomidae and Oligochaeta, with a high abundance of Thiaridae. Diversity indices reveal an unbalanced community and macroinvertebrate distribution characterised by the development of opportunistic taxa such as the gastropod Melanoides tuberculata. Decreases in taxonomic composition and community organisation between the upstream and downstream reaches of the river appear to be linked to less stable environmental conditions at the downstream sampling sites, and were compounded with a gradual increase in stress for organisms from the upper to lower reaches of the river. The composition, distribution and diversity characteristics of taxa collected is an indication that the ecological status of the Alibori River is under pressure, as a result of the agricultural activities along its banks. Keywords: biomonitoring, disturbances, freshwater, physico-chemical parameters
Article
Heritage areas with tourist attractions that offer ecosystem services must be systematically evaluated for their preservation. The objective of the manuscript addressed to the Editor describes the latent environmental damage in the Huacachina lagoon, Ica-Peru. The contact and physical pressure of the dune on the containment barriers was observed, which could prevent the recreation of passers-by in the future. Likewise, an excessive density of the Scirpus californicus species, which is an indicator of the poor quality of the water and which is corroborated by the high turbidity.
Article
Full-text available
Recognizing and investigating the resources of surface water, especially rivers and streams, which are in fact not just strategic sources, are important for the management of well-being. For this purpose, the effect of rainbow trout breeding workshop on the fauna and the number of macro-benthos in the river Haraz were investigated . Sampling was performed seasonally in two seasons of summer and autumn of 1393 by Surber Sampler with three replications at each station. A total of 4 stations were set up before and after the fish breeding farm. In the laboratory, cluster bands were examined qualitatively and quantitatively in the genus or species. The results of the study showed the presence of 11 classes or macrobenthic sequences belonging to 19 families. Most of the genus was Diptera family with 9 genera and 13 genera were identified from other classes. Sampling showed that the highest percentage of Baetidae family was found in Ephemeroptera. The biggest impact of workshop pollution was on Ephemeropterta, Terichoptera and Plecoptera, which is known as the sensitive group of EPT and has reduced its population at station 3 (outlet). On the contrary, the population of the Chironomidae, which is resistant to pollution, has increased.
Article
Full-text available
In order to improve the maize yield in different management zones and achieve precision agricultural management within a large-scale field, correlated component regression (CCR) was used to screen limiting factors of maize yield from topographical attributes (elevation), soil physical factors (sand, silt, clay, bulk density), and initial soil properties (soil organic carbon, total nitrogen, total phosphorus, soil water content, available nitrogen, electrical conductivity). Yield estimation model was established based on yield-limiting factors in each management zone and the whole field. Management zones were delineated by using the fuzzy c-means clustering algorithm (FCM) based on the spatial variation of soil properties. For soil properties, statistically significant differences in most cases were found among different management zones (M1, M2, M3), excepted elevation, silt, and clay. The decrease in the coefficient of variation (CV) of soil properties in the management zones indicated that the distribution of soil properties was more homogeneous than in the whole field. Spatial distribution of yield and management zones were similar, while yield was significantly different in three management zones (M1>M2>M3). The inhomogeneous spatial distribution of soil properties showed that the limiting factors of yield could be varied among management zones. Therefore, the main purpose of this study was to find out the yield-limiting factors, establish yield estimation models based on yield-limiting factors, and find ways to improve the yield in each management zone within a field. Four correlated components (CC1~CC4) were obtained in management zones and the whole field by CCR. The factors which had largely standardized loadings (absolute value of standard loadings was greater than 0.2) on major correlated components (values of standardized weights were greater than 0.7) were identified as the main limiting factors of maize yield in zones. Yield in three management zones was measured and the limiting factors of yield in different zones were evaluated. The results showed that limiting factors for yield were silt, sand, soil organic carbon (SOC), soil moisture content (SWC), available nitrogen (AN), and total nitrogen (TN) in the whole field, which was different from management zones. The limiting factors of M1 were silt, sand, clay, AN, electrical conductivity (EC), TN, and total phosphorus (TP). Limiting factors of M2 were silt, sand, SWC, while the limiting factors were elevation, sand, clay, and EC for M3. Different yield estimation models were established by using CCR in management zones and the whole field. For model estimation, the correlation between simulated and measured yield was high, with R2=0.75 and nRMSE=0.20 in the whole field; in management zones, higher simulation accuracy was found: R2 of yield estimation model was 0.91, 0.84, and 0.76, while nRMSE were 0.15, 0.14, and 0.16 in Z1, Z2, and Z3, respectively. For model validation, R2 of yield estimation model was 0.70, 0.83, 0.78, and 0.71, while nRMSE were 0.21, 0.16, 0.18, and 0.17 in the whole field, Z1, Z2, and Z3, respectively. According to the results, different ways of improving yield were found. For the whole field, soil amelioration and fertilizer application before sowing were the keys to increase yield. The application of organic fertilizer and phosphorus fertilizer, reduction of soil EC, and the improvement of soil water holding capacity, were conducive to the improvement of yield in M1. Because soil texture and SWC were the main factors limiting the yield, improving soil water holding characteristics was also the way to increase yield in M2. For M3, irrigation before sowing could decrease EC of surface soil and improve soil water storage, which was beneficial to the emergence and growth of maize. Organic fertilizer application should also be considered for yield improvement in M3. Distributed management should be adopted based on the limiting factors of maize yield in management zones, while could be more targeted to improve crop yield within a field.
Article
The species composition of macroinvertebrate communities is sensitive to environmental changes. However, the influence of human activity over seasons on the functional characteristics of macroinvertebrate communities is poorly understood. To elucidate the effects of agriculture-induced environmental changes on stream ecosystems in cold regions, we conducted a comparative study of an agricultural stream and a forest stream in the Changbai Mountains in northeast China in the summer, autumn, and winter of 2016. Our results showed that agriculture had significant effects on the species and functional composition. Although some sensitive species with “Swimmer” and “Shredder” traits disappeared, there was a significant increase in species with resilience and resistance traits such as “Bi- or multivoltine” in the agricultural stream. This result was attributed to the effects of agricultural practices on habitat stability, heterogeneity of habitats, water quality, and material cycling of the stream ecosystems. Furthermore, functional richness and functional divergence decreased in the agricultural stream, reflecting the strong effects of agricultural disturbance on the resource-use efficiency and functional diversification of communities. In particular, community stability also showed significant decrease in the agricultural stream in the summer, implying a stronger disturbance during this season. Generally, the functional traits and biodiversity of both streams had significant seasonal dynamics. The decrease in biodiversity in the winter indicated that low temperature and freezing are additional critical factors affecting the stability of stream ecosystems in cold regions.
Article
Full-text available
Water availability on the continents is important for human health, economic activity, ecosystem function and geophysical processes. Because the saturation vapour pressure of water in air is highly sensitive to temperature, perturbations in the global water cycle are expected to accompany climate warming. Regional patterns of warming-induced changes in surface hydroclimate are complex and less certain than those in temperature, however, with both regional increases and decreases expected in precipitation and runoff. Here we show that an ensemble of 12 climate models exhibits qualitative and statistically significant skill in simulating observed regional patterns of twentieth-century multidecadal changes in streamflow. These models project 10-40% increases in runoff in eastern equatorial Africa, the La Plata basin and high-latitude North America and Eurasia, and 10-30% decreases in runoff in southern Africa, southern Europe, the Middle East and mid-latitude western North America by the year 2050. Such changes in sustainable water availability would have considerable regional-scale consequences for economies as well as ecosystems.
Article
Full-text available
This study presents the development of a multimetric index using benthic macroinvertebrates (BMI) to assess the ecological health of highland rivers in Ethiopia. BMI were collected from 22 reference and 82 impaired sites determined based on hydro-morphological, land use, physical and chemical criteria. Of 75 potential metrics tested to integrate the multimetric index, only nine core metrics were selected based on their abilities to istinguish reference and impaired sites, strength of correlation with pertinent environmental parameters and their independence from other metrics. The metrics retained in the multimetric index were total number of taxa, EPT-BH>1sp (Ephemeroptera, Plecoptera and Trichoptera taxa where Baetidae and Hydropsychidae taxa are considered if they consist more than one taxon), % Oligochaeta and Red Chironomidae, % COPTE Coleoptera, donata, Plecoptera, Trichoptera and Ephemeroptera), % EPT-BCH (EPT without Baetidae, Caenidae and Hydropsychidae), ASPT-SASS (Average South African Scoring System Per Taxa), FBI (Family Biotic Index), % hredders and % collector gathering. The final index derived from these metrics was divided in to five river quality class (high, good, moderate, poor and bad). A validation procedure showed that the index is stable along different hydrological conditions and sensitive to the current range of anthropogenic disturbances in Ethiopian highland rivers.
Article
Full-text available
The Soil and Water Assessment Tool (SWAT) model has emerged as one of the most widely used water quality watershed- and river basin-scale models worldwide, applied extensively for a broad range of hydrologic and/or environmental problems. The international use of SWAT can be attributed to its flexibility in addressing water resource problems, extensive networking via dozens of training workshops and the several international conferences that have been held during the past decade, comprehensive online documentation and supporting software, and an open source code that can be adapted by model users for specific application needs. The catalyst for this special collection of papers was the 2011 International SWAT Conference & Workshops held in Toledo, Spain, which featured over 160 scientific presentations representing SWAT applications in 37 countries. This special collection presents 22 specific SWAT-related studies, most of which were presented at the 2011 SWAT Conference; it represents SWAT applications on five different continents, with the majority of studies being conducted in Europe and North America. The papers cover a variety of topics, including hydrologic testing at a wide range of watershed scales, transport of pollutants in northern European lowland watersheds, data input and routing method effects on sediment transport, development and testing of potential new model algorithms, and description and testing of supporting software. In this introduction to the special section, we provide a synthesis of these studies within four main categories: (i) hydrologic foundations, (ii) sediment transport and routing analyses, (iii) nutrient and pesticide transport, and (iv) scenario analyses. We conclude with a brief summary of key SWAT research and development needs. Copyright © by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America, Inc.
Article
Full-text available
Aims: The aims of this study are to evaluate the effects of spatial and temporal variability of the macroinvertebrate fauna in drift and in the substrate of a mountain stream. Methods: The study site is located in Achiras stream (Central, Argentina). This is an endorheic fluvial course whose headwaters are located in the southern extreme of Los Comechingones Mountains. Three replicate Surber samples were collected from benthos with 300 μm, 0.09 m2 nets. Three drifting fauna samples were collected using drift nets, 1 m long, 300 μm and 0.0192 m2. The taxonomic identification of specimens was performed according to the lowest possible taxonomic level. In order to characterize the drifting and benthic fauna, total abundance, taxonomic richness, Shannon and evenness indices were estimated and they were tested with two-way analysis of variance (ANOVA). In order to assess the distribution patterns of drift and benthos samples, we performed Canonical Correspondence Analysis (CCA). Results: A total of 61 taxa were identified in drift and 82 in benthos. A 26.3% taxonomic similarity between the two assemblages was observed, according to the Jaccard index. In drift and benthos, Arthropoda presented higher abundance and Insecta contributed with more taxa and it was also the most abundant. The most abundant orders were Ephemeroptera, Trichoptera and Diptera. In the present study, Anacroneuria sp. (Perlidae) and Podonominae (Chironomidae) were first recorded for benthic community of Achiras stream. Conclusion: In this study we found that the structural organization of the drifting and benthic macroinvertebrate community shows different patterns of variation at spatial and temporal scales.
Article
Full-text available
Human activities within fluvial corridors and surrounding landscapes have persistently stressed riparian ecosystems, particularly in Iberian Mediter-ranean-type streams. The impact of human disturbance relative to natural environmental factors in shaping riparian vegetation is still poorly understood. Both regional variables (such as altitude and precipitation), and site-specific characteristics (such as substrate and riverbank modifications) were analysed as potential determinants of riparian vegetation patterning to determine the relative influences of the diverse land-use types and environmental factors on the composition (including floristic species richness and percentage cover of trees, shrubs and woody climbers) and integrity (width of riparian woods and patterns of longitudinal continuity) of riparian woods in eight river basins of the Tagus fluvial system (Portugal). There was patchy establishment of riparian woods, with generally low average width and low species richness, as well as significant inter-basin differences and upstream-downstream variations in riparian features. Species distribution was clearly determined by environmental factors, such as human disturbance on the riverbanks and geological background , and the environmental variables and the land use in the river valley partially explained the integrity of riparian woody vegetation. The results highlight the predictive capability of reach-level features; it appears that, linked with the geomorphological and climate context, small-scale human disturbances on riparian corridors play a major role in explaining the remaining biological variability.
Article
Full-text available
The effort to manage irrigation water use through the adoption and implementation of agricultural best management practices (BMPs) is crucial for meeting water bodies' sustainability in water-deficient agricultural areas. This paper presents the development of an efficient decision support tool able to suggest the optimal location for placing high-and low-tech irrigation BMPs, such as deficit irrigation, conveyance efficiency improvement, precision irrigation, and wastewater reuse, and demonstrates its application in the water-scarce Pinios river basin in central Greece. The tool uses the SWAT (soil and water assessment tool) model as the BMP and hydrologic simulator and a multiobjective genetic algorithm, which, based on calculated cost data, optimizes the cost-effectiveness of management schemes across the landscape. From the analysis of the results produced and the optimal river basin BMP configurations under the current and a volumetric water pricing scenario and under a +/- 25% variation of the cost parameters, the study concludes that a number of different BMPs at an affordable implementation cost, along with a tiered water pricing system that could address socioeconomic heterogeneities, would form a sustainable action plan against desertification in the highly water-deficient Pinios basin. The methodology and tool are considered to be easily applicable in other river basins and could be used to assist in more cost-effective implementation of environmental legislation. (C) 2014 American Society of Civil Engineers.
Article
Full-text available
Running water ecosystems of Europe are affected by various human pressures. However, little is known about the prevalence, spatial patterns, interactions with natural environment and co-occurrence of pressures. This study represents the first high-resolution data analysis of human pressures at the European scale, where important pressure criteria for 9330 sampling sites in 14 European countries were analysed. We identified 15 criteria describing major anthropogenic degradation and combined these into a global pressure index by taking additive effects of multiple pressures into account. Rivers are affected by alterations of water quality (59%), hydrology (41%) and morphology (38%). Connectivity is disrupted at the catchment level in 85% and 35% at the river segment level. Approximately 31% of all sites are affected by one, 29% by two, 28% by three and 12% by four pressure groups; only 21% are unaffected. In total, 47% of the sites are multi-impacted. Approximately 90% of lowland rivers are impacted by a combination of all four pressure groups.
Article
Full-text available
In an ongoing effort to propose biologically protective nutrient criteria, we examined how total nitrogen (TN) and its forms were associated with macroinvertebrate communities in wadeable streams of Maryland. Taxonomic and functional metrics of an index of biological integrity (IBI) were significantly associated with multiple nutrient measures; however, the highest correlations with nutrients were for ammonia-N and nitrite-N and among macroinvertebrate measures were for Beck's Biotic Index and its metrics. Since IBI metrics showed comparatively less association, we evaluated how macroinvertebrate taxa related to proposed nutrient criteria previously derived for those same streams instead of developing nutrient-biology thresholds. We identified one tolerant and three intolerant taxa whose occurrence appeared related to a TN benchmark. Individually, these taxa poorly indicated whether streams exceeded the benchmark, but combining taxa notably improved classification rates. We then extracted major physiochemical gradients using principal components analysis to develop models that assessed their influence on nutrient indicator taxa. The response of intolerant taxa was predominantly influenced by a nutrient-forest cover gradient. In contrast, habitat quality had a greater effect on tolerant taxa. When taxa were aggregated into a nutrient sensitive index, the response was primarily influenced by the nutrient-forest gradient. Multiple lines of evidence highlight the effects of excessive nutrients in streams on macroinvertebrate communities and taxa in Maryland, whose loss may not be reflected in metrics that form the basis of biological criteria. Refinement of indicator taxa and a nutrient-sensitive index is warranted before thresholds in aquatic life to water quality are quantified.
Article
Full-text available
Reduction of flow constitutes one of the most severe human alterations to rivers, as it affects the key abiotic feature of these ecosystems. While there has been considerable progress in understanding the effects of reduced flow on benthic macroinvertebrates, cascading effects of flow reduction on dissolved oxygen concentrations (DO) have not yet received much attention. We compared the macroinvertebrate composition between reference conditions and a situation after several years of discharge reduction in the Spree River (Brandenburg, Germany). Community composition shifted from rheophilic species to species indifferent to flow conditions. Filter feeders were partially replaced by collector/gatherers, which likely reduces the retention of organic matter, and thus the self-purification capacity of the river section. These shifts were associated with low discharge during summer, cascading into daily DO concentration minima of less than 5 mg l−1 which prevailed 74% of the days in summer. This depletion of DO after flow reduction presumably caused the observed species turnover. Hence, flow reduction in lowland rivers may not only directly impair the ecological functions provided by benthic macroinvertebrates but may also act indirectly by depleting DO concentrations.
Article
Full-text available
The majority of studies comparing the response of biotic metrics to environmental stress in rivers are based on relatively small, homogeneous datasets resulting from research projects. Here, we used a large dataset from Austrian and German national river monitoring programmes (2,302 sites) to analyse the response of fish, diatom and macroinvertebrate metrics to four stressors acting at different scales (hydromorphology, physico-chemistry, riparian and catchment land use). Nutrient enrichment and catchment land use were the main discriminating stressors for all organism groups, over-ruling the effects of hydromorphological stress on the site scale. The response of fish metrics to stress was generally low, while macroinvertebrate metrics performed best. The Trophic Diatom Index (TDI) responded most strongly to all stressors in the mountain streams, while different metrics were responsive in the lowlands. Our results suggest that many rivers are still considerably affected by nutrient enrichment (eutrophication), which might directly point at implications of catchment land use. We conclude that monitoring datasets are well-suited to detect major broad-scale trends of degradation and their impact on riverine assemblages, while the more subtle effects of local-scale stressors require stream type-specific approaches.
Article
Full-text available
Streams and rivers in mediterranean-climate regions (med-rivers) are subjected to sequential, yet contrasting hydrologic disturbances of drying and flooding. Although seasonally predictable, these disturbances can vary in intensity and duration within and among mediterranean-climate regions (med-regions). Consequently, med-rivers differ in the permanence of their aquatic habitats. To persist, species have acquired matched resistance and resilience adaptations. They gain resistance either by enduring the stress or avoiding it. Community recovery (or resilience) is achieved with cessation of hydrologic stress that permits maximization of re-colonization and reproduction. Endurance strategies are usually disturbance-specific, but avoidance enables organisms to cope with both drying and flooding, and is the prevalent resistance strategy. Correspondingly, community persistence depends to a large extent on the integrity of refuges, an aspect that has so far been little explored. Existing information suggests that seasonal community succession becomes more pronounced with increasing aridity and declining water permanence. The invertebrate community in semi-arid med-rivers can therefore undergo succession through three to four identifiable assemblages, whereas in perennial streams the difference between wet and dry period assemblages is smaller. Community turnover is influenced by the intensity of the hydrologic disturbances and varies between wet and drought years.
Article
Full-text available
Reducing nitrate pollution from diffuse agricultural sources is the major environmental challenge in the two adjacent catchments of the Oja–Tirón and Zamaca rivers (La Rioja and Castilla y León, northern Spain). For this reason, part of their territory was designated a Nitrate Vulnerable Zone (NVZ) according to the Nitrates Directive. The Oja Alluvial Aquifer, the Tirón Alluvial Aquifer and their associated rivers are particularly vulnerable to nitrogen pollution due to the shallow water table, the high permeability of alluvial deposits, interconnections between the alluvial aquifers and surface waters and pressures from agriculture. To this end, nine sampling campaigns, organised on a semi-annual basis and focused on the rivers and alluvial aquifers of the two catchments, were carried out from April 2005 to April 2009. The main objectives of the study were: (1) to investigate the chemical forms of nitrogen in river-alluvial aquifer systems of the Oja–Tirón and Zamaca catchments, (2) to improve our understanding of the spatio-temporal patterns of nitrogen distribution in the alluvial aquifers and associated rivers by integrating hydrochemical data and hydrogeological and environmental parameters, (3) to estimate the amount of nitrogen exported from the rivers and alluvial aquifers to the River Ebro, and (4) to evaluate the suitability of the current method of designating NVZs in the area.
Article
Full-text available
Land use change and other human disturbances have significant impacts on physicochemical and biological conditions of stream systems. Meanwhile, linking these disturbances with hydrology and water quality conditions is challenged due to the lack of high-resolution datasets and the selection of modeling techniques that can adequately deal with the complex and nonlinear relationships of natural systems. This study addresses the above concerns by employing a watershed model to obtain stream flow and water quality data and fill a critical gap in data collection. The data were then used to estimate fish index of biological integrity (IBI) within the Saginaw Bay basin in Michigan. Three methods were used in connecting hydrology and water quality variables to fish measures including stepwise linear regression, partial least squares regression, and fuzzy logic. The IBI predictive model developed using fuzzy logic showed the best performance with the R 2 = 0.48. The variables that identified as most correlated to IBI were average annual flow, average annual organic phosphorus, average seasonal nitrite, average seasonal nitrate, and stream gradient. Next, the predictions were extended to pre-settlement (mid-1800s) land use and climate conditions. Results showed overall significantly higher IBI scores under the pre-settlement land use scenario for the entire watershed. However, at the fish sampling locations, there was no significant difference in IBI. Results also showed that including historical climate data have strong influences on stream flow and water quality measures that interactively affect stream health; therefore, should be considered in developing baseline ecological conditions.
Article
Full-text available
1. The fundamental importance of freshwater resources, the rapid extinction rate among freshwater species and the pronounced sensitivity of freshwater ecosystems to climate change together signal a pre-eminent need for renewed scientific focus and greater resources. Against this background, the Freshwater Biological Association in 2008 launched a new series of ‘summit’ Conferences in Aquatic Biology intended to develop and showcase the application of ecological science to major issues in freshwater management. 2. This collection of studies arose from the first summit entitled ‘Multiple Stressors in Freshwater Ecosystems’. Although freshwater science and management are replete with mutiple-stressor problems, few studies have been designed explicitly to untangle their effects. 3. The individual case studies that follow reveal the wide array of freshwaters affected by multiple stressors, the spatial and temporal scales involved, the species and ecosystem processes affected, the complex interactions between ecology and socioeconomics that engender such effects, the approaches advocated to address the problems and the challenges of restoring affected systems. The studies also illustrate the extent to which new challenges are emerging (e.g. through climate change), but also they develop a vision of how freshwaters might be managed sustainably to offset multiple stressors in future. 4. More generically, these case studies illustrate (i) how freshwaters might be at particular risk of multiple-stressor effects because of conflicts in water use, and because the hydrological cycle vectors stressor effects so effectively and so extensively; (ii) that dramatic, nonlinear, ‘ecological surprises’ sometimes emerge as multiple-stressor effects develop and (iii) that good ecology and good ecologists add considerable value to other freshwater disciplines in understanding multiple stressors and managing their effects.
Article
Full-text available
1. Methods are needed to relate changing river flows to ecological response, particularly those which do not require collection of extensive new data for river segments that lack historical data. Using time-series of river biomonitoring data from wadeable lowland streams in Denmark and the East Midlands of the U.K., we describe how local-scale habitat features (indexed through River Habitat Survey or Danish Habitat Quality Survey) and changing river flow (discharge) influence the response of a macroinvertebrate community index. The approach has broad applicability in developing regional flow-ecological response models.
Article
Full-text available
Spatial and temporal patterns of transported organic matter (seston) and macroinverte-brates (drift) and benthic macroinvertebrate densities were examined before, during, and shortly after each of a series of scheduled, experimental floods in a flow-regulated river in the Swiss National Park. Temporal patterns in the lateral transfer of seston, drift, and benthic macroinvertebrates were evaluated in the flooded riparian area during 3 to 4 separate floods of different magnitude. No clear spatial pattern was found in the lateral transfer of seston, drift, or benthic macroinvertebrates, but the concentrations of seston and the densities of macroinvertebrates in the drift usually were lower in samples collected farthest from the main channel. Seston and drift increased significantly (from 1 g to 4–20 g ash-free dry mass/m 3 and 10 to 250–1300 ind./m 3 , respectively) in the initial stages of each flood, but decreased to baseflow levels after 2 to 3 h. Macroinvertebrates responded passively to the floods, and their densities followed the hysteresis pattern of sediment and organic particles entrained during the course of each flood. The total number of macroinvertebrates drifting during each flood ranged from 33 10 6 to 300 10 6 individuals. The average density of macroinvertebrates stranded in the riparian area after each flood ranged from 6000 to 22,000 ind./m 2 . Benthic mac-roinvertebrates were collected from pool, run, bedrock, and riffle habitats in the main channel the day before and the morning after 5 floods to test whether specific habitats provided flow refugia for macroinvertebrates. Floods reduced macroinvertebrate densities by 14% to 92%, averaged across hab-itat types, and the % reduction was related to flood magnitude. Fewer organisms were lost from bedrock habitats (43%) than from the other habitat types, and the most macroinvertebrates typically were lost from pools (90%). Macroinvertebrate responses (e.g., recovery patterns) changed signifi-cantly between early floods and sequentially later floods, reflecting temporal changes in assemblage composition and abundance. Flooding plays an important role in regulat-ing the distribution, abundance, and coexistence of benthic macroinvertebrates in many lotic sys-tems (Resh et al. 1988, Poff and Ward 1998, Lake 2000). Significant decreases in macroinverte-brate densities have been recorded after bed-scouring floods (Giller et al. 1991, Lytle 2000, Maier 2001, Robinson et al. 2003a, b), but mac-roinvertebrate communities are generally highly resilient (Townsend et al. 1987, Boulton et al. 1992) and usually recover to preflood densities within a few weeks or months (Badri et al. 1987, Mackay 1992, Matthaei et al. 1997, Robinson et al. 2003a, b). These recovery periods are shorter than the generation times of most species, and this pattern suggests that organisms use mor-phological, behavioral, and physiological traits (Statzner and Holm 1982, 1989, Waringer 1989), as well as spatial flow refugia (Palmer et al.
Article
Full-text available
Freshwater conservation efforts require an understanding of how natural and anthropogenic factors shape the present-day biogeography of native and non-native species. This knowledge need is especially acute for imperiled native fishes in the highly modified Lower Colorado River Basin (LCRB), USA. In the present study we employed both a taxonomic and functional approach to explore how natural and human-related environmental drivers shape landscape-scale patterns of fish community composition in the LCRB. Our results showed that hydrologic alteration, watershed land use, and regional climate explained 30.3% and 44.7% of the total variation in fish community taxonomic and functional composition, respectively. Watersheds with greater dam densities and upstream storage capacity supported higher non-native functional diversity, suggesting that dams have provided additional "niche opportunities'' for non-native equilibrium life-history strategists by introducing new reservoir habitat and modifying downstream flow and thermal regimes. By contrast, watersheds characterized by greater upstream land protection, lower dam densities, and higher variation in spring and summer precipitation supported fish communities with a strong complement of native species (opportunistic-periodic strategists). In conclusion, our study highlights the utility of a life-history approach to better understand the patterns and processes by which fish communities vary along environmental gradients.
Article
Full-text available
1. Floods and low flows are hydrological events that influence river ecosystems, but few studies have compared their relative importance in structuring invertebrate communities. Invertebrates were sampled in riffles and runs at eight sites along 40 km of a New Zealand gravel-bed river every 1–3 months over 2.5 years, during which time a number of large flood and low flow events occurred. Flows were high in winter and spring, and low in summer and autumn. Four flow-related variables were calculated from hydrological data: flow on the day of sampling (Qsample), maximum and minimum flow between successive samples (Qmax and Qmin, respectively), and the number of days since the last bed-moving flood (Ndays).
Article
Full-text available
With the EC Water Framework Directive (WFD) the ecological status of a water body is defined by comparing the observed biological community composition present with near-natural reference conditions. The ecological status is then classified into five quality classes (high, good, moderate, poor and bad). It is of great importance that `good ecological status' has the same meaning within the European Union, since water bodies not measuring up to these standards have to be improved. Therefore, the Ecological Quality Ratios (EQR) at high-good, and good-moderate quality class boundaries will be intercalibrated. Each country has to report physical, chemical, and biological data from two sites at each of these boundaries and since most data exist for benthic macroinvertebrates, this quality element will be of great importance in the intercalibration process. The aim of this study was therefore to compare the results of different benthic macroinvertebrate metrics used to assess the impact of organic pollution (including eutrophication) (one of the major human impacts on European streams). A selection of the data sampled in the AQEM project was evaluated, where benthic macroinvertebrate- and abiotic data from four countries (Austria, the Czech Republic, Portugal and Sweden) and seven `stream types' were included. An organic pollution (including eutrophication) gradient was defined using Principal Component Analysis and the boundaries for high-good and good-moderate ecological status set by the partners from each country were used to define arbitrary class boundaries. The Average Score Per Taxon (ASPT) was well correlated with the stress gradient in most stream types, whereas the Saprobic Index worked clearly better than ASPT in those countries (Austria and the Czech Republic) where macroinvertebrates are generally identified to lower (species) as opposed to a higher (genus or family) level of identification. Defining harmonised class boundaries is difficult; this process has to consider the natural differences between stream types (e.g. in the reference values of metrics) but has to eliminate different perceptions of ecological quality.
Article
Full-text available
The effect of environmental conditions on river macrobenthic communities was studied using a dataset consisting of 343 sediment samples from unnavigable watercourses in Flanders, Belgium. Artificial neural network models were used to analyse the relation among river characteristics and macrobenthic communities. The dataset included presence or absence of macroinvertebrate taxa and 12 physicochemical and hydromorphological variables for each sampling site. The abiotic variables served as input for the artificial neural networks to predict the macrobenthic community. The effects of the input variables on model performance were assessed in order to identify the most diagnostic river characteristics for macrobenthic community composition. This was done by consecutively eliminating the least important variables and, when beneficial for model performance, adding previously removed ones again. This stepwise input variable selection procedure was tested not only on a model predicting the entire macrobenthic community, but also on three models, each predicting an individual taxon. Additionally, during each step of the stepwise leave-one-out procedure, a sensitivity analysis was performed to determine the response of the predicted macroinvertebrate taxa to the input variables applied. This research illustrated that a combination of input variable selection with sensitivity analyses can contribute to the development of reliable and ecologically relevant ANN models. The river characteristics predicting presence or absence of the benthic macroinvertebrates best were the Julian day, conductivity, and dissolved oxygen content. These conditions reflect the importance of discharges of untreated wastewater that occurred during the period of investigation in nearly all Flemish rivers.
Article
Full-text available
Hydromorphological features are crucial in structuring habitats for freshwater organisms. The quantification of these variables is often performed through accurate measuring or detailed estimation, but their assessment is not always feasible for river management purposes. Economic and time constraints often lead to difficulty in creating simple summaries of collected data for practical use. The Lentic–lotic River Descriptor (LRD) was developed to identify the character of a river site in terms of local hydraulic conditions. Information about the presence of flow types, channel substrates, in-stream vegetation, organic debris and artificial features is included in its calculation. The main aim of this paper is to investigate whether the lentic–lotic character of a river site, as summarized with the LRD descriptor, is relevant to aquatic invertebrate communities in nearly natural river sites. Invertebrate data were collected with multi-habitat, proportional sampling and hydromorphological information was gained by applying the CARAVAGGIO method (river habitat survey technique) in the field. The dataset was generated from High or Good ecological status river sites located in Mediterranean areas of Italy. Correspondence Analysis was performed to relate the invertebrate community structure to a set of catchment-scale, reach-scale and chemical environmental variables. The results of the multivariate analysis indicate that LRD provides a persuasive explanation of the most important axis of variation in benthic data. This paper also presents the optimal LRD range for a set of invertebrate taxa, accompanied by a short discussion of their potential use in conservation issues.
Article
Full-text available
In order to find the segments of Pinios River which lack the retention capacity of the BOD and nutrient input, the difference of the estimated input and output pollution loads was compared at upstream and downstream clustered areas of a total of 73 segments. Catchment areas ranged from 1 to 11,300 km2. Emissions were always higher than the actual transport, therefore retention was assumed to take place. Specific runoff, percentage of the surface water area and the calculated input of pollution loads (BOD, P, N) varied between the different Pinios River basin catchment areas. The transport to the emission load ratio was different between large and small catchments. The rate of retention among consecutive segments revealed that four lowland segments lacked in their relative retention capacity.
Article
Protecting the worlds freshwater resources requires diagnosing threats over a broad range of scales, from global to local. Here we present the first worldwide synthesis to jointly consider human and biodiversity perspectives on water security using a spatial framework that quantifies multiple stressors and accounts for downstream impacts. We find that nearly 80% of the worlds population is exposed to high levels of threat to water security. Massive investment in water technology enables rich nations to offset high stressor levels without remedying their underlying causes, whereas less wealthy nations remain vulnerable. A similar lack of precautionary investment jeopardizes biodiversity, with habitats associated with 65% of continental discharge classified as moderately to highly threatened. The cumulative threat framework offers a tool for prioritizing policy and management responses to this crisis, and underscores the necessity of limiting threats at their source instead of through costly remediation of symptoms in order to assure global water security for both humans and freshwater biodiversity.
Chapter
We introduce a new regression method—called Correlated Component Regression (ccr)—which provides reliable predictions even with near multicollinear data. Near multicollinearity occurs when a large number of correlated predictors and relatively small sample size exists as well as situations involving a relatively small number of correlated predictors. Different variants of ccr are tailored to different types of regression (e.g. linear, logistic, Cox regression). We also present a step-down variable selection algorithm for eliminating irrelevant predictors. Unlike pls-r and penalized regression approaches, ccr is scale invariant. ccr is illustrated in several examples involving real data and its performance is compared with other approaches using simulated data.
Article
Species distribution models are increasingly applied to freshwater ecosystems. Most applications use large scales, coarse resolutions and anthropocentric modelling extents, thus not being able to consider important environmental predictors and ecological processes detectable within a catchment and at finer scales. Moreover, high resolution predictions of species distribution in streams can help improve our understanding of how environmental variables within a catchment affect the distribution of stream macroinvertebrates. We built models at a resolution of 25 m × 25 m for a 488 km2 catchment in northern Germany to determine whether the spatial approach in which environmental predictors are implemented in the model affects the overall performance. We used predictors from four different categories relevant to freshwater ecosystems: bioclimatic, topographic, hydrologic and land use. Two spatial approaches were tested: a local one, or grid based and a cumulative for the upstream area, or subcatchment specific. Models were evaluated in terms of model performance and accuracy in order to identify the approach best suited for each category, as well as the most important predictor in each. In the case of the land use category, the subcatchment approach made a significant difference, increasing performance. A final model, calibrated with the selected predictors, resulted in the highest model performance and accuracy. Our results indicate that species distribution models perform well and are accurate at high resolutions, within small catchments. We conclude that catchment wide models, especially when using predictors from multiple categories, have the potential to significantly improve modelling framework of species distribution in freshwater ecosystems. The information produced by accurate, small scale, species distribution models can guide managers and conservation practitioners, by predicting the effects of management decisions within a catchment. We suggest that highly resolved predictors be applied in models using the catchment approach.
Article
Highly complex interactions between the hydrosphere and biosphere, as well as multifactorial relationships, characterize the interconnecting role of streams and rivers between different elements of a landscape. Applying species distribution models (SDMs) in these ecosystems requires special attention because rivers are linear systems and their abiotic and biotic conditions are structured in a linear fashion with significant influences from upstream/downstream or lateral influences from adjacent areas. Our aim was to develop a modelling framework for benthic invertebrates in riverine ecosystems and to test our approach in a data-rich study catchment.
Article
Streams and rivers in mediterranean-climate regions (med-rivers in med-regions) are ecologically unique, with flow regimes reflecting precipitation patterns. Although timing of drying and flooding is predictable, seasonal and annual intensity of these events is not. Sequential flooding and drying, coupled with anthropogenic influences make these med-rivers among the most stressed riverine habitat worldwide. Med-rivers are hotspots for biodiversity in all med-regions. Species in med-rivers require different, often opposing adaptive mechanisms to survive drought and flood conditions or recover from them. Thus, metacommunities undergo seasonal differences, reflecting cycles of river fragmentation and connectivity, which also affect ecosystem functioning. River conservation and management is challenging, and trade-offs between environmental and human uses are complex, especially under future climate change scenarios. This overview of a Special Issue on med-rivers synthesizes information presented in 21 articles covering the five med-regions worldwide: Mediterranean Basin, coastal California, central Chile, Cape region of South Africa, and southwest and southern Australia. Research programs to increase basic knowledge in less-developed med-regions should be prioritized to achieve increased abilities to better manage med-rivers.
Article
Concentrations of nutrient nitrogen (N) and phosphorus (P) are elevated in rivers across large areas of Europe (European Nitrogen Assessment (ENA), Sutton et al., 2011). Environmental policies have been implemented over the past 20years with the aim of reducing nitrogen inputs to surface waters. However, environmental and ecological status is still below set targets (ENA, Sutton et al., 2011). Identification of patterns in long-term change for nutrient trends in hydrological catchments in England & Wales is required to assess impacts of nutrient management policy and provide better evidence for future policy. Such information could provide essential evidence for supporting policy by combining information from the wider catchment, rather than relying on the analysis of data from individual sites. Surface water quality is subject to considerable spatial and short-period temporal variability, reflecting variability in loading and dilution. This makes it difficult to determine temporal trends at individual monitoring sites with relatively sparse sampling. Here we apply spatiotemporal statistical additive models for both nitrogen and phosphorus in river networks across England & Wales to investigate the overall pattern of nutrient concentrations in these river surface waters over the past 20-40years. Concentrations of Orthophosphate (OP) have generally decreased over time for many of the Large Hydrological Areas with a seasonal pattern highlighting one peak in the summer months. Over the past ten years, Total Oxidised Nitrogen (Nitrate+Nitrite, TON) concentrations have generally been slowly decreasing or fairly constant. However, prior to 2000, concentrations were generally on an upward trend. The seasonal pattern highlights one trough in the summer months. The highest levels for OP and TON broadly occur in the same general areas across England & Wales. On average, over time, the lowest values are evident in the north-west and south-west (particularly for OP) and highest values are evident in the Midlands, Anglian and Southern regions.
Article
1. Issues with ecological data (e.g. non-normality of errors, nonlinear relationships and autocorrelation of variables) and modelling (e.g. overfitting, variable selection and prediction) complicate regression analyses in ecology. Flexible models, such as generalized additive models (GAMs), can address data issues, and machine learning techniques (e.g. gradient boosting) can help resolve modelling issues. Gradient boosted GAMs do both. Here, we illustrate the advantages of this technique using data on benthic macroinvertebrates and fish from 1573 small streams in Maryland, USA.
Article
A central aspect of the Water Framework Directive 2000/60/EC addressed to Member Countries is to proceed to type-specific ecological assessment and classification by establishing typology systems. Sixty-four permanent stream sites distributed throughout mainland Greece and islands were assessed with macroinvertebrate indicators to evaluate their ecological quality. Local and catchment scale parameters were determined and recorded to obtain an integrated assessment of the main factors affecting stream integrity and macroinvertebrate communities. Twenty-three sites were classified as reference or good status in terms of biological, chemical and hydromorphological quality with the use of various metrics. Multivariate statistical techniques were performed (MDS, BIOENV, correlation analysis and PCA) to investigate the main environmental factors structuring benthic macroinvertebrate communities and to select candidate environmental variables for establishing a biotic typology for Hellenic rivers. The results revealed relatively distinct macroinvertebrate communities within defined abiotic zones of the country. Assemblages of macroinvertebrate fauna were most strongly associated to differences in geographical position, altitude, slope, catchment area, current velocity, conductivity and water temperature. In view of the lack of sufficient data at the country level on the three last variables and after considering cause–effect relationships between large scale variables and the latter, it has been demonstrated that a number of catchment scale variables could be used as robust surrogates.
Article
Two-dimensional hydrodynamic models are being used increasingly as alternatives to traditional one-dimensional instream flow methodologies for assessing adequacy of flow and associated faunal habitat. Two-dimensional modelling of habitat has focused primarily on fishes, but fish-based assessments may not model benthic macroinvertebrate habitat effectively. We extend two-dimensional techniques to a macroinvertebrate assemblage in a high-elevation stream in the Sierra Nevada (Dana Fork of the Tuolumne River, Yosemite National Park, CA, USA). This stream frequently flows at less than 0.03 m3 s−1 in late summer and is representative of a common water abstraction scenario: maximum water abstraction coinciding with seasonally low flows. We used two-dimensional modelling to predict invertebrate responses to reduced flows that might result from increased abstraction. We collected site-specific field data on the macroinvertebrate assemblage, bed topography and flow conditions and then coupled a two-dimensional hydrodynamic model with macroinvertebrate indices to evaluate habitat across a range of low flows. Macroinvertebrate indices were calculated for the wetted area at each flow. A surrogate flow record based on an adjacent watershed was used to evaluate frequency and duration of low flow events. Using surrogate historical records, we estimated that flow should fall below 0.071 m3 s−1 at least 1 day in 82 of 95 years and below 0.028 m3 s−1 in 48 of 95 years. Invertebrate metric means indicated minor losses in response to modelled discharge reductions, but wetted area decreased substantially. Responses of invertebrates to water abstraction will likely be a function of changing habitat quantity rather than quality. Copyright © 2011 John Wiley & Sons, Ltd.
Article
Summary • Compared to other ecosystem types, a wide variety of biomonitoring methods are available for rivers. Few studies have, however, compared the response of bioindicators (i.e. different river inhabiting taxonomic groups) to different types of environmental stress. • We regressed diversity, taxonomic distinctness and assemblage composition of fish, invertebrates, macrophytes and benthic diatoms to multivariate gradients in nutrient enrichment and habitat degradation using data from 66 lowland and 77 mountain streams. • In lowland streams, the composition of benthic diatom assemblages, measured by Detrended Correspondence Analysis, showed the strongest response to elevated nutrient concentrations (R2 = 0·830), followed by macrophytes (0·711), fish (0·443) and invertebrates (0·391). Macrophyte richness was slightly better correlated with the habitat gradient (0·253) than diatom richness (0·235) and both were better predictors than either fish (0·147) or invertebrate (0·140) assemblage composition. • For mountain streams, invertebrate assemblage composition was the best predictor of changes in nutrient concentrations (R2 = 0·749), followed by macrophyte (0·396) and benthic diatom (0·325) assemblages and fish diversity (0·099). Invertebrate assemblage composition was also slightly better correlated with the habitat gradient (0·391) compared to macrophyte richness (0·323) and both were better than either benthic diatom assemblage composition (0·206) or fish abundance (0·161). • Macrophyte and benthic diatom assemblages in lowland streams and fish and invertebrate assemblages in mountain streams were correlated with the other taxonomic groups, implying that these taxonomic groups may be used as surrogates for indicating wholesale change in diversity. • Synthesis and applications. Our findings show that response trajectories differ between taxonomic groups and stressor, and even with stream type. For this reason, streams and other ecosystem type's response signatures and first and second principle relations should be considered in the selection of robust, complementary and cost-effective measures for biomonitoring. For instance, our findings of asymmetric response to stress show how different taxonomic groups can be used to strengthen inference of change.
Article
A predictive model (RIVPACS-type) for benthic macroinvertebrates was constructed to assess the biological condition of 1,087 streams sampled throughout the eastern United States from 1993-2003 as part of the U.S. Geological Survey’s National Water-Quality Assessment Program. A subset of 338 sites was designated as reference quality, 28 of which were withheld from model calibration and used to independently evaluate model precision and accuracy. The ratio of observed (O) to expected (E) taxa richness was used as a continuous measure of biological condition, and sites with O/E values <0.8 were classified as biologically degraded. Spatiotemporal variability of O/E values was evaluated with repeated annual and within-site samples at reference sites. Values of O/E were regressed on a measure of urbanization in three regions and compared among streams in different land-use settings. The model accurately predicted the expected taxa at validation sites with high precision (SD = 0.11). Within-site spatial variability in O/E values was much larger than annual and among-site variation at reference sites and was likely caused by environmental differences among sampled reaches. Values of O/E were significantly correlated with basin road density in the Boston, Massachusetts (p < 0.001), Birmingham, Alabama (p = 0.002), and Green Bay, Wisconsin (p = 0.034) metropolitan areas, but the strength of the relations varied among regions. Urban streams were more depleted of taxa than streams in other land-use settings, but larger networks of riparian forest appeared to mediate biological degradation. Taxa that occurred less frequently than predicted by the model were those known to be generally intolerant of a variety of anthropogenic stressors.
Article
Key Words flooding, drying, human impact s Abstract Streams in mediterranean-climate regions (areas surrounding the Mediterranean Sea, parts of western North America, parts of west and south Australia, southwestern South Africa and parts of central Chile) are physically, chemically, and biologically shaped by sequential, predictable, seasonal events of flooding and drying over an annual cycle. Correspondingly, aquatic communities undergo a yearly cycle whereby abiotic (environmental) controls that dominate during floods are reduced when the discharge declines, which is also a time when biotic controls (e.g. predation, compe-tition) can become important. As the dry season progresses, habitat conditions become harsher; environmental pressures may again become the more important regulators of stream populations and community structure. In contrast to the synchronous input of autumn litterfall in forested temperate streams, riparian input to mediterranean-type streams is more protracted, with fall and possibly spring peaks occurring in streams in the Northern Hemisphere and a summer peak existing in their Southern Hemisphere counterparts. We present 25 testable hypotheses that relate to the influence of the stream hydrograph on faunal richness, abundance, and diversity; species coexistence; seasonal changes in the relative importance of abiotic and biotic controls on the bi-otic structure; riparian inputs and the relative importance of heterotrophy compared to autotrophy; and the impact of human activities on these seasonally water-stressed streams. Population increases in mediterranean-climate regions (particularly in fer-tile regions) result in an intensification of the competition for water among different users; consequently, water abstraction, flow regulation, increased salinity, and pollu-tion severely limit the ability of the streams to survive as sustainable, self-regulated systems.
Article
Two types of modification of the hydrological system are present in the same regulated segment of the Lima River (NW Portugal): (a) a reduced and constant flow from hypolimnetic release; (b) an intense irregular flow (daily and seasonal). Using multivariate techniques it was possible to compare the effects of these two kinds of disturbance on the macroinvertebrate communities. The communities colonizing both sites exhibited a higher variation in composition and diversity when compared to undisturbed sites. However, such variability was even more evident in the first case, in spite of the stability of the environmental conditions. Such temporal replacement of species is linked to the dominance of tolerant taxa with short life cycles. In the regulated segment the poor water quality and the lack of litter input impacted mainly on the shredders group. This work shows the failure of the practice of releasing constant flows as an attempt to mitigate regulation impacts.
Article
1. This study investigated the relation of benthic macroinvertebrates to environmental gradients in Central European lowland rivers. Taxonomic structure (taxa) and functional composition (metrics) were related to gradients at four different spatial scales (ecoregion, catchment, reach and site). The environmental variables at the catchment-, reach- and site scales reflected the intensity of human impact: catchment and floodplain land use, riparian and floodplain degradation, flow regulation and river bank and bed modification.
Article
A conceptual, continuous time model called SWAT (Soil and Water Assessment Tool) was developed to assist water resource managers in assessing the impact of management on water supplies and nonpoint source pollution in watersheds and large river basins. The model is currently being utilized in several large area projects by EPA, NOAA, NRCS and others to estimate the off-site impacts of climate and management on water use, non-point source loadings, and pesticide contamination. Model development, operation, limitations, and assumptions are discussed and components of the model are described. In Part II, a GIS input/output interface is presented along with model validation on three basins within the Upper Trinity basin in Texas.
Chapter
Class boundaries of three European assessment systems based on macroinvertebrates were compared and harmonized. Three different approaches to comparison, one based on regression analysis and the other two on statistical testing, were described and used, however only one was considered useful for the harmonization of boundaries. In all cases, the calculations were based on a set of six Intercalibration Common Metrics, combined into a simple multimetric index (ICMi). The ICMi was calculated for three test datasets from Italy, Poland and the UK, all belonging to the same stream type (small lowland siliceous sand rivers). For comparison, a regression model was employed to convert national assessment boundary values into ICMi values. The ICMi was also calculated on samples included in a strictly WFD-compliant benchmark dataset. The values of the ICMi obtained for the quality classes Good and High for the test and benchmark datasets were statistically compared. When significant differences were observed in the harmonization phase, the boundaries of the national method were refined until no further differences were observed. For the test datasets and assessment systems of Italy (IBE index) and Poland (Polish BMWP index) small refinements of the boundaries between High/Good and Good/Moderate classes were sufficient to remove the differences from the benchmark dataset. After harmonization, in the studied stream type, the percentage of samples requiring restoration to Good quality increased by 22 and 6% for Italy and Poland, respectively. For the UK dataset (EQI ASPT) the comparison to benchmark dataset showed no significant differences, thus no harmonization was proposed. A general discussion of the options used to compare boundaries based on the ICMi and their potential for harmonization is provided. Lastly, the option of harmonizing class boundaries through comparison to an external, benchmarking dataset and then re-setting them until no differences are found is supported.
Article
This study estimates hydrological drought characteristics using a water balance derived drought index in Pinios river basin, Thessaly, Greece. The concept of hydrological management at subwatershed scale has been adopted because it encompasses the areal extent of a drought event. Fourteen (14) sub-watersheds of Pinios river basin were delineated according to the major tributaries of Pinios river using GIS. For the assessment of hydrological drought, because none of the sub-watersheds have flow gauge stations at their outlets, a six-parameter monthly conceptual water balance model (UTHBAL model), has been applied regionally to simulate runoff for the period October 1960–September 2002. The synthetic runoff was normalized through Box-Cox transformation and standardized to the mean runoff to produce the water balance derived drought index for hydrological drought assessment. The standardized precipitation index (SPI) at multiple time scales and four indices of the Palmer method (i.e. PDSI, WPLM, PHDI and the Palmer moisture anomaly Z-index) were also calculated to assess hydrological droughts. The results showed that the water balance derived drought index is a good indicator of hydrological drought in all sub-watersheds, since is capable to quantify drought severity and duration. Furthermore, the drought index provides guidance on the selection of an appropriate meteorological drought index for operational hydrological drought monitoring. Hence, SPI at 3- and 6-month timescales and the WPLM could be used along with the water balance derived drought index in risk and decision analyses at the study area. KeywordsDrought indices–Drought severity–Hydrological drought–Meteorological drought–Runoff
Chapter
The aim of the intercalibration exercise presently performed by the EU is to identify and resolve significant inconsistencies between the ecological quality classifications of EU Member States and the normative definitions of the EU Water Framework Directive. Based on benthic macroinvertebrate data of two European stream types (small siliceous mountain streams and medium-sized lowland streams in Central and Western Europe) we correlated the indices of 10 river quality assessment methods (ASPT, BMWP, DSFI, German Multimetric Index, Saprobic Indices) applied in Austria, Czech Republic, Denmark, Germany, Poland, Slovak Republic, Sweden and United Kingdom. National class boundaries were compared via regression analysis. Assessment methods of the same type (Saprobic Indices, BMWP/ASPT scores) showed best correlation results (R 2 > 0.7). The good quality status boundaries of the national methods deviated up to 25%; thus indicating the necessity to harmonize the national classification schemes. Prerequisites of the presented intercalibration approach are (1) a sufficiently large and consistent dataset representative of the respective common intercalibration types and (2) agreement on common type specific reference conditions.
Chapter
The development of an ecological model may involve problems of uncertainty. Ecologists have to deal with imprecise data, ecosystem variability, complex interactions, qualitative aspects, and expert knowledge expressed in linguistic terms. In all these cases, fuzzy logic could provide a suitable solution. Fuzzy logic allows to: use uncertain information such as individual knowledge and experience; to combine quantitative and qualitative data; to avoid artificial precision and to produce results that are found more often in the real world. Developed in the late sixties as a method to create control systems when using imprecise data, fuzzy logic has been used for a very large number of engineering applications, and more recently to develop models of air, water and soil ecosystems.The following sections of this chapter introduce the basic structure of a fuzzy model, describing the variety of options that exist at each stage. An example of fuzzy model is also outlined: the knowledge-driven development of an index of water quality having five qualitative output classes. Finally, possible future developments of fuzzy modelling in ecology are suggested.
Article
The occurrence of families of macroinvertebrates has recently been used as the basis for the BMWP (Biological Monitoring Working Party) system of assigning scores to lotic sites. In this study the performance of the system across 268 sites on 41 rivers providing a wide range of physical and chemical features has been appraised. Changes in score and ASPT (average score per taxon) with respect to season and sampling effort have been examined. Seasonal variations were relatively slight and it is concluded that samples taken in any of the three seasons, spring, summer or autumn, were likely to provide consistent estimates of score and particularly ASPT. Sample replication led to substantial accretion of scores but had little effect on ASPT and therefore more information was obtained for less effort when ASPT was used. Data are presented on score and ASPT values for 8 groups of sites derived by multivariate classificatory techniques. Considerable variability in achievable score and ASPT was observed in the different groups of unpolluted sites. In general, scores were highest in the group at the middle of the range of environmental features and lowest in groups at the bottom of the range (lowland areas). ASPT in contrast showed a relatively steady decline in values between groups at the top (mainly upland rivers) and bottom of the range of environmental features. Attempts were made to predict score and ASPT from physical and chemical data, or physical data alone using multiple regression. Equations used to predict ASPT explained on average a higher proportion of the variance (65%) than those predicting scores (22%). It is suggested that predictive equations for ASPT will enable theoretical ASPT to be calculated, thus providing target values against which observed values can be compared. Recommendations to facilitate use and interpretation of the BMWP score system are presented.
Article
The European Union Water Framework Directive recognises the need for and value of biological monitoring. This paper reviews the modelling approach known as River Invertebrate Prediction and Classification System (RIVPACS) for assessing the ecological quality of river sites using macroinvertebrate sampling. The RIVPACS philosophy is to develop statistical relationships between the fauna and the environmental characteristics of a large set of high quality reference sites which can be used to predict the macroinvertebrate fauna to be expected at any site in the absence of pollution or other environmental stress. The observed fauna at new test sites can then be compared with their site-specific expected fauna to derive indices of ecological quality. All methodological decisions in any such model development have implications for the reliability, precision and robustness of any resulting indices for assessing the ecological quality and ecological grade (‘status’) of individual river stretches. The choice of reference sites and environmental predictor variables, the site classification and discrimination methods, the estimation of the expected fauna, and indices for comparing the agreement, or lack of it, between the observed and expected fauna, are all discussed. The indices are assessed on the reference sites and on a separate test set of 340 sites, which are subject to a wide range of types and degrees of impairment.
Article
Statistical and trend analysis of surface water quality and runoff data from Pinios River have been performed to provide a framework for sustainable water resources management. The trend analysis was performed using the non-parametric Spearman correlation and tested for statistical significance using the Student's t-test. Monthly runoff data from five stations and surface water quality data from six stations on Pinios River have been analyzed. Apart from the statistical and trend analyses, the quality of the Pinios River was assessed for drinking and other urban uses and for irrigation, according to the national, European and international water quality standards. The important information has been gained from this analysis, especially on the identification of significant temporal and spatial trends of water quality parameters and the status of river water quality according to the water quality standards. The analysis indicated that the quality of the river water is, on average fair, and the river water could be used with caution for irrigation purposes.
Article
The long history of substantial human impacts on the landscape of the Mediterranean region, and their effects on fluvial systems, is documented. These effects have included impacts of deforestation and other land use changes, agricultural terracing on a wide scale, water transfers, and irrigation schemes. During the 20th century, major changes were made directly to channels through channelisation, construction of dams of various sizes, and extraction of gravel, and indirectly by reforestation. These changes have caused a major phase of incision on some rivers. Runoff and soil erosion have been affected by types of crops and agricultural practices as well as by the varying extent of cultivation and grazing. Some recent agricultural practices involve wholescale relandscaping of the topography and alteration of surface properties of material. The importance of analysing the connectivity within different land units and of the spatial position of human activity within a catchment is illustrated. The analysis of connectivity is the key to understanding the variability of impact and the extent of propagation of effects.