Influência da condição ecológica dos rios sobre as alterações nos parâmetros físico-químicos ao longo dos rios

Dissertação de mestrado em EcologyRivers supports key ecological processes and provides essential benefits to human welfare. Humans have been changing river processes and services by changing riparian land cover, river hydromorphology and by discharging pollutants on rivers. Excessive nutrient loadings have been severely impacting river processes and services, so improve the river capacity to buffer excessive nutrient loadings is determinant to human well-being by reducing the impact of pollutant discharges. To assess the influence of river water chemistry and hydromorphology on changes in physico-chemical water parameters along rivers, six river segments with different trophic status and channel width were selected in the Ave River watershed (northwestern Portugal). The influence of riparian land cover on river habitat quality and physico-chemical water parameters was assessed by dividing each river segment in stretches based on land cover type, and then comparing habitat quality and changes in physico-chemical water parameters along rivers, among stretches. River segments were classified as mesotrophic (S1-S4), eutrophic (S5) and large (S6), and stretches from each river segment type were analyzed independently. The habitat quality was evaluated using the Fluvial Functional Index (FFI), the HABSCORE (RBP) and the Riparian Forest Quality Index (QBR). Changes in physico-chemical water parameters along rivers were determined measuring differences in ammonium, nitrate, phosphate and oxygen concentrations, and conductivity, pH and temperature between the two sampling sites defining each stretch. Results demonstrated that stretches with more urban and agricultural land use had worse habitat quality than stretches with more natural land cover, regardless river segment type. Nitrate and phosphate concentration tended to increase along stretches with more agricultural and urban land use, but to decrease along stretches with more natural land cover, in all river segment type. Nitrate concentration decreased more along stretches with higher concentrations of nitrate and greater abundance of macrophytes, suggesting that river water chemistry and photosynthetic organisms have a strong influence on nitrate concentration in rivers. Overall results demonstrated that i) the conversion of natural riparian areas to human land use can degrade river habitat quality and increase nutrient concentrations in rivers, with consequences for river ecosystem services and their economic value, and ii) changes in physico-chemical water parameters along rivers can be related to water chemistry, biota and hydromorphology of rivers.Os rios suportam processos ecológicos chave e fornecem benefícios essenciais para o bem-estar humano. Os seres humanos têm vindo a alterar os processos e os serviços que os rios providenciam ao alterarem a cobertura do solo ripário, a hidromorfologia dos rios e por descarregarem poluentes nos rios. Cargas excessivas de nutrientes têm vindo a afectar severamente os processos e os serviços fornecidos pelos rios, pelo que melhorar a capacidade dos rios de moderar o excesso de nutrientes é determinante para o bem-estar humano ao reduzir os impactos das descargas de poluentes. Para avaliar a influência da composição química da água e da hidromorfologia dos rios nas alterações dos parâmetros físico-químicos da água ao longo dos rios, seis segmentos de rio com diferentes estados tróficos e largura de canal foram seleccionados na bacia do Rio Ave (noroeste de Portugal). O efeito da cobertura do solo ripário sobre a qualidade do habitat e os parâmetros físico-químicos da água do rio foi avaliado dividindo cada segmento de rio em trechos de acordo com o tipo de cobertura de solo, e, posteriormente, comparando a qualidade do habitat e as alterações nos parâmetros físico-químicos da água ao longo dos rios, entre trechos. Os segmentos de rio foram classificados em mesotróficos (S1-S4), eutrófico (S5) e largo (S6), e os trechos de cada tipo de segmento de rio foram analisados de forma independente. A qualidade do habitat foi avaliada utilizando o Fluvial Functional Index (FFI), o HABSCORE (RBP) e o Riparian Forest Quality Index (QBR). As alterações nos parâmetros físico-químicos da água ao longo dos rios foram determinadas medindo as diferenças na concentração de amónia, nitrato, fosfato e oxigénio e na conductividade, pH e temperatura entre os dois locais de amostragem que definiam cada trecho. Os resultados mostraram que os trechos com mais uso de solo urbano e agrícola tinham pior qualidade de habitat do que os trechos com mais cobertura de solo natural, independentemente do tipo de segmento de rio. As concentrações de nitrato e fosfato tenderam a aumentar ao longo de trechos com maior ocupação de solo agrícola e urbana, mas a diminuir ao longo de trechos com maior ocupação natural, em todo o tipo de segmentos de rio. A concentração de nitrato diminuiu mais ao longo de trechos com concentrações mais elevadas de nitrato e maior abundância de macrófitas, sugerindo que a composição química da água dos rios e os organismos fotossintéticos têm uma forte influência sobre a concentração de nitrato nos rios. No seu conjunto, os resultados mostraram que i) a conversão de áreas ripícolas naturais para usos de solo humano pode degradar a qualidade do habitat dos rios e aumentar a carga de nutrientes, com consequências para os serviços de ecossistemas de rio e o seu valor económico, e que ii) as alterações nos parâmetros físico-químicos da água ao longo dos rios podem estar relacionadas com a composição química da água, as comunidades biológicas e a hidromorfologia dos rios

Riparian land use and stream habitat regulate water quality

Riparian land use is a key driver of stream ecosystem processes but its effects on water quality are still a matter of debate when proposing measures to improve freshwater quality. The aim of this study was to examine the influence of riparian land use on stream habitat and water chemistry, and to assess in what extent stream habitat also affects water quality. To that end, we selected eight reaches in the Ave River basin (northwestern Portugal) and compared longitudinal variations in water chemistry and stream habitat between reaches with different land use (urban, agricultural and natural), and between reaches with natural riparian areas and different habitats. Stream habitat was assessed using the Fluvial Functional Index, the HABSCORE, and the Riparian Forest Quality Index. Longitudinal variations in water chemistry were determined measuring differences in concentrations of ammonium, nitrate, phosphate and oxygen, and conductivity, pH and temperature between the downstream and the upstream ends of each reach. Nitrate concentration tended to decrease along reaches with more natural riparian areas and to increase along reaches with more urban and agricultural land uses. Longitudinal variations in water chemistry also differed between reaches with natural riparian areas, suggesting that water quality also depends on stream habitat. Moreover, longitudinal variation in water chemistry was proven a simple, useful and low-cost approach to assess the influence of land cover and stream habitat on water quality. Overall results demonstrated that both riparian land use and stream habitat influence water quality and that riparian forests are essential to reduce nutrient export to downstream ecosystems.This study was supported by the CLIMALERT project (ERA4CS) funded by JPI-CLIMATE, the EU Commission and the Portuguese Foundation for Science and Technology (FCT), the EcoAgriFood project (NORTE-01-0145-FEDER-000009) supported by Norte Portugal Regional Operational Programme (NORTE 2020), under the PORTUGAL 2020 Partnership Agreement, through the European Regional Development Fund (ERDF), and the strategic programme UID/BIA/04050/2019 (POCI-01-0145-FEDER-007569), funded by national funds through FCT, and by the ERDF through the COMPETE2020 -Programa Operacional Competitividade e Internacionalizacao (POCI). The authors thank to Francisco Carvalho, Eva Lima-Fernandes, Rocco Scolozzi, Paulo Geraldes, Isabel Fernandes, Jose Trabulo, Bruno Antunes, Ana Pereira, and Sofia Duarte for field and laboratory assistance, and to the Portuguese Environment Agency (APA) for providing GIS data for the Ave River Basin

Modeling the Effectiveness of Sustainable Agricultural Practices in Reducing Sediments and Nutrient Export from a River Basin

Water pollution from unsustainable agricultural practices is a global problem that undermines human health and economic development. Sustainable agricultural practices have been considered to maintain global food production without compromising water quality and ecosystem health. However, the effectiveness of sustainable agricultural practices in reducing sediments and nutrient export and the combination of practices that will best achieve water quality objectives is still under-explored. In this study, we assess the effectiveness of sustainable agricultural practices in reducing sediments and nutrients export to rivers and determine the combination of practices that would allow the highest reductions of sediments and nutrients, using the Soil and Water Assessment Tool (SWAT) in a Portuguese river basin highly affected by agricultural pollution. SWAT was calibrated and validated for river discharge, sediments, phosphorous, and nitrate loads at the outlet of the basin, with a good agreement between simulated and observed values. The effects of filter strips, fertilizer incorporation, and conservation tillage were analyzed considering both individual and combined effects. Our study shows that sustainable agricultural practices can substantially reduce sediments and nutrients export from a river basin, with the highest average combined depletion of sediments, phosphorus, and nitrate export (25%) achieved when fertilizer incorporation, conservation tillage, and filter strips were implemented simultaneously. Additional studies exploring the effect of sustainable agricultural practices across a range of climate and watershed characteristics, as well as their capacity to deal with challenges related to climate change, will further improve our understanding of the effectiveness of sustainable agricultural practices

Hydropower contribution to the renewable energy transition under climate change

Published online: 6 December 2022Climate change is expected to affect hydropower generation by modifying river runoff and increasing reservoir evaporation. Anticipating the impact of climate change on hydropower generation is crucial to develop adaptation strategies and to efficiently plan a renewable energy transition. In this study, we assess the impact of climate change on hydropower generation using the Soil & Water Assessment Tool (SWAT) in Portuguese river basin with strategic importance, since it is responsible for 20% of the national hydropower generation. SWAT was calibrated against 6 reservoir flow-in and 1 river discharge, with a good agreement between simulated and observed values. Future climate projections were based on EURO-CORDEX climate simulations under RCP4.5 and 8.5 scenarios for 2031-2060 (short-term) and 2071-2100 (long-term), compared to 1976-2005. Results reveal that in the short-term, reservoir flow-in is expected to decrease up to 55% in the summer under RCP4.5, and up to 90% in the long-term under RCP8.5. Consequently, the hydropower plants may generate less 79 GWh per year in the short-term under RCP4.5, and less 272 GWh per year in the long-term under RCP8.5, which is equivalent to 11% and 38%, respectively, of the total electricity used in the study area in 2019. Our study shows that, at least in some regions, climate change can substantially reduce hydropower generation and thereby hamper the renewable energy transition. This is relevant for policymakers and water managers by allowing them to anticipate the impact of climate change on hydropower generation and better plan a renewable energy transition.The study was supported by the project CLIMALERT: Climate AlertSmart System for Sustainable Water and Agriculture, an ERA-NET initiated by JPI Climate (ERA4CS programme) co-funded by the EU commission (Grant Agreement 690462) and FCT (ERA4CS/0004/2016). Jose Pedro Ramiao was supported by Fundacao para a Ciencia e Tecnologia (FCT) (SFRH/BD/141486/2018) and the European Social Fund through the "Programa Operacional Regional do Norte" of the European Commission. Claudia Carvalho-Santos is supported by the "Contrato-Programa" UIDP/04050/2020 funded by national funds through the Fundacao para a Ciencia e Tecnologia I.P. Rute Pinto gratefully acknowledges the support of Global Water Futures as part of the Canada First Research Excellence Fund

Multiple introductions and first record of Phoxinus phoxinus in the Douro basin revealed by molecular data

Biological invasions are a major threat to global biodiversity. Freshwater ecosystems are particularly vulnerable to anthropogenic introductions. This is the case of the minnows (Phoxinus genus), which have been used as a live bait since the 1900s. Until recently, Phoxinus phoxinus was thought to be distributed across most of the European watercourses, including the Iberian Peninsula (Ebro Basin and Cantabrian region). In 2007, these Iberian populations were identified as Phoxinus bigerri, including the traslocated populations in the Douro Basin near Burgos (Spain). Currently, little is known about the distribution of Phoxinus bigerri in the Douro Basin. During early summer 2017, we sampled 75 stream reaches using electrofishing across the Douro Basin (Portugal and Spain). We identified 267 individuals as the Pyrenean minnow P. bigerri, and we cliped and stored fin tissues from 153 individuals in 96% ethanol for DNA reference collection. Among those, 26 were barcoded for cytochrome oxidase I (COI) and cytochrome b (Cytb) genes to confirm the taxonomic identification at the species level. Results confirmed for the first time the presence of the common minnow P. phoxinus in the Douro basin, being five individuals collected in the western Douro (Portugal near Porto) closely related to populations from Adour Basin in France. The remaining 21 individuals from eastern Douro (Spain near Brugos) were identified as P. bigerri, as expected. Our study is the first record of P. phoxinus in the Douro Basin, which can be easly missidentified when using only morphologically identifications. The study highlights the value of using molecular approaches for detecting new introductions and tracking spread histories, which can be relevant for designing proper management plans. The P. phoxinus introduction in western Douro (Portugal) seem to be related with human activities (sport fisheries by Portuguese immigrants living in France) rather than geographical proximity.Financial support was provided by Portuguese Foundation for Science and Technology (FCT) Project PTDC/AGR-FOR/1627/2014.info:eu-repo/semantics/publishedVersio

Impacts of diffuse urban stressors on stream benthic communities and ecosystem functioning: A review

Catchment urbanisation results in urban streams being exposed to a multitude of stressors. Notably, stressors originating from diffuse sources have received less attention than stressors originating from point sources. Here, advances related to diffuse urban stressors and their consequences for stream benthic communities are summarised by reviewing 92 articles. Based on the search criteria, the number of articles dealing with diffuse urban stressors in streams has been increasing, and most of them focused on North America, Europe, and China. Land use was the most common measure used to characterize diffuse stressor sources in urban streams (70.7 % of the articles characterised land use), and chemical stressors (inorganic nutrients, xenobiotics, metals, and water properties, including pH and conductivity) were more frequently reported than physical or biological stressors. A total of 53.3 % of the articles addressed the impact of urban stressors on macroinvertebrates, while 35.9 % focused on bacteria, 9.8 % on fungi, and 8.7 % on algae. Regarding ecosystem functions, almost half of the articles (43.5 %) addressed changes in community dynamics, 40.3 % addressed organic matter decomposition, and 33.9 % addressed nutrient cycling. When comparing urban and non-urban streams, the reviewed studies suggest that urbanisation negatively impacts the diversity of benthic organisms, leading to shifts in community composition. These changes imply functional degradation of streams. The results of the present review summarise the knowledge gained to date and identify its main gaps to help improve our understanding of urban streams.This study has received funding from the Iberian Association of Limnology (AIL) through the project URBIFUN (Urbanization effects on the relationship between microbial biodiversity and ecosystem functioning), awarded to Míriam Colls and Ferran Romero. Authors thank as well the Basque Government (Consolidated Research Group IT951-16) and the MERLIN project 101036337 – H2020-LC-GD-2020/H2020-LC-GD-2020-3.info:eu-repo/semantics/publishedVersio