| publications-1171 |
PEER REVIEWED ARTICLE |
2018 |
Annette Baattrup-Pedersen , Niels B. Ovesen , Søren E. Larsen , Dagmar K. Andersen , Tenna Riis , Brian Kronvang , Jes J. Rasmussen |
Evaluating effects of weed cutting on water level and ecological status in Danish lowland streams |
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10.1111/fwb.13101 |
Uncategorized |
Natural Water Bodies |
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AbstractAt present, scientific evidence documenting effects of weed cutting in streams as a measure to improve flood protection and run‐off from agricultural land is scarce, which is surprising considering the huge effect that it has on stream ecology. Instead, weed cutting is performed under the assumption that removal of aquatic plant biomass improves runoff from agricultural land and prevents flooding of adjacent areas provided that it is performed regularly.In this study, we examined linkages between weed cutting practice and water level reductions in 126 small‐ and medium‐sized Danish streams (catchment size <100 km2) with continuously monitored discharge and water level data (from 1990 to 2012). Specifically, we hypothesised that (1) weed cutting reduces stream water levels more in late summer when the biomass of aquatic plants is higher than in early summer; (2) the efficiency of cutting declines with increasing cutting frequency as the aquatic plant community changes with increasing abundance of species able to regrow fast following a cutting event; (3) the high‐frequency cutting in Danish streams lowers the ecological status of the streams as evaluated from aquatic plant assemblages.The average effect of weed cutting on the water level was largest in July, August and September with an average reduction of 16 cm and lowest in early spring and late autumn with an average reduction of 11 cm. Regrowth was largest in June, with an increase in water level of 0.41 cm/day, whereas regrowth was absent in autumn. Regrowth also varied with the frequency of weed cutting, from an average of 0.04 cm/day in streams subjected to one annual cutting to an average of 0.6 cm/day in streams subjected to >6 annual cuttings. Furthermore, we found that the ecological status was either moderate or poor/bad in streams with more than one annual cutting.Our findings highlight that it is by no means certain that the current weed cutting practice is efficient for flood control since (1) regrowth is stimulated by frequent cuttings and a positive feedback loop may develop, necessitating even more frequent cuttings to maintain the discharge capacity of the streams, and (2) many species stimulated by weed cutting, like for instanceSparganium emersum, form dense canopy beds across the entire stream profile and therefore reduce the discharge capacity of the stream more than species growing in confined patches. We encourage more studies with the aim to identify how stream maintenance should be performed to optimise flood control without compromising the ability to reach good ecological stream quality. |
603378 |
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| publications-1172 |
PEER REVIEWED ARTICLE |
2016 |
Pille Meinson , Agron Idrizaj , Peeter Nõges , Tiina Nõges , Alo Laas |
Continuous and high-frequency measurements in limnology: history, applications, and future challenges |
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10.1139/er-2015-0030 |
Uncategorized |
Natural Water Bodies |
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Over the past 15 years, an increasing number of studies in limnology have been using data from high-frequency measurements (HFM). This new technology offers scientists a chance to investigate lakes at time scales that were not possible earlier and in places where regular sampling would be complicated or even dangerous. This has allowed capturing the effects of episodic or extreme events, such as typhoons on lakes. In the present paper we review the various fields of limnology, such as monitoring, studying highly dynamic processes, lake metabolism studies, and budget calculations, where HFM has been applied, and which have benefitted most from the application. Our meta-analysis showed that more than half of the high-frequency studies from lakes were made in North America and Europe. The main field of application has been lake ecology (monitoring, lake metabolism) followed by physical limnology. Water temperature and dissolved oxygen have been the most universal and commonly measured parameters and we review the various study purposes for which these measurements have been used. Although a considerable challenge for the future, our review highlights that broadening the spatial scale of HFM would substantially broaden the applicability of these data across a spectrum of different fields. |
603378 |
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| publications-1173 |
PEER REVIEWED ARTICLE |
2018 |
Markus Venohr , Simone L. Langhans , Oliver Peters , Franz Holker , Robert Arlinghaus , Lewis Mitchell , Christian Wolter |
The underestimated dynamics and impacts of water-based recreational activities on freshwater ecosystems |
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10.1139/er-2017-0024 |
Predictive Analytics |
Natural Water Bodies |
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Recreational activities on, in, and along freshwaters (e.g., boating, bathing, angling) positively contribute to human well-being but can also concurrently stress aquatic ecosystems. While outdoor recreation, aquatic ecosystems, and human well-being form coupled social-ecological systems, inherent fluxes and interactions between these have rarely been properly quantified. This paper synthesizes information on links between water-based recreational activities, effects on freshwater ecosystems integrity and recreational quality, and proposes a novel framework for assessment and integrated management. This framework is based on understanding relationships between recreational quality, demand and use, and recreational use-induced impacts on ecosystem state and function, as well as ecological and social carrying capacities. Current management approaches of freshwater ecosystems addressing economic, environmental, or recreational aspects are poorly linked and harmonized, and are further constrained by inadequate information on the dynamics and densities of recreational uses. Novel assessment and monitoring methods are needed to capture the short-term peak dynamics of water-based recreational uses, and we argue social media could play an increasingly important role here. An integrative recreation ecology management concept combined with peak usage information has great potential to form the basis for next-generation management approaches of freshwater and other ecosystems. |
603378 |
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| publications-1174 |
PEER REVIEWED ARTICLE |
2015 |
Hyunbin Jo , Marc Ventura , Nicolas Vidal , Jeong-Soo Gim , Teresa Buchaca , Leon A. Barmuta , Erik Jeppesen , Gea-Jae Joo |
Discovering hidden biodiversity: the use of complementary monitoring of fish diet based on DNA barcoding in freshwater ecosystems |
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10.1002/ece3.1825 |
Uncategorized |
Natural Water Bodies |
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AbstractEcological monitoring contributes to the understanding of complex ecosystem functions. The diets of fish reflect the surrounding environment and habitats and may, therefore, act as useful integrating indicators of environmental status. It is, however, often difficult to visually identify items in gut contents to species level due to digestion of soft‐bodied prey beyond visual recognition, but new tools rendering this possible are now becoming available. We used a molecular approach to determine the species identities of consumed diet items of an introduced generalist feeder, brown trout (Salmo trutta), in 10 Tasmanian lakes and compared the results with those obtained from visual quantification of stomach contents. We obtained 44 unique taxa (OTUs) belonging to five phyla, including seven classes, using the barcode of life approach from cytochrome oxidase I (COI). Compared with visual quantification, DNA analysis showed greater accuracy, yielding a 1.4‐fold higher number of OTUs. Rarefaction curve analysis showed saturation of visually inspected taxa, while the curves from the DNA barcode did not saturate. The OTUs with the highest proportions of haplotypes were the families of terrestrial insects Formicidae, Chrysomelidae, and Torbidae and the freshwater Chironomidae. Haplotype occurrence per lake was negatively correlated with lake depth and transparency. Nearly all haplotypes were only found in one fish gut from a single lake. Our results indicate that DNA barcoding of fish diets is a useful and complementary method for discovering hidden biodiversity. |
603378 |
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| publications-1175 |
PEER REVIEWED ARTICLE |
2018 |
Annette Baattrup-Pedersen , Annemarie Garssen , Emma Göthe , Carl Christian Hoffmann , Andrea Oddershede , Tenna Riis , Peter M. van Bodegom , Søren |
Structural and functional responses of plant communities to climate change-mediated alterations in the hydrology of riparian areas in temperate Europe |
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10.1002/ece3.3973 |
Uncategorized |
Natural Water Bodies |
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AbstractThe hydrology of riparian areas changes rapidly these years because of climate change‐mediated alterations in precipitation patterns. In this study, we used a large‐scale in situ experimental approach to explore effects of drought and flooding on plant taxonomic diversity and functional trait composition in riparian areas in temperate Europe. We found significant effects of flooding and drought in all study areas, the effects being most pronounced under flooded conditions. In near‐stream areas, taxonomic diversity initially declined in response to both drought and flooding (although not significantly so in all years) and remained stable under drought conditions, whereas the decline continued under flooded conditions. For most traits, we found clear indications that the functional diversity also declined under flooded conditions, particularly in near‐stream areas, indicating that fewer strategies succeeded under flooded conditions. Consistent changes in community mean trait values were also identified, but fewer than expected. This can have several, not mutually exclusive, explanations. First, different adaptive strategies may coexist in a community. Second, intraspecific variability was not considered for any of the traits. For example, many species can elongate shoots and petioles that enable them to survive shallow, prolonged flooding but such abilities will not be captured when applying mean trait values. Third, we only followed the communities for 3 years. Flooding excludes species intolerant of the altered hydrology, whereas the establishment of new species relies on time‐dependent processes, for instance the dispersal and establishment of species within the areas. We expect that altered precipitation patterns will have profound consequences for riparian vegetation in temperate Europe. Riparian areas will experience loss of taxonomic and functional diversity and, over time, possibly also alterations in community trait responses that may have cascading effects on ecosystem functioning. |
603378 |
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| publications-1176 |
PEER REVIEWED ARTICLE |
2017 |
Virgilio Hermoso , Ana Filipa Filipe , Pedro Segurado , Pedro Beja |
Freshwater conservation in a fragmented world: Dealing with barriers in a systematic planning framework |
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10.1002/aqc.2826 |
Uncategorized |
Natural Water Bodies |
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AbstractDisruption of longitudinal connectivity poses one of the most important threats to the persistence of freshwater biodiversity worldwide. Longitudinal connectivity plays a key role by facilitating ecological processes, such as migrations or energy transfer along river networks. For this reason, effective conservation of freshwater biodiversity is highly dependent on a capacity to maintain all processes associated with connectivity. Freshwater protected areas are commonly affected by disruptions of connectivity due to human activities and recent approaches to addressing connectivity when identifying priority areas have overlooked the limitations that human perturbations pose to connectivity.Here, a novel approach is presented to address this issue by accounting for the spatial distribution of barriers using Marxan, a tool commonly applied in conservation planning. This approach was first tested on a simulated example and then applied to the identification of priority areas for the conservation of freshwater vertebrates in the Iberian Peninsula (Spain and Portugal).When using this new approach, the number of disrupted connections within priority areas can be significantly reduced at no additional cost in terms of area needed, which would help maintain connectivity among populations of species with low–medium migratory needs.Given the widespread occurrence of barriers in the study region, the improvement in connectivity within priority areas also resulted in the selection of river reaches closer to the headwaters and the river mouth. Focusing on both extremes of the longitudinal gradient might compromise the effectiveness of conservation efforts for long‐distance migratory species, such as the European eel. This inevitably means that additional management measures, such as barrier removal or construction of fish passages, would be necessary to ensure that these species are able to complete their life cycles.The method demonstrated here could be applied to other regions where connectivity is compromised. |
603378 |
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| publications-1177 |
PEER REVIEWED ARTICLE |
2017 |
José Maria Santos , Rui Rivaes , Isabel Boavida , Paulo Branco |
Structural microhabitat use by endemic cyprinids in a Mediterranean-type river: Implications for restoration practices |
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10.1002/aqc.2839 |
IoT & Sensors |
Natural Water Bodies |
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Abstract Endemic freshwater fish from the Mediterranean region are among the most threatened species in the world owing to increasing river degradation. Because of such threats, the number of river restoration projects has greatly increased. However, they are seldom planned with consideration of the species' life history, often resulting in erroneous practices that compromise their success. This study assessed the seasonal and size‐related microhabitat use by three endemic cyprinids (Iberian barbel, Luciobarbus bocagei; Iberian straight‐mouth nase, Pseudochondrostoma polylepis; and calandino, Squalius alburnoides) using a modified point electrofishing procedure in a Mediterranean river. A multivariate approach was then employed to analyse both structural resource use and availability data. All species showed non‐random microhabitat use. The barbel and nase shifted to faster‐flowing positions (>25 cm s−1) with a coarser substratum (>150 mm particle size) during spring and to sheltered positions (50–100% instream cover) during autumn. Calandino selected more covered areas in autumn (>60% cover) and shifted to shallower positions from this season (>40 cm) to summer (<35 cm). Significant size‐related differences in microhabitat use were consistent for the three species, with smaller individuals occupying on average shallower microhabitats. Significant resource‐use overlap between species size classes increased from autumn to summer, occurring mainly between juvenile and small adult barbel and calandino. The present study helped develop recommendations for river restoration practices that may have a wider application, particularly for other Mediterranean‐type rivers. Cover was found to be critical for all species, in particular for calandino, which could be classified as a shelter‐oriented eurytopic species. Restoration scenarios should therefore consider maintaining cover habitats during unfavourable flow conditions for these species. Lithophilic spawners, which were highly responsive to velocity and substratum, could particularly benefit from the creation of gravel bedforms and artificial riffles to enhance depth and flow variability. |
603378 |
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| publications-1178 |
PEER REVIEWED ARTICLE |
2016 |
Roshni Arora , Klement Tockner , Markus Venohr |
Changing river temperatures in northern Germany: trends and drivers of change |
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10.1002/hyp.10849 |
IoT & Sensors |
Natural Water Bodies |
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AbstractClimate change is one of the main drivers of river warming worldwide. However, the response of river temperature to climate change differs with the hydrology and landscape properties, making it difficult to generalize the strength and the direction, of river temperature trends across large spatial scales and various river types. Additionally, there is a lack of long‐term and large‐scale trend studies in Europe as well as globally. In this study, we investigated the long‐term (25 years; 132 sites) and the short‐term (10 years; 475 sites) river temperature trends, patterns and underlying drivers within the period 1985–2010 in seven river basins of Germany. The majority of the sites underwent significant river warming during 1985–2010 (mean warming trend: 0.03 °C year−1, SE = 0.003), with a faster warming observed during individual decades (1985–1995 and 2000–2010) within this period. Seasonal analyses showed that, while rivers warmed in all seasons, the fastest warming had occurred during summer. Among all the considered hydro‐climatological variables, air temperature change, which is a response to climate forcing, was the main driver of river temperature change because it had the strongest correlation with river temperature, irrespective of the period. Hydrological variables, such as average flow and baseflow, had a considerable influence on river temperature variability rather than on the overall trend direction. However, decreasing flow probably assisted in a faster river temperature increase in summer and in rivers in NE basins (such as the Elbe basin). The North Atlantic Oscillation Index had a greater significant influence on the winter river temperature variability than on the overall variability. Landscape and basin variables, such as altitude, ecoregion and catchment area, induced spatially variable river temperature trends via affecting the thermal sensitivity of rivers, with the rivers in large catchments and in lowland areas being most sensitive. Copyright © 2016 John Wiley & Sons, Ltd. |
603378 |
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| publications-1179 |
PEER REVIEWED ARTICLE |
2016 |
Jiao Gu , Hui Jin , Hu He , Xiaoyu Ning , Jinlei Yu , Bingchang Tan , Erik Jeppesen , Kuanyi Li |
Effects of small-sized crucian carp (Carassius carassius) on the growth of submerged macrophytes: Implications for shallow lake restoration |
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10.1016/j.ecoleng.2016.06.118 |
Uncategorized |
Natural Water Bodies |
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No abstract available |
603378 |
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| publications-1180 |
PEER REVIEWED ARTICLE |
2016 |
Xiufeng Zhang , Zhengwen Liu , Erik Jeppesen , William D. Taylor , Lars G. Rudstam |
Effects of benthic-feeding common carp and filter-feeding silver carp on benthic-pelagic coupling: Implications for shallow lake management |
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10.1016/j.ecoleng.2015.12.039 |
Data Management & Analytics |
Natural Water Bodies |
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No abstract available |
603378 |
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