Growth response to nitrate enrichment helps facilitate success of an alien in New Zealand streams.

Motivated by stream ecosystem degradation by eutrophication, we mimicked slow flowing lowland stream conditions with a novel experimental setup to further our understanding of aquatic plant responses to increases in nitrate and light. We conducted a mesocosm growth experiment of two species from the genus : (alien) and (native), grown at four nitrate and four light levels. We hypothesised that (i) internal nutrient status of the plants would scale with water column nutrient concentration, and that (ii) plant performance would reflect the nutrient status of the plant.

Lake morphological characteristics and climatic factors affect long-term trends of phytoplankton community in the Rotorua Te Arawa lakes, New Zealand during 23 years observation.

Monitoring the long-term dynamics of lake phytoplankton can help understand their natural temporal variability, as well as assess potential impacts of interventions aimed at improving lake ecological condition. However, investigating long-term changes in lake ecosystems has received scant attention. In the present study, we analyzed a long-term dataset of phytoplankton communities collected from 1990 to 2013 from eleven of the 12 Rotorua Te Arawa lakes in New Zealand, to explore their responses to changing abiotic conditions.

A mobile observatory powered by sun and wind for near real time measurements of atmospheric, glacial, terrestrial, limnic and coastal oceanic conditions in remote off-grid areas.

Climate change is rapidly altering the Arctic environment. Although long-term environmental observations have been made at a few locations in the Arctic, the incomplete coverage from ground stations is a main limitation to observations in these remote areas. Here we present a wind and sun powered multi-purpose mobile observatory (ARC-MO) that enables near real time measurements of air, ice, land, rivers, and marine parameters in remote off-grid areas.

Weed cutting in a large river reduces ecosystem metabolic rates in the case of River Gudenå (Denmark).

Problems related to extensive macrophyte growth are widespread both in modified and man-made canals and streams, and in streams with natural morphology and rich vegetation. The weed cutting is a common management practice in order to reduce flood risk and enhance water conveyance. Although the short- and long-term impacts on the stream physical habitats and biota have been extensively studied, only little information exists on the effects of weed cutting on ecosystem metabolism, especially for larger rivers.

Effects of the herbicides metazachlor and flufenacet on phytoplankton communities - A microcosm assay.

Agrochemicals are the main pollutants in freshwater ecosystems. Metazachlor and flufenacet are two common herbicides applied in fall (i.e.

Danish wetlands remained poor with plant species 17-years after restoration.

For more than two decades, wetland restoration has been successfully applied in Denmark as a tool to protect watercourses from elevated nutrient inputs from agriculture, but little is known about how the flora and fauna respond to restoration. The main objective of this study was therefore to: (1) examine plant community characteristics in 10 wetland sites in the River Odense Kratholm catchment, restored between 2001 and 2011 by re-meandering the stream and disconnecting the tile drains, and (2) explore whether the effects of restoration on plant community characteristics change with the age of the restoration. Specifically, we hypothesised that plant community composition, species richness and diversity would improve with the age of the restoration and eventually approach the state of natural wetland vegetation.

Microbial biofilm community dynamics in five lowland streams.

Stream biofilms are complex aggregates of diverse organism groups that play a vital role in global carbon and nitrogen cycles. Most of the current studies on stream biofilm focus on a limited number of organism groups (e.g.

Influences of pesticides, nutrients, and local environmental variables on phytoplankton communities in lentic small water bodies in a German lowland agricultural area.

Agrochemicals such as pesticides and nutrients are concurrent chemical stressors in freshwater aquatic ecosystems surrounded by agricultural areas. Lentic small water bodies (LSWB) are ecologically significant habitats especially for maintaining biodiversity but highly understudied. Phytoplankton are ideal indicator species for stress responses.

Influence of plant habitats on denitrification in lowland agricultural streams.

The aim of this study was to assess potential differences in denitrification in contrasting stream habitats in agricultural lowland streams located in Denmark. The study focused on three types of habitats i) vegetated habitats with emergent plants, ii) vegetated habitats with submerged plants, iii) bare sediments. Denitrification rates were measured in situ using denitrification chambers and nitrogen isotope pairing technique three times during a growing season.

Probing the Response of the Amphibious Plant to Nutrient Enrichment and Shading by Integrating Eco-Physiological With Metabolomic Analyses.

Amphibious plants, living in land-water ecotones, have to cope with challenging and continuously changing growth conditions in their habitats with respect to nutrient and light availability. They have thus evolved a variety of mechanisms to tolerate and adapt to these changes. Therefore, the study of these plants is a major area of ecophysiology and environmental ecological research.

Short-period hydrological regimes override physico-chemical variables in shaping stream diatom traits, biomass and biofilm community functions.

Despite increasing interest in hydrological effects on riverine ecosystems, few studies have documented the impact of hydrology on biofilm community functions, and those existing have typically focused on annual-based hydrological indices. In this study, we conducted monthly samplings during a year in five lowland streams with different flow regimes and investigated the impacts of hydrological conditions and physico-chemical variables on the trait composition of diatoms growing on artificial substrates, biomass (chlorophyll a and ash free dry weight), and biofilm community functions (biochemical processes, i.e.

Hydraulic effects of stormwater discharge into a small stream.

The focus of this study is to describe the hydraulic effects of stormwater discharge, thus sediment transport occurring as a result of increased discharge from a stormwater detention pond, based on measurements made in a small high-slope Danish stream. In order to extrapolate the findings and predict the result of larger discharge flow rates from the detention pond in this study, 11 traditional threshold equations were tested, and results were compared to the sediment transport experiment with five formulas predicting the threshold based on shear stress and six based on stream power. The sediment transport experiment was constructed as a staircase pattern, step-wise increasing the discharge.

Effects of low flow and co-occurring stressors on structural and functional characteristics of the benthic biofilm in small streams.

Low flow and co-occurring stress is a more and more frequent phenomenon these years in small agricultural streams as a consequence of climate change. In the present study we explored short and longer term structural responses of the stream benthic algae community and biofilm metabolism to multiple stress in small streams applying a semi-experimental approach. We hypothesized that i) a reduction in flow in combination with secondary stress (nutrients and sediments) have immediate effects on the benthic algae community in terms of biomass (chlorophyll a, biovolume), taxonomic and trait (lifeform and size distribution) compositions as well as on metabolism (GPP and CR), and ii) that changes in the benthic algae community persist due to altered environmental settings but that functional redundancy among benthic algae species provides a high level of resilience in metabolism (GPP and CR).

Hydromorphology as a controlling factor of macrophytes assemblage structure and functional traits in the semi-arid European Mediterranean streams.

Macrophytes have a crucial impact on stream functioning. However, there is a significant gap of knowledge about how hydromorphological fluctuations affect their structural and functional responses in southern Mediterranean streams. In this study, we investigated the impact of hydromorphology on macrophyte stream assemblages in Cyprus and analysed their structural and functional responses.

Environmental filtering of native and non-native stream macrophyte assemblages by habitat disturbances in an agricultural landscape.

Understanding how inter-specific variation in functional traits affects native and non-native species responses to stream disturbances, is necessary to inform management strategies, providing tools for biomonitoring, conservation and restoration. This study used a functional trait approach to characterise the responses of macrophyte assemblages to reach-scale disturbances (measured by lack of riparian shading, altered hydromorphology and eutrophication), from 97 wadeable stream sites in an agriculturally impacted region of New Zealand. To determine whether macrophyte assemblages differed due to disturbances, we examined multidimensional assemblage functional structure in relation to eleven functional traits and further related two functional diversity indices (entropy and originality) to disturbances.

Microbial Organic Matter Utilization in High-Arctic Streams: Key Enzymatic Controls.

In the Arctic, climate changes contribute to enhanced mobilization of organic matter in streams. Microbial extracellular enzymes are important mediators of stream organic matter processing, but limited information is available on enzyme processes in this remote area. Here, we studied the variability of microbial extracellular enzyme activity in high-Arctic fluvial biofilms.

The future of European water management: Demonstration of a new WFD compliant framework to support sustainable management under multiple stress.

The Water Framework Directive (WFD), which is the most comprehensive instrument of EU water policy, is more relevant than ever. Sixty percent of Europe's surface water bodies still fail to achieve good ecological status and a multitude of new stressors continue to emerge. A sustained and wholehearted water management effort is therefore of highest priority.

Structural and functional responses of plant communities to climate change-mediated alterations in the hydrology of riparian areas in temperate Europe.

The 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.

Hydrological and environmental variables outperform spatial factors in structuring species, trait composition, and beta diversity of pelagic algae.

There has been increasing interest in algae-based bioassessment, particularly, trait-based approaches are increasingly suggested. However, the main drivers, especially the contribution of hydrological variables, of species composition, trait composition, and beta diversity of algae communities are less studied. To link species and trait composition to multiple factors (i.

Multiple stress response of lowland stream benthic macroinvertebrates depends on habitat type.

Worldwide, lowland stream ecosystems are exposed to multiple anthropogenic stress due to the combination of water scarcity, eutrophication, and fine sedimentation. The understanding of the effects of such multiple stress on stream benthic macroinvertebrates has been growing in recent years. However, the interdependence of multiple stress and stream habitat characteristics has received little attention, although single stressor studies indicate that habitat characteristics may be decisive in shaping the macroinvertebrate response.