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Freshwater biodiversity is severely threatened, and despite many efforts to halt biodiversity loss the decline continues. Here, we used a transplantation approach to explore whether failure to reverse this trend for freshwater plants reflects that restoration measures applied to streams are inadequate for restoring suitable habitat conditions for plant species in decline.We identified declining species within the plant genus Potamogeton and introduced five of these (Potamogeton compressus L., Potamogeton gramineus L., Potamogeton lucens L., Potamogeton praelongus Wulfen., and Potamogeton pusillus L.) into five restored lowland stream reaches in three different habitat types to examine species establishment and growth.We found that plant establishment varied among streams and species, but we did not see any effect of habitat type within streams on either species growth or survival. Potamogeton compressus and P. pusillus failed to overwinter, while P. gramineus, P. lucens, and P. praelongus were all able to establish viable stands and to overwinter successfully in several of the experimental streams.Our results suggest that suitable habitats are available for declining Potamogeton species in restored stream reaches in Denmark, but their continued growth may be challenged by limited overwintering success. Consequently, we find it likely that dispersal constraints prevent declining Potamogeton species from naturally recolonising restored stream reaches.Understanding the importance of life history traits, such as overwintering and dispersal, can be crucial for the recovery of plant diversity in streams. Here we show that species that survived during winter were those with extensive growth of roots and rhizomes making them more adapted to withstand high flows than species relying on seeds and turions for overwintering. The creation of calmer backwater habitats can therefore be crucial when restoring stream reaches since these habitats may facilitate overwintering of species lost from the main channel during winter. [ABSTRACT FROM AUTHOR]

1 Freshwater habitats in cultivated and densely populated lowland regions of Europe have experienced profound changes during the last 100years. We take advantage of the long interest in aquatic plants in Denmark to compare the submerged flora in lakes and streams in 1896 and 1996. 2 Most of the lakes which contained a diverse submerged vegetation 100 years ago now have the high phytoplankton biomasses and summer transparencies below 2.0 m characteristic of eutrophication. The majority of 17 lakes included in both old and recent studies have lost all or most of their submerged species. Species richness for those lakes that were vegetated did not, however, differ significantly between old and recent studies. 3 Species richness declined markedly in the 13 streams included in both studies. Over all sites, there was also a significant decline of species richness per locality. Potamogeton species declined from 16 to 9, despite an 8-fold increase in the number of sites surveyed. 4 Similar compositions and rank-abundances of Potamogeton species in lakes and streams studied 100 years ago reflect suitable growth conditions and mutual exchange of propagules. Today, low habitat diversity and frequent disturbance in streams and low recruitment from lakes favours only robust, fast-growing species capable of regrowth following weed cutting and dredging. 5 A positive interspecific relationship observed in the contemporary stream vegetation between mean local abundance and number of occupied sites was probably promoted by redistribution of plants as a result of disturbance and efficient dispersal in the interconnected stream network. 6 The freshwater macrophyte flora in north-west Europe presently includes a high proportion of rare species which are threatened by extinction. Both species typical for oligotrophic conditions (e.g.P. ,filiformis and P. polygonifolius) and another group of large, slow-growing species (e.g.P. alpinus, P. lucens, P. praelongus and P. zosterifoli... [ABSTRACT FROM AUTHOR]

In Denmark suction cup-measured nitrate concentrations in soil water and N leaching have been used as a means for monitoring the impact of changes in the consumption of commercial fertilizer and improved utilisation of nitrogen in manure by agriculture. The measurements are a part of the Danish Agricultural Monitoring Programme (NOVANA) and are carried out in five small agricultural dominated catchments covering differences in climate, soil types and farming practices within the country. Statistical analyses allowing for annual variations in climate showed that nitrate concentrations in root zone water from loamy and sandy catchments decreased by, respectively, 23 and 48% during 1991–2003, after which no further decrease occurred until 2010/11. The aim of this study is to describe how the year to year variations in percolation and field balance characterise N leaching for 30 soil water stations in the period 1991–2010. A general linear model for annual observations of N leaching, N leaching = 3479 + 0.140 × percolation + 0.080 × surface N balance − 1.737 year, explained 29% of the variation. When N leaching was calculated as a mean for each soil water station for the period 1991–2010, the field N balance explained about 44% of the variation in leaching between the 16 soil water stations located in loamy catchments. A lower proportion, 36%, was recorded for the 14 soil water stations located in sandy catchments, but the signature increased to 60% if an outlier field, having a large excess input of manure, was omitted. From these results for Danish catchments, we conclude that field N balances are able to predict the risks of leaching provided that measurements are integrated over 30 soil water stations or a relatively long monitoring period. However, the data showed that the leaching responses to the field balance are different for loamy and sandy soils and depend on farm type. [ABSTRACT FROM AUTHOR]

In Denmark suction cup-measured nitrate concentrations in soil water and N leaching has been used as a means for monitoring the impact of changes in consumption of commercial fertilizer and improved utilisation of nitrogen in manure by agriculture. The measurements are a part of the Danish Agricultural Monitoring Programme (NOVANA) and are carried out in five small agricultural dominated catchments covering differences in climate, soil types and farming practices within the country. Statistical analyses allowing for annual variations in climate showed that nitrate concentrations in root zone water from loamy and sandy catchments decreased by, respectively, 23 and 48% during 1991–2003, after which no further decrease occurred until 2010/11. The aim of this study is to describe how the year to year variations in percolation and field balance characterise N leaching for 30 soil water stations in the period 1991–2010. A general linear model for annual observations of N leaching, N leaching = 3479 + 0.140 × percolation + 0.080 × surface N balance − 1.737 year, explained 29% of the variation. When N leaching was calculated as a mean for each soil water station for the period 1991–2010, the field N balance explained about 44% of the variation in leaching between the 16 soil water stations located in loamy catchments. A lower proportion, 36%, was recorded for the 14 soil water stations located in sandy catchments, but the signature increased to 60% if an outlier field, having a large excess input of manure, was omitted. From these results for Danish catchments, we conclude that field N balances are able to predict the risks of leaching provided that measurements are integrated over 30 soil water stations or a relatively long monitoring period. However the data showed that the leaching responses to the field balance are different for loamy and sandy soils and depend on farm type. [ABSTRACT FROM AUTHOR]

Terrestrial adult stages of freshwater insects may be exposed to pesticides by wind drift, over-spray, contact or feeding. However, studies addressing insecticide effects on freshwater invertebrates focus primarily on the impact of pesticides reaching the streams and potentially harming the aquatic juvenile stages. This is also reflected in the current risk assessment procedures, which do not include testing of adult freshwater insects. In order to assess the potential impact of insecticides on adult stages of freshwater insects, we exposed six common species to the insecticides Karate (lambda-cyhalothrin) and Confidor (imidacloprid). Dose-response relations were established, and LD 50 estimates were compared to those of the honey bee, Apis mellifera L. (Hymenoptera: Apidae), which is the standard terrestrial test insect when pesticides are evaluated prior to commercial release. Generally, the tested species were more sensitive to the studied insecticides than the honey bee. In order to examine whether the sensitivity of adult stages of freshwater insects corresponds with the sensitivity of the juvenile stages of the same species, the ranking of the two life stages with respect to the toxicity of Karate was compared, revealing some correspondence, but also some dissimilarities. Our results strongly indicate that terrestrial adult stages of aquatic insects are not adequately protected by current risk assessment procedures., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

The combination of intensive agricultural activities and the close connectivity between land and stream emphasise the potential risk of pesticide exposure in Danish streams. Benthic macroinvertebrates are applied in the assessment of stream ecological status, and some sensitive species have been shown to respond strongly to brief pulses of pesticide contamination. In this study we investigate the impact of agriculturally derived pesticides on stream macroinvertebrate communities in Denmark. As a measure of toxic pressure we apply the Runoff Potential. We investigated a total of 212 streams. These were grouped into distinct classes according to the magnitude of pesticide contamination in the period from 2003-2006. A total of 24 different macroinvertebrate indices were applied to detect effects of pesticide runoff (e.g. the SPEAR-index and the number of EPT taxa). We found high predicted pesticide runoff in 39% of the streams, but we found no significant effect of predicted pesticide exposure on stream macroinvertebrate indices. We, additionally, examined the influence of a series of environmental parameters ranging from site scale to catchment scale on the macroinvertebrate community. Relative proportions of gravel, sand and silt in bed sediments explained most of the variation in macroinvertebrate indices as well as the upstream riparian habitat quality. We suggest that the Runoff Potential model overestimate pesticide runoff contamination in Danish streams due the presence of buffer strips enforced by Danish legislation. When pesticide runoff contamination is low to moderate, poor physical properties (indirectly related to agricultural activity) are the main impediment for the ecological quality of Danish streams.

Introduction: Since the beginning of the nineties, skate-boards, in-liners, roller skates, and during the past years non-powered scooters have gained increasing popularity. This surge of enthusiasm has resulted in an increasing number of injuries involving scooters., Material and Methods: The subject of our study was to ascertain injuries resulting from scooter usage based on consecutive sampling of patients treated at the casualty department of Odense University Hospital in Denmark between January 1st 1996 and December 31st 2001., Results: 162 patients were registered. 86% of the injuries occurred in the years 2000 and 2001. The major part took place among children under the age of fifteen (93% of all). 94% of the injuries were sustained because the person tumbled when scooting. The injuries were distributed as follows: skull/face 51 (32%), upper extremity 78 (48%), lower extremity 31 (17%), and trunk 2 (1%). 43 persons sustained a fracture of which 32 (74%) were located to the upper extremity., Discussion: Based on the distribution of severe injuries by body regions the results advocates usage of wrist protection at all ages when using a scooter, and parents are advised to restrict usage of scooters to children above the age of eight. Furthermore the study underlines the need for precise registration and code procedures in the emergency room. Otherwise injuries resulting from new products or behaviours cannot be identified.