S. J. Saltveit

Natural History Museum, Norway

Rivers of the Boreal Uplands vary greatly in size and hydrological regime. The most typical feature of all rivers is their importance in valleys as landscape elements and as key economic centers. To reduce perturbations and maintain catchments for coming generations, 388 parts of or entire catchments are protected through a special Protection Plan...

The Norwegian electrical energy supply system is based on hydropower. The now deregulated energy market has led to increased use of hydropeaking production, leading to greater fluctuations in discharge and water levels below hydropower stations. The power station HOL 1, with an outlet to the Storåne River, is a large hydropeaking facility. With ove...

The Norwegian river Suldalslågen, known for its population of large‐sized Atlantic salmon (Salmo salar), has been regulated for hydropower in 1966–1967 and in 1980. The initial regulation increased winter flows and reduced summer flows and major floods. The second regulation, involving abstraction of water to a power station in an adjacent fjord, l...

Constructed stormwater ponds mitigate runoff volumes and pollution, and provide other ecosystem services, such as supporting biodiversity, but these services attracted relatively less attention. The impacts of the pollution levels in the water column and sediments, the physical characteristics of ponds, and the presence of amphibians on the macroin...

Altering hydrological and thermal regimes in hy-dropower-regulated rivers has the potential to impact early life stages of salmonid, including al-evins and eggs. Hydropeaking can lead to de-watering of spawning grounds and impact their natural development and survival, with different levels of affectation to alevins vs. eggs due to their tolerance...

Interactions between birds and fish are often overlooked in aquatic ecosystems. We studied the influence of Atlantic salmon and brown trout on the breeding population size and reproductive output of the white‐throated dipper in a Norwegian river. Acidic precipitation led to the extinction of salmon, but salmon recolonized after liming was initiated...

Global change threatens invertebrate biodiversity and its central role in numerous ecosystem functions and services. Functional trait analyses have been advocated to uncover global mechanisms behind biodiversity responses to environmental change, but the application of this approach for invertebrates is underdeveloped relative to other organism gro...

Alterations in hydrological and thermal regimes can potentially affect salmonid early life stages development and survival. The dewatering of salmon spawning redds due to hydropeaking can lead to mortality in early life stages, with higher impact on the alevins as they have lower tolerance to dewatering than the eggs. We present a set of modelling...

Recently, increased attention has been paid to biodiversity conservation provided by blue-green solutions such as engineered ponds that are primarily established for water treatment and flood control. However, little research has been done to analyse the factors that affect biodiversity in such ponds. The purpose of this study was to evaluate the i...

An effect of hydropower and hydropeaking regulation in rivers is stranding of fish. Those fishes that survive stranding may experience stranding as a stressful situation. In four experimental stranding experiments (each with 6 individuals in 10 control and 10 treatment replicates), the energetic consequences of two forms of stranding (i.e . trappin...

Alterations in hydrological and thermal regimes can potentially affect salmonid early life stages development and survival. The dewatering of salmon spawning redds due to hydropeaking can lead to mortality in early life stages, with higher impact on the alevins as they have lower tolerance to dewatering than the eggs. Flow-related mitigation measur...

The Water Framework Directive (WFD) requires the assessment of the ecological status of freshwater bodies including lotic ecosystems. Ecological status assessment relies on a number of indices that have been developed to indicate various types of environmental stress on ecological integrity. The indices require different types of data including dif...

The life cycle, including egg development and nymphal growth and nutrition of Amphinemura standfussi was studied both in the laboratory and in the field. In the laboratory eggs from a lowland river (Sørkedalselva) and two mountain lakes (Øvre Heimdalsvatn, Blåtjern), laid during August and September, hatched between December and April with peak hat...

This book summarises state-of-the art about environmental impacts from hydro-peaking operations in rivers, introducing rapid and frequent changes in discharge and water level. The book is considered relevant also for other types of abrupt changes in the operation of hydropower plants such as fallouts, or other controlled or non-controlled operation...

During their early life stages (egg maturation, hatching, alevin development), between late autumn and early spring, young Atlantic salmon are exposed to surface-groundwater interactions in the hyporheic zone and may depend on influx of subsurface water during periods of regulated low discharge for survival. Two studies, one in a seasonally regulat...

Groundwater may create refuges for Atlantic salmon egg survival during low flows in regulated rivers and thus play an important role for survival during winter. To investigate the links between the survival of salmon embryos and hyporheic hydrological processes during permanent winter drawdown, a 100-m-long and 50-m-wide gravel area in a regulated...

Hydropeaking in regulated rivers is likely to become more frequent with increasing demands for renewable energy. Sudden fluctuations affect surface and subsurface flow regimes and change hydrological interactions occurring in the hyporheic zone. The hyporheic zone plays an important role for salmon embryonic development, and groundwater influx may...

Most rivers and streams in the city of Oslo, Norway, rise in the surrounding forests, and all run through industrial and urban areas before they reach the sea. Most of these rivers have a long history of poor water quality in the middle and lower reaches until the early 1980s. This was reflected in low benthic diversity and the absence of fish. How...

In order to understand the factors giving rise to a stable and annual outbreak of the pest blackfly species Simulium truncatum (Lundström, 1911) (Simuliidae), the oviposition habitat has been localized and the egg density quantified at different contour levels in the studied regulated river channel bank. Larvae and adults of 12 blackfly species wer...

The genetic effects on Atlantic salmon, Salmo salar L., populations from potential bottleneck situations caused by human activities in two Norwegian rivers, Lærdalselva and Batnfjordelva, were studied by analysing DNA from fish scales collected before and after the populations had been exposed to human-induced changes: river regulation, Gyrodactylu...

Species traits have been identified as a component of biodiversity that is worthy of investigation as a tool for exploring ecological effects of anthropogenic disturbances. We used meta-analysis to show how selected species traits of Ephemeroptera and Plecoptera can be used to examine the ecological effects of flow and water-level regulation in fre...

Overview of environmental mitigations in regulated rivers (report in Norwegian)

Publisher Summary In Europe, the Boreal forest ecosystem centers around 60°N. The northern limit is roughly along the July 13 °C isotherm and the southern limit along the July 18 °C isotherm. This chapter describes the rivers within this region along the western coast of the Scandinavian Peninsula that drain into the Skagerrak or North Sea. A total...

Summer habitat use by sympatric Arctic charr Salvelinus alpinus, young Atlantic salmon Salmo salar and brown trout Salmo trutta was studied by two methods, direct underwater observation and electrofishing, across a range of habitats in two sub-arctic rivers. More Arctic charr and fewer Atlantic salmon parr were observed by electrofishing in compari...

Interspecific and intraspecific differences in egg development, nymphal growth and the life cycles of Fennoscandian stoneflies are examined in relation to zoogeographical aspects and evolutionary trends. Data on other European and North American species are also considered. Egg development shows considerable diversity, the main categories being ovo...

Abstract– Downstrcam displacement of salmonid fry due to flow increase, from 12–15 m3/s to >100 m3s, was documented in the river Suldalslåen, Western Norway. In May only fry of brown trout (Sulmo trutta) occurred in the drift, while from the beginning of June only newly emerged Atlantic salmon (Sulmo sular) were found. The maximum number of Atlanti...

Abstract Stocking is undertaken in the River Suldalslågen, western Norway, to compensate for an estimated annual loss of 20 000 Atlantic salmon smolts, Salmo salar L., caused by regulating the river for hydropower production. The annual contribution to angling catches from stocked hatchery fish varied from 7 to 334 kg, or <15% of the total number c...

Mass morality in minnows Phoxinus phoxinus (L) was investigated in the Vinje water system, southern-central Norway. The main clinical feature was the development of extensive haemorrhagic skin lesions from which was isolated a non-pigmented, fish-pathogenic strain of Aeromonas salmonicida.

Two methods, visual observation from the river bank and visual observation underwater by diving, were compared for microhabitat studies in young brown trout and Atlantic salmon in a stream. A wide range of habitat conditions were surveyed. Each method yielded different results with respect to microhabitat use. River bank observations missed small f...

Seasonal microhabitat selection by sympatric young Atlantic salmon and brown trout was studied by diving. Both species, especially Atlantic salmon, showed seasonal variation with respect to surface and mean water velocities and depth. This variation is partly attributed to varying water flows and water temperatures. In winter the fish sought shelte...

Direct underwater observation of micro-habitat use by 1838 young Atlantic salmon Salmo salar [mean LT 7·9 ± 3.1(s.d.) cm, range 3·19] and 1227 brown trout Salmo trutta (LT 10·9 ± 5·0 cm, range 3·56) showed both species were selective in habitat use, with differences between species and fish size. Atlantic salmon and brown trout selected relatively...

To provide environmental guidelines for operation of peaking hydropower plants, stranding experiments with juvenile brown trout (Salmo trutta) were conducted in a 3.8 m wide and 19.2 m long artificial stream. We found a significant decrease in stranding of trout fry by reducing the dewatering speed from >60 cm h−1 to <10 cm h−1. At water temperatur...

Two morphologically distinct moss communities were found in the River Suldalslågen. The liver moss community consists of species which form a dense mat on the bottom, while the river moss (Fontinalis) community forms long tufts. Moss growth has increased since hydropower regulations due to reduced floods and increased winter flows. Increased moss c...

1. Macroinvertebrate communities in two Norwegian glacial rivers, one in the western fjords (Dalelva) and one in the eastern mountains (Leirungsåi), were investigated during three time periods in 1996 and 1997. 2. Channel stability variables (substratum heterogeneity/Pfankuch index/hydraulic stress) and water temperature accounted for 54% of the to...

1. The influence of 11 environmental variables on benthic macroinvertebrate communities was examined in seven glacier-fed European streams ranging from Svalbard in the north to the Pyrenees in the south. Between 4 and 11 near-pristine reaches were studied on each stream in 1996–97. 2. Taxonomic richness, measured at the family or subfamily (for Chi...

1. Invertebrate drift was studied in a glacially fed river and a non-glacial tributary in western Norway. Samples were taken during two consecutive 24-h periods in May, July and October 1997. The 3 months are characterized by snowmelt, ice melt and rainfall runoff, respectively. The main glacial river has colder, more turbid water, especially durin...

Field experiments showed that sudden reductions in river flow may cause high mortality of juvenile salmonids through stranding. A 75-m2 enclosure in the drawdown zone of a regulated river was stocked with a known number of wild 0+ and/or 1+ wild Atlantic salmon (Salmo salar) and brown trout (Salmo trutta). The number stranded was estimated by count...

To identify possible critical minimum flows, habitat availability and habitat selection by young Atlantic salmon and brown trout on selected stream reaches were studied in a spatially and temporally heterogeneous Norwegian west coast river. Based on direct underwater observations of 1768 individuals across transects on each reach, unimodal habitat...

The lowermost 20 km of the River Surna, north-western Norway receives cool water during summer from a hypolimnetic release mountain reservoir. The benthic fauna is completely dominated by insects. Benthic densities immediately below the power station are much lower than at all other localities. Although benthic densities increase downstream of the...

Techniques for reducing adverse effects of river and lake regulation are being developed and tested within the framework of the Norwegian Biotope Adjustment Programme. The programme is illustrated by studies of a river flowing through the wetland area, Lesjaleirene, which has been drained and channelized to provide additional agricultural land. The...

Since the regulation of the river Lærdalselva in 1974 many juvenile Atlantic salmon Salmo salar and brown trout S. trutta have been stocked above the natural reach of anadromous fishes to compensate for possible loss in Atlantic salmon production. The parental material for the stocking was obtained from the lower parts of the river. In 1988 the num...

The lowermost 20 km of the River Surna, northwestern Norway receives cool water during summer from a hypolimnetic release mountain reservoir. In this part of the river, yearlings of both Atlantic salmon and brown trout are significantly smaller compared with those in the upper section of the river, which is unaffected by the cold water release. The...

Surface observation, diving, and electrofishing were compared as methods to study habitat use by young brown trout Salmo trutta and Atlantic salmon S. salar in a Norwegian river. These three methods often gave widely disparate information about habitat use by young of these two species. The probability of encountering individual fish varied when th...

The river Lærdalselva, West Norway, was regulated in the autumn of 1974. Regulation led to an increase in winter flow and a decrease in summer flow in a section where there was natural production of salmon. A slight decrease in summer temperature was also recorded in the uppermost part of this section. No data existed on juvenile Atlantic salmon be...

This report attempts to establish guide-lines for electrofishing in population studies and is the result of literature studies and experience from electrofishing in Denmark, Finland, Norway and Sweden. Equipment, safety and training, sampling design and precision requirements for various types of investigations, population estimation and fishing pr...

Impoundment and diversion of watercourses for power production and water supply can have profound effects on the mayfly fauna. To explain such effects a species-specific approach is adopted on account of differing habitat requirements and life histories in the order and even within genera. Environmental conditions such as discharge and flow pattern...

Stoneflies (Plecoptera) are a widespread and abundant order of benthic freshwater insects, especially in the running waters of temperate regions. They occupy a central role in trophic relationships both in terms of functional feeding groups and as fish food organisms. Although recorded from a range of freshwater habitats, the greatest species diver...

In the fjord lake Randsfjorden, Norway, the whitefish (Coregonus lavaretus) has four sympatric populations (Enge 1959). One of these spawns in the lower parts of the main inlet River Dokka-Etna, while the others spawn in the lake.