Eva Bergman

Eva Bergman
Karlstads Universitet · Department of Environmental and Life Sciences

Professor

About

93
Publications
16,396
Reads
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2,709
Citations
Citations since 2017
27 Research Items
1172 Citations
2017201820192020202120222023050100150200
2017201820192020202120222023050100150200
2017201820192020202120222023050100150200
2017201820192020202120222023050100150200
Introduction
Research including studies on migrating fish in regulated rivers, on food web ecology in riparian ecosystem; on fish adapting to a changing climate
Additional affiliations
January 1999 - present
November 1987 - June 1988
Michigan State University
Position
  • Guest PhD-student
January 1984 - November 1997

Publications

Publications (93)
Article
Full-text available
Retention of forested buffers around streams following forest cutting operations is a common management technique used to protect aquatic resources and conserve the surrounding ecosystem services. Species richness, or α-diversity, is commonly used as an indicator of the effects of forestry management although it provides very little information abo...
Article
Full-text available
Non-technical summary Rivers are crucial to the water cycle, linking the landscape to the sea. Human activities, including effluent discharge, water use and fisheries, have transformed the resilience of many rivers around the globe. Sustainable development goal (SDG) 14 prioritizes addressing many of the same issues in marine ecosystems. This revie...
Article
Full-text available
Large boreal rivers in Sweden are generally impounded by hydropower dams and a large proportion of main stem shallow flowing habitats have been lost. Tributaries often contain the last undisturbed habitats and could be important for the conservation of species diversity. In particular, tributary mouth areas could be biodiversity hot-spots, due to t...
Technical Report
Full-text available
Vattenkraften är viktig för Sveriges omställning till fossilfri elproduktion. För att öka vattenkraftens hållbarhet som energikälla behövs miljöåtgärder som gör att elproduktionens miljöeffekter minimeras där det är möjligt. Regleringen av vattenflöden leder ofta till att vattendragens ekosystem förändras med förlust av biologisk mångfald och ekosy...
Preprint
Rivers networks represent hierarchical dendritic habitats within terrestrial landscapes and differences in connectivity and land use influence dispersal, and consequently biodiversity patterns. We, therefore, measured variation in water chemistry and fish abundance and related these to a number of landscape characteristics (e.g. wetland, urban, woo...
Article
Full-text available
River connectivity is a major environmental factor affecting fish migration through river systems. Anthropogenic barriers cause substantial delays and mortality to long-migrating diadromous fish, such as salmonids. Downstream bypasses have received little attention over the years and can be constructed in several ways, with bypass acceptance by fis...
Article
Full-text available
Decomposition is essential to carbon, nutrient, and energy cycling among and within ecosystems. Several methods have been proposed for studying litter decomposition by using a standardized and commercially available substrate. One of these methods is the Tea Bag Index (TBI) which uses tea bags (green and rooibos tea) incubated for ~90 days. The TBI...
Preprint
Large boreal rivers in Sweden are generally impounded by hydropower dams and a large proportion of their main stem shallow flowing habitats have been lost. Tributaries often contain relatively undisturbed habitats and could be important for the conservation of species diversity. Tributary mouth areas could be biodiversity hot-spots, due to the vici...
Article
Full-text available
1. Predator-prey interactions are one of the main ecological factors influencing the structure of fish communities. The impact of wading and diving semi-aquatic predators on riverine fish populations is poorly known. We studied the effect of feral American mink predation on brown trout juveniles during winter in two experiments conducted in semi-na...
Article
Full-text available
As top consumers and generalist predators, spiders are ideal organisms to study food webs and complex ecological functions using stable isotopes. Most researchers use whole-body samples to analyze stable isotope ratios in spiders. Spiders can regrow lost legs and produce multiple molts during a life cycle, and nonlethal sampling utilizing legs and...
Article
Full-text available
Historically, ecological engineered solutions for fish passage across anthropogenic barriers in rivers has mainly focused on facilitating upstream passage for long-migrating diadromous fish, such as salmonids. More recently, passage solutions have shifted their focus to a more holistic ecological perspective, allowing passage for species with diffe...
Article
Temperature during egg incubation and early development influences later life stages of fishes, potentially influencing survival. Throughout its distribution, Atlantic salmon (Salmo salar Linnaeus, 1758) have experienced population declines, and in view of ongoing global warming, we tested if temperature during the earliest developmental stages mod...
Article
Managing and conserving threatened migratory salmonid populations in large river-lake ecosystems is challenging not only because of the ecosystems’ large size, but also because there is often more than one anthropomorphic stressor. The River Klarälven-Lake Vänern ecosystem, situated in Norway and Sweden, is a large highly modified ecosystem, home t...
Article
Worldwide declines in salmonid populations have generated major interest in conservation and restoration of wild populations and riverine habitats. Species reintroductions to previous habitats raises questions about their potential impact on these systems. In River Klarälven, landlocked Atlantic salmon (Salmo salar) has been extinct from upper reac...
Article
Passage of hydropower plants by upstream-migrating salmonid spawners is associated with reduced migration success, and the need for knowledge of fish behavior downstream of dams is widely recognized. In this study, we examined fishway passage of landlocked Atlantic salmon in River Klarälven, Sweden and brown trout in River Gudbrandslågen, Norway, a...
Article
Full-text available
Background Temperature affects many aspects of performance in poikilotherms, including how prey respond when encountering predators. Studies of anti-predator responses in fish mainly have focused on behaviour, whereas physiological responses regulated through the hypothalamic-pituitary-interrenal axis have received little attention. We examined pla...
Article
Recreational fishing has grown substantially worldwide; for some recreational fisheries both catch and economic value now exceeds that of commercial fisheries. Monitoring of recreational fisheries effort and catch is therefore important for sustainable fisheries management. We developed and implemented an angler survey to estimate effort and catch...
Article
Low winter temperatures constrain predator‐detection and escape capabilities, making poikilotherms vulnerable to predation. Investigations of temperature effects on predator–prey interactions can therefore be of special importance in light of ongoing climate change, where winter temperatures are predicted to increase substantially at northern latit...
Article
Full-text available
In this study, the growth rate, gut fullness, diet composition and spatial distribution of brown trout was compared between artificial channels with and without fine wood (FW). Access to FW resulted in significantly lower brown trout growth rates over the study period from late summer to early winter as water temperatures declined from 17 °C to 1 °...
Article
Full-text available
Cross‐boundary fluxes of organisms and matter, termed “subsidies,” are now recognized to be reciprocal and of roughly equal importance for both aquatic and terrestrial systems, even if terrestrial input to aquatic ecosystems has received most attention. The magnitude of aquatic‐to‐terrestrial subsidies is well documented, but the drivers behind the...
Article
Full-text available
Non-anadromous Atlantic salmon (Salmo salar) exhibit a combination of variation in life history, habitat, and species co-existence matched by few vertebrates. Distributed in eastern North America and northern Europe, habitat ranges from hundreds of metres of river to Europe’s largest lakes. As juveniles, those with access to a lake usually migrate...
Preprint
Full-text available
Cross-boundary fluxes of organisms and matter, termed 'subsidies', are now recognized to be reciprocal and of roughly equal importance for both aquatic and terrestrial systems, even if terrestrial input to aquatic ecosystems has received most attention. The magnitude of aquatic to terrestrial subsidies is well documented, but the drivers behind the...
Article
Full-text available
Populations of fishes provide valuable services for billions of people, but face diverse and interacting threats that jeopardize their sustainability. Human population growth and intensifying resource use for food, water, energy and goods are compromising fish populations through a variety of mechanisms, including overfishing, habitat degradation a...
Article
The purpose of this study was to investigate behavior and survival of radio-tagged wild- and hatchery-reared landlocked Atlantic salmon smolts as they migrated past three hydropower dams equipped with fish bypass solutions in the Winooski River, Vermont, USA. Among hatchery-released smolts, those released early were more likely to initiate migratio...
Article
Studying fish behaviour at hydropower dams is needed to facilitate the design and improvement of fish passage solutions, but few studies have focused on Atlantic salmon kelts. Here, we used radio telemetry (n = 40, size range = 50–81 cm) and acoustic sonar to study kelt movements in the forebay as well as their dam passage survival and subsequent m...
Article
Full-text available
Behavioral assays constitute important research tools when assessing how fish respond to environmental change. However, it is unclear how behavioral modifications recorded in laboratory assays are expressed in natural ecosystems, a limitation that makes it difficult to evaluate the predictive power of laboratory-based measurements. In this study, w...
Article
In boreal streams, juvenile salmonids spend substantial amounts of time sheltering in the streambed and in stream wood, presumably as a means of protection against the physical environment and from terrestrial endothermic predators. Relatively little is known about sheltering by salmonids in response to instream ectothermic predators. We tested the...
Article
Passage of fish through hydropower dams is associated with mortality, delay, increased energy expenditure and migratory failure for migrating fish and the need for remedial measures for both upstream and downstream migration is widely recognised. A functional fish passage must ensure safe and timely passage routes that a substantial portion of migr...
Article
Full-text available
Protection provided by shelter is important for survival and affects the time and energy budgets of animals. It has been suggested that in fresh waters at high latitudes and altitudes, surface ice during winter functions as overhead cover for fish, reducing the predation risk from terrestrial piscivores. We simulated ice cover by suspending plastic...
Article
Full-text available
Most studies of stream wood have focused on pieces ≥0.1 m diameter. However, this approach may overlook an important feature of small streams, where wood <0.1 m can constitute the majority of wood pieces. We examined the effect of fine wood (FW) on local drift of stream macroinvertebrates. The study was carried out at seven sites in four boreal for...
Article
Full-text available
In-stream wood can increase shelter availability and prey abundance for stream-living fish such as brown trout, Salmo trutta, but the input of wood to streams has decreased in recent years due to harvesting of riparian vegetation. During the last decades, fine wood (FW) has been increasingly used for biofuel, and the input of FW to streams may ther...
Article
Prior to out-migration, salmonid fish typically undergo physiological and morphological changes — a process known as smolting. This study indicates that smolting in brown trout (Salmo trutta) is affected by feeding conditions in spring immediately prior to out-migration. This conclusion was reached after experimentally testing the effect of seasona...
Article
Repeat salmonid spawners may make large contributions to total recruitment and long term population stability. Despite their potential importance, relatively little is known about this phase of the life history for anadromous populations, and nothing has been reported for landlocked populations. Here, we studied post-spawning behaviour and survival...
Article
Full-text available
Surface ice in rivers and lakes buffers the thermal environment and provides overhead cover, protecting aquatic animals from terrestrial predators. We tested if surface ice influenced the behavior (swimming activity, aggressive encounters, and number of food items eaten) and stress level (coloration of eyes and body) of stream-living brown trout Sa...
Article
Full-text available
Upstream migration by adult salmonids is impeded by dams in many regulated rivers, as is the case for landlocked Atlantic salmon, Salmo salar, in the River Klarälven, Sweden. There, the salmon cannot reach the spawning grounds due to the presence of eight dams. Hence, hatchery-reared smolts are released downstream of the dams, and upstream migratin...
Article
Full-text available
Periphyton communities of a boreal stream were exposed to different light and nutrient levels to estimate energy transfer efficiency from primary to secondary producers using labeling with inorganic 13C. In a one-day field experiment, periphyton grown in fast-flow conditions and dominated by opportunistic green algae were exposed to light levels co...
Article
The migratory behaviour of hatchery-reared landlocked Atlantic salmon Salmo salar raised under three different feeding regimes was monitored through the lower part of the River Klarälven, Sweden. The smolts were implanted with acoustic transmitters and released into the River Klarälven, 25 km upstream of the outlet in Lake Vänern. Early mature male...
Article
The effects of feed quality and quantity on growth, early male parr maturation and development of smolt characteristics were studied in hatchery-reared landlocked Atlantic salmon Salmo salar. The fish were subjected to two levels of feed rations and two levels of lipid content from first feeding until release in May of their second year. Salmo sala...
Article
Full-text available
Co-management is of increasing interest for fisheries management. We explore possibilities for, and barriers to, developing a co-management system, using threatened populations of landlocked Atlantic Salmon and Brown Trout as examples. Good management of natural resources requires not only knowledge about the resource, but also suitable tools to co...
Article
Changes to the riparian vegetation of forest streams during timber harvesting may have considerable impacts on stream biota, but few studies have attempted to separate the effects of individual factors that are altered during clear-felling operations.We studied the effects of large wood and terrestrial invertebrate supply, two factors affected by f...
Article
Intensive forestry and other activities that alter riparian vegetation may disrupt the connectivity and the flux of energy between terrestrial and aquatic habitats and have large effects on biota, especially in small streams. We manipulated the amount of in-stream wood and the flux of terrestrial invertebrate subsidies to determine how these factor...
Article
Full-text available
The foraging success of predators depends on how their consumption of prey is affected by prey density under different environmental settings. Here, we measured prey capture rates of drift-feeding juvenile brown trout and European grayling at different prey densities in an artificial stream channel at 5 and 11 °C. Capture rates were lower at 5 than...
Article
Full-text available
Preferring one social partner over another can enhance fitness. This paper reports that juvenile grayling were significantly more likely to enter and forage in new, upstream habitats when paired with familiar versus unfamiliar social partners. Fish paired with unfamiliar partners or when alone were more reluctant to enter the new area. The entry ti...
Article
Relatively little is known about the downstream migration of landlocked stocks of Atlantic salmon Salmo salar L. smolts, as earlier migration studies have generally focused on upstream migration. However, in watersheds with many hydroelectric plants (HEPs), multiplicative loss of downstream-migrating salmon smolts can be high, contributing to popul...
Article
1. Winter ice conditions in boreal streams are highly variable, and behavioural responses by fish to river ice may affect overwinter survival rates. One type of ice, surface ice, stabilises water temperatures, reduces instream light levels and may provide overhead cover. 2. Because surface ice is believed to afford protection against endothermic pr...
Article
Full-text available
Drift-feeding salmonids in boreal streams face temperatures below physical optima for extensive periods of the year. Because juvenile salmonids react to low water temperatures by becoming nocturnal, knowledge about their foraging ability at low light intensities in cold water is needed to accurately estimate energy intake during non-summer conditio...
Article
Full-text available
This article describes the results of a nationwide questionnaire study of 3229 Swedish upper secondary school teachers’ conceptual understanding of sustain-able development in relation to their subject discipline and teaching experience. Previous research has shown that teachers have difficulties understanding the complex concept of sustainable deve...
Technical Report
Full-text available
Forskargruppen Naturresurs Rinnande Vatten på ämnet biologi vid Karlstads universitet medverkar i det Interregfinansierade projektet Vänerlaxens fria gång. Under två år har vi genomfört projekt i Klarälven i syfte att lära oss mer om laxens biologi i Klarälven. För att kunna genomföra en god förvaltning av ett ekosystem måste man ha goda kunskaper...
Article
Conservation of migratory salmonids requires understanding their ecology at multiple scales, combined with assessing anthropogenic impacts. We present a case-study from over 100 years of data for the endemic landlocked Atlantic salmon (Salmo salar, Salmonidae) and brown trout (Salmo trutta, Salmonidae) in Lake Vänern, Sweden. We use this case-study...
Article
Prey capture success and foraging mode were studied in brown trout Salmo trutta at temperatures ranging from 5.7 to 14.0° C. At low temperatures, there was a positive correlation between prey capture success and the proportion of time that the fish spent holding feeding stations. This correlation was not found at temperatures >10° C.
Article
Full-text available
Background: According to the Swedish curriculum teachers in all subjects have a responsibility to integrate a holistic perspective of sustainable development (SD) and teach according to an education for sustainable development (ESD) approach. However previous research has shown that teachers from different subjects perceive SD differently.Purpose:...
Article
Full-text available
Subsidies of energy and material from the riparian zone have large impacts on recipient stream habitats. Human-induced changes, such as deforestation, may profoundly affect these pathways. However, the strength of individual factors on stream ecosystems is poorly understood since the factors involved often interact in complex ways. We isolated two...
Data
Trout diet. Seasonal changes in the frequency of occurrence (O%) and mean relative biomass (A%) of the most important food items in the diet of young (Y) and old (O) trout in unmanipulated (U), light (L), terrestrial invertebrate reduction (TR) and terrestrial invertebrate reduction and light (TRL) treatments throughout the study period. Chironomid...
Article
Summary1. Changes in riparian vegetation owing to forest harvesting may affect the input of large wood, a major structural element, to streams. Studies of large wood impacts on stream fish have focused on population‐level responses, whereas little attention has been given to how wood affects fish behaviour.2. In a laboratory stream experiment, we t...
Conference Paper
The River Klarälven /Trysilelva/Femundselva is home to the endemic, landlocked and iteroparous Atlantic salmon, which historically migrated up to 400 km between Lake Vänern in Sweden and spawning and nursery areas in Sweden and Norway. Fragmentation and loss of longitudinal connectivity caused by the development of 11 run-of-river power plants over...
Conference Paper
Trout foraging in small forested streams is largely affected by the surrounding forest, both by affecting habitat structure and prey availability. In this presentation we focus on trout responses to woody debris and terrestrial invertebrates, two factors influenced by riparian zone structure, potentially affecting streams and foraging of brown trou...
Conference Paper
Hydroelectric plants (HEPs), with their dams and turbines, interrupt connectivity in water bodies and constitute barriers and sources of mortality for upstream-migrating spawners and downstream-migrating smolts and kelts. In watersheds with multiple dams the cumulative losses of migrating juvenile salmon can be high, contributing to population decl...
Article
Abstract –  The possibility to increase the proportion of migrating hatchery-reared smolts by reducing their food ration was studied. Lake-migrating, hatchery-reared salmon (Salmo salar) and trout (Salmo trutta) smolts were either fed normal rations, based on recommendations from the fish-farming industry, or reduced (15–20%) rations. They were rel...
Article
Terrestrial invertebrate subsidies are believed to be important energy sources for drift-feeding salmonids. Despite this, size-specific use of and efficiency in procuring this resource have not been studied to any great extent. Therefore, we measured the functional responses of three size classes of wild brown trout Salmo trutta (0+, 1+ and >= 2+)...
Article
Full-text available
Effects of temperature and group size of roach Rutilus rutilus on foraging behaviour of perch Perca fluviatilis and R. rutilus were tested in two laboratory experiments. A temperature experiment with P. fluviatilis and R. rutilus in aquaria (with either one P. fluviatilis or two R. rutilus) was tested at five temperatures: 4, 8, 12, 16 and 20° C, a...
Article
Full-text available
We examined relationships among perch population variable parameters in two types of lakes, lakes with perch (P-lakes, n = 15) and lakes with perch and roach (PR-lakes, n = 10) using redundancy analysis (RDA) to relate population variables to environmental factors. Effects from environmental factors were tested for significance by means of permutat...
Article
Abstract – Alternative reproductive tactics are commonly reported for salmonids (Pisces) and typically involve large migratory and small resident individuals. Variation in migratory tendency should reflect the different benefits and costs that the two different phenotypes face with regard to fitness. Therefore, the effect of food availability on th...
Article
Summary1. Invasive dreissenid mussels are known to cause large ecosystem changes because of their high filter-feeding capacity, while native bioturbators may interfere with the mussels filter feeding. In this experiment, we investigated indirect environmental interactions between invasive filter-feeding dreissenid mussels (zebra and quagga mussels)...
Article
The decision to migrate or not is regarded as genetically controlled for many invertebrate and vertebrate taxa. Here, we show that the environment influences this decision. By reciprocally transplanting brown trout (Salmo trutta L.) between two sections in a river, we show that both migratory and non-migratory behaviour can be environmentally induc...
Article
Abstract— We studied habitat use, foraging rates and behavior of 10 cm and 12 cm long brown trout, Salmo trutta, at two densities, 1.5 and 3.0 fish. m−2, in artificial streams that contained either the amphipod, Gammarus pulex, alone or G. pulex together with the piscivore, northern pike, Esox lucius. Gammarus were stocked in and largely restricted...
Article
The indirect behavioral effect of piscivorous pike (Esox lucius) on the growth and diet of brown trout (Salmo trutta) as well as the consequences of the pike-trout interaction for benthic macroinvertebrates and periphytic algae were studied in nine 2 × 3 m field stream enclosures. The indirect effect of pike on trout behavior was studied by holding...
Article
The impact of young-of-the-year (YOY) fish predation on zooplankton dynamics and cascading effects down to phytoplankton were studied in lake enclosures using different densities of larval and juvenile European perch ( Perca fluviatilis ). Two experiments, one in June and one in August, were performed in Lake Dagstorpssjon, a slightly eutrophic lak...
Article
The benthic macroinvertebrate community in a severely eutrophicated South Swedish lake, Lake Ringsjn, was found to re-establish after the lake was subjected to a substantial reduction of cyprinids (mainly bream and roach). Being totally dominated by chironomids and oligochaetes during the 1980s, the lake became repopulated by groups like Amphipoda,...
Article
In Lake Ringsjn, southern Sweden, we estimated yearly variations in both 0+ and older fish abundances, following the fish reductions in 1988–1992. Between 1987 and 1994, the total planktivore biomass decreased fourfold whereas the abundance of 0+ fish increased twenty times. The resulting change in predation pressure from planktivorous fish on zoop...
Article
The aim of this chapter is to present a general description of Lake Ringsjn and its catchment area, serving as a background for the following, more specific chapters. We briefly describe human activities and land use, as well as the human demographics in the catchment area. Moreover, we present important historical events behind the development and...
Article
Lake Ringsjn in southern Sweden was restored by biomanipulation by means of a reduction in zooplanktivorous cyprinids. The fish community in the three different Basins of Lake Ringsjn were followed between 1987 and 1994. In 1990, c. 100 tons (60% of the community) were removed from Stofta Basin, in 1988, c. 500 tons (80%) were removed from Eastern...
Article
Abundance, biomass and sizes of crustaceans were followed before, during and after a fish reduction in the three basins of Lake Ringsjön, southern Sweden. Zooplankton were sampled over the summer season (May–September) for eight years. Although the fish reduction occurred in different years in the three basins, the zooplankton community did not dif...
Article
In limnology, nutrients have historically been regarded as main regulators of the ecosystem; that is, organisms in lakes were seen as regulated from the bottom of the food chain. Long after the seminal works of Hairston et al. (1960), Hrbáek et al. (1961) and Brooks & Dodson (1965) this `bottom-up' view prevailed. It was not until the late 1970s an...