| 1. |
- Arvidsson, Björn L, 1952-, et al.
(författare)
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Recruitment of the threatened mussel Margaritifera margaritifera in relation to mussel population size, mussel density and host density
- 2012
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Ingår i: Aquatic conservation. - Malden, MA : John Wiley & Sons. - 1052-7613 .- 1099-0755. ; 22, s. 526-532
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Tidskriftsartikel (refereegranskat)abstract
- Anthropogenic, abiotic factors are considered main causes of recruitment failure of unionid mussels, including the freshwater pearl mussel (Margaritifera margaritifera). In this large-scale investigation, we instead examined the relationship between biotic factors and mussel recruitment.Juvenile mussel density was positively related to both mussel population size and density of which the last appeared to be a more accurate measure of recruitment.Host fish density of young-of-the-year and older brown trout (Salmo trutta) were positively related to recruitment. Moreover, the mean density of both age classes of fish, when grouped into density classes was positively related to juvenile mussel density, an effect that decreased at trout densities above 10 trout 100 m-2.There was a higher relative importance of mussel population size and density than trout density to recruitment.To increase recruitment of juvenile mussels, managers may apply measures that increase mussel density, and trout density up to about 10 trout 100 m-2 in connection to mussel beds. Mussel beds may also be managed and one possible measure within small and sparse mussel populations may be to concentrate the remaining mussels to areas where trout density is high. Likewise, young-of-the-year trout may also be moved to areas of high mussel density, as young trout individuals are relatively resident during their first year. This may increase mussel larval infection rates and mussel recruitment.
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| 2. |
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| 3. |
- Calles, Olle, 1974-, et al.
(författare)
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Fish Migration River Monitoring Plan
- 2014
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Fish have problems passing the Afsluitdijk Dam that separates the Wadden Sea from Lake IJsselmeer. To re-establish the connectivity and thereby allow fish to pass there is an initiative to build a fishway, the Fish Migration River (FMR), at the Konwerderzand sluice complex. This report proposes a monitoring program to evaluate the functionality of the FMR, but also to monitor passage possibilities through the existing sluices. The goals of the monitoring plan are to estimate 1) The overall passage past the Afsluitdijk dam to and from Lake IJsselmeer, 2) The attraction efficiency, 3) The passage efficiency, and 4) The use of the FMR as habitat and for acclimatization for the transition into freshwater.We present an overview of previous and ongoing monitoring in the area to establish the current state of knowledge. The report also includes a presentation of available and suitable methods for a future monitoring program considering the broad spectra of target fish species, and their abundances. The proposed program includes a description of study design and available techniques and cost-estimates of the monitoring program.The proposed program will target ten species: European eel (aal), flounder (bot), three-spined stickleback (dreidoornige stekelbaars), twait shad (fint), North Sea houting (houting), river lamprey (rieverprik), smelt (spiering), Atlantic salmon (zalm), brown trout (forel) and sea lamprey (zeeprik). The monitoring program includes plans for how to capture, tag and track the study fish using the most suitable tagging techniques. Furthermore, the most optimal sites for installation of automatic data detection stations are identified.The total cost for the proposed project is 3.5 M€ and covers both investments in equipment and costs for personnel. However, if costs for investments in techniques such as RFId-stations and fish counters are excluded, the total cost is reduced to 1 M€ for a program running two years before and four years after the completion of the FMR. The program is considered sufficient to evaluate the FMR at Kornwerederzand from the most important perspectives: the overall passage efficiency and the use of the FMR as habitat.It should be noted that this report is the first step towards a full-scale monitoring program, giving insight into possible methods, study design and associated costs. The next important step will be to develop the program in more detail and to start the initial phase of the monitoring project. We predict that such activities will identify the need for, and the relevance of, a more extensive monitoring program to study the effects of the FMR on a population level and on a large geographical scale.
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| 4. |
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| 5. |
- Ferreira-Rodríguez, Noé, et al.
(författare)
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Freshwater Mussels as Sentinels for Safe Drinking Water Supply in Europe
- 2023
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Ingår i: ACS - ES & T Water. - : American Chemical Society (ACS). - 2690-0637. ; 3:12, s. 3730-3735
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Tidskriftsartikel (refereegranskat)abstract
- In the context of the European Union (EU) Drinking Water Directive, freshwater mussels (Order Unionoida: Bivalvia) can help us face the challenges of safe drinking water provisions for all citizens in the EU. Specifically, the implementation of high frequency noninvasive (HFNI) valvometers allows the early detection of eventual pollution events in drinking water treatment plants. Currently real-time behavioral analysis is deployed in a number of EU countries, and we foresee a bright future as new technological advances are developed concerning HFNI valvometers.
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| 6. |
- Filipsson, Karl, et al.
(författare)
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Do predator odours and warmer winters affect growth of salmonid embryos?
- 2023
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Ingår i: Ecology of Freshwater Fish. - : John Wiley & Sons. - 0906-6691 .- 1600-0633. ; :1
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Tidskriftsartikel (refereegranskat)abstract
- Conditions early in ontogeny can have considerable effects later on in life. Many salmonids spawn during the autumn, and temperature during subsequent embryogenesis may have far-reaching effects on life-history traits, especially when considering ongoing climate change. Even biotic conditions during embryogenesis, such as predation threat, may affect later life stages. Here, we examined how predator odours and increased temperatures affect embryonic growth and development of a fish (brown trout Salmo trutta). We found that embryos had lower body mass and greater yolk volume close to hatching when subjected to predator odours. Trout embryos incubated at temperatures representing natural winter conditions were larger than embryos incubated at higher temperatures, although the latter hatched earlier. Fry sizes at emergence did not differ between treatments, perhaps because of compensatory growth during spring. This study shows that predator presence can have similar effects on embryonic growth of salmonids as warming winters, with possible impact later in ontogeny.
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| 7. |
- Filipsson, Karl
(författare)
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Early life stages of brown trout - Anti-predator responses under warming winters
- 2022
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- During winter, juvenile salmonids in boreal streams are vulnerable to predation, mainly from mammals and birds. Encounters with terrestrial predators can be reduced or avoided if fish limit activity to the darker periods of the day or to periods with surface ice. As piscivorous fish also are active in winter, they may be a threat under low light conditions when juvenile salmonids do not avoid terrestrial predators. Abiotic conditions, especially temperature, have major effects on fish in winter. High temperatures alter ice conditions in winter and lead to increased metabolism and physiological performance of fish. Water temperature also influences embryogenesis, with repercussions for fish throughout their life. Considering the rapid warming of winters in boreal regions, insights into how salmonids are adapted to winter conditions can aid in efforts to predict and mitigate anthropogenic effects that alter the winter environment.In this doctoral thesis, I explore anti-predator responses of brown trout (Salmo trutta) during its early life stages. I have examined the effects of predators, temperature, light and ice on the behaviour and physiology of juvenile trout during winter. In addition, I have studied how temperature and predators affect embryogenesis and the behaviour of fry after hatching. Anti-predator responses were evident in both the behaviour and physiology of juveniles and during embryogenesis. Trout exhibited diel behavioural changes when piscivorous fish were present, and were more vigilant towards piscivorous fish in darkness. Furthermore, temperature affected trout behaviour and physiology, with higher activity levels and lower mRNA expression of stress-related genes at higher temperatures. Trout also behaved differently depending on the temperature they experienced as eggs, as increased egg-incubation temperatures resulted in trout being more active and prone to risk taking.
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| 8. |
- Filipsson, Karl, et al.
(författare)
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Effects of temperature and a piscivorous fish on diel winter behaviour of juvenile brown trout (Salmo trutta)
- 2019
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Ingår i: Freshwater Biology. - : Wiley. - 0046-5070 .- 1365-2427. ; 64:1+, s. 1797-1805
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Tidskriftsartikel (refereegranskat)abstract
- 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 latitudes. Behavioral responses of stream fishes to terrestrial predators in winter are well recognised, whereas responses to predatory fish have received little attention. Using stream flumes, we examined the anti-predator behaviour of one-summer-old brown trout (Salmo trutta) at 3 and 8 degrees C in the presence and absence of burbot (Lota lota) under night, dawn, and daylight conditions. Burbot was placed upstream of the trout, separated by net screens. Lower temperature and the presence of burbot reduced trout activity. Light increased trout shelter use, and trout sheltered more in the presence of burbot. An interaction between the presence of burbot and light conditions affected trout position in the flumes: at night and dawn, trout positioned themselves further downstream when burbot were present than when absent, whereas during the day, trout maintained the same position in the presence or absence of the predator. Our results suggest that piscivorous fish, in addition to terrestrial predators, shape the behaviour of prey fishes in streams during winter. We show how predator avoidance results in altered diel patterns of juvenile brown trout under winter conditions, and that temperature has additional effects on trout behaviour.
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| 9. |
- Filipsson, Karl, et al.
(författare)
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Encystment of parasitic freshwater pearl mussel (Margaritifera margaritifera) larvae coincides with increased metabolic rate and haematocrit in juvenile brown trout (Salmo trutta)
- 2017
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Ingår i: Parasitology Research. - : Springer Science and Business Media LLC. - 0932-0113 .- 1432-1955. ; 116, s. 1353-1360
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Tidskriftsartikel (refereegranskat)abstract
- © 2017 The Author(s)Gill parasites on fish are likely to negatively influence their host by inhibiting respiration, oxygen transport capacity and overall fitness. The glochidia larvae of the endangered freshwater pearl mussel (FPM, Margaritifera margaritifera (Linnaeus, 1758)) are obligate parasites on the gills of juvenile salmonid fish. We investigated the effects of FPM glochidia encystment on the metabolism and haematology of brown trout (Salmo trutta Linnaeus, 1758). Specifically, we measured whole-animal oxygen uptake rates at rest and following an exhaustive exercise protocol using intermittent flow-through respirometry, as well as haematocrit, in infested and uninfested trout. Glochidia encystment significantly affected whole-animal metabolic rate, as infested trout exhibited higher standard and maximum metabolic rates. Furthermore, glochidia-infested trout also had elevated levels of haematocrit. The combination of an increased metabolism and haematocrit in infested fish indicates that glochidia encystment has a physiological effect on the trout, perhaps as a compensatory response to the potential respiratory stress caused by the glochidia. When relating glochidia load to metabolism and haematocrit, fish with low numbers of encysted glochidia were the ones with particularly elevated metabolism and haematocrit. Standard metabolic rate decreased with substantial glochidia loads towards levels similar to those of uninfested fish. This suggests that initial effects visible at low levels of encystment may be countered by additional physiological effects at high loads, e.g. potential changes in energy utilization, and also that high numbers of glochidia may restrict oxygen uptake by the gills.
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| 10. |
- Filipsson, Karl, 1991-
(författare)
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From behaviour to genes: anti-predator responses of brown trout (Salmo trutta) under winter conditions
- 2020
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Temperature has major effects on the performance of poikilotherms. In encounters with predators, low winter temperatures constrain predator detection and escape capabilities in prey fishes. Most studies of the anti-predator responses of fish under winter conditions focus on endothermic terrestrial predators, whereas effects of piscivorous fish are generally overlooked. The studies presented in this thesis explore behavioural and physiological responses of juvenile brown trout (Salmo trutta) at winter temperatures of 3 and 8 °C in the presence and absence of a winter-active piscivorous fish (burbot, Lota lota). In Paper I, I report behavioural responses of trout in relation to the time of day. At the lower temperature and in the presence of burbot, trout reduced their activity. Trout used overhead shelter the most during the day and in the presence of burbot. Trout also spatially avoided burbot at night and at dawn but not during the day. In Paper II, I examined plasma cortisol and mRNA expression of stress-related genes. A redundancy analysis showed that both temperature and the presence of burbot explained a significant amount of the observed variation. Trout had higher cortisol levels when exposed to the burbot. Analyses of individual gene expressions revealed that trout had higher mRNA expression at 3 than at 8 °C for 11 of the 16 examined genes. Only one gene, RBP1, was expressed to a higher degree in the presence of burbot, but there were also interaction effects between temperature and burbot presence for two genes coding for serotonin and glucocorticoid receptors. My studies show that piscivorous fish shape anti-predator responses of juvenile brown trout, both behaviourally and at the gene level, under winter conditions. The observed thermal effects on mRNA levels underscore the importance of temperature in fish stress responses, with implications for stream salmonids in a warmer climate.
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