| 1. |
- Charrieau, Laurie M., et al.
(författare)
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Decalcification and survival of benthic foraminifera under the combined impacts of varying pH and salinity
- 2018
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Ingår i: Marine Environmental Research. - : Elsevier BV. - 0141-1136. ; 138, s. 36-45
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Tidskriftsartikel (refereegranskat)abstract
- Coastal areas display natural large environmental variability such as frequent changes in salinity, pH, and carbonate chemistry. Anthropogenic impacts – especially ocean acidification – increase this variability, which may affect the living conditions of coastal species, particularly, calcifiers. We performed culture experiments on living benthic foraminifera to study the combined effects of lowered pH and salinity on the calcification abilities and survival of the coastal, calcitic species Ammonia sp. and Elphidium crispum. We found that in open ocean conditions (salinity ∼35) and lower pH than usual values for these species, the specimens displayed resistance to shell (test) dissolution for a longer time than in brackish conditions (salinity ∼5 to 20). However, the response was species specific as Ammonia sp. specimens survived longer than E. crispum specimens when placed in the same conditions of salinity and pH. Living, decalcified juveniles of Ammonia sp. were observed and we show that desalination is one cause for the decalcification. Finally, we highlight the ability of foraminifera to survive under Ωcalc < 1, and that high salinity and [Ca2+] as building blocks are crucial for the foraminiferal calcification process.
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| 2. |
- Charrieau, Laurie M., et al.
(författare)
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The effects of multiple stressors on the distribution of coastal benthic foraminifera: A case study from the Skagerrak-Baltic Sea region
- 2018
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Ingår i: Marine Micropaleontology. - : Elsevier BV. - 0377-8398. ; 139, s. 42-56
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Tidskriftsartikel (refereegranskat)abstract
- Coastal ecosystems are subjected to both large natural variability and increasing anthropogenic impact on environmental parameters such as changes in salinity, temperature, and pH. This study documents the distribution of living benthic foraminifera under the influence of multiple environmental stressors in the Skagerrak-Baltic Sea region. Sediment core tops were studied at five sites along a transect from the Skagerrak to the Baltic Sea, with strong environmental gradients, especially in terms of salinity, pH, calcium carbonate saturation and dissolved oxygen concentration in the bottom water and pore water. We found that living foraminiferal densities and species richness were higher at the Skagerrak station, where the general living conditions were relatively beneficial for Foraminifera, with higher salinity and Ωcalc in the water column and higher pH and oxygen concentration in the bottom and pore water. The most common species reported at each station reflect the differences in the environmental conditions between the stations. The dominant species were Cassidulina laevigata and Hyalinea balthica in the Skagerrak, Stainforthia fusiformis, Nonionella aff. stella and Nonionoides turgida in the Kattegat and N. aff. stella and Nonionellina labradorica in the Öresund. The most adverse conditions, such as low salinity, low Ωcalc, low dissolved oxygen concentrations and low pH, were noted at the Baltic Sea stations, where the calcareous tests of the dominant living taxa Ammonia spp. and Elphidium spp. were partially to completely dissolved, probably due to a combination of different stressors affecting the required energy for biomineralization. Even though Foraminifera are able to live in extremely varying environmental conditions, the present results suggest that the benthic coastal ecosystems in the studied region, which are apparently affected by an increase in the range of environmental variability, will probably be even more influenced by a future increase in anthropogenic impacts, including coastal ocean acidification and deoxygenation.
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| 3. |
- Charrieau, Laurie, et al.
(författare)
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Rapid environmental responses to climate-induced hydrographic changes in the Baltic Sea entrance
- 2019
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Ingår i: Biogeosciences. - : Copernicus GmbH. - 1726-4189 .- 1726-4170. ; 16, s. 3835-3852
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Tidskriftsartikel (refereegranskat)abstract
- The Öresund (the Sound), which is a part of the Danish straits, is linking the marine North Sea and the brackish Baltic Sea. It is a transition zone where ecosystems are subjected to large gradients in terms of salinity, temperature, carbonate chemistry, and dissolved oxygen concentration. In addition to the highly variable environmental conditions, the area is responding to anthropogenic disturbances in e.g. nutrient loading, temperature, and pH. We have reconstructed environmental changes in the Öresund during the last c. 200 years, and especially dissolved oxygen concentration, salinity, organic matter content, and pollution levels, using benthic foraminifera and sediment geochemistry. Five zones with characteristic foraminiferal assemblages were identified, each reflecting the environmental conditions for respective period. The largest changes occurred ~ 1950, when the foraminiferal assemblage shifted from a low diversity fauna, dominated by the species Stainforthia fusiformis to higher diversity and abundance, and dominance of the Elphidium group. Concurrently, the grain-size distribution shifted from clayey – to more sandy sediment. To explore the causes for the environmental changes, we used time-series of reconstructed wind conditions coupled with large-scale climate variations as recorded by the NAO index, as well as the ECOSMO II model of currents in the Öresund area. The results indicate increased changes in the water circulation towards stronger currents in the area since the 1950's. The foraminiferal fauna responded quickly (< 10 years) to the environmental changes. Notably, when the wind conditions, and thereby the current system, returned in the 1980's to the previous pattern, the foraminiferal species assemblage did not rebound, but the foraminiferal faunas rather displayed a new equilibrium state.
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| 4. |
- 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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| 5. |
- 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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| 6. |
- 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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| 7. |
- 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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| 8. |
- 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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| 9. |
- Filipsson, Karl, et al.
(författare)
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Heavy loads of parasitic freshwater pearl mussel (Margaritifera margaritifera L.) larvae impair foraging, activity and dominance performance in juvenile brown trout (Salmo trutta L.)
- 2018
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Ingår i: Ecology of Freshwater Fish. - : Wiley. - 0906-6691 .- 1600-0633. ; 27:1, s. 70-77
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Tidskriftsartikel (refereegranskat)abstract
- © 2016 John Wiley & Sons A/S.The life cycle of the endangered freshwater pearl mussel (Margaritifera margaritifera) includes a parasitic larval phase (glochidia) on the gills of a salmonid host. Glochidia encystment has been shown to affect both swimming ability and prey capture success of brown trout (Salmo trutta), which suggests possible fitness consequences for host fish. To further investigate the relationship between glochidia encystment and behavioural parameters in brown trout, pairs (n = 14) of wild-caught trout (infested vs. uninfested) were allowed to drift feed in large stream aquaria and foraging success, activity, agonistic behaviour and fish coloration were observed. No differences were found between infested and uninfested fish except for in coloration, where infested fish were significantly darker than uninfested fish. Glochidia load per fish varied from one to several hundred glochidia, however, and high loads had significant effects on foraging, activity and behaviour. Trout with high glochidia loads captured less prey, were less active and showed more subordinate behaviour than did fish with lower loads. Heavy glochidia loads therefore may negatively influence host fitness due to reduced competitive ability. These findings have implications not only for management of mussel populations in the streams, but also for captive breeding programmes which perhaps should avoid high infestation rates. Thus, low levels of infestation on host fish which do not affect trout behaviour but maintains mussel populations may be optimal in these cases.
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| 10. |
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