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Salmonid behaviour under winter conditions
Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences. (Naturresurs rinnande vatten)ORCID iD: 0000-0002-4417-6636
2015 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Winter conditions are believed to play an important role in the population dynamics of northern temperate stream fish, challenging the ability of fish to physiologically and behaviourally adapt. Climate change is predicted to increase both mean temperature and temperature fluctuations, especially during winter, leading to dynamic environmental conditions in terms of river ice production and flow. Therefore, knowledge about the winter ecology of stream fish is important for predicting and mitigating anthropogenic impacts on fish production in boreal streams. Stream salmonids are relatively active throughout winter, and behavioural responses to different winter conditions may be critical for survival. Yet, relatively little is known about overwintering behaviour of salmonids, particularly in streams with ice. In this doctoral thesis, I report the results from experimental field and laboratory studies on the behavioural ecology of juvenile salmonids under winter conditions. My results from the field show that salmonids grow more and use a broader range of habitats in the presence of surface ice than in its absence. Results from the laboratory experiments show that the presence of surface ice increases food intake rates, reduces stress and affects social interactions. These laboratory results may explain the positive effects of ice cover on growth that was found in the field experiment. Moreover, I show that drift-feeding ability is reduced at low temperatures, and that nocturnal drift foraging under winter conditions has a low efficiency.

Abstract [sv]

Vinterförhållanden kan spela en avgörande roll för förekomsten av fisk i våra vattendrag. Laxfiskar, som till exempel lax, öring och harr, är vinteraktiva och måste därför anpassa sin fysiologi och sitt beteende till en miljö som karakteriseras av låga och föränderliga vattenflöden, liten tillgång på föda, kallt vatten, is och mörker. Trots att dessa anpassningar är avgörande för chansen att överleva vintern, vet man relativt lite om laxfiskars vinterbeteende, speciellt i vattendrag som täcks av is. I denna avhandling presenterar jag resultat från fält- och laboratoriestudier av laxfiskars beteende under vinterförhållanden och resultaten visar att närvaron av yttäckande is ökar tillväxt och födointag, minskar stress samt påverkar var fiskar uppehåller sig och hur fiskarna interagerar med varandra. Jag har också undersökt hur laxfiskars beteende i rinnande vatten påverkas av ljusintensitet och vattentemperatur i samband med födointag. Resultaten visar att den minskade dagaktiviteten som laxfiskar uppvisar på vintern medför en kostnad i form av försämrad förmåga att fånga byten.

Abstract [en]

Winter conditions are believed to play an important role in the population dynamics of northern temperate stream fish, challenging the ability of fish to physiologically and behaviourally adapt. Climate change is predicted to increase both mean temperature and temperature fluctuations, especially during winter, leading to dynamic environmental conditions in terms of river ice production and flow. Therefore, knowledge about the winter ecology of stream fish is important for predicting and mitigating anthropogenic impacts on fish production in boreal streams.

Stream salmonids are active throughout winter, and behavioural responses to different winter conditions may be critical for survival. Yet, relatively little is known about overwintering behaviour of salmonids, particularly in streams with ice. This doctoral thesis focuses on the behavioural ecology of salmonids under winter conditions, and results from field and laboratory experiments show that the presence of surface ice increases food intake rates, reduces stress and affects social interactions, with effects on growth and habitat use. Moreover, drift-feeding ability is reduced at low temperatures, and nocturnal drift foraging under winter conditions has a low efficiency.

Place, publisher, year, edition, pages
Karlstad: Karlstads universitet, 2015. , 40 p.
Series
Karlstad University Studies, ISSN 1403-8099 ; 2015:55
Keyword [en]
climate change, drift, energy budget, foraging, grayling, ice cover, lotic, metabolic rate, predation, salmon, stream, stress, temperature, trout
National Category
Ecology
Research subject
Biology
Identifiers
URN: urn:nbn:se:kau:diva-38354ISBN: 978-91-7063-674-5 (print)OAI: oai:DiVA.org:kau-38354DiVA: diva2:868880
Public defence
2016-01-22, 9C203, Nyquistsalen, Universitetsgatan 2, Karlstad, 10:15 (English)
Opponent
Supervisors
Note

Artikel 1 i avhandlingen som manuskript. Nu publicerad.

Available from: 2015-12-17 Created: 2015-11-11 Last updated: 2016-12-07Bibliographically approved
List of papers
1. Ice cover affects the growth of a stream-dwelling fish
Open this publication in new window or tab >>Ice cover affects the growth of a stream-dwelling fish
2016 (English)In: Oecologia, ISSN 0029-8549, E-ISSN 1432-1939, Vol. 181, no 1, 299-311 p.Article in journal (Refereed) Published
Abstract [en]

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 sheeting over five 30-m-long stream sections in a boreal forest stream and examined its effects on the growth and habitat use of brown trout (Salmo trutta) during winter. Trout that spent the winter under the artificial ice cover grew more than those in the control (uncovered) sections. Moreover, tracking of trout tagged with passive integrated transponders showed that in the absence of the artificial ice cover, habitat use during the day was restricted to the stream edges, often under undercut banks, whereas under the simulated ice cover condition, trout used the entire width of the stream. These results indicate that the presence of surface ice cover may improve the energetic status and broaden habitat use of stream fish during winter. It is therefore likely that reductions in the duration and extent of ice cover due to climate change will alter time and energy budgets, with potentially negative effects on fish production.

Place, publisher, year, edition, pages
Berlin Heidelberg: Springer Berlin/Heidelberg, 2016
Keyword
Climate change, Energy budget, Global warming, Salmonid, Winter
National Category
Ecology
Research subject
Biology
Identifiers
urn:nbn:se:kau:diva-39125 (URN)10.1007/s00442-016-3555-z (DOI)000374564000026 ()26787075 (PubMedID)
Available from: 2016-01-25 Created: 2016-01-25 Last updated: 2017-12-06Bibliographically approved
2. Effects of ice cover on the diel behaviour and ventilation rate of juvenile brown trout
Open this publication in new window or tab >>Effects of ice cover on the diel behaviour and ventilation rate of juvenile brown trout
2013 (English)In: Freshwater Biology, ISSN 0046-5070, E-ISSN 1365-2427, Vol. 58, no 11, 2325-2332 p.Article in journal (Refereed) Published
Abstract [en]
  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 predators, we predicted that metabolic costs associated with vigilance would be lower under surface ice than in areas lacking surface ice. This potentially favourable effect of ice cover was tested by observing ventilation rates of juvenile brown trout (Salmo trutta) in a laboratory stream at dawn, during the day and at night in the presence and absence of real, light-permeable surface ice. Further, we offered trout drifting prey during daylight to test whether ice cover increased daytime foraging activity.
  3. Ice cover reduced ventilation rates during the day, but not at night or dawn. Moreover, fish made more daytime foraging attempts in the presence of ice cover than in its absence.
  4. We suggest that the most plausible explanation for these results is that fish experience a reduced perceived predation risk under surface ice.
Place, publisher, year, edition, pages
John Wiley & Sons, 2013
Keyword
foraging, metabolic rate, predation, salmonid, winter
National Category
Ecology
Research subject
Biology
Identifiers
urn:nbn:se:kau:diva-28784 (URN)10.1111/fwb.12212 (DOI)000325156400010 ()
Note

Publication was published as manuscript in licentiate thesis "Winter behaviour of stream salmonids: effects of temperature, light, and ice cover"

Available from: 2013-08-28 Created: 2013-08-28 Last updated: 2017-12-06Bibliographically approved
3. Day and night drift-feeding by juvenile salmonids at low water temperatures
Open this publication in new window or tab >>Day and night drift-feeding by juvenile salmonids at low water temperatures
2014 (English)In: Environmental Biology of Fishes, ISSN 0378-1909, E-ISSN 1573-5133, Vol. 97, no 5, 505-513 p.Article in journal (Refereed) Published
Abstract [en]

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 conditions. In a laboratory stream channel, we studied temperature effects on the drift-feeding behaviour of juvenile Atlantic salmon, brown trout, and European grayling in simulated daylight and moonlight at temperatures ranging from 2 °C to 11 °C. Prey capture probability was positively related to temperature, but the temperature dependence did not agree with predictions of the Metabolic Theory of Ecology. Furthermore, reaction distance was positively related to temperature for the three species, which may be one of the underlying mechanisms responsible for the temperature effects on prey capture probability. Overall, the three species had similar capture rates at the different temperature and light levels, although there were species differences. European grayling had a slightly higher prey capture probability than brown trout, and brown trout had a shorter reaction distance than Atlantic salmon and European grayling. These results have implications for both energetics-based drift-foraging theory and for studies of winter ecology.

Place, publisher, year, edition, pages
Springer Netherlands, 2014
Keyword
Foraging, grayling, reaction distance, salmon, trout, winter
National Category
Ecology
Research subject
Biology
Identifiers
urn:nbn:se:kau:diva-29309 (URN)10.1007/s10641-013-0190-y (DOI)000334126100006 ()
Note

Publication was published as manuscript in licentiate thesis "Winter behaviour of stream salmonids: effects of temperature, light, and ice cover"

Available from: 2013-10-07 Created: 2013-10-07 Last updated: 2017-12-06Bibliographically approved
4. Prey capture rates of two species of salmonids (Salmo trutta and Thymallus thymallus) in an artificial stream: effects of temperature on their functional response
Open this publication in new window or tab >>Prey capture rates of two species of salmonids (Salmo trutta and Thymallus thymallus) in an artificial stream: effects of temperature on their functional response
2014 (English)In: Marine and Freshwater Behaviour & Physiology, ISSN 1023-6244, E-ISSN 1029-0362, Vol. 47, no 2, 93-99 p.Article in journal (Refereed) Published
Abstract [en]

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 at 11 °C, and the difference was most pronounced at high prey densities. At high prey densities, we also observed that European grayling had higher capture rates than brown trout. Type III functional response curves, i.e. sigmoidal relationships between capture rates and prey densities, fitted the data better than type I (linear) and II (hyperbolic) curves for all four combinations of temperatures and species. These results may explain the dominance of grayling in stream habitats with low water velocities and results such as these may be of use when developing foraging-based food web models of lotic ecosystems that include drift-feeding salmonids.

Place, publisher, year, edition, pages
London, UK: Taylor & Francis, 2014
Keyword
drift, feeding, foraging, food web, grayling, lotic, prey density, trout
National Category
Ecology
Research subject
Biology
Identifiers
urn:nbn:se:kau:diva-32035 (URN)10.1080/10236244.2014.900210 (DOI)000335822300003 ()
Available from: 2014-05-06 Created: 2014-05-06 Last updated: 2017-12-05Bibliographically approved
5. Ice cover alters the behavior and stress level of brown trout Salmo trutta
Open this publication in new window or tab >>Ice cover alters the behavior and stress level of brown trout Salmo trutta
Show others...
2015 (English)In: Behavioral Ecology, ISSN 1045-2249, E-ISSN 1465-7279, Vol. 26, no 3, 820-827 p.Article in journal (Refereed) Published
Abstract [en]

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 Salmo trutta at temperatures of 3–4 °C in indoor experimental flumes. We hypothesized that an individual’s resting metabolic rate (RMR, as measured by resting ventilation rate) would affect winter behavior. Therefore, groups of 4 trout, consisting of individuals with high, low, or mixed (2 individuals each) RMR, were exposed to experimental conditions with or without ice cover. Ice cover reduced stress responses, as evaluated by body coloration. Also, trout in low RMR groups had a paler body color than those in both mixed and high RMR groups. Trout increased their swimming activity under ice cover, with the highest activity found in high RMR groups. Ice cover increased the number of aggressive encounters but did not influence the number of drifting food items taken by each group. In mixed RMR groups, however, single individuals were better able to monopolize food than in the other groups. As the presence of surface ice increases the activity level and reduces stress in stream-living trout, ice cover should influence their energy budgets and production. The results should be viewed in light of ongoing global warming that reduces the duration of ice cover, especially at high latitudes and altitudes.

Place, publisher, year, edition, pages
Oxford: Oxford University Press, 2015
Keyword
aggression, climate change, energy budget, metabolic rate, winter
National Category
Ecology
Research subject
Biology
Identifiers
urn:nbn:se:kau:diva-35931 (URN)10.1093/beheco/arv019 (DOI)000356585100024 ()
Available from: 2015-04-29 Created: 2015-04-29 Last updated: 2017-12-06Bibliographically approved

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