Foraging efficiencies on drifting and benthic prey in juvenile salmonids - effect of light
Stream living salmonids are generally regarded as drift feeders that rely upon their vision when foraging. It has been shown that salmonids become nocturnal at low water temperatures, but have a low foraging efficiency as light intensity is low, due to their dependence upon vision. Shifting from dri...
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Karlstads universitet, Institutionen för miljö- och livsvetenskaper
2016
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ftkarlstadsuniv:oai:DiVA.org:kau-41939 2024-06-09T07:44:50+00:00 Foraging efficiencies on drifting and benthic prey in juvenile salmonids - effect of light Födosökseffektivitet på driftande och bentiska byten hos juvenila laxfiskar - effekt av ljus Larsson, Pia L. M. 2016 application/pdf http://urn.kb.se/resolve?urn=urn:nbn:se:kau:diva-41939 eng eng Karlstads universitet, Institutionen för miljö- och livsvetenskaper http://urn.kb.se/resolve?urn=urn:nbn:se:kau:diva-41939 info:eu-repo/semantics/openAccess Foraging benthic prey drifting salmon trout salmonids light day night Biological Sciences Biologiska vetenskaper Student thesis info:eu-repo/semantics/bachelorThesis text 2016 ftkarlstadsuniv 2024-05-15T09:11:29Z Stream living salmonids are generally regarded as drift feeders that rely upon their vision when foraging. It has been shown that salmonids become nocturnal at low water temperatures, but have a low foraging efficiency as light intensity is low, due to their dependence upon vision. Shifting from drift feeding to benthic feeding, has been suggested, and analyses of gut contents during winter have shown that the diet of salmonids mainly consists of benthic invertebrates. Most experimental studies of salmonid foraging have only offered the fish drifting prey or only given the fish access to benthic prey in total darkness. Such conditions rarely occur in nature and the importance of benthic foraging to salmonids may therefore have been underestimated. In this study I conducted a stream laboratory experiment to test if low light intensity caused juvenile Atlantic salmon (Salmo salar) and brown trout (Salmo trutta) (age 0+) to forage more on benthic than drifting prey. The salmon foraged on both drifting and benthic prey during high light but consumed only benthic prey during low light (by one of six fish). Trout foraged on both drifting and benthic prey during both high and low light, but foraging efficiency was lower during low than high light and foraging efficiency was lower for benthic prey than for drifting prey. These results indicate that both species forage more opportunistically than previously thought. Strömlevande laxfiskar anses generellt vara driftätare som förlitar sig på synen när de födosöker. Det har visats att laxfiskar blir nattaktiva vid låga vattentemperaturer, men har en låg födosökseffektivitet då ljusintensiteten är låg, på grund av sitt beroende av synen. Skifte från driftätande till att äta bentiska byten, har föreslagits, och analyser av maginnehåll under vintern har visat att laxfiskars diet huvudsakligen består av bentiska evertebrater. De flesta experimentella studier av laxfiskars födosök har endast erbjudit fisken driftande byten eller endast gett fisken ... Bachelor Thesis Atlantic salmon Salmo salar Karlstad University: Publications (DIVA) |
institution |
Open Polar |
collection |
Karlstad University: Publications (DIVA) |
op_collection_id |
ftkarlstadsuniv |
language |
English |
topic |
Foraging benthic prey drifting salmon trout salmonids light day night Biological Sciences Biologiska vetenskaper |
spellingShingle |
Foraging benthic prey drifting salmon trout salmonids light day night Biological Sciences Biologiska vetenskaper Larsson, Pia L. M. Foraging efficiencies on drifting and benthic prey in juvenile salmonids - effect of light |
topic_facet |
Foraging benthic prey drifting salmon trout salmonids light day night Biological Sciences Biologiska vetenskaper |
description |
Stream living salmonids are generally regarded as drift feeders that rely upon their vision when foraging. It has been shown that salmonids become nocturnal at low water temperatures, but have a low foraging efficiency as light intensity is low, due to their dependence upon vision. Shifting from drift feeding to benthic feeding, has been suggested, and analyses of gut contents during winter have shown that the diet of salmonids mainly consists of benthic invertebrates. Most experimental studies of salmonid foraging have only offered the fish drifting prey or only given the fish access to benthic prey in total darkness. Such conditions rarely occur in nature and the importance of benthic foraging to salmonids may therefore have been underestimated. In this study I conducted a stream laboratory experiment to test if low light intensity caused juvenile Atlantic salmon (Salmo salar) and brown trout (Salmo trutta) (age 0+) to forage more on benthic than drifting prey. The salmon foraged on both drifting and benthic prey during high light but consumed only benthic prey during low light (by one of six fish). Trout foraged on both drifting and benthic prey during both high and low light, but foraging efficiency was lower during low than high light and foraging efficiency was lower for benthic prey than for drifting prey. These results indicate that both species forage more opportunistically than previously thought. Strömlevande laxfiskar anses generellt vara driftätare som förlitar sig på synen när de födosöker. Det har visats att laxfiskar blir nattaktiva vid låga vattentemperaturer, men har en låg födosökseffektivitet då ljusintensiteten är låg, på grund av sitt beroende av synen. Skifte från driftätande till att äta bentiska byten, har föreslagits, och analyser av maginnehåll under vintern har visat att laxfiskars diet huvudsakligen består av bentiska evertebrater. De flesta experimentella studier av laxfiskars födosök har endast erbjudit fisken driftande byten eller endast gett fisken ... |
format |
Bachelor Thesis |
author |
Larsson, Pia L. M. |
author_facet |
Larsson, Pia L. M. |
author_sort |
Larsson, Pia L. M. |
title |
Foraging efficiencies on drifting and benthic prey in juvenile salmonids - effect of light |
title_short |
Foraging efficiencies on drifting and benthic prey in juvenile salmonids - effect of light |
title_full |
Foraging efficiencies on drifting and benthic prey in juvenile salmonids - effect of light |
title_fullStr |
Foraging efficiencies on drifting and benthic prey in juvenile salmonids - effect of light |
title_full_unstemmed |
Foraging efficiencies on drifting and benthic prey in juvenile salmonids - effect of light |
title_sort |
foraging efficiencies on drifting and benthic prey in juvenile salmonids - effect of light |
publisher |
Karlstads universitet, Institutionen för miljö- och livsvetenskaper |
publishDate |
2016 |
url |
http://urn.kb.se/resolve?urn=urn:nbn:se:kau:diva-41939 |
genre |
Atlantic salmon Salmo salar |
genre_facet |
Atlantic salmon Salmo salar |
op_relation |
http://urn.kb.se/resolve?urn=urn:nbn:se:kau:diva-41939 |
op_rights |
info:eu-repo/semantics/openAccess |
_version_ |
1801373652075151360 |