Responses to declining zoobenthos abundance : Changes over time in diet and growth of Arctic charr (Salvelinus alpinus)
A decline in the density of zoobenthos has taken place in Lake Abiskojaure in the northern Swedish mountains between 1988 and 2019 but no response can be seen in the abundance (CPUE) of Arctic charr (Salvelinus alpinus) that feed mainly on benthic invertebrates. To evaluate if possible shifts in res...
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Umeå universitet, Institutionen för ekologi, miljö och geovetenskap
2020
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ftumeauniv:oai:DiVA.org:umu-179106 2023-10-09T21:47:49+02:00 Responses to declining zoobenthos abundance : Changes over time in diet and growth of Arctic charr (Salvelinus alpinus) Skarp, Douglas 2020 application/pdf http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-179106 eng eng Umeå universitet, Institutionen för ekologi, miljö och geovetenskap http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-179106 info:eu-repo/semantics/openAccess charr zoobenthos growth diet Ecology Ekologi Student thesis info:eu-repo/semantics/bachelorThesis text 2020 ftumeauniv 2023-09-22T13:53:25Z A decline in the density of zoobenthos has taken place in Lake Abiskojaure in the northern Swedish mountains between 1988 and 2019 but no response can be seen in the abundance (CPUE) of Arctic charr (Salvelinus alpinus) that feed mainly on benthic invertebrates. To evaluate if possible shifts in resource use of charr explain this lack of change in population abundance, stomach contents (i.e. diet) of charr between 1985 and 2020 were analyzed. Charr diets changed during the study period, with decreasing contributions to the diet of larger sized prey and increasing contribution of smaller sized prey and zooplankton. A corresponding recent decline in charr growth, size, and condition factor was observed. The proportion of large prey in diets and charr growth both show a hump-shaped relationship with time before the recent decline, indicating consumption of large prey had a positive effect on charr growth. Densities of zooplankton in the lake did not change with time, meaning increases in diet proportions are driven by something else. Declines in nitrogen and phosphorous over time may have contributed to the decline in zoobenthos densities through nutrient limitation of primary production. The results from this study suggest charr has changed diet towards smaller, less energetically efficient prey as a response to declining zoobenthos levels, and that this has had a negative effect on charr growth, size, and condition factor. Additional declines in nutrients and zoobenthos abundance may further worsen charr performance and eventually be manifested as declining charr abundance. Bachelor Thesis Arctic charr Arctic Salvelinus alpinus Zooplankton Umeå University: Publications (DiVA) Abiskojaure ENVELOPE(18.611,18.611,68.294,68.294) Arctic |
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Open Polar |
collection |
Umeå University: Publications (DiVA) |
op_collection_id |
ftumeauniv |
language |
English |
topic |
charr zoobenthos growth diet Ecology Ekologi |
spellingShingle |
charr zoobenthos growth diet Ecology Ekologi Skarp, Douglas Responses to declining zoobenthos abundance : Changes over time in diet and growth of Arctic charr (Salvelinus alpinus) |
topic_facet |
charr zoobenthos growth diet Ecology Ekologi |
description |
A decline in the density of zoobenthos has taken place in Lake Abiskojaure in the northern Swedish mountains between 1988 and 2019 but no response can be seen in the abundance (CPUE) of Arctic charr (Salvelinus alpinus) that feed mainly on benthic invertebrates. To evaluate if possible shifts in resource use of charr explain this lack of change in population abundance, stomach contents (i.e. diet) of charr between 1985 and 2020 were analyzed. Charr diets changed during the study period, with decreasing contributions to the diet of larger sized prey and increasing contribution of smaller sized prey and zooplankton. A corresponding recent decline in charr growth, size, and condition factor was observed. The proportion of large prey in diets and charr growth both show a hump-shaped relationship with time before the recent decline, indicating consumption of large prey had a positive effect on charr growth. Densities of zooplankton in the lake did not change with time, meaning increases in diet proportions are driven by something else. Declines in nitrogen and phosphorous over time may have contributed to the decline in zoobenthos densities through nutrient limitation of primary production. The results from this study suggest charr has changed diet towards smaller, less energetically efficient prey as a response to declining zoobenthos levels, and that this has had a negative effect on charr growth, size, and condition factor. Additional declines in nutrients and zoobenthos abundance may further worsen charr performance and eventually be manifested as declining charr abundance. |
format |
Bachelor Thesis |
author |
Skarp, Douglas |
author_facet |
Skarp, Douglas |
author_sort |
Skarp, Douglas |
title |
Responses to declining zoobenthos abundance : Changes over time in diet and growth of Arctic charr (Salvelinus alpinus) |
title_short |
Responses to declining zoobenthos abundance : Changes over time in diet and growth of Arctic charr (Salvelinus alpinus) |
title_full |
Responses to declining zoobenthos abundance : Changes over time in diet and growth of Arctic charr (Salvelinus alpinus) |
title_fullStr |
Responses to declining zoobenthos abundance : Changes over time in diet and growth of Arctic charr (Salvelinus alpinus) |
title_full_unstemmed |
Responses to declining zoobenthos abundance : Changes over time in diet and growth of Arctic charr (Salvelinus alpinus) |
title_sort |
responses to declining zoobenthos abundance : changes over time in diet and growth of arctic charr (salvelinus alpinus) |
publisher |
Umeå universitet, Institutionen för ekologi, miljö och geovetenskap |
publishDate |
2020 |
url |
http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-179106 |
long_lat |
ENVELOPE(18.611,18.611,68.294,68.294) |
geographic |
Abiskojaure Arctic |
geographic_facet |
Abiskojaure Arctic |
genre |
Arctic charr Arctic Salvelinus alpinus Zooplankton |
genre_facet |
Arctic charr Arctic Salvelinus alpinus Zooplankton |
op_relation |
http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-179106 |
op_rights |
info:eu-repo/semantics/openAccess |
_version_ |
1779310844361834496 |