The role of crawling predators in the decline and distribution of blue mussels in Norwegian coastal waters
Blue mussels (Mytilus spp.) are declining in coastal areas around the world. In Norway, they thrive on floating structures, while on rocky shores they have widely disappeared. Proposed and elsewhere reliable drivers such as climate change, pollution, disease, parasites, hybridization, and failed rec...
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The University of Bergen
2022
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ftunivbergen:oai:bora.uib.no:11250/3021981 2023-05-15T18:49:53+02:00 The role of crawling predators in the decline and distribution of blue mussels in Norwegian coastal waters Meister, Nadja 2022-09-26T22:00:31Z application/pdf https://hdl.handle.net/11250/3021981 eng eng The University of Bergen https://hdl.handle.net/11250/3021981 Copyright the Author. All rights reserved population decline community shifts refugia predator recovery invertebrate predators 751999 Master thesis 2022 ftunivbergen 2023-03-14T17:41:29Z Blue mussels (Mytilus spp.) are declining in coastal areas around the world. In Norway, they thrive on floating structures, while on rocky shores they have widely disappeared. Proposed and elsewhere reliable drivers such as climate change, pollution, disease, parasites, hybridization, and failed recruitment would not discriminate between floating structures and rocks. Therefore, we hypothesize that crawling predators, unable to reach floating structures, drive the Norwegian decline. A known ferocious crawling predator without pelagic stage is the dogwhelk Nucella lapillus. The antifouling tributyltin (TBT) made this snail sterile but is now banned and populations are recovering rapidly. We surveyed trees hanging into seawater and floating docks together with nearby rocky shores for blue mussels and dogwhelks, and conducted a predator exclusion experiment with caged blue mussels (40-80 mm). Blue mussels were present on all floating docks (65% cover), but only on 18% of rocky shores (≤5% cover). Similarly, they were found on 83% of trees without bottom contact, but only on 1% touching the seafloor. In cages, mortality due to other factors than dogwhelks was extremely low (1%) and confirms that blue mussels continue to thrive when out of reach from predators. Additionally, we conducted pilot experiments to assess dogwhelks’ feeding and crawling potential to drive a blue mussel decline of the observed magnitude and pattern. Dogwhelks drilled and fed effectively on blue mussels of any size (up to 131 mm). They more often managed to reach blue mussels on top of branches and concrete bricks than on top of ropes and chains that usually hold floating docks in place. Muddy bays are another refugium for blue mussels in Norway, and dogwhelks needed markedly more time to reach blue mussels on mud than on sand. This tentatively suggests that Norwegian blue mussel refugia, such as floating docks and muddy bays, are out of reach from dogwhelks. Shifts in community structure towards a new ecosystem state with few blue mussels ... Master Thesis Dogwhelk Nucella lapillus University of Bergen: Bergen Open Research Archive (BORA-UiB) Norway |
institution |
Open Polar |
collection |
University of Bergen: Bergen Open Research Archive (BORA-UiB) |
op_collection_id |
ftunivbergen |
language |
English |
topic |
population decline community shifts refugia predator recovery invertebrate predators 751999 |
spellingShingle |
population decline community shifts refugia predator recovery invertebrate predators 751999 Meister, Nadja The role of crawling predators in the decline and distribution of blue mussels in Norwegian coastal waters |
topic_facet |
population decline community shifts refugia predator recovery invertebrate predators 751999 |
description |
Blue mussels (Mytilus spp.) are declining in coastal areas around the world. In Norway, they thrive on floating structures, while on rocky shores they have widely disappeared. Proposed and elsewhere reliable drivers such as climate change, pollution, disease, parasites, hybridization, and failed recruitment would not discriminate between floating structures and rocks. Therefore, we hypothesize that crawling predators, unable to reach floating structures, drive the Norwegian decline. A known ferocious crawling predator without pelagic stage is the dogwhelk Nucella lapillus. The antifouling tributyltin (TBT) made this snail sterile but is now banned and populations are recovering rapidly. We surveyed trees hanging into seawater and floating docks together with nearby rocky shores for blue mussels and dogwhelks, and conducted a predator exclusion experiment with caged blue mussels (40-80 mm). Blue mussels were present on all floating docks (65% cover), but only on 18% of rocky shores (≤5% cover). Similarly, they were found on 83% of trees without bottom contact, but only on 1% touching the seafloor. In cages, mortality due to other factors than dogwhelks was extremely low (1%) and confirms that blue mussels continue to thrive when out of reach from predators. Additionally, we conducted pilot experiments to assess dogwhelks’ feeding and crawling potential to drive a blue mussel decline of the observed magnitude and pattern. Dogwhelks drilled and fed effectively on blue mussels of any size (up to 131 mm). They more often managed to reach blue mussels on top of branches and concrete bricks than on top of ropes and chains that usually hold floating docks in place. Muddy bays are another refugium for blue mussels in Norway, and dogwhelks needed markedly more time to reach blue mussels on mud than on sand. This tentatively suggests that Norwegian blue mussel refugia, such as floating docks and muddy bays, are out of reach from dogwhelks. Shifts in community structure towards a new ecosystem state with few blue mussels ... |
format |
Master Thesis |
author |
Meister, Nadja |
author_facet |
Meister, Nadja |
author_sort |
Meister, Nadja |
title |
The role of crawling predators in the decline and distribution of blue mussels in Norwegian coastal waters |
title_short |
The role of crawling predators in the decline and distribution of blue mussels in Norwegian coastal waters |
title_full |
The role of crawling predators in the decline and distribution of blue mussels in Norwegian coastal waters |
title_fullStr |
The role of crawling predators in the decline and distribution of blue mussels in Norwegian coastal waters |
title_full_unstemmed |
The role of crawling predators in the decline and distribution of blue mussels in Norwegian coastal waters |
title_sort |
role of crawling predators in the decline and distribution of blue mussels in norwegian coastal waters |
publisher |
The University of Bergen |
publishDate |
2022 |
url |
https://hdl.handle.net/11250/3021981 |
geographic |
Norway |
geographic_facet |
Norway |
genre |
Dogwhelk Nucella lapillus |
genre_facet |
Dogwhelk Nucella lapillus |
op_relation |
https://hdl.handle.net/11250/3021981 |
op_rights |
Copyright the Author. All rights reserved |
_version_ |
1766243507308068864 |