Native clams facilitate invasive species in an eelgrass bed

Whether the non-native seaweedSargassum muticumcan displace or impact native eelgrassZostera marinahas been debated in the literature, based on differing substrate requirements of the 2 species. Field observations in Bamfield, British Columbia, Canada, revealed that the non-nativeS. muticumsuccessfu...

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Bibliographic Details
Published in:Marine ecology. Progress series (Halstenbek) 2011-03, Vol.424, p.87-95
Main Authors: White, Laura F., Orr, Lindsay C.
Format: Article
Language:English
Subjects:
Animal organs
Clams
Ecological invasion
Habitats
Introduced species
Invasive species
Marinas
Seaweeds
Sediments
Tunicates
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Summary:Whether the non-native seaweedSargassum muticumcan displace or impact native eelgrassZostera marinahas been debated in the literature, based on differing substrate requirements of the 2 species. Field observations in Bamfield, British Columbia, Canada, revealed that the non-nativeS. muticumsuccessfully inhabits an eelgrass bed through colonizing siphons of the native clamTresus capax. Numerical or physical facilitation ofS. muticuminto the eelgrass bed byT. capaxmay be tempered by seaweed quality or condition. We used field sampling to investigate whether seaweed condition differs between 2 attachment substrates (clam siphon and rock) as a proxy for habitat quality. Attachment substrate promoted different morphologies ofS. muticum; individuals attached to clam siphons expressed morphologies consistent with sheltered areas compared to individuals attached to rock, which expressed wave-exposed morphologies. Habitat association with the different morphologies supported differences in the epibiont communities colonizingS. muticum. Further,S. muticumsubsequently facilitated incursion of the non-native tunicatesStyela clavaandBotrylloides violaceousinto the eelgrass bed through habitat provisioning. By facilitating 2 additional invaders,S. muticumenhances the level of invasion in the eelgrass bed. This non-native seaweed has the potential to disrupt the persistence of eelgrass in this system.
ISSN:0171-8630
1616-1599
DOI:10.3354/meps08958