The Role of Submerged Aquatic Vegetation in Structuring the Nearshore Fish Community Within an Estuary of the Southern Gulf of St. Lawrence
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Artificial fertilizers are contributing to the replacement of eelgrass (Zostera marina) by sea lettuce (Ulva lactuca) in estuaries of Prince Edward Island (PEI), Canada. In this study, we found that the nearshore fish community differed between areas dominated by these two vegetations within an estuary in every month sampled (April–August). Adult northern pipefish (Syngnathus fuscus), threespine stickleback (Gasterosteus aculeatus), blackspotted stickleback (Gasterosteus wheatlandi), and Atlantic silverside (Menidia menidia) were most strongly associated with eelgrass, while mummichog (Fundulus heteroclitus), ninespine stickleback (Pungitius pungitius), and American eel (Anguilla rostrata) were often more numerous in sea lettuce. Sea lettuce stations tended to have more young-of-the-year mummichog, fourspine stickleback (Apeltes quadracus), and Gasterosteus sp. than eelgrass stations but fewer young-of-the-year northern pipefish and Atlantic silverside. Fish richness and abundance were significantly lower in the sea lettuce than eelgrass habitat during August when benthic hypoxia occurred. We conclude that the loss of eelgrass from PEI estuaries will result in significant declines in fish biodiversity.
KeywordsMacroalgae Eelgrass Seagrass Fish community Eutrophication Habitat
Fieldwork would not have been possible without the help of Jennifer van der Lee, Alex Campbell, Christina Pater, and Joubin Saffary. Marie-Hélène Thériault, Aquatic Science Biologist, Department of Fisheries and Oceans, processed the sediment samples. Funding was provided by a Natural Sciences and Engineering Research Council of Canada postgraduate scholarship to AS, Aquanet funds to MvdH, Canada Research Chair funding to MvdH, and by the Province of Prince Edward Island.
Conflict of Interest Notification Page
This manuscript has been read and approved by all authors listed on the title page, and all authors have made a substantial contribution to one or more of the design, execution, and reporting of the scientific study. All sources of financial support for the work are described in the acknowledgements of the paper, and none of the authors holds any financial interests in any reported findings. Beyond employment with the institutions listed on the title page and receiving NSERC grants and scholarships, none of the authors has a financial relationship with the organizations that supported the research, and no future benefit is anticipated from these or any other source as a result of this work. The authors have full control of all primary data and will make those data available to the journal for review upon request. We are unaware of any potential conflicts of interest.
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