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Response of microphytobenthic biomass to experimental nutrient enrichment and grazer exclusion at different land-derived nitrogen loads

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dc.contributor.author Lever, Mark A.
dc.contributor.author Valiela, Ivan
dc.date.accessioned 2011-04-21T15:29:31Z
dc.date.available 2011-04-21T15:29:31Z
dc.date.issued 2005-06-09
dc.identifier.citation Marine Ecology Progress Series 294 (2005): 117-129 en_US
dc.identifier.uri http://hdl.handle.net/1912/4487
dc.description Author Posting. © Inter-Research, 2005. This article is posted here by permission of Inter-Research for personal use, not for redistribution. The definitive version was published in Marine Ecology Progress Series 294 (2005): 117-129, doi:10.3354/meps294117. en_US
dc.description.abstract Effects of eutrophication on the relative importance of nutrients and macroherbivores as controls of microphytobenthic standing crop were examined in estuaries with different nitrogen loading rates: Sage Lot Pond (14 kg ha–1 yr–1), Green Pond (178 kg ha–1 yr–1), and Childs River (601 kg ha–1 yr–1). We selected 5 sites with similar salinity ranges on shallow-water, sandy substrates per estuary. In year-round experiments, we fertilized sediments with nitrogen + phosphorus to examine nutrient limitation. We conducted exclusion experiments to determine the significance of macroherbivores as controls of microphytobenthic biomass and examined possible interactions between nutrients and grazing in cages fertilized with nitrogen + phosphorus. Cages fertilized with nitrogen only were also included to determine if nitrogen availability was limiting. Nitrogen + phosphorus addition increased sediment chlorophyll a (chl a) content (herein used as a proxy for biomass) by a similar magnitude across estuaries. Grazer exclusion also increased chl a, but to a different extent across estuaries: the magnitude of the response increased with increasing nitrogen loading rates. We found no interactions between nutrients and grazing. Strong chl a increases in response to nitrogen only addition indicated N limitation in Sage Lot Pond and Green Pond. In the highly eutrophic Childs River estuary we found virtually no response to nitrogen-only additions, suggesting the possibility of phosphorus limitation in this estuary. en_US
dc.description.sponsorship This study was supported by a Sounds Conservancy Fellowship awarded by the Québec-Labrador- Foundation. en_US
dc.format.mimetype application/pdf
dc.language.iso en en_US
dc.publisher Inter-Research en_US
dc.relation.uri http://dx.doi.org/10.3354/meps294117
dc.subject Microphytobenthos en_US
dc.subject Biomass en_US
dc.subject Nutrients en_US
dc.subject Grazers en_US
dc.subject Eutrophication en_US
dc.subject Nitrogen load en_US
dc.title Response of microphytobenthic biomass to experimental nutrient enrichment and grazer exclusion at different land-derived nitrogen loads en_US
dc.type Article en_US
dc.identifier.doi 10.3354/meps294117


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