Journal
JOURNAL OF MARINE SYSTEMS
Volume 88, Issue 3, Pages 434-445Publisher
ELSEVIER
DOI: 10.1016/j.jmarsys.2010.12.003
Keywords
Bacteria; Protists; Sinking velocity; Sedimentation; Organic carbon; Recycling; Hudson Bay; Subarctic
Funding
- Natural Sciences and Engineering Research Council (NSERC) of Canada
- National Centre for Arctic Aquatic Research Excellence (N-CAARE) (Fisheries and Oceans Canada)
- Canadian Museum of Nature
- Network of Centres of Excellence (NCE) of Canada ArcticNet
- Institut des sciences de la mer de Rimouski (ISMER)
- Fondation de l'UQAR
- Quebec-Ocean
- ArcticNet
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This study investigates, for the first time, the role of free-living and particle-attached bacteria in the sinking export and recycling of organic matter in the Hudson Bay system (i.e. Hudson Bay, Hudson Strait, and Foxe Basin), a large subarctic estuarine system. During the late summers of 2005 and 2006, the abundance, cell size, nucleic acid content, and sinking velocity of free-living and particle-attached bacteria were studied simultaneously, using a new approach that combines the settling column method with flow cytometry. Biomass, production, and respiration of both types of bacteria were estimated using published models. Our results showed that particle-attached bacteria were, on average, twice as large as and contained 1.3 times more nucleic acid than free-living bacteria. Particle-attached bacteria also sank faster than predicted by Stoke's Law, with estimated sinking velocities comparable to those of chlorophyll a biomass and protist cells. Each individual cell of the particle-attached bacterial community had high carbon demand, but their low abundances (<3% of total bacterial numbers) resulted in low total carbon demand. Therefore, the main contributors to POC recycling were found to be free-living bacteria using the non-sinking dissolved organic material, which is released from particles due to the hydrolytic activity of particle-attached bacteria. (C) 2010 Elsevier B.V. All rights reserved.
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