Denitrification in a large river: consideration of geomorphic controls on microbial activity and community structure

Tatariw, Corianne and Chapman, Elise L. and Sponseller, Ryan A. and Mortazavi, Behzad and Edmonds, Jennifer W. (2013) Denitrification in a large river: consideration of geomorphic controls on microbial activity and community structure. Ecology, 94 (10). pp. 2249-2262. ISSN 0012-9658

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Ecological theory argues that the controls over ecosystem processes are structured hierarchically, with broader-scale drivers acting as constraints over the interactions and dynamics at nested levels of organization. In river ecosystems, these interactions may arise from broadscale variation in channel form that directly shapes benthic habitat structure and indirectly constrains resource supply and biological activity within individual reaches. To evaluate these interactions, we identified sediment characteristics, water chemistry, and denitrifier community structure as factors influencing benthic denitrification rates in a sixth-order river that flows through two physiographic provinces and the transitional zone between them, each with distinct geomorphological properties. We found that denitrification rates tracked spatial changes in sediment characteristics and varied seasonally with expected trends in stream primary production. Highest rates were observed during the spring and summer seasons in the physiographic province dominated by fine-grained sediments, illustrating how large-scale changes in river structure can constrain the location of denitrification hotspots. In addition, nirS and nirK community structure each responded differently to variation in channel form, possibly due to changes in dissolved oxygen and organic matter supply. This shift in denitrifier community structure coincident with higher rates of N removal via denitrification suggests that microbial community structure may influence biogeochemical processes.

Item Type: Article
Language: English
Future Forest Subject: Skogsbruk i klimatförändringens tid > Natur
Depositing User: Christer Enkvist
Date Deposited: 28 Feb 2017 14:22
Last Modified: 28 Feb 2017 14:22

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