Premium
Denitrification in a large river: consideration of geomorphic controls on microbial activity and community structure
Author(s) -
Tatariw Corianne,
Chapman Elise L.,
Sponseller Ryan A.,
Mortazavi Behzad,
Edmonds Jennifer W.
Publication year - 2013
Publication title -
ecology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.144
H-Index - 294
eISSN - 1939-9170
pISSN - 0012-9658
DOI - 10.1890/12-1765.1
Subject(s) - denitrification , biogeochemical cycle , benthic zone , community structure , environmental science , ecology , ecosystem , sediment , river ecosystem , habitat , spatial ecology , microbial population biology , spatial variability , hydrology (agriculture) , nitrogen , geology , biology , chemistry , paleontology , statistics , mathematics , geotechnical engineering , organic chemistry , bacteria
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.