Abundance, activity and community structure of denitrifiers in drainage ditches, in relation to sediment characteristics, vegetation and land-use

TY - JOUR

T1 - Abundance, activity and community structure of denitrifiers in drainage ditches, in relation to sediment characteristics, vegetation and land-use

AU - Veraart, A.J.

AU - Dimitrov, M.

AU - Schrier-Uijl, A.P.

AU - Smidt, H.

AU - de Klein, J.J.M

N1 - 6162, ME; Data archiving: Data archived at MDA.

PY - 2017

Y1 - 2017

N2 - Drainage ditches are ubiquitous yet understudied features of the agricultural landscape. Nitrogen pollution disrupts the nutrient balance of drainage ditch ecosystems, as well as the waterbodies in which they drain. Denitrification can help ameliorate the impact of N-fertilization by converting reactive nitrogen into dinitrogen gas. However, factors affecting denitrification in drainage ditches are still poorly understood. In this study, we tested how within-ditch and regional environmental conditions affect denitrifier activity, abundance, and community structure, to understand controls on denitrification at multiple scales. To this end, we quantified in situ denitrification rates and denitrifier abundance in 13 drainage ditches characterized by different types of sediment, vegetation and land-use. We determined how denitrification rates relate to denitrifier abundance and community structure, using the presence of nirS, nirK and nosZ genes as a proxy. Denitrification rates varied widely between the ditches, ranging from 0.006 to 24 mmol N m−2 h−1. Ditches covered by duckweed, which contained high nitrate concentrations and had fine, sandy sediments, were denitrification hotspots. We found highest rates in ditches next to arable land, followed by those in grasslands; lowest rates were observed in peatlands and nature reserves. Denitrification correlated to nitrate concentrations, but not to nirK, nirS and nosZ abundance, whereas denitrifier-gene abundance correlated to organic matter content of the sediment, but not to nitrate concentrations. Our results show a mismatch in denitrification regulators at its different organizational scales. Denitrifier abundance is mostly regulated at within-ditch scales, whereas N-loads, regulated by landscape factors, are most important determinants of instantaneous denitrification rates.

AB - Drainage ditches are ubiquitous yet understudied features of the agricultural landscape. Nitrogen pollution disrupts the nutrient balance of drainage ditch ecosystems, as well as the waterbodies in which they drain. Denitrification can help ameliorate the impact of N-fertilization by converting reactive nitrogen into dinitrogen gas. However, factors affecting denitrification in drainage ditches are still poorly understood. In this study, we tested how within-ditch and regional environmental conditions affect denitrifier activity, abundance, and community structure, to understand controls on denitrification at multiple scales. To this end, we quantified in situ denitrification rates and denitrifier abundance in 13 drainage ditches characterized by different types of sediment, vegetation and land-use. We determined how denitrification rates relate to denitrifier abundance and community structure, using the presence of nirS, nirK and nosZ genes as a proxy. Denitrification rates varied widely between the ditches, ranging from 0.006 to 24 mmol N m−2 h−1. Ditches covered by duckweed, which contained high nitrate concentrations and had fine, sandy sediments, were denitrification hotspots. We found highest rates in ditches next to arable land, followed by those in grasslands; lowest rates were observed in peatlands and nature reserves. Denitrification correlated to nitrate concentrations, but not to nirK, nirS and nosZ abundance, whereas denitrifier-gene abundance correlated to organic matter content of the sediment, but not to nitrate concentrations. Our results show a mismatch in denitrification regulators at its different organizational scales. Denitrifier abundance is mostly regulated at within-ditch scales, whereas N-loads, regulated by landscape factors, are most important determinants of instantaneous denitrification rates.

KW - international

UR - http://mda.vliz.be/mda/directlink.php?fid=VLIZ_00000479_5788e54d38ca9

U2 - 10.1007/s10021-016-0083-y

DO - 10.1007/s10021-016-0083-y

M3 - Article

SN - 1432-9840

VL - 20

SP - 928

EP - 943

JO - Ecosystems

JF - Ecosystems

IS - 5

ER -