Influence of chironomid larvae on oxygen and nitrogen fluxes across the sediment-water interface (Lake Taihu, China).
The microscale distribution of oxygen, the nitrogen flux and the denitrification rates in sediment inhabited by chironomid larvae (Tanypus chinensis) were measured in eutrophic Lake Taihu, China. The presence of the chironomids in the sediment increased the oxygen diffusional flux from 10.4 +/- 1.4 to 12.7 +/- 2.5 mmol O2/(m2 x day). The burrows of the larvae represented "hot spots" and strongly influenced the nitrogen cycles and diagenetic activity in the sediment. The results indicate that the bioturbation effects of Tanypus chinensis chironomid larvae increased the capacity of the sediment as a sink for nitrate and a source for ammonium. Nitrate influx and ammonium outflux were increased 8.8 and 1.7 times, respectively. Under bioturbation, the amount of nitrate consumed was greater than the amount of ammonium released. The total denitrification rate was also enhanced from 0.76 +/- 0.34 to 5.50 +/- 1.30 mmol N/(m2 x day). The net effect was that the bioturbated sediments acted as a net sink for inorganic nitrogen under direct and indirect bioturbation effects compared to the control.
State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing 210008, China. shangjingge@163.com
Jingge
J
Shang
Lu
L
Zhang
Chengjun
C
Shi
Chengxin
C
Fan
D000818:Animals; D002681:China; D002683:Chironomidae; D058440:Denitrification; D019015:Geologic Sediments / Q000032:analysis*; D060106:Lakes; D007814:Larva; D009584:Nitrogen / Q000032:analysis*; D010100:Oxygen / Q000032:analysis*; D014874:Water Pollutants, Chemical / Q000032:analysis*
D014874:Water Pollutants, Chemical; D009584:Nitrogen; D010100:Oxygen