Research Objectives:
This project investigates the distribution, phylogenetic affinities and aspects of the ecology of ammonium-oxidizing bacteria (AOB) in the Palmer LTER (Long Term Ecological Research) study area. The goals of this project are to:
+ Obtain more conclusive information concerning composition of antarctic ammonia oxidizers;
+ Begin characterizing their ecophysiology and ecology; and
+ Obtain cultures of the organism for more detailed studies.
Researchers will characterize water column and sea ice AOB assemblages phylogenetically and quantify different kinds of AOB in various samples. They will measure nitrification rates across the LTER study area in water column, sea ice and sediment samples. They will determine grazing rates on AOB and evaluate their sensitivity to UV light. The investigators will assess the significance of urea nitrogen as a source of reduced nitrogen to AOB. Finally, the group will evaluate the temperature response of nitrification over temperature ranges appropriate to polar regions. This work is expected to provide insights into the ecology of AOB and the knowledge needed to model how water column nitrification will respond to changes in the polar ecosystems accompanying global climate change.
Project team members will collect water samples at regular intervals at six stations per day. They will take sediment samples which return an undisturbed surficial surface layer. In the lab, they will perform incubations and UV experiments in a temperature- and light-controlled environment, either a flowing sea-water bath or an incubator. The project includes fieldwork at Palmer Station and onboard the R/V Laurence M. Gould.
