Tank, J.L. and S.K. Hamilton
Presented at the All Scientist Meeting (2002-10-04 )
In this talk we present an overview of a large cross-site research project known as the Lotic Intersite Nitrogen Experiment (LINX). The LINX study approach and experimental design were conceived and refined over the course of several workshops, some supported by LTER and others by independent grants. The original LINX project was funded by a grant from NSF to Virginia Tech, with 4 principal investigators and 10 subcontracts to other institutions. Six of the ten primary study streams were associated with LTER sites: Coweeta, Hubbard Brook, KBS, Andrews, Konza, and Luquillo. The LINX experiments were performed in 1997 and 1998. The experiments entailed 6-week additions of ammonium labeled with 15N to entire streams, providing a tracer that was employed to determine ammonium uptake, nitrogen transformations, and food web transfer of nitrogen. A couple of additional sites participated with their own funding. Most of the more difficult isotopic measurements were accomplished by sending samples to the Marine Biological Laboratory in Woods Hole.Results of the LINX research have appeared so far as 19 journal articles, with about 8 more in review. In general, papers dealing with specific sites appeared first, followed by papers with synthesis across sites. Site papers dealt with the core results as well as “spinoff studies”, often performed by students. The LINX experiments have been the topic of 6 theses and dissertations and at least 70 presentations at scientific meetings. The coordination of LINX was successful for several reasons. First, at least one of the four principal investigators visited each of the sites during the experiments. Second, a post-doctoral associate (Jennifer Tank) went to each of the sites to organize the data collection and ensure that the same techniques were used at every site. Third, nearly all of the researchers involved in the LINX regularly attend the annual meetings of the North American Benthological Society (NABS), and a day prior to each NABS meeting was set aside for a LINX meeting to work out the methods, discuss initial results, and eventually to plan synthesis efforts and discuss the results of those efforts. Most of the core group of LINX researchers are now involved in a new cross-site project known as LINX 2, funded through the NSF program called Integrated Research Challenges in Environmental Biology. The emphasis of this project is nitrate retention and transformation in streams. Experiments are scheduled for the next three years.
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