Janine Rüegg

Contact: jrueegg@nd.edu

I am a fourth year PhD student in the Lamberti Lab. I joined the lab in 2006 after receiving my master’s degree from the Swiss Federal Institute of Technology, Zurich, Switzerland in 2003 and working different teaching and research jobs in aquatic ecology and botany. My current research focuses on the effects of Pacific salmon on stream ecosystems during their spawning runs.

I am looking at the effects of salmon spawners on benthic biofilms on Prince of Wales Island in Alaska. Biofilms are a complex of algae, fungi, and bacteria growing on submerged surfaces and thus are the basis of instream production. Salmon spawners have a dual effect on these biofilms in that they provide resources such as nutrients and tissue but also disturb the sediments when migrating upstream and building their nests. I want to establish which factors of the environmentdetermine the net outcome of this balance for biofilms. Preliminary research has shown that the balance might be determined by a combination of salmon spawner density and sediment size. My research has show that biofilms in our study streams are indeed nutrient limited and salmon nutrients alleviated this limitation to some degree, suggesting that enrichment by salmon is important to the productivity of these streams. Currently, I am investigating how spatial and temporal variation among stream and year influence our perception of salmon effects and whether environmental determinants of biofilm response to salmon are consistent among streams and years. To investigate this a bit closer I conducted additional studies that encompass scales from the riffle to the stream in multiple streams as well as looking at the seasonal variation within a specific stream.

More generally, I am interested in ecosystem heterogeneity and how it might influence our understanding of ecosystems. Understanding heterogeneity as an ecosystem attribute and determining how it influences our perception will help in ecosystem conservation and restoration. Heterogeneity can be either natural or caused by human influences but these types of heterogeneities might be structurally and functionally different. Further, I am interested in resource subsidies, how they vary in space and time and how their effects might be dependent on the heterogeneity of the recipient ecosystem. Resources subsidies are an important linkage between ecosystems and can contribute significantly to the productivity of recipient ecosystems. Human effects can alter the amount and/or the timing of a resource as well as the ecosystem boundary properties. However, little is know about the larger scale and longer term effects of resource subsidies making conservation and restoration difficult.