US Long-Term Ecological Research Network

The importance of the position of a lake in the landscape relative to hydrologic flow has been a focus of the Long-Term Ecological Research Project, based at the UW-Madison Center for Limnology, for almost two decades. We have found that there are strong patterns in water chemistry, primary productivity, and morphology driven by ground and surface water inputs (Magnuson et. al. 1990, Kratz et al. 1997, Riera et al. in press). Also, lake size and physico-chemical conditions within a lake have been shown to influence community structure in fishes (Tonn and Magnuson 1982, Tonn et al.1990). However, we know much less about how landscape level traits, such as surface water connections, influence biotic diversity and community structure within lakes and whether the species pool changes across watersheds of North-Central Wisconsin (Hrabik and Magnuson 1999). The primary goal of our project is to conduct field experiments that contrast lake chemical and geographical properties and explore the role of those properties in shaping biotic diversity and community structure.

Specifically, we will be addressing two broad ecological questions:

1. What is the relative importance of water chemistry and stream connections in shaping biotic diversity and community structure in lakes?
2. Are there significant differences in biotic communities between connected lakes within the same drainage area, or between lakes located in separate watersheds?

To address these questions, we collected data on fish, benthos, aquatic plants, zooplankton, and phytoplankton communities as well as water chemistry in lakes located in Vilas, Onieda and Forest counties, Wisconsin during the summers of 1998 and 1999