US Long-Term Ecological Research Network

Our vision is to gain a predictive understanding of the ecology of lakes at longer and broader scales than has been traditional in limnology. Our conceptual framework uses a nested set of spatial scales, from individual lakes and their watersheds, to hydrologically-linked sets of lakes, entire lake districts, multiple lake districts within the Great Lakes region, and comparative studies of lakes and lake districts around the globe. Our research program is interdisciplinary and aims to understand the ecology of lakes in relation to relevant atmospheric, geochemical, landscape and human processes. Within the NTL domain, we have observed shifts in driver and response variables that are both gradual and abrupt on time scales of years to decades. Examples of rapid changes in lake responses that have been particularly conspicuous to both researchers and many Wisconsin residents include the collapse of valuable Walleye fisheries; increasing fluctuations in lake levels; arrival of new aquatic invaders; and sudden declines in lake water clarity, among others. At the same time, we are also seeing changes in drivers that can cause abrupt change, but abrupt changes have not followed, leading us to ask why. Our research activities are inspired by these observations and are organized around the overarching question: What are the causes and consequences of abrupt ecological change in lakes and their surrounding landscapes? We address the following questions about abrupt ecological change:

Climate variability and lake phenology
What are lake phenological responses to a warmer and more variable climate that may lead to abrupt ecological change?

Interacting drivers and abrupt change in urban aquatic ecosystems
How do interactions of land use/land cover and climate change affect urban aquatic ecosystems?

Interacting drivers and water quality
How do external drivers interact with aquatic invasive species to regulate water quality?

Managing for abrupt change in whole-lake experiments
What causes intentional ecosystem manipulations to persist, revert, or lead to novel states?

Carpenter and class

Research Highlights

The most important NTL research findings are summarized in these highlights.


Transformational Science

NTL is transforming our understanding of aquatic ecosystems by pioneering new approaches and perspectives.


NTL's research infrastructure, data, and knowledge advancements have been leveraged extensively with independently funded projects.