Site: North Temperate Lakes LTER
North Temperate Lakes LTER graduate students Luke Winslow and Lucas Beversdorf visiting a buoy equipped with sensors measuring physical, chemical, and biological attributes of Lake Mendota, Wisconsin.
Paul Hanson

Some of the most pressing ecological issues are global in nature. Highly valued ecosystem services, such as those provided by lakes and reservoirs, will come increasingly under stress in the future. Studying lake ecosystems at the continental, or even global scale requires a broadly distributed network of sites that can leverage local knowledge, data, and expertise toward the goal of understanding patterns and process at broad spatio-temporal scales. Scaling from sites to the globe is as much a cultural and technological challenge as it is a scientific one.

NTL-LTER researchers have been leaders in the formation and operation of the Global Lake Ecological Observatory Network (GLEON), a grass-roots network of ecologists, engineers, and information technology experts who study lake ecosystems. GLEON is a ‘learning organization’ — one in which the governance, strategic planning, and organizational evolution are tightly coupled with the scientific agenda defined by its membership. Science initiatives emerge from working groups and address issues such as understanding lake physical responses to climate change, factors controlling lake metabolism and carbon cycling, and processes leading to phytoplankton blooms. Work on these initiatives is greatly enhanced by data from sites distributed around the world.

GLEON has developed technologies for automating data retrieval from lake sensors, archiving those data in easily accessible repositories, and making those data available to scientists and the general public. GLEON is also developing a repository for scientific, economic, and social data for the world’s lakes (LakeBase). GLEON has initiatives in innovative analysis of lake data, using signal processing, numerical simulation, and system identification as some of the tools to draw inference from data. Scientific progress has resulted from the combined expertise of members from all career stages, with graduate students playing especially active roles in all aspects of the organization, from science to technology to governance, and even the formation and management of the GLEON Student Association, which has more than 50 members.

Graph for
Sensor data from NTL-LTER study lake, Crystal Lake, WI showing changes in dissolved oxygen, algae (measured in terms of the concentration of chlorophyll) and water temperature from spring turnover when the lake is mixing and conditions are homogeneous in the lake, to mid-summer stratification in June-July when distinct thermal layers in the lake create distinct chemical and biological conditions. Detailed sensor data also illustrate short-term 'micro-stratification' in the upper 5 m of the water column associated with calm, hot summer days. Measurements such as these are being used to improve current understanding of lake heat budgets and patterns of primary production in lakes.
Jordan Read,