by Conservation MN SpotlightIn common usage, “sentinel” means someone standing guard or watch. In Minnesota, it now means a small force of scientists and natural resource managers standing guard over two dozen of our lakes to watch for changes that may be subtle in the short-term, but dramatic in the long term.It’s one of the few programs of its kind in the nation. Dubbed “Sustaining Lakes In a Changing Environment,” or SLICE, the watch over so-called sentinel lakes is tracking how residential and urban development, agriculture, invasive species, and climate change are affecting or will affect water quality, lake habitats, and fish populations.The short-term goal of SLICE is to identify and focus attention on key indicators of lake health that are responsive to watershed and climate changes. The long-term goal is to monitor these indicators in representative lakes across the state and to be on the watch for signs that a lake’s habitat or fish community may be under stress.“SLICE puts us into the position of detecting change in our lakes before it’s too late and having some idea of the mechanism that’s causing the change,” says Ray Valley, Minnesota DNR research biologist and SLICE coordinator. “Armed with this information, we can take measures to mitigate the problem if it’s acute, or adapt to changes that are for most intents and purposes, irreversible.”For example, many threats to water quality and habitat can be addressed at the local level through partnerships with local governments to implement low-impact development and agricultural practices. Another example is enforcing rules that limit the amount of aquatic plant habitats lakeshore owners can remove from lakes. These are both examples of ways we can protect water quality and habitat, and enhance the resilience of lakes to changes we have less control over, like warming water temperatures and longer growing seasons due to climate warming.“Proactive responses aren’t possible without good long-term monitoring data,” says Valley.Possible indicators emerging from SLICE may range from a complex index that scores the health of the fish community based on the composition of net catches, to simple indicators like total phosphorus, or temperature and dissolved oxygen profiles.