IISG’s science writer, Anjanette Riley, is at the 2013 International Association for Great Lakes Research conference at Purdue University. She’ll be blogging from the sessions all week providing an inside look at the newest research on the health of the Great Lakes. Here’s today’s post:
“The Great Lakes got their report card this morning during a three-part presentation by members of the State of the Lakes Ecosystem Conference (SOLEC). It wasn’t good. In two of the three categories used to evaluate the health of the basin—water quality, aquatic wildlife, and landscapes and natural processes—the lakes were declared ‘fair and deteriorating.’ It was only in the third category, which covers things like habitat restoration and land use, that the region showed clear signs of overall improvement.
Most of the drivers behind worsening water quality and wildlife health likely sounded familiar to everyone in the room. Clodophora, a green algae common in the region, is washing up on more and more shorelines and threatening drinking water. New contaminants are being introduced to aquatic ecosystems. Invasive species are out-competing native fish and permanently changing the food web. And coastal wetlands used by fish for spawning are disappearing.
What was not as familiar, at least to me, were concerns over the spread of nutrients throughout the lake. In recent years, nutrients that are carried into the lakes in stormwater runoff, like phosphorus, have built up along the coastline instead of being pushed to deeper waters. In nearshore waters, these trapped nutrients mean more algae; so much more that it can block sunlight and reduce oxygen that fish and other wildlife need to survive. Offshore, though, the loss of nutrients means that there is not enough phytoplankton for wildlife to feed on. Paul Horvatin, one of the presenters, told the room that it is still unclear why the nutrients are not moving as they should.
But there were some improvements over past years. The most notable to me was the growing number of restoration and dam removal projects that are opening up new waterways for fish to spawn, restoring the natural flow of rivers and tributaries, and reconnecting habitats, some of which have been divided for close to 100 years. The region has also seen improvements in land use practices, such as reforestation and increased reliance on green infrastructure. Extensive development and agriculture in the southern part of the Great Lakes basin, though, have caused enough damage in the past that more modern changes to land use practices and policies will take time to really show results. These ecosystems are more stressed then their northern counterparts and will require ongoing restoration and impact mitigation.”
IISG’s science writer, Anjanette Riley, is at the 2013 International Association for Great Lakes Research conference at Purdue University. She’ll be blogging from the sessions all week providing an inside look at the newest research on the health of the Great Lakes. Here’s today’s post:
“It was during a presentation today on the impacts of climate change to water levels that I learned a startling fact: Lake Erie’s water level trends have in essence made a 180 degree turn. Historically, water levels in the Great Lakes are at their highest in summer when increased rain and stormwater runoff add more water to the lakes than they lose to evaporation, and levels are lowest in the winter months. In recent decades, though, this trend has been reversing, leaving water levels higher in January than they are in June.
According to data collected by the Great Lakes Environmental Research Lab (GLERL), one of the biggest driving forces behind this shift is increased evaporation over the lake during the hot summer months.
Evaporation is also a primary culprit in Lake Superior’s falling water levels. Here, though, warmer water temperatures that mean less ice in winter are causing greater evaporation across seasons. And less water is entering the lake from rain and stormwater runoff.
The story is different still in Lakes Michigan and Huron, where water levels reached an all-time low in the 1990s and have largely stayed there since.
Of course, there is still some variation in water levels year over year. The water in Lake Erie, in fact, rose by almost 3 feet over the course of just four months in 2011. But these jumps, as the presentation attendees were told, appear to be the exception to the rule. In these three lakes, water levels are trending down.”
