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By Scott Williams
VLMP Executive Director
Hard as it may be to believe— and accept—another summer has passed. And a glorious summer it was for those of you who were gathering water quality data, or conducting an invasive aquatic plant screening survey on your lake. In dramatic contrast to the relentlessly rainy summer of 2009, the past several months have, for the most part, been bright, dry, warm, and relatively calm. It could not have been more pleasant—or could it?
Last summer will also be remembered for conditions that may have ominous implications for the future of Maine's lakes and ponds. It began in late winter when, following a period of extended, unusually warm weather, ice-out records were shattered throughout the state. Most lakes and ponds throughout Maine were free of ice nearly a month ahead of their historic average.
Thompson Lake
photo by Scott Williams
But we all know that Maine weather can fluctuate from one extreme to another in short order. And so, following the early departure of the ice, we braced for a two foot snowstorm and sub zero temperatures. But nothing even close to that happened. Instead, with only a few brief excursions, the weather continued to warm for the next several weeks, resulting in what may have been the warmest spring on record. The transition from winter to early summer, instead of being gradual, was immediate. I can honestly say that I have never experienced a winter-spring-summer period in Maine anything like it.
Algae boolms like this one on Sabattus Pond could become more common as our lakes become warmer
Compared to lakes throughout much of the country Maine's lakes are clear and clean—for many reasons, not the least of which is our relatively cool climate, which results in chilly water temperatures throughout much of the year. Temperature has a strong bearing on the growth of algae and rooted aquatic plants, both native and invasive. Our northerly climate helps minimize algae growth, and it limits the species of rooted aquatic plants that are able to survive in our lakes. The fact that Maine lakes spend part of the year covered with ice and snow slows down virtually all biological processes in the ecosystem. Of course there are many other influences on these processes, but cold lake water plays a strong role in distinguishing our lakes from their southerly neighbors, which for the most part are less clear, greener, weedier, and they are unable to support coldwater fisheries.
Water that is rich in dissolved oxygen, and which stays relatively cool during the warmest time of the year, is essential to the survival of fish like trout and salmon, which spend much of their life cycle in the deepest, coldest areas of Maine's lakes and ponds. A relatively high percentage of Maine's lakes are able to provide such habitat, even during the late summer. But that could change if water temperatures begin to rise, and the deep, cold water sought by trout and salmon begins to lose more oxygen because the water is warmer and the period of thermal stratification lasts longer. Both are likely outcomes of a warming climate.
Virtually all of the known threats to the health of our lakes would very likely worsen in a warming climate. We may already be experiencing the early effects of this phenomenon. For the past several years, volunteer lake monitors and lake dwellers have reported increasing amounts of metaphyton (aka: filamentous algae, or "green cotton candy") growing in the shallow littoral areas of their lakes. Speaking from personal experience, I have seen a great deal more of this growth in the past decade than in several decades of living on and near lakes in Maine. What is interesting, and perhaps ominous, is that the metaphyton is being observed and reported in lakes and ponds with a wide range of water quality—from Maine's clearest to those with relatively poor Secchi read- ings and moderate phosphorus levels. If phosphorus is not the primary driver of this phenomenon, it is likely that some function of the weather is. My out-on-a-limb hunch is that it is temperature-driven. Unfortunately, there is not much data available to track the presence and abundance of metaphyton in Maine's lakes and ponds. Whether you are screening your lake for invasive plants or taking Secchi readings, we could use your help with this!
Last spring and summer were pretty wonderful. It surely was a great time to be working on the water. But I hope it was an anomaly. Unfortunately, all of the credible scientific data suggest otherwise. Some of the consequences to lakes of climate warming are pretty intuitive. But the inter-relationship of complex aquatic ecosystems with their watersheds involves many variables, and we can only guess at some of the changes we face, unless we are able to confront climate change aggressively.
Next summer, the VLMP will launch a new workshop series for volunteer monitors, covering various ways in which they can monitor the effects of climate change on their lakes. We will also be posting information on our website. So please stay tuned!
Maine Volunteer Lake Monitoring Program
vlmp@mainevlmp.org
24 Maple Hill Road, Auburn, ME 04210
(207) 783-7733
www.MaineVolunteerLakeMonitors.org
copyright 2010 Maine Volunteer Lake Monitoring Program | website comments to: vlmp@mainevlmp.org
