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Maine Water Resources Research Institute Grant supporting new research on Gloeotrichia blooms in the Belgrades

 

By Dr. Denise Bruesewitz, Colby College

Maine lakes are facing increasing pressures from human activities, and recent studies show that water quality of many Maine lakes is in decline. Cyanobacterial blooms, for example the bloom that caused the Toledo, OH drinking water crisis this past summer, have been increasing both globally and in the state of Maine. The Maine Department of Environmental Protection lists over 40 lakes in the state as lakes that commonly experience blooms.

In particular, a species of cyanobacteria called Gloeotrichia echinulata (I’ll call them ‘Gloeo’) form blooms in low nutrient lakes and are increasingly common in Maine and across New England. Cyanobacterial blooms are usually linked to eutrophic lakes, but Gloeo typically occurs in lower nutrient systems like Long Pond. The Gloeo blooms in the northeastern US are capable of producing the hepatotoxin microcystin-LR, which can cause liver damage in humans, pets and livestock. Maine DEP has measured microcystin toxin in the water of some Maine lakes and detected concentrations that were above the guideline for safe drinking water.

            Cyanobacterial blooms, particularly Gloeo blooms, appear to be increasing in northeastern US lakes. A recent survey of New England lakes documented Gloeo in 27 of 37 sampled lakes, including all 13 Maine lakes in the study. A number of other monitoring efforts in Maine continue to document regular Gloeo blooms in Maine lakes, including Auburn Lake and Panther Pond (Holly Ewing, Bates College), Great Pond and Long Pond of the Belgrade Lakes (The Belgrade Regional Conservation Alliance citizen science monitoring & Colby College), as well as Moose Pond and other western Maine Lakes (The Lakes Environmental Association of Bridgton, Maine). Gloeo is clearly a growing concern in Maine lake ecosystems as many of these lakes, including some that are used as drinking water sources, are facing chronic problems of annual Gloeo blooms. When Gloeo blooms and produces toxins, the costs of water treatment and filtration may increase substantially. Lakes used recreationally may also face restrictions to access for swimming, boating, and fishing during bloom events. Additionally, as community awareness of Gloeo blooms increases, the occurrence of these blooms can cause declines in property values along affected lakes leading to reduced tax revenue.

            This summer, a new research project funded by the Maine Water Resources Research Institute is taking a closer look at Gloeo blooms on Long Pond and Great Pond of the Belgrades. This work will is a collaborative effort between Colby College (Denise Bruesewitz & Whitney King) and Bigelow Laboratory (Peter Countway) and a group of undergraduate students. The main goals of this work is to:

  1. Develop a rapid DNA-based assay to detect Gloeotrichia echinulata in Maine lakes. The majority of our measurements of Gloeo in Maine lakes stem from citizen science observations and microscopy-based counting techniques. While these are wonderful sources of information, the use of a DNA-based assay to measure Gloeo abundance would represent a major advancement in our ability to monitor a potentially harmful cyanobacterium in Maine lakes.
  2. Measure Gloeo abundance, toxin concentrations and microbial diversity for bacteria and phytoplankton in each lake. As concern over Gloeo blooms in Maine is growing, it is important to link Gloeo abundance measurements to the concentrations of microcystin toxins and other lake data (such as nutrients, oxygen and temperature). Additionally, we will provide a basis for understanding biological community dynamics that may favor or suppress Gloeo blooms.
  3. Measure N use and N-fixation rates of plankton communities in each lake. Like many other species of cyanobacteria, Gloeo can ‘fix’ di-nitrogen gas (N2), or make that nitrogen available for use in biomass production. Traditionally, phosphorus limitation was thought to prevent cyanobacterial blooms in low nutrient lakes, but Gloeo has been shown to overcome this limitation by using phoshpurs from the sediment. No previous research has directly measured nitrogen use and nitrogen fixation during Gloeo blooms in northeastern US lakes. N fixation is an energetically-expensive process, so it remains unclear when Gloeo fix nitrogen, and how much nitrogen they may be making available in our lakes. If Gloeo have ‘extra’ stores of sediment phosphours, measurement of their use of nitrogen (ammonium and nitrate) from the water column and the timing of when they resort to nitrogen fixation will be important to improve our understanding of the role of nutrients in bloom formation.
  4. Provide undergraduate student experiences spanning chemistry, genetics, limnology, microbiology and ecosystem ecology. This research will provide an excellent experience in cross-disciplinary, collaborative research for several undergraduate students at Colby College. The students will use state-of-the-art facilities and novel techniques working alongside experienced scientists.
  5. This work may reveal early-warning indicators of toxic algal blooms in Maine lakes. A major goal of the proposed work is to develop a mechanistic understanding of the interactions between nitrogen availability and microbial community structure. We also have the unique ability to link our measurements to data from ‘Goldie’ the high-frequency environmental monitoring buoy in Great Pond. This will allow us to examine bloom patterns that may develop after small-scale mixing events. This research will inform our understanding of cyanobacteria bloom dynamics and we hope that this work will provide new tools and data for improved predictions and assessment of Gloeo blooms in Maine lakes.

We look forward to sharing the results of this work at the MLRC as we work this summer. Please contact Denise (dabruese@colby.edu) or Whitney (dwking@colby.edu) for further details, or if you would be interested in monitoring Gloeo blooms from your dock through the summer months.

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