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Winter 2010 Home Page
General Notices
President's Message
Lakeside Notes
Littorally Speaking
Welcome Aboard New Monitors
National Lakes Assessment
Algal Toxins
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Volunteer Lake Monitors Assist DEP in Two Year Study - S.W.
You may be surprised to learn that, although algae are vital to virtually all forms of life in lakes and ponds, under certain circumstances they can be very toxic. Documented toxic blue-green algal blooms (aka: cyanobacteria) have been reported in North America for many years, and toxic algae, in general, have actually been documented dating back to ancient Rome.
But recently, perhaps due to a number of circumstances, which may include the effects of climate change (milder winter temperatures, reduced ice cover and warmer summers), algal blooms in the United States and Canada have been on the increase, as have poisonings of wildlife and domestic animals, fish, and aquatic biota from toxic blooms.
Cyanotoxins, the toxic compounds that are formed by cyanobacteria, have also been implicated in human illness, and even death. Toxic blooms probably have negative economic impacts on water uses—certainly drinking water—and property values, as well. In a position paper on toxic cyanobacteria blooms, the North American Lake Management Society states: “The human health, ecological, and economic impacts of cyanobacteria blooms can be very high.” (see NALMS Position Statement 8:
www.nalms.org/nalmsnew/userfiles/file/nalms_position_8_cyanobacteria.pdf)
Cyanobacteria blooms occur in all freshwater systems, including lakes and ponds. However, the intensity and duration of an algal bloom very likely determines the extent to which compounds associated with the algae reach unhealthful toxic levels. Because the degree to which algal blooms occur is related to the availability of nutrients, like phosphorus, in the water, the large majority of Maine’s clear, low nutrient lakes may be at somewhat lower risk of experiencing algal toxins than bodies of water in the southern part of the U.S. Although the algae/bacteria that form blooms most often accumulate in “scums” that are visible on the water surface, in a wide range of colors from bright blue to brown, some of the bacteria that produce toxins do not form surface scums.
There is still much to be learned about why some blooms produce more toxins than others. In an effort to determine potential levels of cyanotoxins in Maine lakes that have a history of significant algal blooms, the Maine DEP sampled 31 lakes during the summers of 2008 and 2009. VLMP volunteers who monitored lakes on the list assisted DEP staff with this project.
The following summary of the algae toxins monitoring project was prepared late in 2009 by DEP Biologist Roy Bouchard.
Monitoring Maine Lakes for Algae Toxins
By By Roy Bouchard
Maine DEP
Lakes Assessment Biologist
During the summers of 2008 and 2009 , Maine DEP monitored a total of 31 lakes, 10 of them multiple times and all at least once in August for a total of more than 80 open water samples. All of them have a history of supporting dense cyanophyte (“blue-green” algae) blooms in the recent past.
Typically, samples were composited from 2-3 stations within 1/4 mile of our standard open water monitoring stations at the deepest part of the lake. Our standard protocol calls for an integrated epilimnetic (composite surface layer) sample which is filtered and frozen to preserve toxins present in plankton. Additionally, surface scums were sampled when encountered (seven samples). Toxin analyses were performed at ESF-Syracuse by Dr. Greg Boyer's lab, which used PPIA analysis to detect total algal toxin microcystin (MC) LR-equivalents (all activity of microcystin congeners and nodularins combined). Above a response of 0.5 ppb, these samples were also run on HPLC-MS to differentiate major microcystin congeners and 7 variants of nodularins. Algal toxins anatoxin-a and cylindrospermopsin were run by high performance liquid chromatography and mass spectrometry (HPLC-MS: chromatography physically separates the molecules by size, shape and electric charge, and MS gets signals about how each piece of the mix responds to a signal.. Certain chemical groups show up as separate peaks as they react in a magnetic field). 2009 results for PSP and BMAA are pending. In addition to toxin analysis we analyzed water samples for Total Phosphorus, Nitrogen (TKN and NO2-NO3), and Chlorophyll_a.
Algal surface scum in
a lake experiencing a "bloom"
What We Found in 2008
No samples tested positive for less common toxins (Anatoxins or Cylindrospermopsin). Saxitoxin was not analyzed in this year’s samples, but is highly unlikely. However, we did find microcystins in 13 of the 41 core (epilimnetic) samples from open water. The detected concentrations ranged from 0.27 ug/L to 1.05 ug/L. (micrograms per liter —or ug/L is equivalent to parts per billion—or ppb) These low levels were a bit unexpected, since we had a number of days when the Secchi readings were below 1.5 meters and some lakes were below 1 meter the day we sampled. Other states report similar levels in their better quality waters. However, they often report much higher microcystin levels compared with our “worst case” situations since their total phosphorus can be an order of magnitude higher and many bloom conditions sampled are far worse than ours.
The lab noted that in a number of cases, the detection limit for MC was at or above 0.1 ppb, due to the relatively low concentration and limited amount of material presented on each filter. With higher sensitivity, it is probable that more detects would have been reported.
As expected, four of the six surface scums (sampled by volunteers or our staff) had moderate to high concentrations of microcystins (324-21,476 ppb dry weight). These values are in line with what is reported from studies all around the world. Unfortunately, these are usually expressed in terms of % microcystins by weight of dried material and thus can’t easily be related to open water numbers referenced above.
What We Found in 2009
This year our samples were submitted as paired filters for analysis, increasing the sensitivity and lowering the reporting limit. Results for microcystins show MC above detection limit on detect on 32 of 43 open water samples ranging from 0.029 to 1.93 ug/L. Three were above the World Health Organization (WHO) drinking water advisory standard of 1 ug/L.
The six surface scum samples contained high levels of microcystins and ranged from 11 to almost 12,000 ug/L on a wet weight basis and 1.7 to 451 ug/g dry wt.
All of the toxicity in samples run by LCMS was attributed to microcystin-LR and no nodularin was identified. No samples were positive for Anatoxin -a or Cylindrospermopsin. The laboratory report notes that in their experience "…less than 4% of all samples analyzed test positive for anatoxin-a, homo-anatoxin or its metabolites. Even fewer test positive for cylindrospermopsin, which is extremely rare in northern latitudes."
Open water sample microcystin concentrations for both years are shown below. When complete, a project summary will be posted at www.maine.gov/dep/blwq/docmonitoring/lake
Maine Volunteer Lake Monitoring Program
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