Why is the Lake Clearer When Zebra Mussels are Present? Do Zebras Cause Harmful Algae Blooms?

According to Larry Eichler, a Research Scientist at Lake George’s Darrin Fresh Water Institute, zebra mussels are non-selective filter feeders; meaning they live on all types of algae and do not selectively “filter” toxic blue green algae out.  But their presence is the reason many lakes experience an increase in water clarity following their introductions.  Ergo, this scientist feels that the presence of zebra mussels is not implicated in the formation of harmful algae blooms (HAB’s).

About getting rid of algae, Dr. Eichler suggests increasing water flow/aeration by artificial circulation (e.g. aerators, Solar Bee circulators, etc.) as suggestions to reduce available phosphorus and ultimately the quality of algae present in lakes and ponds.  The literature is somewhat mixed about the effectiveness of this technique but some successes have been reported.

In eutrophic (moderate to high algal productivity) lakes and ponds (like Ballston Lake), dying algae are constantly raining down on the lake bottom where their decomposition consumes oxygen.  The well mixed surface waters (epilimnion) are constantly replenished with oxygen, so low oxygen levels rarely occur in this zone and resultant fish kills are even more rare.  In the deeper waters below the thermocline, low oxygen levels during the period of summer stratification are common and fish generally avoid these areas.

BLIA would like to thank our Lake Management Vice President, Dr. David Pierce for being in touch with Dr. Eichler about the relationship between Zebra Mussels and Algae and lake clarity. Another fine example or your BLIA Board at work on your behalf.