“JUST WHAT IS THAT FOAM?”
The foaming of surface waters on lakes is not a new phenomenon. It is a natural process that has been going on for a long time in many different parts of the world. Foam is created when the surface tension of water (attraction of surface molecules to each other) is reduced and the air is mixed in, forming bubbles. When organisms, such as algae, plants, fish and/or zebra mussels die and decompose they release cellular products (surfactant) into the water, which reduces the surface tension. When the wind blows, the waves on the lake agitate this surface agent, thus transforming it into sudsy white foam. Currents and boats also mix air with the organic compounds present in the lake to produce foam. The foam will frequently form parallel streaks in the open water, caused by wind-induced surface currents. It will also collect in large quantities on windward shores, coves, or in eddies.
In 2003, Researchers from SUNY ESF, Finger Lakes Community College and the Canandaigua Lake Wateshed Council performed chemical testing on the foam. Report can be found here: 2003 Foam Report.
Recently, CLWA launched a new research initiative with Global Aquatic Research to further examine the composition of the foam during the harmful algae bloom season. A summary of this research can be found below.
FOAM STUDY SUMMARY: CANANDAIGUA LAKE
Global Aquatic Research (GAR) and the Canandaigua Lake Watershed Association (CLWA) surveyed and sampled lake foam with the help of citizen scientists throughout the late summer and fall of 2019.
NEW RESEARCH CONDUCTED
- Many chemical analyses were performed on the foam and the results were compared with the chemical signatures of tributary streams, lake water, invasive mussels, plankton, and seaweed, in order to identify the source of the foam.
- Carbon isotope and fatty acid signatures indicate the source of the foam comes from within the lake.
- Very high concentrations of carbon and low concentrations of nitrogen in the foam suggest it is enriched in one type of biological component that is low in nitrogen. This means that invasive mussel proteins are not the source.
- FTIR (fourier-transform infrared spectroscopy), an advanced technique used to identify organic substances, indicated the foam is primarily made of carbohydrates, in particular polysaccharides, which are long chains of sugars. A range of aquatic organisms commonly produces these, but the FTIR signature of the foam was most similar to the
phytoplankton sample from the lake.
- All measurements were consistent with Microcystis algae, the cyanobacteria that are responsible for the harmful algal blooms (HABs) and produce the microcystin toxins responsible for beach closures, as the source of these foam-causing polysaccharides.
WHAT’S GOING ON IN THE LAKE?
- Plankton, which include all microscopic plants and animals suspended in the lake water, are filtered by the invasive zebra and quagga mussels. Microcystis cyanobacteria are a poor food source for the mussels. The mussels eat other plankton and spit the cyanobacteria out. Over time this selectively concentrates the cyanobacteria in the water.
- Phosphorous and nitrogen concentrations in the lake support phytoplankton growth, and during the summer when sunlight is abundant, cyanobacteria grow at fast rates.
- Microcystis cyanobacteria release polysaccharides outside of their cells in order to create large colonies and to regulate their environment. These “exopolysaccharides” or “EPSs” are produced in large quantities during phytoplankton blooms and change the chemistry of the surface of the lake.
- Invasive mussels get “sick” when feeding on the cyanobacteria and start producing polysaccharide rich mucus of their own while recycling and ejecting the cyanobacteria EPSs, exacerbating the problem.
- Over time, these EPSs, which are not very soluble in the water and are stable in the environment, accumulate in the SML (see Foam Facts) and provide the right conditions for foam production. In fact, these types of polysaccharides are used in industries to stabilize foam and create emulsions.
WHAT CAN WE DO TO PREVENT THIS?
Limit nutrient inputs into the lake. This can help control both cyanobacteria and mussels, which proliferate from abundant phosphorus and nitrogen.
The best ways to reduce nutrients are to:
- Use less fertilizer
- Control animal waste and wastewater discharge
- Reduce erosion
- Preserve and plant shrubs, trees, and groundcover along tributary streams.
IS THE FOAM SAFE?
Some foam can concentrate pollutants at much higher levels than in the surrounding environment. This part of the study is ongoing. However, we have found microcystin toxins in the foam at higher concentrations than in nearby lake water, and in a few cases, higher than the NYS Department of Health’s recreational limit.
Future research should assess the foam’s potential to accumulate heavy metals and industrial toxins (including PFASs) in addition to further investigation of microcystin toxins in the foam.
- CLWA and GAR are developing a phase 2 plan to assess 4-season sampling and further testing for pollutants.
- CLWA needs your support to fund this expanded foam research and to support our efforts to improve waterquality throughout our watershed.
As part of this ongoing research initiative, we are documenting observations of lake foam from citizens using the survey form below. Your reports help us document the extent and timing of these foaming events, and may help us make research decisions on sampling efforts.
If you would like to submit a foam report, please use our Lake Foam Observation Survey.