Solana Key Algae Report tested Positive for "Anabaena"

Solana Key Algae Report tested Positive for "Anabaena"
The following report has been provided by Heather Larratt from Larratt Aquatic Consulting.

LAC received a 1 liter algae sample dated August 27 from the Town of Osoyoos on August 30. The sample was collected by dipping the bottle into the floating algae scum from Solana Key. It was refrigerated and analyzed on September 2.

The test results apply to Solana Key only and does not apply to the rest of Osoyoos Lake.

The sample contained extremely high concentrations (>80,000 – 100,000 cells/mL) of one type of cyanobacteria (blue-green algae), Anabaena spp. Anabaena is capable of producing cyanotoxins including:
Skin toxins:  lyngbyatoxin-a, lipopolysaccharides
Liver toxins: cylindrospermopsins, microcystins
Nerve toxins: anatoxins, BMAA (B-N-methylamino-L-alanine), neosaxitoxins, saxitoxins

The risk of toxicity increases as the cell density increases, with various thresholds established in the literature.  Since this is not drinking water, the following thresholds are applicable.  Thresholds of >15,000 cells per mL indicate that toxin presence is likely, and >100,000 cells/mL causes a high risk of cyanotoxin poisoning if the water is ingested, and may result in acute illness.  These cyanobacteria float high in the water column, but drop to deeper water as they die.  They can accumulate in surface scums, driven by the wind. I would assume that this sample was collected from such a scum.

There is no effective control for these blooms other than reducing the amount of nutrient reporting to Solana Key.  Cooler fall weather may bring some relief.

This is not the first time that cyanobacteria have bloomed in Osoyoos Lake.  Unfortunately with climate change (warming) and increasing development throughout the Okanagan Valley, the frequency of these cyanobacteria proliferations is likely to increase.

I would recommend that residents become familiar with the appearance of a cyanobacteria scum and that they avoid all contact with the cyanobacteria scum, both for themselves and for pets.  A more dispersed form of a cyanobacteria bloom looks like tiny balls or tiny grass clippings suspended in the water.  Caution would be advisable for bathing in this – some people react more than others.
 
Figure 1: Anabaena from Solana Key, Osoyoos Lake Aug 27 2013.