I feel there is a lot of wrong information with this article simply on the basis so little is known about cyanobacteria and the number of species. Confirming whether a bloom is toxic or not is like looking for a needle in a haystack …. impossible. I’m highly disappointed with the article. Click here to read the full article or an excerpt below.
Cyanobacteria are natural
inhabitants of Alberta’s lakes and more than 100
species of cyanobacteria have been recorded.
Since the first reports over 100 years ago, numerous
cases of animal poisonings have occurred worldwide,
including periodic episodes within Alberta. Even
reports of human illness and death have been documented in several countries over the years. Continuing research has shown that cyanobacteria
can produce different types of toxins. The most
common of these globally are the liver toxins called microcystins. Less common are
several neuro- (nerve) toxins, including anatoxin-a, anatoxin-a(s) and saxitoxin
(otherwise known as paralytic shellfish poison). Furthermore, some cyanobacteria
produce mild dermal toxins that act as skin irritants.
Can Toxicity be Predicted? – Not all species of cyanobacteria produce toxins, yet
some species produce several types of toxin. Even within a single species, some
strains are toxic while others are not. This makes the prediction of toxicity an
arduous task and certainly more difficult than simply predicting bloom occurrence.
In most cases, however, toxic and non-toxic
strains of a species occur simultaneously. The
concentration of toxin(s) is dependent on the
density of toxin-producing species in a lake.
Intensity and species composition of blooms
varies both over time and with location in lakes,
as a result so too will toxicity. Lakes that have
never had a problem can suddenly become toxic
and, conversely, lakes that have shown toxicity
in the past may not be for several years. Some
parts of the lake could become toxic while others
could remain safe. Caution should be exercised
at any lakes where blooms have occurred in the
How is Toxicity Determined? –
Confirming the presence of toxins in lakes
and reservoirs is not a routine procedure. If
the death or distress of animals is observed
near a lake or human illness occurs,
several methods, each with their own
limitations, can be used to determine
whether cyanobacterial toxins are
implicated. Currently, laboratories in the
Province are able to rapidly determine the
concentrations of the liver toxin microcystin and the neurotoxin anatoxin-a.
Trained analysts can determine the presence of potentially toxic cyanobacteria
microscopically, but this technique cannot distinguish toxic from nontoxic strains
because the strains look alike. However, the presence of toxin-producing species is
generally considered an appropriate indicator of the presence of one or more toxins
and their density is a reasonable indicator of the degree of toxicity.