Hello and welcome to this series on cyanobacteria.
Over the next few episodes, we'll be looking at
what cyanobacteria is, why we should care about it,
how we might detect it and any mitigations that we need to consider.
I have the pleasure of being joined by an absolute expert panel today
from the Lutra team.
We have Brett Clapham and Jonathan Church.
Both, either Principal or Senior Process Engineers
and specialise in water treatment here at Lutra.
From the Cawthron team, I have the joy of welcoming Jonathan Puddick,
and Catherine Moisan, who will be talking from a more scientific
aspect around cyanobacteria.
So let's kick into it.
first of all, what is cyanobacteria?
Jonathan, maybe I'll get you to start.
So cyanobacteria can kind of think
of them as little floating plants, which are
sometimes in our waterways around New Zealand and around the world.
So like plants, they harvest light from the sun and use that as their energy source.
So that means that they can live in really simple lifestyles.
So you can find them all over the place and actually rivers
and lakes aren't the only places you'll find them.
But from a drinking water perspective, you know,
that's where we get our water from..
They are one of the oldest organisms on Earth, right?
Yeah.
So billions of years that been around for and they sort of
were the first organisms that we had on the planet.
You know, they basically put the oxygen
into the atmosphere for all of us to be able to breathe.
So they evolved long before anything else was around.
Yeah, so very hardy.
Yeah, exactly.
And this also means that they've thought of lots of clever ways
to be able to exist in places where we wouldn't expect them to.
That's when we sometimes see problems is because cyanobacteria,
they're able to do clever things like live in places
where they don't have the nutrients
that other ones might to need to be able to grow.
They can also use
quite random nutrient sources.
So in a river, which we might think is clean.
They can take sediment and actually extract the nitrogen
and phosphate from that as a source to be able to grow.
So, you can't exactly predict where they might pop up.
So if I say, I mean, they
sound quite harmless and producing oxygen is always good thing.
So I guess, why should I care about cyanobacteria?
Yeah.
So lots of cyanobacteria are good and you know, they are completely natural
part of freshwater ecosystems.
But some cyanobacteria are able to produce compounds
which are harmful to humans and animals, we call these toxins.
And so it's not every type of cyanobacteria.
But when you do have cyanobacteria present in a waterway,
it does indicate to you that other types of cyanobacteria,
which might be able to produce toxins, could also grow in that environment.
So that's why we sort of have this blinkers on
to look out when we start to see cyanobacteria in a waterway
because it may mean that there could be toxin producing
cyanobacteria and you could have toxins present.
Yes.
So you mentioned that they need light from the sun and also in surface
water sources.
So does that mean wells and bore sources are safe from these organisms?
Yeah, so if you don't have light present, you won't have a large growth
of cyanobacteria.
And often people use to cyanobacteria
in a sort of lake or river setting where they get these
big masses starting to form and we call these blooms.
So when you don't have much light, you're not going to have
a large amount of growth.
In a well or bore setting, what you need to be worried about there, is if you have a connected
water source, which is quite close. Are the toxins from that water supply
where you've got lots of cyanobacteria growing, potentially, actually infiltrating
and getting into that
“Safe” water source; the bore or the groundwater.
So that's what we need to be careful and mindful about.
Is this connectivity between different water bodies.
Yeah.
And they also produce taste and odour compounds, right?
Yeah. And that can be really handy.
These musty tastes and aromas, they're sort of like
an early warning sign that you might have cyanobacteria present.
Yeah, the way I had it described to me is the sort of smell you get after rain.
Yes. Musty, dirty.
That sort of musty, dirty smell.
Yeah, sort of leafy,
you imagine you're walking through the bush and you stirring up the leaves
that sort of that pleasant aroma for a cyanobacteria scientist.
I was going to say, in a winery type term;
I think they call those earthy undertones.
Oh yeah.
So I mean, if your water has earthy undertones
then potentially there is something present.
Yes, so that’s good for the people from Wellington.
Yes, yes. They’ll be able to understand that.
So I mean, putting that into, I guess, simple terms.
So do we consider cyanobacteria?
I mean, just to everyday people?
Is that algae?
Yeah, yeah.
So quite often when we're talking about cyanobacteria to the public, we'll call it
toxic algae because otherwise there is a lot of confusion.
It's bacteria, but it's not bacteria like E. coli.
It's acting like algae and plants.
So yeah, we quite often do refer to it as toxic algae.
And in fact, it's often called Blue Green Algae as well. OK.
The reason for that is that they have a pigment
that when they are in very high numbers, you can actually see them in the water.
The bloom will look bluish or vivid green.
So yeah, that’s where the common name comes from.
OK, that makes sense.
in fact produces it. Right, OK.
So I guess, this brings me on to the toxins, which you've mentioned before.
So I believe these are called cyanotoxins.
So I guess when and how are these produced.
So cyanotoxins, they will be present if you have a cyanobacteria,
which is able to produce these toxins. So they have genes or DNA code
which allow them to build up these toxic compounds.
And so some cyanobacteria will have those genes
and they're able to go through and actually produce this compound
and the compound doesn't produce necessarily to sort of
harm us, or animals.
It's probably for some other purpose that they produce
it which has been beneficial for them. Yes.
So one great way to be able to figure out whether you have toxic cyanobacteria
is if we go in and we look for those genes
responsible for the toxin production.
And it's really difficult just by actually looking
at a cyanobacteria to know whether it's producing toxins or not.
So we can't look down a microscope and know for sure,
is this a toxin producing cyanobacteria or not?
But Catherine's lab;
what they can do is look under the microscope
and identify what type of cyanobacteria is present in a waterway.
So what that tells us is: Has this species
of cyanobacteria been known to produce toxins in the past.
So that's sort of a pretty good first gate
to tell you, do you have a potential threat there,
that you should be looking into a little bit deeper?
Or, you know, actually is the risk level quite low
because no one's ever seen toxins produced in that type of cyanobacteria before.
Yeah.
So that's the speciation test right, where you know all the different species that are present.
And what you're saying is that often
the species can be there, but they they don't produce anything.
So really, I see that as a three tiered approach.
If you like, you can look at the water sample and see
which species are there, whether they potentially produce toxins.
But because we can't see that, you know, we can't see from the morphology
of the algae whether it produces or not, then we can move on to the gene test.
And that will tell us whether this strain of algae
has got the potential/ is able to produce toxins or not.
And then if that gene test tells us yes, there's a risk,
then we can move on to the actual toxin testing to determine whether it
So in terms of theses genes, how does it work?
cyanobacteria, just decide to turn them on? Is there anything that sort of triggers
those genes to go from a passive presence to an active one?
Well, that's a good question; so
a cyanobacteria that has the gene won't necessarily produce toxins
that are environmental triggers that will get it to switch on or off.
So again, it's not because it's got the gene that it will necessarily
produce the toxins.
So that might lead back to what you were saying about the,
the different energy sources and their ability
to adapt and turn the genes on and off to
cope with their environments.
And sometimes they produce the toxins at the same time.
Are there certain environmental conditions you'd say that's kind of the worst time
when you would expect cyanotoxins?
JP might be able to comment on that.
We don't really have good knowledge on the triggers
for cyanotoxin production.
So, you know, sort of that's where we need to start
getting in to cyanotoxin testing; like it'd be really nice
if we could chuck together a model which says at that this temperature
at this light intensity and with these nutrients,
we are expecting to have this level of cyanotoxins present.
But it's just sort of not the case.
We're not quite there yet.
So, you know, that's why we need to sort of, if we've got cyanobacteria present,
they have the capability to produce toxins because they've got those genes.
That's when we start doing cyanotoxin testing
because we don't know if it's this much cyanotoxin there
or whether its lots that we've actually got present.
So what we can say is if there's more cyanobacteria present in a waterway,
then there's likely to be more cyaontoxins present.
You know, you've got more factories out there producing this stuff.
So essentially they can also live in a passive state as well.
So just because you have, I guess, cyanobacteria or algae in your
water source, it doesn't necessarily mean that they're producing toxins.
they can also sit in more of a passive state.
Would that be correct?
Yeah.
So that quite often be there just sort of chugging along.
They'll have a low level of toxins present.
And then there are scenarios where you might get up regulations in toxin production.
And, you know, it's also quite natural for any freshwater environment
to have a low level of cyanobacteria present,
there are a natural part of that ecosystem and other things are feeding
on them.
So, you know, you shouldn't be sort of terrified if there’s cyanobacteria there.
Oh, something's wrong
with my freshwater environment because there's cyanobacteria.
It's when sort of the levels start going up.
Yeah.
So I guess bringing this back into, the context of drinking water
and I guess drinking water treatment, and this is probably more at the Lutra team,
How do cyanobacteria or cyanotoxins affect water treatment.
Yeah well, probably the first first thing is the taste and odour, that would be easily
the most common problem that happens in New Zealand.
Essentially, the cyanobacteria release,
a very low level of compounds like Geosmin and 2MIB.
Which impart a musty, earthy kind of taste in the water.
And people can pick this up because even though the concentrations are minute
the human sensory
organs are quite capable of smelling and tasting it very easily.
So yeah, so when your water tastes like dirt it, that can often be the reason why.
So I guess, yeah, that's a palatability issue.
They also, obviously, as we've talked
about, have the ability to release the actual toxins themselves.
And there's a myriad of different types of toxins,
and all of them have very, very low levels at which they can be harmful to humans
at the microgram, nanogram level.
So that in itself is obviously a much more serious issue
because yeah a bad taste in the water,
yes, that's a concern.
But really, the toxins are the things that can kill you. That's where the real risk lies.
Yeah.
It's also encouraging because 2MIB
and Geosmin can be detected at very low levels by the palate.
But those levels aren’t harmful, they're quite a bit more
harmful for those two molecules.
But as Jonathon was saying is, that's where you must be
aware that there could be other cyanotoxins in the source water.
Then also the drinking water standards,
they have these levels of concentrations that are acceptable.
Beyond which, if they become harmful, based on the World Health Organization
levels and also with the updates to the drinking water standards coming in
July 2022. There is going to be a greater onus put on water supplies to be aware of
what's in their source water and the potential risk of cyanobacteria,
and cyanotoxins.
And I guess there's also the practical aspect of water treatment
and what cyanobacteria can actually do to the water treatment plant,
and that's often an undesirable side effect.
So even if you don't have a taste and odour problem or a cyanotoxin problem.
Algae itself can cause nasty things to happen in your processes.
One or two examples is because they can be buoyant.
They're difficult to settle out.
So if you have a process
which needs to settle the solids,
the algae tend not to.
So therefore they kind of float up and go out onto your filters
or your membranes or whatever you have downstream.
And also, because they can, they can have funny
aspects like being quite filamentous I understand;
which act's sort of like a polymer in terms of water treatment
and causes filters to become blinded, you know?
So the presence can affect your production of water
and the efficiency of the treatment plant and not just the
not just, you know, the taste and odour or cyanotoxins.
Is there any clever ways to get around it?
Well, yeah.
I mean, in terms of the floating issue, a dissolved
air flotation process works absolutely fantastically on those kind of algael species
because it essentially accelerates the floating and then you scrape them off.
And that's quite good.
In terms of settling,
there’s also ways to settle things faster, like using sand ballasted actiflow
type systems, which basically add a very dense micro sand,
which gets caught up with the algae and makes it settle like a stone.
So, you know, these kind of processes can remove them.
But yeah, it's just about I wouldn't say they're that common.
And and, you know, it's
probably more the case of plants that don't have the right treatment
are the ones that are going to get the blooms.
Excellent.
Well, I think that's probably enough for the introduction to cyanobacteria.
So when we come back in our next
episode, we'll look at how we go about detecting these
and then followed by how we might mitigate some of the risks behind cyanobacteria.