July 3, 2022

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Algae, what are they? are they all toxic? How can I know?
WT Staff

WT Interview with Dr. Arthur Zastepa, Research Sicentist, Environment & Climate Change Canada. The transcription below has been edited for clarity and length.

WT - I have with me, Dr. Arthur Zastepa on the phone, he is a scientist from Environment Canada that has extensive knowledge of algae; thanks for doing this.

My understanding is there are 2000 different types of algae. When I look at a lake in Canada, and there is algae of some sort, most people call what we see ďblue-greenĒ, but I also see in Florida that red algae is also very dangerous. Can you lay out what type of algae we would expect to see in Canada and how dangerous are these things?

Dr. Zastepa - Yes, you mention the blooms in marine systems, just because you see proliferations, green or other colours in the lakes does not mean that it's harmful to health or toxic per se.

You bring up a good point about these marine blooms called ďred tidesĒ, and actually those are toxin producers, what some people worry about in Florida, are not necessarily cyanobacteria.†

ďRed tidesĒ can be dominated by things called dinoflagellates or diatoms that can produce the toxins, which are very different from the cyanobacteria that are more commonly a problem in our freshwater systems and inland lakes. Even there, when you see a bloom in freshwater lakes depending on the colour, which can range from red to yellow to green to blue-green, it can indicate different organisms, like diatoms that you see in marine systems.

In the freshwater we havenít seen any diatoms that produce toxins. There can also be green algae blooms, you can have red coloured blooms, cryptophytes accumulating in freshwater systems.

So, it really depends on whatís there. When you do see a blue-green hue or turquoise or kind of a blue green paint thatís spilled in the water, thatís more indicative of cyanobacteria bloom, these are the ones that produce toxins in the freshwater systems that we worry about. You have to look at the microscopy, even within the cyanobacteria the same species can be toxin or non toxin producers, so you really have to do additional analysis to determine if you have a toxic cyanobacteria that you should be worried about, it could just be nontoxic green algae or diatomic.

WT - There seems to be different advice given by provinces, one province says this if you see algae, one province says that if you see algae, should we just agree with what we see on the signs about algae? My understanding is that once an algae blooms and then disappears, that there is still toxicity in the water. I am curious about the different statements that different provinces make, if the algae bloom goes away, does this then make it alright, does this mean it's gone?

Dr Zastepa - Ok well, that is a good question, tough question to answer. There is evidence that toxins tend to hang around after the visual blooms dissipate or are no longer there. It really depends on the system, if itís isolated system with low water flow, higher residence time where the water sticks around, there is a higher chance of it sticking around, if toxins are produced, a higher chance of it sticking around, slow degradation.

If you have a rapidly flowing system, more movement, (toxins are) more likely to get dissipated.

WT - When the outbreak in Lake Erie shut down the Toledo water system for four days, there was quite a bit of confusion about when it was safe again. When we talked to Toledo communications people, they said the outbreak is over, you can drink the water again, people inside the water plant and various people that run the city water seemed quite convinced themselves that they knew or thought they knew the water was still toxic Ė what do you make of that? Is this where the situation gets strange?

Dr Zastepa - My understanding is that the 2014 bloom that affected Toledo wasnít one of the more intense blooms that we have seen, something like we saw in 2011 or 2015, it was relatively smaller in terms of the biomass and chlorophyll production, relative to other years. However, what I think happened there was a lot of bloom lysis, break up of the bloom, release of the toxin from the inside of the cells, into the dissolved phase, possibly that is why there was a breakthrough in the drinking water. Dissolved toxin is a lot harder to treat in drinking water systems. It was a bit of a perfect storm of circumstances there. There seems to be a viral infection on the bloom that led partly to some of the lysis that was happening and the toxin in the dissolved phase.

WT - I want to bring it back to Ontario, Dr. Melody Lindsay recently wrote a report for the Haliburton County Home Buildersí Association, she is a specialist in Biological Sciences and Microbiology, she did a report on the Minden Hills and Gooderham Lakes and islands east and several other places where there were outbreaks. The report explains how toxic algal blooms form and what area residents and water stewards can do to limit their effects and eradicate them. But at the Haliburton County council meeting on November 25th last year, there seemed to be quite a bit of confusion about what they should be saying to people, the local real estate association got involved. You are a scientist, you have training, what do you say to people in these situations where theyíve had outbreaks, what can they do about it, first off, and second, what should they be telling people that are using the lakes and rivers? Iím wondering is there ever a solution to this? I see by the numbers they are increasing every year; can you speak to that?

Dr Zastepa - Sure. First of all, I work on the lake side, in terms of looking at the ecology, and the toxin and other chemical production of these blooms. I donít really participate in these kinds of decision makings on the lake management side, but that being said, when I look at a lake myself and try to assess the risk, seeing biomass forming and so on, the first thing I would think about is, what is the history of that lake? When you do have blooms, what are they generally dominated by? There are lakes where you have blooms, they are nutrient rich, but the dominance is generally green algae, which are not toxin producers. But when you have a lake that has a history of cyanobacteria production like for example, the western basin of Lake Erie, and cyanobacteria dominance and toxin production, when you see these kinds of accumulation, then I think you should be very concerned, because it has a history of being dominated by these toxin producers, but other lakes may not be.

Just because you see biomass accumulation, like in many parts of the eastern basin of Lake Erie, that biomass is often a eukaryote and should not lead to drinking water issues from the cyanobacterial toxin side.

So, itís a difficult question because you donít want to prevent people from using the water recreationally when there is little risk. At the same time, you donít always want to be saying there is a risk or be overly cautious because people can become desensitized to that.†

So, knowing your history of the lake helps a lot, and then looking at it from the perspective of, who is most at risk? If you have such a bloom and you have pets or young children, maybe it's best to take extra precautions and not use it until the Ministry or other bodies take a look and see whether it's cyanobacteria, see whether toxins or possible and so on.†

As an adult, whatís the likeliness of you ingesting enough water for it to be a risk? So maybe using the water or wading in or using a watercraft may not be a huge risk despite some accumulations that may look like green algae. So, despite some accumulations that look like green algae, knowing the history of the lake, knowing who is using the lake, how they are using it matters.

If there is signage posting that blue-green algae may be present, and there is a potential for toxin, then I think those provincial postings need to be respected.

WT - One thing people want to know most, there are tremendous residential set ups around a lot of lakes in Canada, this is where people want to put their home, beside a lake. I look at the real estate values across the country, the resale value of the homes where blue-green is involved. If I am buying a home on a lake, do I have a hope, can I ask someone to test this water and tell me if I am going to have a blue-green outbreak? If they could tell me there is going to be an outbreak, is there anything I can do about that? Can I get ready? Can I try and put something in the water to get rid of blue-green algae?

Dr. Zastepa - Preventive or mitigating measures? Well, I donít want to make any comments on real estate and effects like that, itís outside my area of expertise, but sure you could have your water tested and there are certain indicators that you could look at to get an idea of the likeliness of this lake being dominated by cyanobacteria and possibly leading to toxin production, or whether it is already. Looking at phosphorous and nitrogen, looking at whoís there in the water in those blooms, is it green algae thatís dominating the blooms that are there or is it cyanobacteria there already? Looking at these things should give you an idea.

In a high nutrient lake, you are likely to get some phytoplankton biomass produced, you can look at it in a little more detail at some of the other parameters to see if shifts might be toward cyanobacteria dominance, phytoplankton dominance, or diatom dominance or green algae dominance. It is also determined by time of year, you could have a bit of each in there, depending on the time of year.

WT - If I am about to buy a house, what do I do? So, I grab some water and send it off to the lab, I ask them to look at, test for what exactly?

Dr. Zastepa - Iím not going to advise anyone on what to do when they should buy a house, but if you want to look at the state of your water body, I should also add that the hydrodynamics is really important in a system. One part of the lake can be relatively healthy, but another part of the lake could be in degradation, just because maybe it's an isolated embayment that traps nutrients and traps biomass and could start accumulating material in that one spot.†

We have an interesting beach called Bayfront Beach in Hamilton harbour thatís shaped like a crescent moon, like a baseball glove, and a lot of the biomass that grows in Hamilton harbour, because of the currents, and because of the shape of the beach there, it catches a lot of that material, and a lot of that material accumulates there, with scum on the beaches and so on. Just offshore, the water quality is fairly good, so the management and remediation people suggested putting out some platforms a little bit offshore where people can swim out past those accumulations.

In terms of parameters, you want to measure, phosphorous and nitrogen, you really want to look at bioavailable phosphate, thatís a portion of total phosphorous that algae and cyanobacteria are able to use quickly, it's dissolved and available to incorporate into biomass. You may want to look at specific nitrogen, more bioavailable ammonia, nitrate, nitrite and so on.

Looking at the bathymetry of your lake, the hydrodynamics, the shoreline; is it shallow? Is it conducive to warming up very quickly? Some of these cyanobacteria, some of them, not all of them, enjoy warm temperatures, so if your lake is shallow, maybe itís at higher risk of being dominated by cyanobacteria. But if it has some deep, colder water maybe there is some resistance to that.

For example, Lake Erie is a good example, on the west side you have toxin producing cyanobacterial blooms dominating. In the centre and east side of the lake, itís a little different, there are deeper and cooler waters, where the bigger problem is Cladophora, benthic algae which are non-toxic growing on rocks and washing up to shore. You get some beaches and embayments where you have cyanobacteria, but the bigger problem is the Cladophora issue.

WT - Do you agree with people that are saying ok thereís more and more outbreaks, it's getting worse and worse because of climate change, or do you think itís simply because there are more lakes being exposed to people, and therefore more eyes on the lake? Is this an out-of-control problem, is this a climate change thing?

Dr. Zastepa - That is a great question, and it comes up a lot in some of the discussions I have.

I have some reservations about the all-encompassing, broad statements of ďblooms are increasingĒ, ďtheyíre getting worseĒ, and so on, I think the answers to that would be system specific. I think part of it is certainly more eyes, more testing, but it also depends on what space of time you are looking at? Are you looking at the last ten or twenty years? Well maybe some systems are actually showing improvement in those last ten or twenty years because of some of the management actions we have introduced, limiting external phosphorous and so on. Are you looking at over centuries of whatís happening?

Some of the data we have from Lake Erie and Lake of the Woods, does not indicate an indisputable increase in the severity/intensity of cyanobacterial blooms. If you look at Lake Erie, if you look at the data NOAA produces in their bloom forecasting, there is a lot of variation, the data spins back to 2002 if I am not mistaken, there is a lot of variation, there was large severity in 2011; since then it has petered out a little bit, itís gone up and down, it hasnít really gone crazy yet this year, we are still looking at what may come to the end of August, but if you look at some of that data, there is variation there, so we canít say that blooms are getting irrefutably worse.

If you look back to the 60ís Lake Erie water quality agreement and efforts to make Lake Erie better, I think it's improved. Maybe most recently we are having some issues, toxins coming into the drinking water and satellite images we get, but I would be cautious to say this as an over-arching, all-encompassing statement.

There was a study of the data in marine systems globally, that looked at this question, they did not find irrefutable evidence that blooms are increasing, getting worse everywhere.

I think we need to dig into that a little bit more, kind of put the brakes a little bit on saying such statements. It can be true in some systems, but especially when you look at some of the lower nutrient systems where maybe we havenít seen blooms there before, like Lake Superior. You may have heard Lake Superior now has blooms in the last few years. Do we really know the history of Lake Superior, what it was like ten, twenty, thirty, fifty, a hundred years ago?

For example, according to data in smaller lakes, for example Lake Baptiste in Alberta, cyanobacteria and their toxins have been around for 150 years, going back to pre-European settlement times, in those specific areas. It's kind of been around. So, the idea of, when you look at it from a management perspective, the idea that we need to get rid of all cyanobacteria, and all toxin production is maybe not completely realistic. Lake Baptiste is a historically eutrophic lake, thereís been a little bit of that going on historically, so you have to put it in perspective.

WT - What about an instant test for this blue-green algae, if I show up at a lake and Iím going to let my dog go here, my kids, can I scoop some water, test and say ďgo kids, goĒ?

Dr Zastepa Ė I would say yes, but I donít know if it's completely accessible to the general public just because of cost maybe.

There are a few rapid tests you could do, they do have these mini-microscopes you could bring into the field, you could even attach them to your phone, there are apps, you can take water on a slide, put it up to your phone, you can see whatís there, so if you have an idea what high risk cyanobacteria are relative to other, phytoplanktonic algae you can make an assessment that way. The one I saw was about four or five hundred dollars, I think.

There are also apps you can put on your phone, either free or very low cost. You can take a picture of the water, there are spectral algorithms to analyze, is it the cyanobacteria signature or phytoplankton signature, you can also upload that data where it will be used by other scientists to make sense of bloom distribution, so thatís kind of cool.

There are also probes, spectral/optical probes you can put in there, a lot more expensive, that can distinguish between four different algae groups, red, yellow, green or blue green. If you have blue-green you might not want to use the water.

From the toxin testing side, there is a strip test available, kind of like the pH paper, so you are probably familiar with the pH strip, there are test trips for one group of toxins called microcystins and I think there are others in development for other toxins. You collect the water in a vial, add a re-agent, shake it up and then you put the strip inside, take it out and read it. Depending on the intensity of the line that shows up it can give you a rough idea, a semi-quantitative test to see if there are microcystin toxins in the water or not, so itís a good screening test.

WT - I really enjoyed this interview, thank you.

Dr. Zastepa - I appreciate the questions, great questions. Thanks for the opportunity.

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