Scientists believe they have identified a little-known algal species believed to be the source of the brevetoxins causing South Australia’s algal bloom. The algae known as "Karenia Cristata" hasn't been found in Australian waters before.
00:00So we started researching it back in March when the first reports came out and we were
00:07working with Saadi and Persa, the South Australian government scientists, and they sent us water
00:11samples.
00:13And then the first thing we did was examine them under the microscope.
00:16And then it was sort of obvious that there was, it became obvious that there was more
00:21than one Caerinius species present in the bloom, but they look extremely similar to
00:27one another.
00:28And then we knew we had to use genetic methods to tell them apart.
00:32And so that's why it's taken quite some time to sort this out?
00:35That's exactly right.
00:36So we ended up using four different molecular genetic methods, as well as isolating the culture
00:41from single cells to grow it in the lorritory.
00:45And the images that we've got up on the screen now show kind of like a bit of foam around
00:49and a bit of discolouration in the water.
00:51But what you found and what you've had to sort out is actually microscoping it in size.
00:57That's right.
00:58So the algal cells themselves are about 30 microns in diameter, which a micron being
01:02a thousandths of a millimetre.
01:04So you can see them clearly under a light microscope, but not with a naked eye.
01:08Yeah.
01:09And I think we can bring that up now.
01:11And what can, this is it?
01:13That's it.
01:14Wow.
01:15That's what you've done all this work.
01:16That's right.
01:17And so explain these images for us.
01:19So the top ones are with a light microscope.
01:22So that's looking down a microscope.
01:24You can see some of the grooves and images that are typical of the Carina species.
01:29And then the bottom ones that are black and white are with what's called a scanning electron microscope.
01:34So that uses electrons rather than light to be able to distinguish the various things down to a very low level of resolution.
01:43So you can see a much more detail on the cell surface and then you can distinguish what the species is.
01:50And so within a square metre of this water that's been affected, there would be billions of these?
01:55Absolutely.
01:56So at some point we got to a million cells per litre.
02:00Wow.
02:00So, yeah, very dense.
02:02And so what else can you tell us about Carina chrystata?
02:05Very little.
02:06So it's been found only twice before in the world.
02:10Once in South Africa in the 1990s, where it caused a bloom that lasted for a couple of months.
02:17At that time, the toxin wasn't identified.
02:20And then one other time, it was identified from a single cell from a small island off the coast of Canada.
02:27But there was no bloom at that time.
02:29It was just an identification.
02:31And that's the sum total of all we know about this species.
02:34Wow.
02:34So how does it feel for you to have come across this when so little is known about it?
02:38Yeah, it was unexpected.
02:40We did know that we were looking for a Carina species that produced brevi toxins.
02:44But this species, no, we had no idea.
02:48Yeah.
02:48And so do you think it's probably been in Australian waters all the time or it's only a recent arrival or you just don't know?
02:57We just don't know.
02:58Probably it's been present for a while.
03:01I'm just guessing based on the fact that we know so little about our marine biodiversity that the chances are good that we would have missed it, especially microbial species.
03:10We really don't investigate generally in Australia.
03:13OK, so now that it's been identified, or it's got to be peer-reviewed yet, but it's most probably been identified, what can be done to – because, yeah, it's been such a devastating thing for a number of South Australian communities over the past couple of months.
03:30Is there anything that can be done to try to clear up what's there or prevent it happening again?
03:38Potentially.
03:39Potentially.
03:40So now that we have it isolated into culture, we can do those types of experiments on it in culture where we can work out if any of the mitigation methods might work on Carina cristata.
03:50We also know a lot more about – well, we can start to understand a lot more about its physiology, what sorts of temperatures it grows best in and nutrient conditions it grows best in, and then we can hopefully predict a future bloom in a lot better, more accurate way than we would have been without knowing this.
04:08And so what are some possible mitigating measures that might be able to be used?
04:13And we start this discussion on the basis of we don't know exactly what's going to work, but what might possibly work?
04:22Well, sorts of methods that people have tried internationally with Carina brevis blooms, so a different species but similar, are clay.
04:30So they take some modified clays and they sprinkle a tiny amount on the surface of the water, and so we know that that could work in small areas.
04:41So it's not going to work, obviously, across an entire sort of ocean basin area, but in maybe a small enclosed bay, that might be an option in the future.
04:53So I think it's about having those sorts of options if a bloom does pop up in the future and we catch it early enough when it's still very small.
05:01And what more work are you going to be doing on this now?
05:03So we'd like to develop some new genetic tools so that people would be able to identify Carina crostata in the field much faster than we've been able to identify it here, you know, eight months.
05:16No, be able to sort of identify it in a matter of an hour or so in the field.
05:21Okay, well, congratulations on your work. We're obviously still waiting for the peer review, but yes, so many people in South Australia will be relieved to know that we actually have identified now, probably identified it, and may be able to look at mitigation, ways to mitigate it in future.
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