Oyster Translocation Trial Outcomes Webinar

Okay. Can you hear me? Can I just do a sound check? People can hear me. How do I know? >> Yeah, there we go. Thank you very much. >> Thank you for your patience. Um, we've got a a good afternoon today to talk about our voice transformation research results. Um, my name's Mike Ste. I'm the executive director for the South Australian Research and Development Institute um from the Department of Primary Industries and Regions. And I just want to um acknowledge that we ensure the land, sea, water and sky healthy for future generations and strive to better understand uh the average people's spiritual relationship with country across the state. Um, in the spirit of reconciliation, uh, our commitment is to build progressive and trusting relationships to share knowledge and learn from each other. We recognize and own a difficult past and together we walk forward. We acknowledge the many aboriginal people of this country as the oldest continuous living culture in the world. Um, which is great acknowledgement. First, we also acknowledge that it supports the White River Initiative um and ending the violence against women and children. Thank you for tuning in today. Um hopefully you can hear and see us clearly. And the purpose of today's webinar is to provide you with an update on the results of the Pacific oyster transllication trials that we conducted to validate potential risks associated with transferring bile or perennial cells or the al species and bretoxin during the potential relay if oysters are from closed harvesting areas to open areas. So some really consequential results that have research here as you all recall this has taken very or has been a very contentious issue with a number of risk assessments undertaken one commission through as well as by person bio security to help inform decision making at the time. However industry are very keen for an experimental trial to be undertaken to validate these risk assessments. Now these trials were funded under the industry R&D program of the agloom summer plan managed by the department of state development and were conducted by Sardi from December 2025 to February 2026. A commitment was made to bring industry together to present the results and also to provide the opportunity for industry to ask questions of SARI and the South Australian seafood quality assurance program sasquap about the results and how they will be utilized in decision- making moving forward. Today I'll have um with me Dr. Sashi Na who's the agriculture program leader at Sardi who's led this research and many of you would know and we'll also provide an overview of the outcomes. also have Sarah Sperling the acting general manager of the food safety bio security and Emily Melo the general manager agriculture and also with me uh and you uh oh sorry Emily's with me and also have um representatives from the industry here as well uh and there'll be an opportunity to ask questions of uh Sashi Sarah and Emily and myself later in the program um if if you I ask that you hold your questions to the end, please. There is a Q&A function on the webinar where you can post your questions as you think of them and we'll try and work through them as through as many as we can as part of the panel discussion. Now, I'm going to give an an overall update, maybe some background because I'm unsure uh what level of understanding the the audience has. Um so I I'll have a crack at getting everybody up to speed. Um many of you would would already understand this and then we'll hand over to Sashi. So here we go. The South Australia's halfway hour. So what we do know um and we have actually uh increased our level of understanding over the past 16 months considerably um and and a real testament to to the team here in South Australia and also the national collaborators but the halfway species is a mix of Corinian species and there's about half a dozen of them in in in the bloom historically was dominated by Mickey Motoy and then we saw a change I'll talk about that in a minute. But what separates a carousia species is known as a mixotrophic dinoflagula. That means it can get its energy from photosynthesis and also means it can get its energy through um organic material. So it can consume on particulate matter. It has a couple of fleella or little tails which means it can it can move and it can move quite quickly. Uh which means it can go up to the surface during the day to photosynthesize and down to the bottom during the night um to to feed on other material. Some species not all in this in this complex produce biotoxins and many of us are familiar with the bretoxins which are underpinning today's conversation. They can uh impact fish. Um, and the reason why they're called harmful algoloom species is because not all all of them are toxic, but they can still create levels of harm for gill breathing marine organisms. So, carennia species can effectively clog up the gills. They can have various biochemical interactions with the gills and also if a bloom um suddenly decomposes, it can draw a lot of the oxygen out of the water and as a consequence will have considerable um fish mortalities or any any marine mortalities that rely on gills to breathe. And indeed, we've got plenty of images that have reflected that over the year. There's also some public health um uh concerns particularly through mainly consumption of um bio valves that accumulate the various biotoxins that corinia species can produce and that's why we've got the SAS program in place and there are other um health concerns also for people who particularly suffer from asthma or have um lung complaints or breathing complaints. uh if the uh uh coria species are aerosolized um through storm wind action um particularly um and also if there's any bre toxins in the air as well. Um so yeah and and as we all know had a significant impact in South Australia impacting around about 30% of the state's coastline. So this gives us a bit of a graphic of of what actually happened. Um all right so this is a a image of the chlorophyll anomaly. So when you see these clouds of chlorophyll have gone up to red it means it's high density and the purple spots represent the cells of carian that have been validated and as you can see from March it's pushed off ignited from furio peninsula pushed off through back passage investigator straight working its way up through the oyster regions of York Peninsula. It also sparked off over in Boston Bay and similar a little more a little bit later and worked its way out the west coast. Spencer Golf wasn't as impacted but nonetheless still impacted as much as Golf St. Vincent. You can see here in Gulf St. Vincent where it was hanging around the Metropolitan Coast continuing through um September, October. At this stage we're getting large foaming events, huge amount of fish washing up. Now you can see it tracking around just before Christmas um the northern part of Kangaroo Island down to the southern end of York Peninsula. The big sways that you see down here is not bloom related. That's the upwelling that we would expect. It's important to understand that the chlorophyll in our water doesn't necessarily mean that it's harmful. In fact, a lot of the chlorophyll in there is a really good part of our ecosystem in terms of supporting private productivity. But a good exercise or at least illustration to see the the extent and persistence of what we now know is a an unprecedented halfway bone in in in Australia and probably ranking up in the top five in the world. Conditions have improved but monitoring remains important as vastly disappeared throughout the majority of the state. There's a little bit of activity bubbling along the air peninsula and air peninsula are familiar with corium loans or at least presence of corium Mickey Moto and they have seen it for many years. Um and there is a little bit of activity around port which is also dominated by Mickey Moto at this stage. We're expecting data to be upload uploaded later this evening. Um, so if you're interested, jump on the dashboard um uh towards uh 6 or 7:00 tonight for the update. So the the questions that I quite often get is what is it? What caused it? Can we fix it? And can we forecast it? So what is it? Um largely a complexity of different coria species. And there's been some work done on the molecular diagnostics. Corania cristarda the one to the left there here um is the one that produces the the bremy toxins and there are other various morph morphometric or different species on the right there. So what happened this timeline's really interesting. So right at the beginning of the bloom it was identified that um the water samples that we took immediately uh were distributed to halfway bloom experts. They looked down a microscope and said oh it's Mickey Moto. Okay. Okay. So, we thought, well, that's that makes sense. But then we started detecting bremy toxins in our oyster harvesting areas. Well, hang on a minute, but Mickey Moto doesn't produce broom toxins, so it's clearly going to be something else in the mix. Then um some work done at the University of Technology Sydney through molec molecular analysis identified. So, cristarda is the guy that's producing the bretoxin. We don't know a lot about this particular species. Um then we then went back and had a look at some of our historic information through our biomecular observing and we found that cristarda has been a resident in South Australia as a natural part of our ecosystem since we started recording data back in 2016. So it's not a species that's been introduced. It hasn't come in through ballast water. Um it has been here the whole time at relatively low levels when the conditions were aligned. Um it proliferated. So what caused it? Um well the information now there's a report that's just been released today actually fortuitously. So you'll probably see some of this on the news this evening. What caused it? We did say early on that there was three extraordinary environmental events that led to this bloom. the Murray River flood in in 23 strong upwelling through the 23 24 summer um that persisted through time and then we had a a heat wave a marine heat wave in 2025. What caused it? Well, there was a whole heap of detailed work that's retrospectively gone back to find all the lines of evidence that we can get or the data sources rather covering satellite imagery, climate nutrient data, upwelling indexes, etc. uh and then pulled it together and effectively said, "Well, these three massive events, the Murray River flood, the record upwelling and the or those two rather really primed the system in terms of productivity. We saw elevated levels of chlorophyll. We saw ev ever elevated levels of productivity and the marine marine heat wave and the low level upwelling event in 2025 created warm, calm, layed stratified conditions that were nutrientrich, which was the perfect Goldilocks environment for Corenia to proliferate because Corinia loves those conditions and can out compete other species that don't. Can we fix it? That's another one that comes up a lot. Well, there's there's a range of options out there in terms of physical, chemical, biological, and ecosystem based methodology. Um, but in general, these things generally apply to small localized areas. Um, and the science is not mature in many of those uh options. However, there is work that is happening concurrently through the office for al bloom research that's looking into access um assessing the ability of these. But in general worldwide, they tend to apply around um confined areas whether it's aquaculture production areas, whether it's ponds, um dams, uh harbors, um esties, etc. rather than applying it to the vast ocean and the various tidal and death conditions that are experienced at a at a at an oceanographic or even at a golf level. Can we forecast it? Well, we're going to have a red hot crack at trying to forecast this. There's been a significant amount of investment into undertaking monitoring. We've got six of these big harmful alg bloom um monitoring boys that are distributed throughout the state. There's one at Coff Bay, Boston Bay, uh, Stanbury, Stilda, American River, Victor Harour. There's a couple more smaller versions that will be implemented um, at some stage, but these boys are picking up all the pedigree information that we're going to need for oceanographic modeling. Plus they have realtime sensors for corinia species and another species called shatella which has also been a problem for finfish aquaculture around the world and particularly around um southern air peninsula. This is our or there's an example of the the level of forecasting that we can have at this stage. This is relatively um uh in its early stages of development because this relies on particle tracking with a really greater depth of an understanding of the role that um all the biologic ecology of the different corinius species which we're working towards. Okay, this is a a scary looking um schematic, but this is essentially what we're aiming for is pulling together all the information that we have through satellite imagery, all the information that we're gaining through our institute monitoring, whether it's through our boys or whether it's through active sampling or our research vessels or working with industry, pulling all our information around the biology and identification of the various species, integrating it with our understanding of the meteorological data, our oceanographic data, any of the environmental drivers. Some of that is maturing at the moment and then pushing it through um a series of multivariate sort of statistics and models to see if we can then effectively come up with a hab early warning system. So we can then be in a position to say well we think that a hab is got a probability of occurring in this particular area at this particular time which we can then inform industry quite early on and say all right well now's the time to harvest now's the time to change your operation community you would expect to see potentially de fish wash up and who knows maybe we'll be in a position later on down the track where we have a tool where we can go and mitigate or guard against it straight away. So, this is effectively where we're working towards at the moment and there's a there's some funding to support that. I'll whip through that really quickly. Um, there's a lot of information and there's a heap more other stuff that we're doing through the office of our globe, office for research. It's established here. Um and and and the key key to that um and as as part of our role here at SARI anyway is to undertake research and development that will not only meet the needs of industry but also help um develop the sustainable and economic production of our of our primary industries and also help inform regulation which is probably a really good segue into the next the next presentation. All right. I'll stop sharing and then I will pass over to thank you. Just bear with us as we very well. >> Thank you, Mike. Uh good afternoon all. Um what I'll be presenting today is a large body of work that we undertook uh late last year moving into this year about the potential transfer of coria species and bidtoxins during oyster relays from have impacted farms. So this was said DSD funded oyster transllocation trials with stakeholders from DS which included DSD department of state development sea the research council sasqua persa fisheries and agriculture. So the primary objectives of these trials were to understand the potential transfer of vegetative cells of Corinia species through transllocated uh oysters from a habacted area. In this case we picked where we got oysters from Kangoo Island to a non-hab impacted area which was bay when they were co-ultivated with each other in clean sea water. So that was that was one objective. The next objective was to evaluate the efficacy of the transllocation treatment protocol on viability of corinia vegetative cells of corinia species and then the potential for active or passive transfer of bioaccumulated brevitosis which is a which are the biotoxins from cranium mainly from oysters originating from a hab impacted farm in this case kango island into a bio toxin-free non-handed oysters sourced from smoky bay co-ultivated in clean sea water. Then to look at the residence time of bioaccumulated bretoxins and live oysters from habacted farm maintained in clean sea water filtered sea water there's not a lot of literature um ex that exists on the residence times. This was probably one of the most comprehensive trials that's ever been undertaken that answers many of these questions you have had for a long time. So the first question was is the transllocation management protocol effective in mitigating the risk of transfer of viral cells of corinia from hab impacted oysters during oyster relay. So the question that comes up is what is the transllocation management protocol for oyster relay? What is the prescribed protocol? It basically outlines that oysters for relay needs to be washed, bathed or hos in portable water or filtered sea water that's been filtered down to one micro particle size. That is followed by a 24-hour drying phase in dark to desiccate the external surfaces at a temperature of less than 10° centigrade to clean a cool room. Then using clean baskets during the transfer and then any equipment that is used for this purpose is washed down which includes graders, baskets, bins etc. So those are the four dot points which kind of outline the management protocol. So what we did was we basically looked at um the oyster liquor as the first one um to determine whether there were any cells present in hab impacted oysters. And if you look at this table we talk about uncleaned oysters versus cleaned oysters. Uncleaned oysters were not subjected to the management treatment protocol. They were harvested and straight away they went into the cool room. The clean oyster on the other hand was subjected to the management protocol and then went to the cool room before being uh brought to our west beach. So we looked at the oyster liquor as a first example. Um, and then what we found was that the unclean oyster liquor from sourced from Kangaroo Island had close to 3,700 cells per liter plus or minus 1,64 cells per liter with three replicates which 16 oysters comp in each replicate. So we found that there were about 3,700 cells. When you look at the ambient SAS squab data on the day, the water the seawater had 6,436 cells per liter. The same one when it was subjected to the management protocol, we detected nothing in the oyster liquor and but we did see a large number of eggs. The logical explanation for this is is that when you bring in unclean oysters, the moment you take them out of the water, the shelves the shells close the the two shells close tight and they retain that liquor or the seawater that is trapped and then they're only released when they're exposed to sea water again. So in this case, the unclean oysters did not have the opportunity to release them. Whilst the clean oysters was subjected to an exposure to water and they either briefly depending on if it's freshwater, seawater and the duration of exposure they either open briefly or uh and then they shut shut the shells. Um so that explains why we were seeing the uh the cells in the oyster. As one would expect the the oysters that originated from the non-hab impacted area which is Smoky Bay, we did not detect any cells either in the seawater or in the unclean oyster lea or in the clean oyster lea. Then we looked at the what was growing epiphically or in the oyster shell oyster shell surface. So for this we scraped the surface of the shell and resuspended the material that we collected into see clean filtered seawater and then counted them. So in this case both the hab impacted oysters or the non-hab impacted oysters both clean whether they were subjected to the management protocol or not had no sense whatsoever. We did however find some dinoises accuminata, one of the other hab species on the shelves, but their numbers were very low. There were like 2,500 to 3,000 cells from scraped from 36 oyster surfaces, which was not a big concern. General assemblage I've outlined there showed there were dietmobacteria. So there was assemblage of other species on the surf sh surface as one would expect. So the key take-home message from that small trial was that the risk associated with transfer of vegetative cells of corinia from transllocation through oyster liquor or as epipites on live oyster shells is quite low. We do recommend additional farm trials to remove confounding factors that influence this trial and I'll talk about that in a minute and also to determine the blooming potential which we couldn't do when we did this trial at uh at short notice. So the recommendation recommended improvements to the study includes repeating the control study to test the efficacy of the management strategies and the key weaknesses of the current trial included the transportation time was not standardized. We brought back oysters from Smoky Bay that took um and also oysters had to be moved from Kangro Island to West Beach and these times were not standardized and as a result that was identified as one of the confounding factors. This was done at the peak of summer uh around the 9th of December. So we did expect that the oysters would be stressed during transport under high ambient temperatures. Spawning risks were another one which we did encounter during this trial and the suggested improvements to this includes to where to uh was identified to be doing this trial on a farm when the the counts were high. So rather than bringing it to west beach to do it straight all the farm to remove any confforming factors with regards to transportation time and length and also the corinia being very delicate it's recommended that we undertake the counts soon after collection on farm without undertaking any movement whatsoever. The trial to be extended to ascertain the blooming potential which means whatever potential vegetative cells might be growing either epithetically on the shells or residing in the oyster liquor by cultivating them in a growth media for about a week and seeing whether they tend to bloom or not and then of course increasing the replication. These trials have or what has been proposed the improvements that have been proposed have been funded by DSD should the accounts ever increase to more than 5,000 cells per liter in any of the farms oyster farms in over the coming years. The next question was is depuration a pathway for transfer of viable cells of corinia from h have implanted oysters during a delay. The depuration pathway is mainly what goes through the gut passage and comes out and that was one of the other considerations as part of this trial. So what we did in for this trial was we co-cultivated clean hab import hab oysters or oysters sourced from a hab impacted area that is Kangu Island with non-hab impacted oysters from smoky bay in triple bay for one week. We then ascertained the corinia in seawater where this trial was undertaken both in the morning and in the afternoon which is twice daily and these were the setups. So we had we ran them in triplicates. We had three large tanks with a small impeller to keep cells in suspension and uh also to uh recirculate to circulate water within the tanks. And this is this was the setup that was used and this was sampled morning and afternoon for kinia counts. So that's another photograph of the experimental setup. From day zero to day nine, no corinia cells were detected either in the morning samples or in the afternoon samples in either of the feed replicates. We did however find that the assemblage was dominate. There was an assemblage of other planktonic species. It was dominated by copyp porti marine worms dietm cyobactal filaments egg masses oyster eggs flagagulinate seaweed. So it's it was not devoid of life. It very much was but no corinia was detected which is a promising sign. So this is how the corinia council undertaking large number of samples came back to the lab. We then followed the zasqua protocol of concentrating the sample and then counting them with a centigraph cell and triplicate counting of each sample was undertaken to remove any potential errors in counting. So the key take-home message from this trial was that the risk associated with transfer of vegetative cells of corinia through depiration that through the gut passage of hab impacted oysters subjected to transllocation management protocol is lower. Then we looked at the brevitoxin aspects of the the algae. So the short-term and long-term dynamics in brevxins and its analoges in oyster tissue and oyster liquor. Now to just to give you a bit of a background on brevitoxins. Brevito toxins cause neurotoxic shellfish poisoning which is a foodborn toxy from the consumption that comes up from the consumption of brevitoxins or brevtoxin analogs largely through seafood. These class of com uh compounds or the brevitoxins are thermally stable and they're lipophilic which means they are they bind they show a tendency to bind to fats or lipids and they are not inactivated by cooking or freezing which makes it extremely challenging to to counter that. Now brevitoxin 1 and brevitoxin 2 are the two parent bio toxins that are biosynthesized by the marine dinoflagulate. Now what is important to note and I put an asterct there is brevitoxin one is not synthesized by the species of corinia that we see we saw here in the algo in the south austan algo bloom which is corinia cristada. Corinia cristada does not produce bvtoxin one it only produces brevitoin 2. On the other hand, the one that you see in the northern hemisphere, especially in uh North America, which is Corinia brevis, produces both brevtoxin one and bretoxin 2. So shellfish, particularly oysters, tend to bioaccumulate brevitoin in tissue through filter feeding. So they filter feed corinous cells when they're in large numbers and then bioaccum tend to bioaccumulate the brevtoxins in tissue. In the shorter term, this is not does not cause any major issues to the oyster. They just accumulate. But in the longer term, we have seen some impacts to oyster. We're talking about beyond 9 10 weeks. And neurotoxic shellfish poisoning is characterized by gastrointestinal and neurological symptoms that include vomiting, diarrhea, numbness, tingling in facial regions and extremities. So no fatalities have been recorded from NSP yet. However, there was a mass toxity event of over 180 people that occurred in 1992 in New Zealand associated with the consumption of brevitoxin contaminated caucus and green muscles. And the toxicity effect is through brevitoxin binding to the voltage gated sodium channels on cell membranes opening the cell pores resulting in influx of sodium ions into the cell and causing the excitation of the nerve impulses which is the the way it impacts on uh in humans and other animals. So the food standards Australian New Zealand fzans has recommended the regulatory limits to be around 200 m units per 100 gram of shellfish tissue. That translates to approximately 0.8 mg of vervitoxin 2 equivalent per kg of oyster tissue. And this is how it's measured. The output that we get in terms of concentration is what we get out of an LCMS uh which is the instrument that we use for measuring bretoxins. So just to give you an idea as to what the metab metabolic transformation processes are of brevoxin 2 and the production of the various analogs. I'll just go through this little uh schematic. So as I mentioned earlier, Corinia brevis produces brevitoxin one and brevitoxin 2. They're biosynthesized by the algae microalgae. Uh we do not see brevxin one in corinia cristarda. So karina cristata was the main uh hab former in uh South Australia and we do not see brevox in one production. So brevitoxin 2 and what I've not so I've put two stars the red star indicates that it's it's been reported in literature that is common in Pacific oysters and the purple star is based on the persistence in this trial and also in the field observation. So brevitoxin 2 is commonly found in um pacific oysters which is biosynthesized by the algae. When it under goes oxidation it produces the analog brevitoxin B5 which is also common in um in Pacific oysters. When this combines or gets conjugated with torine which is an amino acid it produces levytoxin B1. Noting that all analoges of brevitoxin are basically metabolic analoges during the various transformative processes where there is oxidation, reduction, conjugation or comabolism in oysters. When brevitoxin 2 under goes reduction which is an aldihide group in brevitoxin 2 gets transformed to an alcohol group. It produces brevytoxin 3 which is a persistent brevitoin that we find. It's waterborn and we've been seeing this not only in oyster tissue but also in um oyster liquor and also in uh field-based observations farm based observations. When brevitoxin 2 under goes cysteine another amino acid it performs brevitoxin B2 which is one of analoges. Brevitoxin B2 is also a persistent analog and is also commonly noted in Pacific oysters. When this further goes through conjugation with fatty acids like minestrol and pal palml it forms brevitoxin B4. We do find some at times but it has not been a persistent form. Bermattoxin B2 further goes through a metabolic transformative product processing process in that involves microbes within shellfish and that's a process called as comet metabolism and that produces a very common bretoxin analog which is S deoxytoxin P2 which was not only known to occur in Pacific oysters but was also observed in this study as being persistent and was one of the most dominant and low. So then with that background in mind the question was is there a difference in brevtoxin concentrations and its analoges in cleaned and uncleaned oysters. When I say cleaned again cleaned was subjected to management protocol whereas unclean was not. So we looked at the total privoxin concentrations here and um in both oyster tissue and oyster liquor and note the benchmark which is the dotted red line which is a8 mg per kg of total bretoxins as recommended by fazans as the safe regulatory limit. The green box should have been Smoky Bay. Obviously, there was nothing detected in Smoky Bay. That's why nothing is showing up in the graph. And Kangro Island is denoted in orange. So, when we looked at um cleaned versus unclean in oyster tissue, we did not see any statistically significant differences for for three replicates. And that was um at a level of between 2.14 uh mg per kg was what was recorded which was about um um which was significantly higher than the threshold recommended safety threshold. On the other hand, when you look at the oyster liquor, there was hardly any. It was very close to limits of detection. So it could be safely said that oyster liquor hardly had any bretoxin in them. When you look at the analogs, the the oyster tissue, the analogs in the oyster tissue were very comparable between clean and uncleaned oysters. So um and largely dominated by SDox, Brevitoxin B2, Brevitoxin B3 and Brevitoxin 2 which is what I mentioned earlier. There may be subtle differences in some of the levels of the analogs but overall that was very comparable between the two. Oyster liquor on the other hand hardly there was absolutely very low levels of various analoges detected and it was worth not worth teasing out any further. In summary, no brevito toxin was detected in oyster tissue or liquor of clean or unclean um uh oysters from Smoky Bay, which was to be expected because that is supposed to be our clean site. No significant differences differences in tissue bretoxin concentrations of cleaned and uncleaned oysters from Kango Island was noted. So the mean private oxygen concentrations varied between 2.02 02 mg per kilo to about 2.14 significantly higher than the prescribed safe limits of8 mg per kilo of oyster tissue tissue bretoxin concentrations were about 2.5 to 2.7 times higher than the safe threshold of8 mgs per kilo in liquor about it was about 30 to 35 to 40 times lower than the tissue levels and was always below the regulatory levels. The brevitoin analoges in cleaned and uncleaned oysters were quite comparable except for the brev presence of brevtoxin B1 in cleaned oyster tissue. The dominant bretoxin analogs were sdoxy brevitoin B2 and brevitoxin 3 in both cleaned and uncleaned oyster tissue. So when you look at the analoges they were very comparable in oyster liquor but again they were very very low in terms of magnitude almost close to detection limits of the instrument. So the next question was do brevitoxin transfer from cleaned habacted oysters to clean non-hab impacted oysters when they co-ultivated for 8 days which is a very shortterm uh study to look at in the short term do they transfer between have impacted and no have impacted oysters. So these were the oysters that we got from Kanguan and Smoky Bay. They were transferred into oyster baskets, clean oyster baskets and they were then maintained in the large tanks that I showed earlier. On the right is the panel that you see for oyster tissue. On the left on sorry on the right is what you see for oyster liquor and on the left is what you see for oyster tissue. And as I mentioned earlier the uh Smoky Bay is in green and Kangro Island which is the hab impacted site in uh orange. Now we did notice a very small amount of brevitoin that transferred uh but it was minuscule to the point that it was very close to detection limits. So as you can see within the span of one week there was a significant reduction from about 2.14 mg per kilo to around about 1.02 or so mgs per kilo 1.2 mgs per kilo or within a week. So that's about a close to a 50% reduction in braidtoxins in oyster tissue. In oyster liquor again the same story. There was hardly anything detected very close to detection limits of the instrument. When we look at the analoges, it was the same story again. There was some small changes in brevoxin analoges, but the dominant ones being espoxin, brevitoxin B2, brevitoxin 2, and brevitoxin 3 being the dominant ones. Again, in the oyster liquor, there was hardly anything detected for those. um it was there was some detection but it was close to limits of detection mainstream. So the key summary from this short 8day co- cultivation trial was that there were we did notice a 50% reduction in bid toxin concentrations in tissue over 8 days in having impacted oysters. This reduction was about 20% oyster liquor but oyster liquor to begin with was very small. Anyway, the tissue transfer of brevitoin from have impacted oysters to non-have impacted oysters was insignificant after 8 days of co- cultivation and even if you looked at the profile it was mainly brevoxin 3 that was transferred but again it was not significant. The total brevitoxin concentration in liquor was about 35 to 110 times lower than tissue which explains that that pathway for any movement of brevitoxin can be safely ruled out. Small concentrations of brevitoxin that transferred from HAB to non-habacted oyster liquor at the end of was um was very small at the end of 8 days. mostly brevitoxin 3 with smaller concentrations of SDox, Brevitoxin B2 and Brevitoxin B2. So the bretoxin analoges varied in tissue at the end of 8 days. There was a decline in bretoxin B5 and SDox bretoxin B2, but again we saw a 50% decline in total. Oh, >> think it's moving on here. >> Moving there. It's not moving on screen. >> Stop. >> Yeah. I'm sorry. Start again. >> Okay. Okay. Okay. >> Just catch up with >> Okay. So, the key questions were the next set of questions were do Brevtoxin transfer from clean habacted oysters to clean non-hab impacted oysters when co- cultivated for nine weeks. That was the longest duration that's a long duration study that we did. And then that study also answer was uh we had the question um on what does the residence time of bretoxin have impacted oysters the declined and how long it took to decline to regulatory limits of8 mgs per uh kg when co- cultivated when cultivated in hfree conditions. So that is like simulating a potential limb. So what we did was we co-cultivated clean hab oysters that is one subjected to the management protocol sourced from Kango Island with non-hab impacted oysters sourced from smoky bay in triplicates in tanks for 9 weeks that's 63 days we monitored coria in seaborder in fact um the samples were collected um um um daily but bretoxin samples were only collected um weekly and the weekly variation bretoxin concentrations in have impacted tissue and liquor was noted and uh was measured. So these this was one of the three tanks that we used and you can see these were have impacted oysters. um equal number of habitat oysters were put um cleaned oysters were put in baskets and they were co-cultivated with non-habacted oysters from Smoky Bay in the same tank. The way we ran this trial was with feeding. So early in the morning every day early in the morning we would take water quality measurements collect a corinia sample and then we would drain the tank to simulate what happens in a farm to replicate um a low tide and then that stayed for 4 hours in a subjected to air drying. The oysters were air dried. After 4 hours we started gradually filling up the tanks and during the process of filling up the tanks which simulated a high tide we would add feed which is in the form of either paste algae or live algo cultures bottled paste were used for this on alternate days. So this was the water photograph showing the water quality sampling in the morning, Corinia sampling in the morning and then um on alternate days we were feeding with live algae and water alpha base. Um how we've we were noticing that the live algae was a lot better preferred. So once we got to a stage where our live algultures in our hatchery um grew to a substantially large volume, we uh pretty much started using live algae over water algae uh to to make sure that it was uh that we could run the trials the best conditions. So this is what the mixed live algae production was in the hatchery under controlled conditions. And then we would um drain it out into this big tank and then we would um feed them to the oysters in the pool farm at every week. Um we would then sub uh take the oy sample uh subsample the oysters and we would shuck it and then um process the oyster tissue by homogene homogenizing it and homogenized samples were then shipped to Cthron Institute in New Zealand and uh later in the year we started shipping it to Agilelex and we did the same thing after shutting what oyster liquor was collected that was also sent for analysis. So the results were that um this is the 9week result as you can see this is for the tissue and obviously Smoky Bay is co-h plotted with Kangro Island. There was nothing in Smoky Bay. So therefore nothing was transferred to the Smoky Bay oysters all through the nine peas. Kangro Island oysters, the hab impacted oysters started at about 2.14 milligrams per kilo and that was on day zero and then that reduced to below the regulatory limits on the first week of the trial. However, on week two, it did go up marginally and um that's a similar trend that we see in wild oysters too. and then subsequently it declined after week three onwards to below the regulatory limits of8 mgs per kilo. The only logical explanation for that week 2 spike could be that it was probably in a um analog that was not current that's not currently measured by the LCMS technique that may have transformed into one of the other analoges. um most likely um brevito sdoxy brevitoxin B2 um after week 2 onwards as you can see the dominant brevitoxin analoges were brevito sdoxy brevitoxin B2 which is the most dominant followed by brevitoxin B2 and a small amount of brevitoin 3 which is the the the transformative product which is the one that has been that's Auto reduce. So that's the plot showing the changes in provoxin analoges over time across nine weeks. As you can see, there was nothing detected in Smoky Bay oysters. It was all in Kango Island oysters and that declined after week three onwards. So you can as you can see the dominant one analog that was present all through the trial was SD oxintoxin B2 um followed by U brevitoxin B2. So in summary, we're seeing a 75% reduction in total brevoxin concentrations in tissue in the first week followed by a small spike in week two followed by a decline to levels below threshold from week three onwards. There was no tissue transfer of brevitoxin from impacted to non-hab impacted oysters oysters all through the trial from day zero to week nine. There were only minor changes in brevitoxin analoges that we observed over tissue in in tissues over time. After the after day zero, the changes in brevxin analogs were very subtle. The dominant ones being sdoxy brevitoxin B2 which is the most dominant accounting for about 40 to 60% of the total brevitoxins followed by brevitoxin 3 which is about 10 to 30% and brevitoxin B2 which is about 10 to 20% and a very small fraction of about 5% of brevtoxin 2 which is the biosynthesized fraction in oyster. When you look at the liquor, there was hardly anything. So it was as good as close to being close to the detection limits after week after day zero there's very little detected or um which was insignificant. So that kind of is an interesting story and when you tease it out a bit a bit more again it is immaterial because in oyster liquor the overall concentrations were very low but it's largely made up by brevito sdoxy brevitoxin B2 which then transformed to um brevitoxin B2 by the by week four after which nothing was detected. So in summary the bretoxin concentrations in the lea was about 40 times lower than in tissue. Again say we can safely rule out that this was one mechanism for transfer which we initially thought before at the time of the planning this trial. We thought maybe liquor was the major uh vehicle for transmission of brevitoxins, but that's now been conclusively proven that it's an insignificant factor for transfer. A 10-fold reduction in brevox toxin concentrations in oyster liquor was observed in the first week. There was no bretoxin transfer through liquor of hab impacted to non-hab impacted oysters and the significant changes in liquor over time. There was significant changes but again the levels are 15 times below the safe threshold limit. So it's not a key consideration. When you look at the tissue, the total brevoxin concentrations in the tissue fell below the safe threshold levels from week three onwards that is 21 days. There was a line spike in week two after which it declined and stayed below the threshold for the trial gradually declining over the period of a period of 9 weeks. There was no tissue transfer of brevtoxin from have impacted to non-hab impacted oysters at any time scales. Either the short 8day trial or the 9week long trial we did not observe any tissue transfer to have impacted to not have impacted when they are co-ultivated together and that has that is um that is of relevance from a relay perspective. Changes in bretoxin analoges in tissue over time is minor. the profile profiles were relatively stable and that's probably and that is very much uh in line with what has been reported in the literature the few studies that have been done on pacific oysters as I mentioned before the oyster liquor is not a major vehicle for brevopsin mobilization in oysters so the key aspects to consider in from this study is that this study was undertaken where the hab impacted oyster tissue registered a total brevtoxin concent concration of 2.04 mg per kilo which was the level at when it was sampled from Calgo Island. The decline in tissue bretoxin over time and potential transfer from impacted to non-hab impacted oysters are all based at the threshold level of 2.14 because that's the only oysters we could source at the time of the trial. The key question is whether this trend is comparable if tissue concentrations of hab impacted oysters reach between 20 to 30 mg per kilo as observed in certain farms during the peak of the hab. Um Stanbury is a good example of that where it reached around close to 20 mg per kilo at the peak of the hand. could be extrapolated. What could be extrapolated? Uh this trend could be extrapolated from some of the depiration trials that have been undertaken. But then we got to keep in mind that depiration trial in trials involve no feeding whatsoever. Um and is not comparable to a scenario into a classified area because there fed uh natural food that comes with the tides. So the deputation trials obviously do have an impact on oyster condition if it is done or undertaken over a long period of time. So the key question there was what happens if the brevitoins total brevitoxin concentrations go beyond 2.14 mg per kilo. So obviously we didn't have that um any samples from um from uh that we could use in our experimental trials. So then we looked at the extensive data that SAS collected uh from various um classified areas during the peak of the South Australian uh bloom. So these are the observations from the five farms and the key objectives of this trial or or this study was to assess the rate of reduction of brevoxin from hab impacted farms with the peak brevoxin concentrations of up to 20 mgs per kilo. Then we wanted to look at the relationship between Corinia cell counts in real time and how that translated with brevidopsin concentrations and tissue from various um um from the the five farms that we chose as the farms or the classified areas comparing the brevtoxin analoges or the profiles from hab impacted farms corresponding with brevtoxin peaks. So the first one that we looked at was Kango Island logical because American river which is Todd Packer's farm was the one that we used oysters from there was used for this experimental trial. So it was logical to look at that. What we found was there was a very clearcut delay between peak of corinia bloom to the peak of brevitox uh concentration in the oyster tissue and that is to be expected because they are filter feeders. So when the there's a peak of crania in the water they will be filter fed and eventually they do bioaccumulate and that's reflected with that short lag in concentrations. What we did observe was that it took about six weeks from the peak of uh the brevitoin uh concentration in the tissue for that to get down to the regulatory levels of8 mg per cube. When you look at the profiles, the brevitoin analogs again mirrors what we saw in the experimental trial with SD oxygen bretoxin B2 being the most dominant followed by um followed by uh brevoxin B2 and uh also brevitoxin B4. I'll summarize that in a minute with all the other um farms standpril and the cell concentrations reach peaks of about 800,000 cells of corinia per liter. Again a very similar observation where the corinia peaks where the brevitoin peaks followed corinia peaks. In this case it was it took about 19 weeks for the tissue concentrations to drop to regulatory levels of8 mg per kilo. That was a really good observation because that's because we know that at 2.12 mg or 2.14 mg per kilo in the experimental setup we were able to see that reduction within 3 weeks. But when it gets to about 20 mg per kilo from the farm observation we are seeing that it took about 19 weeks. Again the analogs were very comparable dur and then we looked at the classified area of Port Vincent. Um and in that in that particular farm again the similar observation but it the peaks of bre the brevitoin peak was around 13 mg or 12 something mg per kilo took about 14 weeks for that to reduce to the regulatory levels of8 mg per kilo. Again the analogs were very comparable dominated by SD oxygen oxen B2 Franklin harour we selected two farms S S S S S S S S S S S S S S S S S S S S S SWB two uh classified areas S S S S S S S S S S S S S S S S S S S S S S S S S S S S S S S S S S S S S S S SWB2 and S S S S S S S S S S S S S S S S S S S S S S W B9 and that's where the location of the uh the two classified areas are. In this case, the uh when we looked at S SWB2, the peak bretoxin concentrations were around 1.9 milligs per kilo and that took about 4 weeks to decline to the regulatory levels. Profiles were comparable. When you looked at SWP9, which is an adjacent farm, adjacent classified area, sorry, adjacent classified area, the peak bretoxin concentrations reached uh 2.5 m milligrams per kilo and that took about 7 weeks. Noting that this is likely to be slightly different from a relay scenario or from the experimental setup is the screen cell present in the Oh sorry. So when you look at the brevitoin analogs or the profiles during in various farms at the peak of the bre or peak of bretoxins the profiles were very comparable except for American river where there was a slight um uh difference seen with brevox in B1 uh showing up in the profiles. None of the other farms showed that that could be explained due to two reasons. One is thank you that is um due to two potentially two reasons. One is that that was a time when we transitioned from gothron institute to agile for the analysis. So there were subtle difference in the reporting limits or it could also be due to the composition of the phytolanton that they were filter feeding at Kangu Island because this is largely due to the to this is a torine um conjugate. Other than that when you compare the profiles of the analogs they were very comparable across the various farms various classified areas two in Gulf San Vincent uh one in American river and one in um and two in Spencer G upper Spencer Gul just clearly shows that regardless of where it's spially located the tendency or the the the reproducibility of the trends are very uh similar. So we put all that in a table summarizing um and that's when we observe some interesting trend with peak private concentrations with the duration it took for that peak to red decline to regulate regulatory limits of8 mg per kilo. So we this is the summary table and what we thought we would we were interested in looking at was can the duration of rivtopsin concentrations to decline to regulatory limits of point or less than8 mg per kilo be predicted based on this observations and the answer is yes we could and we saw a really good correlation when we plotted that observation and with an R square of.901 which we were not expecting. This was an accidental observation but what we got out of that was quite valuable. So when we use that predictive model to plug in various concentrations as observed through the various farms of the experimental results. Now with the experimental result the first one that you see on the top 2.14 mgs per kilo was what was observed in Kango Island what was brought to West Beach as per the predictive uh um when you plug it into the regression equation the prediction says it would take about 3.8 8 weeks for it to decline to the reg regulatory regulatory levels of8 mg per kilo but experimentally we validated that it took 3 weeks so there's a really good correlation there so it's very comparable probably a bit more conservative when it got to about 1.83 Day three took about three and a it's estimates that it takes about 3 and a half weeks. Once it increased to about 19.94 mg per kilo as observed in Stanbury it predicts predicted that it'll take about 18.9 or 19 weeks for it to reach uh the regulatory limits of8 mg per kilo. So the key observations from this farm observations or the classified area observations where there's a lag between corinia cell counts and brevitoxin concentrations. The changes in brevxin analogs in oyster tissue during brevtoxin peaks from various hab impacted farms is minor. Even though they are very specially spread that change in analogs was minor. Persistence of pretoxin in concentrations in oysters from onfarmm observations in the pres presence of crania cells is lot longer as one would expect than in experimental observations where we don't have any corinia in the background or in a depiration trial onfarmm observ farm obs data clearly demonstrates a linear relationship between rividoxin concentrations and the time it takes to reach safe levels of8 mg per kilo. This could be regarded as more conservative than in a relay situation where one would expect that there'll be no background uh levels of crania at all or any private toxin presence in the in the water sediment or poor water. experimental data is very comparable to oysters relate from a hab impacted farm or a hab impacted area to a non-hab impacted area because there would be no background levels. So in conclusion, the oysters subjected to transllocation management protocol did not register any cells either growing epithetically on the shell or in the oyster me. No kina cells established when unccleaned and cleaned oysters were co-ultivated for one week. That 8week trial brevitoin concentrations in oyster tissue during the experimental trial declined to regulatory levels with 3 weeks at initial levels of 2.14 mg per kilo. The concentrations in oyster liquor is negligible or close to detection limits in all the trials. So we can safely rule out oyster liquor to be any to be contributing in contributing in any way shape or form in um brevitoxin uh transformation toxin um trans transfer. So during nine weeks of co- cultivation no bretoxin transferred from have impacted oysters from can oil or cultivated with half-free oysters from smoky lake in our trials. The changes in brevitoxin analoges in oyster tissue during the trial was negligible on farm observations clearly demonstrate a lag between peaks of corinia cell counts and brevtoxin concentration. Brevtoxin analogs in oyster tissue corresponding with brevitoxin peaks from various habacted farms is comparative. The persistence of raid toxin oyster tissue from onfarmm observations in the presence of kinia cells is longer than experimental observation which includes depiration and tissue wash out depation in the first few days but tissue wash out occurring subsequently on farm data demonstrates a linear relationship between brevitoxin concentrations and the time it takes to reach regulatory levels of 8 or decline to reg regulatory levels of less than8 mg per kilo. Higher the bretoxin concentration, the longer it takes for it to be washed out from the tissue. As we have now seen with those observations, I would like to uh acknowledge the project steering committee um uh from BSD SEO the research council um Persa Saska Persa Fisheries and Aquaculture and from Saudi um there's been a lot of input into this trial over the duration we used to meet when we met and that has shaped this trial which we have come the experimental trial that was undertaken at Saudi commenced on the 9th of December. We went through the Christmas break over New Year monitoring daily uh until it finished in midf. And I want to acknowledge my team from SAR funding support from Algra Bloom industry research and development program oysters for the trials Todd and from KI oysters Joe and Linton from Smoky Bay Oysters. There's a lot of logistics involved in moving them across during the peak of Christmas. um and they were absolutely uh helpful in making ensuring that we got those oysters in time to run these trials and thank them greatly for that farm data. Alli from SAS provided that and we put that in a presentable format and that has formed a large basis of some of these conclusions. We did seek biotoxin advice from Tim uh from Cthron Institute also contributed substantially in giving advice on how the results were interpreted and the brevtoxin samples were analyzed at Corth Institute and Agile. We still have water samples that we'll be doing in Sardi down the brings me to the end of the presentation. Thank you very much. And that's a beautiful photograph from Coffin Bay on a beautiful sunny day. Thank you very much, Sashi. That is a comprehensive body of work there and and I acknowledge that there was quite a lot of information that was disseminated um relatively quickly. So we we will distill that information um into a simple summary and also all together the slide set um to distribute uh in in in good time so you can then revisit that. I think the recording uh will also be provided so you can get a little bit more of an interpretation from the slides um which can help you um distill that information and and and as always you know um society industry connect well um um and and Ursa if we need to answer any more questions going forward but now there's an opportunity for people online um to ask questions now. Um, and we we're here for another half hour or so. Um, so they are coming through. Uh, I can read them out. Um, you put them in through the the Q&A and we'll and we'll, um, go through them accordingly. First one is when assessing when assessing risk of transllocation protocol efficacy. What was the cell results from a nontransllocation protocol control? Asked another way. There were no cornea in 0 to9 days. What was the cell counts in the control outcomes? The cell counts at the time when we sourced it from Kangro Island was close to 6,000 uh 6,000 cells per liter. Um that was a background level and then once it was brought in then it was maintained in clean sea water. Thank you. I will be patient um for anyone who would like to type in acknowledging that um you know that was a lot of information that we delivered today. >> Yeah. And we will monitor both the Q&A but also the chat which a lot of people are familiar with. No stress. That's fine. we will distribute the information >> and we're happy to chat with Lindley as well whether um there's an opportunity to provide a a much more condensed version of that at the October Oyster seminar if um if you feel that there'd be value in either hearing that again or potentially for others that haven't made it today to have the opportunity to to hear it All right. Well, >> that's very quiet. >> I'll give it I'll give it 30 seconds. Oh, hang on. >> This one is All right. Okay. Is there an estimate on how long it will take transfer protocols to reflect this information is from what we've seen with the information from this study um the information we request for a relay request would remain the same and the relay process would remain the same. that question answer that one. Okay. Um, another one here. Am I right in recalling the corenia cell counts from KI were below transllocation level anyway when conducting this? What would counts over a million cells contribute? I.e. as per full HAB highest levels. What were other diet levels in the same time? So we don't have a limit for a number of what level of coria would see a closure of an area. So we would only take into account the tropy toxin levels in closing area. Um the level of coria we don't have any numbers that would um impact how we would manage a relay. I think from what the research has shown that once it's gone through that management protocol of the the cleaning process and stored out of water for 24 hours and those four points that Sashi had mentioned um the risk is low >> there's another set another question there what were other diet time levels in that in that at the same time we we got the data we haven't really looked at the diet levels in uh for this presentation, but um that's something we can certainly will be looking at down the track. But we have the community structure um of the plant. No more coming through and that's okay. um there'll be plenty of opportunity for us to um reply to any any questions that come through our session. >> So if that's the case, >> wondering there's just a couple of questions around the relay protocols guys, have we clarified that for you? >> So that that question that um Sarah answered, can you confirm that the relay protocols will remain unchanged? So, um the relay pro um request form is on the website and we'll we'll send that link out with the the key points from the summary that we put together with that. Um it's part of the relay request. There is um information that we'll require on where are you going to locate the stock, how are they going to be quarantined. There is a need to test stock um that has been relayed. um to to release it. Now that is the standard process. The implementation of that standard process prior to this um has been improved. So that's probably the change that industry will see um in terms of whether it's for biotoxins or ecoli. If you're going through a relay process, the need to test relay stock. um that's something that has come from the national review that DAFF undertook of the relay process. So that's something that we will be um overseeing. >> So just so I'm hearing that right, there's there's an available online the protocols that that um industry need to adhere to. >> So it would make sense to pull that out and package it in this so it's consistent with the topic of the day. >> Absolutely. Yeah. And I guess the one thing that this research has given us more um visibility of is potentially how long it might take for a relayed oyster to then return to those um under that point a um to be able to you know to be um >> suitable for sale >> suitable for sale. So um you know as you've seen there's that direct correlation. So those that were sort of, you know, much higher in the in the brev toxin content of the oyster will potentially take much longer to return to that um point A level and be able to be solved. But what it will but what it does do is give us that confidence that we could potentially move those oysters and they could be in an area um and at least they're able to be um you know kept in their um environment. they're able to continue feeding uh as long as they're able to be kept separate from the other oysters uh for testing purposes. Um then you you'd have to just wait for that period for the brevatsin to clear and um at least you have them out of the environment that they were accumulating more bretoxin. Will the testing also be required for relaying of juvenile stock >> to move that stock out of its quarantine status as part of its relay? Um, yes, but I will seek clarification from DAP on that one if we have any um options around that. But I'd say yes. >> Yes, but we'll seek clarification. >> Yeah. I'm assuming that the the idea behind that is that juvenile stock would not be not profitable to sell um 60 days. Yeah. Well, do not sus when we are talking realize you were referring only to an harvest area under closure or being currently affected by a HAB. >> Only those areas that are closed. If an area is impacted by HAB but hasn't closed, doc is free to move. Will other industry stakeholders within bay areas be aware of any relocations? or will it be available within industry via some way? How will that be communicated? Where is that? >> So if a relay is approved, yes. Will industry stakeholders be aware that a relocation has been approved and trans um relaying transportation? >> It's not our throat fault to notify anyone other than the person who's relaying the stock and the um accredited producer who's receiving the stock. So that's protocol. All right, I'll stretch it out 30 seconds to see if there's any other takers acknowledging that we can catch up again session. going once. >> Yeah, it's hard and and and it's awkward because we're looking at ourselves on a big screen. So, um thank you for everybody who participated. Um like I said a lot of content that'll be summarized and distributed um both both in summary form and in full form plus the associated um procedures that are relevant. Um really appreciate your time. I I feel like this is a good platform to disseminate key bits of information to ensure that the scientists, the regulators and industry are in the room. Um I think um I think it's a good format. So thank you very much. Um we will draw this to a close and um look forward to connecting with you again another time. Enjoy the weekend. Crow's already lost so I've got nothing. Thank you everyone. >> Thanks everyone.