An On-Farm Workflow for Predictive Management of Paralytic Shellfish Toxin-Producing Harmful Algal Blooms for the Aquaculture Industry.

Paralytic shellfish toxins (PSTs) produced by marine dinoflagellates significantly impact shellfish industries worldwide. Early detection on-farm and with minimal training would allow additional time for management decisions to minimize economic losses. Here, we describe and test a standardized workflow based on the detection of sxtA4, an initial gene in the biosynthesis of PSTs. The workflow is simple and inexpensive and does not require a specialized laboratory. It consists of (1) water collection and filtration using a custom gravity sampler, (2) buffer selection for sample preservation and cell lysis for DNA, and (3) an assay based on a region of sxtA, DinoDtec lyophilized quantitative polymerase chain reaction (qPCR) assay. Water samples spiked with Alexandrium catenella showed a cell recovery of >90% when compared to light microscopy counts. The performance of the lysis method (90.3% efficient), Longmire's buffer, and the DinoDtec qPCR assay (tested across a range of Alexandrium species (90.7-106.9% efficiency; r2 > 0.99)) was found to be specific, sensitive, and efficient. We tested the application of this workflow weekly from May 2016 to 30th October 2017 to compare the relationship between sxtA4 copies L-1 in seawater and PSTs in mussel tissue (Mytilus galloprovincialis) on-farm and spatially (across multiple sites), effectively demonstrating an ∼2 week early warning of two A. catenella HABs (r = 0.95). Our tool provides an early, accurate, and efficient method for the identification of PST risk in shellfish aquaculture.

Temporal variability in the growth-enhancing effects of different bacteria within the microbiome of the diatom Actinocyclus sp.

Reciprocal metabolite exchanges between diatoms and bacteria can enhance the growth of both partners and therefore fundamentally influence aquatic ecosystem productivity. Here, we examined the growth-promoting capabilities of 15 different bacterial isolates from the bacterial community associated with the marine diatom Actinocyclus sp. and investigated the magnitude and timing of their effect on the growth of this diatom. In the presence of its microbiome, Actinocyclus sp. growth was significantly enhanced relative to axenic cultures. Co-culture with each of the 15 bacterial isolates examined here (seven Rhodobacteraceae, four Vibrionaceae, two Pseudoalteromonadaceae, one Oceanospirillaceae and one Alteromonadaceae) increased the growth of the diatom host, with four isolates inducing rates of growth that were similar to those delivered by the diatom's full microbiome. However, the timing and duration of this effect differed between the different bacteria tested. Indeed, one Rhodobacteraceae and one Alteromonadaceae enhanced Actinocyclus sp. cell numbers between days 0-6 after co-incubation, five other Rhodobacteraceae promoted diatom cell numbers the most between days 8-12, whilst four Vibrionaceae, one Oceanospirillaceae and one Rhodobacteraceae enhanced Actinocyclus sp. cell abundance between days 14-16. These results are indicative of a succession of the growth-enhancing effects delivered by diverse bacteria throughout the Actinocyclus sp. life cycle, which will likely deliver sustained growth benefits to the diatom when its full microbiome is present.

Response of planktonic microbial assemblages to disturbance in an urban sub-tropical estuary.

Microbes are sensitive indicators of estuarine processes because they respond rapidly to dynamic disturbance events. As most of the world's population lives in urban areas and climate change-related disturbance events are becoming more frequent, estuaries bounded by cities are experiencing increasing stressors, at the same time that their ecosystem services are required more than ever. Here, using a multidisciplinary approach, we determined the response of planktonic microbial assemblages in response to seasonality and a rainfall disturbance in an urban estuary bounded by Australia's largest city, Sydney. We used molecular barcoding (16S, 18S V4 rRNA) and microscopy-based identification to compare microbial assemblages at locations with differing characteristics and urbanisation histories. Across 142 samples, we identified 8,496 unique free-living bacterial zOTUs, 8,175 unique particle associated bacterial zOTUs, and 1,920 unique microbial eukaryotic zOTUs. Using microscopy, we identified only the top <10% abundant, larger eukaryotic taxa (>10 µm), however quantification was possible. The site with the greater history of anthropogenic impact showed a more even community of associated bacteria and eukaryotes, and a significant increase in dissolved inorganic nitrogen following rainfall, when compared to the more buffered site. This coincided with a reduced proportional abundance of Actinomarina and Synechococcus spp., a change in SAR 11 clades, and an increase in the eukaryotic microbial groups Dinophyceae, Mediophyceae and Bathyoccocaceae, including a temporary dominance of the harmful algal bloom dinoflagellate Prorocentrum cordatum (syn. P. minimum). Finally, a validated hydrodynamic model of the estuary supported these results, showing that the more highly urbanised and upstream location consistently experienced a higher magnitude of salinity reduction in response to rainfall events during the study period. The best abiotic variables to explain community dissimilarities between locations were TDP, PN, modelled temperature and salinity (r = 0.73) for the free living bacteria, TP for the associated bacteria (r = 0.43), and modelled temperature (r = 0.28) for the microbial eukaryotic communities. Overall, these results show that a minor disturbance such as a brief rainfall event can significantly shift the microbial assemblage of an anthropogenically impacted area within an urban estuary to a greater degree than a seasonal change, but may result in a lesser response to the same disturbance at a buffered, more oceanic influenced location. Fine scale research into the factors driving the response of microbial communities in urban estuaries to climate related disturbances will be necessary to understand and implement changes to maintain future estuarine ecosystem services.

Abiotic and biotic factors controlling sexual reproduction in populations of Pseudo-nitzschia pungens (Bacillariophyceae).

Pseudo-nitzschia pungens is a widely distributed marine pennate diatom. Hybrid zones, regions in which two different genotypes may interbreed, are important areas for speciation and ecology, and have been reported across the globe for this species. However, sexual reproduction between differing clades in the natural environment is yet to be observed and is difficult to predict. Here we carried out experiments using two mono-clonal cultures of P. pungens from different genotypes to measure the frequency and timing of sexual reproduction across varying biotic (growth phases and cell activity potential) and abiotic conditions (nutrients, light, turbulence). We found the mating rates and number of zygotes gradually decreased from exponential to late stationary growth phases. The maximum zygote abundance observed was 1,390 cells mL-1 and the maximum mating rate was 7.1%, both which occurred during the exponential growth phase. Conversely, only 9 cells mL-1 and a maximum mating rate of 0.1% was observed during the late stationary phase. We also found the higher the relative potential cell activity (rPCA) in parent cells, as determined by the concentration of chlorophyll a per cell and the ratio of colony formation during parent cultivations, revealed higher mating rates. Furthermore, sexual events were reduced under nutrient enrichment conditions, and mating pairs and zygotes were not formed under aphotic (dark) or shaking culture conditions (150 rpm). In order to understand the sexual reproduction of Pseudo-nitzschia in the natural environment, our results highlight that it is most likely the combination of both biotic (growth phase, Chl. a content) and abiotic factors (nutrients, light, turbulence) that will determine the successful union of intraspecific populations of P. pungens in any given region.

Mapping the development of a Dinophysis bloom in a shellfish aquaculture area using a novel molecular qPCR assay.

Diarrhetic shellfish toxins produced by certain species of the marine dinoflagellate Dinophysis can accumulate in shellfish in high concentrations, representing a significant food safety issue worldwide. This risk is routinely managed by monitoring programs in shellfish producing areas, however the methods used to detect these harmful marine microbes are not usually automated nor conducted onsite, and are often expensive and require specialized expertise. Here we designed a quantitative real-time polymerase chain reaction (qPCR) assay based on the ITS-5.8S ribosomal region of Dinophysis spp. and evaluated its specificity, efficiency, and sensitivity to detect species belonging to this genus. We designed and tested twenty sets of primers pairs using three species of Dinophysis - D. caudata, D. fortii and D. acuminata. We optimized a qPCR assay using the primer pair that sufficiently amplified each of the target species (Dacu_11F/Dacu_11R), and tested this assay for cross-reactivity with other dinoflagellates and diatoms in the laboratory (11 species) and in silico 8 species (15 strains) of Dinophysis, 3 species of Ornithocercus and 2 species of Phalacroma. The qPCR assay returned efficiencies of 92.4% for D. caudata, 91.3% for D fortii, and 91.5% for D. acuminata, while showing no cross-reactivity with other phytoplankton taxa. Finally, we applied this assay to a D. acuminata bloom which occurred in an oyster producing estuary in south eastern Australia, and compared cell numbers inferred by qPCR to those determined by microscopy counts (max abund. ∼6.3 × 103 and 5.3 × 103 cells L-1 respectively). Novel molecular tools such as qPCR have the potential to be used on-farm, be automated, and provide an early warning for the management of harmful algal blooms.

Diatom Biogeography, Temporal Dynamics, and Links to Bacterioplankton across Seven Oceanographic Time-Series Sites Spanning the Australian Continent.

Diatom communities significantly influence ocean primary productivity and carbon cycling, but their spatial and temporal dynamics are highly heterogeneous and are governed by a complex diverse suite of abiotic and biotic factors. We examined the seasonal and biogeographical dynamics of diatom communities in Australian coastal waters using amplicon sequencing data (18S-16S rRNA gene) derived from a network of oceanographic time-series spanning the Australian continent. We demonstrate that diatom community composition in this region displays significant biogeography, with each site harbouring distinct community structures. Temperature and nutrients were identified as the key environmental contributors to differences in diatom communities at all sites, collectively explaining 21% of the variability observed in diatoms assemblages. However, specific groups of bacteria previously implicated in mutualistic ecological interactions with diatoms (Rhodobacteraceae, Flavobacteriaceae and Alteromonadaceae) also explained a further 4% of the spatial dynamics observed in diatom community structure. We also demonstrate that the two most temperate sites (Port Hacking and Maria Island) exhibited strong seasonality in diatom community and that at these sites, winter diatom communities co-occurred with higher proportion of Alteromonadaceae. In addition, we identified significant co-occurrence between specific diatom and bacterial amplicon sequence variants (ASVs), with members of the Roseobacter and Flavobacteria clades strongly correlated with some of the most abundant diatom genera (Skeletonema, Thalassiosira, and Cylindrotheca). We propose that some of these co-occurrences might be indicative of ecologically important interactions between diatoms and bacteria. Our analyses reveal that in addition to physico-chemical conditions (i.e., temperature, nutrients), the relative abundance of specific groups of bacteria appear to play an important role in shaping the spatial and temporal dynamics of marine diatom communities.

Using qPCR and high-resolution sensor data to model a multi-species Pseudo-nitzschia (Bacillariophyceae) bloom in southeastern Australia.

Harmful algal blooms, including those caused by the toxic diatom Pseudo-nitzschia, can have significant impacts on human health, ecosystem functioning and ultimately food security. In the current study we characterized a bloom of species of Pseudo-nitzschia that occurred in a south-eastern Australian oyster-growing estuary in 2019. Using light microscopy, combined with molecular (ITS/5.8S and LSU D1-D3 rDNA regions) and toxicological evidence, we observed the bloom to consist of multiple species of Pseudo-nitzschia including P. cf. cuspidata, P. hasleana, P. fraudulenta and P. multiseries, with P. cf. cuspidata being the only species that produced domoic acid (3.1 pg DA per cell). As several species of Pseudo-nitzschia co-occurred, only one of which produced DA, we developed a rapid, sensitive and efficient quantitative real-time polymerase chain reaction (qPCR) assay to detect only species belonging to the P. pseudodelicatissima complex Clade I, to which P. cf. cuspidata belongs, and this indicated that P. cuspidata or closely related strains may have dominated the Pseudo-nitzschia community at this time. Finally, using high resolution water temperature and salinity sensor data, we modeled the relationship between light microscopy determined abundance of P. delicatissima group and environmental variables (temperature, salinity, rainfall) at two sites within the estuary. A total of eight General Linear Models (GLMs) explaining between 9 and 54% of the deviance suggested that the temperature (increasing) and/or salinity (decreasing) data were generally more predictive of high cell concentrations than the rainfall data at both sites, and that overall, cell concentrations were more predictive at the more oceanic site than the more upstream site, using this method. We conclude that the combination of rapid molecular methods such as qPCR and real-time sensor data modeling, can provide a more rapid and effective early warning of harmful algal blooms of species of Pseudo-nitzschia, resulting in more beneficial regulatory and management outcomes.

A Comparative Analysis of Methods (LC-MS/MS, LC-MS and Rapid Test Kits) for the Determination of Diarrhetic Shellfish Toxins in Oysters, Mussels and Pipis.

Rapid methods for the detection of biotoxins in shellfish can assist the seafood industry and safeguard public health. Diarrhetic Shellfish Toxins (DSTs) are produced by species of the dinoflagellate genus Dinophysis, yet the comparative efficacy of their detection methods has not been systematically determined. Here, we examined DSTs in spiked and naturally contaminated shellfish-Sydney Rock Oysters (Saccostrea glomerata), Pacific Oysters (Magallana gigas/Crassostrea gigas), Blue Mussels (Mytilus galloprovincialis) and Pipis (Plebidonax deltoides/Donax deltoides), using LC-MS/MS and LC-MS in 4 laboratories, and 5 rapid test kits (quantitative Enzyme-Linked Immunosorbent Assay (ELISA) and Protein Phosphatase Inhibition Assay (PP2A), and qualitative Lateral Flow Assay (LFA)). We found all toxins in all species could be recovered by all laboratories using LC-MS/MS (Liquid Chromatography-tandem Mass Spectrometry) and LC-MS (Liquid Chromatography-Mass Spectrometry); however, DST recovery at low and mid-level concentrations (<0.1 mg/kg) was variable (0-150%), while recovery at high-level concentrations (>0.86 mg/kg) was higher (60-262%). While no clear differences were observed between shellfish, all kits delivered an unacceptably high level (25-100%) of falsely compliant results for spiked samples. The LFA and the PP2A kits performed satisfactorily for naturally contaminated pipis (0%, 5% falsely compliant, respectively). There were correlations between spiked DSTs and quantitative methods was highest for LC-MS (r2 = 0.86) and the PP2A kit (r2 = 0.72). Overall, our results do not support the use of any DST rapid test kit as a stand-alone quality assurance measure at this time.

Phenotypic trait variability as an indication of adaptive capacity in a cosmopolitan marine diatom.

Determining the adaptive capacity of marine phytoplankton is important in predicting changes in phytoplankton responses to ocean warming. Phytoplankton may consist of high levels of standing phenotypic and genetic variability, the basis of rapid evolution; however, few studies have quantified trait variability within and amongst closely related diatom species. Using 35 clonal cultures of the ubiquitous marine diatom Leptocylindrus isolated from six locations, spanning 2000 km of the south-eastern Australian coastline, we found evidence of significant intraspecific morphological and metabolic trait variability, which for 8 of 9 traits (growth rate, biovolume, C:N, silica deposition, silica incorporation rate, chl-a, and photosynthetic efficiency under dark adapted, growth irradiance, and high-light adaptation) were greater within a species than between species. Moreover, only two traits revealed a latitudinal trend with strains isolated from lower latitudes showing significantly higher silicification rates and protein:lipid content compared to their higher latitude counterparts. These data mirror recent studies on diatom intraspecific genetic diversity, which has found comparable levels of genetic diversity at a single site to those thousands of kilometres apart, and provide evidence of a functional role of diatom diversity that will allow for rapid adaptation via ecological selection on standing variation in response to changing conditions.

Sexual reproduction and genetic polymorphism within the cosmopolitan marine diatom Pseudo-nitzschia pungens.

Different clades belonging to the cosmopolitan marine diatom Pseudo-nitzschia pungens appear to be present in different oceanic environments, however, a 'hybrid zone', where populations of different clades interbreed, has also been reported. Many studies have investigated the sexual reproduction of P. pungens, focused on morphology and life cycle, rather than the role of sexual reproduction in mixing the genomes of their parents. We carried out crossing experiments to determine the sexual compatibility/incompatibility between different clades of P. pungens, and examined the genetic polymorphism in the ITS2 region. Sexual reproduction did not occur only between clades II and III under any of experimental temperature conditions. Four offspring strains were established between clade I and III successfully. Strains established from offspring were found interbreed with other offspring strains as well as viable with their parental strains. We confirmed the hybrid sequence patterns between clades I and III and found novel sequence types including polymorphic single nucleotide polymorphisms (SNPs) in the offspring strains. Our results implicate that gene exchange and mixing between different clades are still possible, and that sexual reproduction is a significant ecological strategy to maintain the genetic diversity within this diatom species.

First Detection of Paralytic Shellfish Toxins from Alexandrium pacificum above the Regulatory Limit in Blue Mussels (Mytilus galloprovincialis) in New South Wales, Australia.

In 2016, 2017 and 2018, elevated levels of the species Alexandrium pacificum were detected within a blue mussel (Mytilus galloprovincialis) aquaculture area at Twofold Bay on the south coast of New South Wales, Australia. In 2016, the bloom persisted for at least eight weeks and maximum cell concentrations of 89,000 cells L-1 of A. pacificum were reported. The identity of A. pacificum was confirmed using molecular genetic tools (qPCR and amplicon sequencing) and complemented by light and scanning electron microscopy of cultured strains. Maximum reported concentrations of paralytic shellfish toxins (PSTs) in mussel tissue was 7.2 mg/kg PST STX equivalent. Elevated cell concentrations of A. pacificum were reported along the adjacent coastal shelf areas, and positive PST results were reported from nearby oyster producing estuaries during 2016. This is the first record of PSTs above the regulatory limit (0.8 mg/kg) in commercial aquaculture in New South Wales since the establishment of routine biotoxin monitoring in 2005. The intensity and duration of the 2016 A. pacificum bloom were unusual given the relatively low abundances of A. pacificum in estuarine and coastal waters of the region found in the prior 10 years.

Impact of fluorescence on Raman remote sensing of temperature in natural water samples.

A comprehensive investigation into the impact of spectral baseline on temperature prediction in natural marine water samples by Raman spectroscopy is presented. The origin of baseline signals is investigated using principal component analysis and phytoplankton cultures in laboratory experiments. Results indicate that fluorescence from photosynthetic pigments and dissolved organic matter may overlap with the Raman peak for 532 nm excitation and compromise the accuracy of temperature predictions. Two methods of spectral baseline correction in natural waters are evaluated: a traditional tilted baseline correction and a new correction by temperature marker values, with accuracies as high as ± 0.2°C being achieved in both cases.

The Genetic Basis of Toxin Biosynthesis in Dinoflagellates.

In marine ecosystems, dinoflagellates can become highly abundant and even dominant at times, despite their comparatively slow growth rates. One factor that may play a role in their ecological success is the production of complex secondary metabolite compounds that can have anti-predator, allelopathic, or other toxic effects on marine organisms, and also cause seafood poisoning in humans. Our knowledge about the genes involved in toxin biosynthesis in dinoflagellates is currently limited due to the complex genomic features of these organisms. Most recently, the sequencing of dinoflagellate transcriptomes has provided us with valuable insights into the biosynthesis of polyketide and alkaloid-based toxin molecules in dinoflagellate species. This review synthesizes the recent progress that has been made in understanding the evolution, biosynthetic pathways, and gene regulation in dinoflagellates with the aid of transcriptomic and other molecular genetic tools, and provides a pathway for future studies of dinoflagellates in this exciting omics era.

The Microbiome of the Cosmopolitan Diatom Leptocylindrus Reveals Significant Spatial and Temporal Variability.

The ecological interactions between phytoplankton and marine bacteria have important implications for the productivity and biogeochemistry of ocean ecosystems. In this study we characterized the microbial assemblages associated with multiple isolates of the ecologically important diatom Leptocylindrus using amplicon sequencing of the 16S rRNA gene, to examine levels of conservation of the microbiome across closely related species or strains. We also assessed if the microbiome structure of a given diatom strain was dependent on the location from which it was isolated and if the microbiome of cultured isolates significantly changed overtime from the seawater in which they were isolated. The bacterial assemblages from 36 strains belonging to three species (Leptocylindrus danicus, Leptocylindrus convexus, and Leptocylindrus aporus) isolated from six locations spanning > 1000 km of south east Australian coastline over 1 year, were dominated by the Rhodobacteraceae (∼60%) and the Flavobacteriaceae (∼10%). Across all strains, only one 'core OTU' (Roseovarius sp.) was identified across all samples. We observed no significant differences in bacterial community composition between diatom species. Significant differences in microbiome structure were, however, observed between diatom strains collected at different sampling times and from differing locations, albeit these two factors were coupled. Moreover, while bacterial communities under domestication varied from the seawater in which they were isolated, they remained specific to the location/month of origin, i.e., different regions and time points harbored distinct bacterial communities. Our study delivers new knowledge in relation to diatom-bacterial associations, revealing that the location/time from which a diatom is isolated plays an important role in shaping its microbiome.

Diarrhetic Shellfish Toxin Monitoring in Commercial Wild Harvest Bivalve Shellfish in New South Wales, Australia.

An end-product market survey on biotoxins in commercial wild harvest shellfish (Plebidonax deltoides, Katelysia spp., Anadara granosa, Notocallista kingii) during three harvest seasons (2015⁻2017) from the coast of New South Wales, Australia found 99.38% of samples were within regulatory limits. Diarrhetic shellfish toxins (DSTs) were present in 34.27% of 321 samples but only in pipis (P. deltoides), with two samples above the regulatory limit. Comparison of these market survey data to samples (phytoplankton in water and biotoxins in shellfish tissue) collected during the same period at wild harvest beaches demonstrated that, while elevated concentrations of Dinophysis were detected, a lag in detecting bloom events on two occasions meant that wild harvest shellfish with DSTs above the regulatory limit entered the marketplace. Concurrently, data (phytoplankton and biotoxin) from Sydney rock oyster (Saccostrea glomerata) harvest areas in estuaries adjacent to wild harvest beaches impacted by DSTs frequently showed elevated Dinophysis concentrations, but DSTs were not detected in oyster samples. These results highlighted a need for distinct management strategies for different shellfish species, particularly during Dinophysis bloom events. DSTs above the regulatory limit in pipis sampled from the marketplace suggested there is merit in looking at options to strengthen the current wild harvest biotoxin management strategies.

A new diatom species P. hallegraeffii sp. nov. belonging to the toxic genus Pseudo-nitzschia (Bacillariophyceae) from the East Australian Current.

A new species belonging to the toxin producing diatom genus Pseudo-nitzschia, P. hallegraeffii sp. nov., is delineated and described from the East Australian Current (EAC). Clonal cultures were established by single cell isolation from phytoplankton net hauls collected as part of a research expedition in the EAC region in 2016 on the RV Investigator. Cultures were assessed for their morphological and genetic characteristics, their sexual compatibility with other Pseudo-nitzschia species, and their ability to produce domoic acid. Light and transmission electron microscopy revealed cells which differed from their closest relatives by their cell width, rows of poroids, girdle band structure and density of band straie. Phylogenetic analyses based on sequencing of nuclear-encoded ribosomal deoxyribonucleic acid (rDNA) regions showed this novel genotype clustered within the P. delicatissima complex, but formed a discrete clade from its closest relatives P. dolorosa, P. simulans, P. micropora and P. delicatissima. Complementary base changes (CBCs) were observed in the secondary structure of the 3' nuclear ribosomal transcribed spacer sequence region (ITS2) between P. hallegraeffii sp. nov. and its closest related taxa, P. simulans and P. dolorosa. Under laboratory conditions, and in the absence of any zooplankton cues, strains of P. hallegraeffii sp. nov. did not produce domoic acid (DA) and were not sexually compatible with any other Pseudo-nitzschia clones tested. A total of 18 Pseudo-nitzschia species, including three confirmed toxigenic species (P. cuspidata, P. multistriata and P. australis) have now been unequivocally confirmed from eastern Australia.

A database of chlorophyll a in Australian waters.

Chlorophyll a is the most commonly used indicator of phytoplankton biomass in the marine environment. It is relatively simple and cost effective to measure when compared to phytoplankton abundance and is thus routinely included in many surveys. Here we collate 173, 333 records of chlorophyll a collected since 1965 from Australian waters gathered from researchers on regular coastal monitoring surveys and ocean voyages into a single repository. This dataset includes the chlorophyll a values as measured from samples analysed using spectrophotometry, fluorometry and high performance liquid chromatography (HPLC). The Australian Chlorophyll a database is freely available through the Australian Ocean Data Network portal (https://portal.aodn.org.au/). These data can be used in isolation as an index of phytoplankton biomass or in combination with other data to provide insight into water quality, ecosystem state, and relationships with other trophic levels such as zooplankton or fish.

Recent Trends in Marine Phycotoxins from Australian Coastal Waters.

Phycotoxins, which are produced by harmful microalgae and bioaccumulate in the  marine food web, are of growing concern for Australia. These harmful algae pose a threat to  ecosystem and human health, as well as constraining the progress of aquaculture, one of the fastest  growing food sectors in the world. With better monitoring, advanced analytical skills and an  increase in microalgal expertise, many phycotoxins have been identified in Australian coastal  waters in recent years. The most concerning of these toxins are ciguatoxin, paralytic shellfish  toxins, okadaic acid and domoic acid, with palytoxin and karlotoxin increasing in significance. The  potential for tetrodotoxin, maitotoxin and palytoxin to contaminate seafood is also of concern,  warranting future investigation. The largest and most significant toxic bloom in Tasmania in 2012  resulted in an estimated total economic loss of~AUD$23M, indicating that there is an imperative to  improve  toxin  and  organism  detection  methods,  clarify  the  toxin  profiles  of  species  of  phytoplankton and carry out both intra- and inter-species toxicity comparisons. Future work also  includes the application of rapid, real-time molecular assays for the detection of harmful species  and toxin genes. This information, in conjunction with a better understanding of the life histories  and  ecology  of  harmful  bloom  species,  may  lead  to  more  appropriate  management  of  environmental, health and economic resources.