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Introduction
My research is focused on molecular ecology of toxic phytoplankton and seeks to uncover the ecological and biological mechanisms that enhance the frequency and toxicity of harmful algal blooms (HABs).
Additional affiliations
September 2014 - May 2019
January 2006 - December 2007
February 2002 - December 2005
Publications
Publications (145)
Thirty-four cyst types capable of seeding plankton dinoflagellate populations have been identified in Tasmanian
estuarine sediments. The most common cysts were those of Gonyaulax grindleyi, G. spinifera, Gymnodinium
catenatum, Gyrodinium sp., Polykrikos schwartzii, Protoperidinium conicum, P. pentagonum, P. subinerme,
Scrippsiella spp. and Zygabiko...
Diatom and dinoflagellate species that are not endemic to a region can be inadvertently introduced when their resistant resting stages are discharged with the ballast-tank waters and sediments of bulk cargo vessels. A survey of 343 cargo vessels entering 18 Australian ports showed that 65% of ships were carrying significant amounts of sediment on t...
Interactions with the bacterial community are increasingly considered to have a significant influence on marine phytoplankton populations. Here we used a simplified dinoflagellate-bacterium experimental culture model to conclusively demonstrate that the toxic dinoflagellate Gymnodinium catenatum H. W. Graham requires growth-stimulatory marine bacte...
The potential of ballast water to act as a major introduction vector for toxic dinoflagellates and other phytoplankton is beyond doubt; however, evidence that links the suspected introduced species with a source population is less convincing, especially without supporting historical and biochemical data, or consideration of palaeobiogeographical sc...
Many parasitic Apicomplexa, such as Plasmodium falciparum, contain an unpigmented chloroplast remnant termed the apicoplast, which is a target for malaria treatment. However, no close relative of apicomplexans with a functional photosynthetic plastid has yet been described. Here we describe a newly cultured organism that has ultrastructural feature...
Harmful algal blooms (HABs) have had significant adverse impacts on the seafood industry along the Tasmanian east coast over the past 4 decades. To investigate the history of regional HABs, we performed analyses of sedimentary ancient DNA (sedaDNA) in coastal sediments up to ~9000 years old collected inshore and offshore of Maria Island, Tasmania....
The application of meta-barcoding, qPCR, and metagenomics to aquatic eukaryotic microbial communities requires knowledge of genomic copy number variability (CNV). CNV may be particularly relevant to functional genes, impacting dosage and expression, yet little is known of the scale and role of CNV in microbial eukaryotes. Here, we quantify CNV of r...
Yersiniosis of cultured Atlantic salmon is a recurrent fish health management challenge in many continents. The causative organism, Yersinia ruckeri, can reside latently in the gut and lead to acute infection and disease during hatchery and sea‐transfer stages. One potential prevention approach is the administration of probiotic bacteria to suppres...
This datasheet on Gymnodinium catenatum covers Identity, Overview, Distribution, Dispersal, Diagnosis, Biology & Ecology, Environmental Requirements, Natural Enemies, Impacts, Uses, Prevention/Control, Further Information.
Dinoflagellates are a functionally diverse group of organisms, rich in morphological complexity and features, that has formed the basis of a well-developed classical taxonomy. Their extensive fossil record of resistant resting stages (dinocysts) is unique among protists and has supported a comparatively early development of detailed evolutionary th...
Harmful algal blooms (HABs) have significantly impacted the seafood industry along the Tasmanian east coast over the past four decades. To investigate the history of regional HABs, we applied sedimentary ancient DNA analyses ( sed aDNA) to coastal sediments up to ∼9 000 years old collected inshore and offshore Maria Island, Tasmania. We used metage...
Marine sedimentary ancient DNA (sedaDNA) is increasingly used to study past ocean ecosystems, however, studies have been severely limited by the very low amounts of DNA preserved in the subseafloor, and the lack of bioinformatic tools to authenticate sedaDNA in metagenomic data. We applied a hybridisation capture ‘baits’ technique to target marine...
Chlorophyll-a (chl-a) concentration is an indicator of algal biomass. The Sentinel 2 platform offers greatly improved spatial resolution over other satellite platforms designed for water based chl-a retrievals and includes a “red-edge” band at 704 nm not present on the Landsat 8 operational land imager. This study provides validation of an improved...
Blooms of the toxic dinoflagellate Alexandrium catenella have affected shellfish industries globally due to their capacity to produce paralytic shellfish toxins (PST). This study aimed to investigate the toxicity effect of exudate A. catenella on larvae of blue mussel Mytilus galloprovincialis and Pacific oyster Crassostrea gigas and filtration met...
Marine sedimentary ancient DNA ( sed aDNA) is increasingly used to study past ocean ecosystems, however, studies have been severely limited by the very low amounts of DNA preserved in the subseafloor, and the lack of bioinformatic tools to authenticate sed aDNA in metagenomic data. We applied a hybridisation capture ‘baits’ technique to target mari...
A recently published study analyzed the phylogenetic relationship between the genera Centrodinium and Alexandrium, confirming an earlier publication showing the genus Alexandrium as paraphyletic. This most recent manuscript retained the genus Alexandrium, introduced a new genus Episemicolon, resurrected two genera, Gessnerium and Protogonyaulax, an...
The study of ancient DNA from sediments (sedaDNA) is a new tool to characterise past marine ecosystems from deep ocean sediments, and has great potential for paleoclimate research. Recent improvements in ship-board sediment coring procedures have allowed far greater levels of contamination control and, along with refinements in sedaDNA sample proce...
Marine sedimentary ancient DNA (sedaDNA) provides a powerful means to reconstruct marine palaeo‐communities across the food web. However, currently there are few optimized sedaDNA extraction protocols available to maximize the yield of small DNA fragments typical of ancient DNA (aDNA) across a broad diversity of eukaryotes. We compared seven combin...
The use of probionts has been considered to be an effective technology in enhancing growth performances and survival rate of aquaculture species. This study examined the effect of three probiotic candidates (Bacillus amyloliquefaciens MA228, Enterobacter ludwigii MA208, and Pediococcus acidilactici MA160) on the growth and survival rates of juvenil...
A recently published study analyzed the phylogenetic relationship between the genera Centrodinium and Alexandrium, confirming an earlier publication showing the genus Alexandrium as paraphyletic. This most recent manuscript retained the genus Alexandrium, introduced a new genus Episemicolon, resurrected two genera, Gessnerium and Protogonyaulax, an...
Paralytic shellfish toxin producing dinoflagellates have negatively impacted the shellfish aquaculture industry worldwide, including in Australia and New Zealand. Morphologically identical cryptic species of dinoflagellates that may differ in toxicity, in particular, species of the former Alexandrium tamarense species complex, co-occur in Australia...
There is little information on the microbial communities associated with modified atmosphere (MA)-packaged live mussels. There is also a dearth of information on how pre-packaging depuration modifies the microbial communities and spoilage of live mussels. Amplicon sequencing was used to describe spoilage microbial succession in MA-packaged live mus...
Bloom of toxic dinoflagellate, Alexandrium fundyense has inflicted significant economic loss of both wild fisheries and aquaculture farming. This toxic dinoflagellate is capable of producing extracellular (exudates) and intracellular toxic compound (lysates), causing mass mortality of shellfish in hatchery operation. Despite its significant impacts...
Over the last 15 years, great effort has gone into the development of chlorophyll-a (chl-a) retrieval algorithms for case 2 waters, where variations in the water leaving radiance signal are not well correlated with concentrations of chl-a. In this study, we investigate the effectiveness of Moderate Resolution Imaging Spectroradiometer (MODIS)-deriv...
Development, calibration and validation of improved monitoring and management tools to limit the impact of biotoxin outbreaks on the Tasmanian seafood industry
During October 2012, a shipment of blue mussels (Mytilus galloprovincialis) from the poorly monitored east coast of Tasmania, Australia, was tested by Japanese import authorities and found to be contaminated with unacceptable levels of Paralytic Shellfish Toxins (PSTs; 10 mg/kg). Subsequently local oysters, scallops, clams, the viscera of abalone a...
The palaeoceanography of southern Australia has been characterized by fluctuating sea levels during glacial periods, changing temperature regimes and modified boundary currents. Previous studies on genetic structuring of species in southeastern Australia have focused mainly on the differentiation of eastern and western populations while the potenti...
Under the current commercial practice, live mussels only have 10 days’ shelf-life. Observed spoilage indices reduce consumers’ acceptance, palatability and shelf-life of modified atmosphere packaged (MAP) live mussels. The aims of this study are to isolate specific spoilage bacteria from modified atmosphere packaged live mussels, evaluate isolates...
The recent dinoflagellate blooms of species of the former Alexandrium tamarense species complex on the east-coast of Australia have resulted in significant financial loss to the shellfish industry and public health threats. The requirement for an early detection system to mitigate the impact of this increasingly unpredictable and severe threat is e...
Marine phytoplankton cells grow in close association with a complex microbial associate community known to affect the growth, behavior, and physiology of the algal host. The relative scale and importance these effects compared to other major factors governing algal cell growth remain unclear. Using algal-bacteria co-culture models based on the toxi...
A total of 20 lactic acid bacteria (LAB) were isolated from the gastrointestinal tracts of Atlantic salmon (Salmo salar) and screened for antimicrobial activity against six fish pathogens using either a microtiter plate assay or a well diffusion assay. The results indicated that three LAB exhibited antimicrobial activity against at least two pathog...
The health of marine bivalve larvae is greatly affected by bacteria in the environment particularly when reared in marine hatcheries. This is generally because high stocking densities resulting in high organic loads of both food and faeces, can support increased bacterial growth and biomass levels. Increased bacterial load can lead to larval diseas...
One of the first recorded fatal cases of human Paralytic Shellfish Poisoning (PSP) after eating shellfish contaminated with dinoflagellate toxins occurred in 1793, when Captain George Vancouver and his crew landed in British Columbia in an area now known as Poison Cove. He noted that it was taboo for local Indian tribes to eat shellfish when the se...
Bacillary necrosis associated with Vibrio species is the common cause of larval and spat mortality during commercial production of Australian blue mussel Mytilus galloprovincialis. A total of 87 randomly selected Vibrio isolates from various stages of rearing in a commercial mussel hatchery were characterised using partial sequences of the ATP synt...
Seaweed morphology is often shaped by the hydrodynamic environment. However, exposure to air at low tide represents an additional factor potentially affecting the morphology of intertidal species. Here we examined the relationships between the morphology of Hormosira banksii (Turner) Decaisne, an important intertidal habitat-forming seaweed in sout...
Background
Marine microbial protists, in particular, dinoflagellates, produce polyketide toxins with ecosystem-wide and human health impacts. Species of Gambierdiscus produce the polyether ladder compounds ciguatoxins and maitotoxins, which can lead to ciguatera fish poisoning, a serious human illness associated with reef fish consumption. Genes as...
Resting cysts play an important role in the origin and initiation of Alexandrium dinoflagellate blooms in different coastal environments. Alexandrium catenella causes major economic impacts for the Chilean shellfish and fish farm industries, but the environmental conditions that regulate the encystment timing and cyst production rate in the seasona...
A post-column reaction system based on droplet microfluidics was developed for capillary electrophoresis (CE). Analytes were separated using capillary zone electrophoresis (CZE) and electrophoretically transferred into droplets. The use of a micro cross for positioning a salt bridge-electrode opposite the separation capillary outlet is the key elem...
The paralytic shellfish toxin (PST)-producing dinoflagellate Gymnodinium catenatum grows in association with a complex marine bacterial community that is both essential for growth and can alter culture growth dynamics. Using a bacterial community replacement approach, we examined the intracellular PST content, production rate, and profile of G. cat...
Paralytic shellfish toxins (PSTs) are produced by marine and freshwater microalgae and accumulate in shellfish including mussels, oysters and scallops, causing possible fatalities when inadvertently consumed. Monitoring of PST content of shellfish is therefore important for food safety, with currently approved methods based on HPLC, using pre- or p...
A need to improve larval rearing techniques led to the development of protocols for catecholamine-induced settlement of flat oyster, Ostrea angasi, larvae. To further refine these techniques and optimize settlement percentages, the influence of salinity or temperature on development of O. angasi larvae was assessed using epinephrine-induced metamor...
The morphology and genetic affinity of a novel raphidophyte belonging to the genus Chattonella Biecheler is described for the first time from the Oman Sea along the south-east coast of Iran. While morphologically very similar to Chattonella subsalsa Biecheler, the Iranian isolates contain a distinct red eyespot. A comparison of LSU-rDNA and rDNA-IT...
This workshop aimed to expose the participants to simple techniques for manipulation of single cells and cysts, with current and emerging DNA technologies to identify the genetic and taxo-nomic affinities of cyst/cell morphotypes and link different life-cycle stages of dinoflagellates. The workshop was attended by over 45 participants (from 23 coun...
The living dinoflagellate cyst flora of the southeast coast of Iran that borders the Oman Sea, are described for the first time. Forty cyst types were identified using a combination of morphological examination and germination of live specimens. Calciodinellid cysts (Scrippsiella
and related species) dominated (> 80 %) the cyst assemblage at Pasaba...
The influence of algal diet on survival, growth and development of hatchery reared flat oyster, Ostrea angasi, larvae was investigated in a series of uni, binary and ternary algal diet trials. Early stage larvae (140–230 μm shell length) generally grew faster than late-stage larvae (230–340 μm shell length) when fed unialgal diets. Of the 24 algal...
Phytoplankton cells and resting cysts of the species Scrippsiella trochoidea are regular and dominant components of the dinoflagellate flora of coastal marine waters and sediments around the world. This species is a common harmful bloom forming species in coastal waters. In this study, for the first time cyst of S. trochoidea were isolated from the...
Phytoplankton underpin the marine food web in shelf seas, with some species having properties that are harmful to human health and coastal aquaculture. Pressures such as climate change and anthropogenic nutrient input are hypothesized to influence phytoplankton community composition and distribution. Yet the primary environmental drivers in shelf s...
Full taxonomic data set.
(XLS)
Increasing scientific awareness since the 1980s of the chain-forming dinoflagellate Gymnodinium catenatum has led to this species being reported with increased frequency in a globally increasing number of countries (23 at present). G. catenatum exhibits little molecular genetic variation in rDNA over its global range, in contrast to RAPD fingerprin...
Resting cyst and motile thecate cell stages of three heterotrophic Protoperidinium oblongum, Protoperidinium sp and Protoperidinium claudicans were assessed. Cysts were isolated from sediment collected from southeast coast of Iran. Individual live cysts were incubated under optimal conditions for germination. Results showed that Protoperidinium obl...
A new chloroplast-containing species of the sand-dwelling benthic dinoflagellate Thecadinium was isolated and cultured from a single cell collected from shallow waters of the marine Loch Ewe in North West Scotland. The cultured cells are described by light and scanning electron microscopy and the genetic affinities examined by comparison of ribosom...
Gymnodinium catenatum Graham (Dinophyceae) is one of several marine dinoflagellates responsible for outbreaks of paralytic shellfish poisoning (PSP), a problem that is considered to be increasing globally. Bacteria associated with these dinoflagellates have been implicated as potentially involved with the production of PSP toxins, and this study so...
Gymnodinium catenatum Graham (Dinophyceae) is one of several marine dinoflagellates responsible for outbreaks of paralytic shellfish poisoning (PSP), a problem that is considered to be increasing globally. Bacteria associated with these dinoflagellates have been implicated as potentially involved with the production of PSP toxins, and this study so...
The effect of diet quality on reproduction and energy storage in bivalves has not been widely investigated. Food quality and quantity influences reproductive success in many bivalve species, and the timing and rate of reproductive maturation is a dominant influence on natural population dynamics, whereas understanding and controlling reproduction i...
The toxic, chain-forming dinoflagellate Gymnodinium catenatum Graham was cultured from vegetative cells and benthic resting cysts isolated from estuarine waters in Tasmania, Australia. Rapidly dividing, log phase cultures formed long chains of up to 64 cells whereas stationary phase cultures were composed primarily of single cells (23-41 pm long, 2...
Oligonucleotide primers, specific for conserved regions of the genes encoding the β- and α-phycocyanin subunits of phycobilisomes (cpcB and cpcA) of cyanobacteria, were used to amplify a DNA fragment containing the intervening intergenic spacer region (cpcBA-IGS) of 19 strains of three morphospecies of cyanobacteria. Six Australian strains were ide...
The toxic dinoflagellate Gymnodinium catenatum Graham produces a newly discovered sub-class of paralytic shellfish toxins (PSTs, saxitoxins) that contain a hydroxybenzoate moiety in place of the carbamoyl group (GC toxins; GC1, GC2 & GC3). GC toxins bind strongly to sodium channels and their lipophilic nature may increase their potential to bioaccu...
A new gymnodinioid dinoflagellate, Gymnodinium trapeziforme sp. nov. is described from laboratory cultures established by germination of microreticulate resting cysts collected along the southeast coast of Iran bordering the northern Oman Sea. The vegetative cells are small, biconical to ovoid, with a horseshoe-shaped apical groove that encircles t...
Cryptoperidiniopsis brodyi is a common heterotrophic dinoflagellate known to often co-occur with Pfiesteria species in eastern U.S. estuaries. In this study, C. brodyi from Australia and Pfiesteria piscicida from ballast water from Indonesia were characterized by morphological and genetic analyses. Two P. piscicida strains originating from ballast...
A new species of Scrippsiella is described by light and electron microscopy from laboratory cultures established from resting cysts collected from the southeast coast of Iran. Comparative morphological analyses and sequencing of the rDNA-ITS and 5.8S rDNA show that the new species, Scrippsiella irregularis sp. nov., is allied to but distinct from S...