Lecturer/Senior Lecturer/Associate Professor, James Cook University (2007- ) Senior Research Fellow, University of Queensland ARC Centre of Excellence (2003-2007). Post-doctoral Research Fellow, University of Queensland (2001-2003) PhD James Cook University (2001), BSc, BSc (Hons)
Bill studies the dinoflagellate Symbiodinium, and his research focuses on linking changes in the gene expression of Symbiodinium and corals to physiological of the algae and the intact coral holobiont (its host), and subsequent ecological changes. In particular, he is interested in how these dinoflagellates respond to human induced stress, such as climate change, what effects these changes have on the coral host and how these responses of the alga effect the future of coral reefs as we know them.
Full publications list and additional information
- Symbiodinium genomics
- Symbiodinium diversity in symbiosis
- Symbiodinium physiology
- Coral acclimation to climate change
- Coral stress responses
- Coral bleaching
- Metabolomics of symbiotic organisms
The success of coral reefs is dependent upon the symbiosis between the scleractinian (reef building) coral and a unicellular dinoflagellate of the genus Symbiodinium (also called zooxanthellae) that lives within the coral tissues. These photosynthetic zooxanthellae provide the majority of the energy that the coral host requires to live, grow, reproduce and generate the calcium carbonate reef. However, in addition to being key to the survival of reefs they may also be the weak link in the survival of coral reefs in the future. Coral reefs are the world are currently threatened by a variety of anthropogenic stressors such as global warming, increasing CO2 concentrations and eutrophication, and it is often the zooxanthellae that are the most susceptible to these stress events. Despite their importance, not only to corals but also in the general phytoplankton community, we know very little of their genomes.
Dinoflagellates as a group have a unique genetic heritage; they have very large genomes (often larger than that of humans), only about half of them are photosynthetic, their chromosomes remain permanently condensed, they are the only known eukaryote known to utilise 5-hydroxymethyluracil and their chloroplast genomes have been greatly reduced. Despite these novel characteristics it is only recently that various groups have begun to examine the genetic compliment of dinoflagellates.
My study organism of choice is the dinoflagellate Symbiodinium, and my research focuses on linking changes in the gene expression of Symbiodinium to physiological of the algae and the intact coral holobiont (its host), and subsequent ecological changes. Research of this type can broadly be called ecological genomics. In particular we are interested in how these dinoflagellates respond to human induced stress, such as climate change, what effects these changes have on the coral host and how these responses of the alga effect the future of coral reefs as we know them.
Current research projects
1. Characterising the Symbiodinium transcriptome
One of the major research efforts in the group is to explore the transcriptome of Symbiodinium, without a knowledge of which genes are present in an organism it is impossible, in particular we are interested in genes that are expressed in response to stress (see Leggat et al. 2007). We now have over 6000 expressed sequences tags (ESTs) which encode over 4000 different genes, and further sequencing efforts which include several highly successful 454 sequencing projects have resulted in over 385,000 EST’s and 100,000 contigs characterised so far. This research is demonstrating that we are still finding many new and novel genes. This research has thrown up a number of novel findings to date (see Weird “Engine of the Reef” Revealed) which have changed the way in which we look at these unique algae. Currently more than half of the genes that we have found are of unknown function, indicating how little we know about these important organisms. We are now comparing our analysis with other EST projects performed on Symbiodinium from the Caribbean to determine if there are significant differences between the alga from the Great Barrier Reef and those in the Caribbean (see collaborative research projects listed below).
2. Symbiodinium microarrays
This group (with other collaborators) have developed the first cDNA microarray for Symbiodinium (clade C3). Use of these microarrays provides a key platform for the study of the Symbiodinium and is important in studies examining how Symbiodinium respond to stress and also how different strains behave. Further development ofSymbiodinium microarrays is underway in the Leggat laboratory (with national and international collaborators) (see links below) based on recent extensive 454 sequencing programs of various Symbiodinium clades.
3. The response of Symbiodinium to stress- are they a weak link in the coral symbiosis?
There is a range of evidence that indicates that in the coral-algal symbiosis it is Symbiodinium which hare the weak link. We are examining how both the algae and coral respond to stress, in particular those caused by humans such as global warming, increasing CO2 levels and eutrophication. This research effort is aimed to determine how the alga (and subsequently the intact association) responds to stress by linking changes in the expression of key genes to physiological responses. In addition we are taking a broad scale approach by utilising microarray technology. This group (with collaborators) have developed the first cDNA microarrays for Symbiodinium which will allow for the use of the cutting edge technology coupled with more traditional physiological and field based studies.
4. Symbiodinium ecotypes
Although generically called Symbiodinium this genus contains huge diversity (which might be equivalent to that found in other orders of dinoflagellates), to date there are eight different “clades” (A-H) that have been characterised using molecular techniques. Within each clade there are numerous subclades. A variety of studies have shown that there are recognisable patterns of distribution of Symbiodinium (at both the cladal and subcladal level) between different hosts and across environmental gradients. Some Symbiodinium can be considered to be generalists while others are specialists, yet despite this we still do not know what the functional differences between the different Symbiodinium types are. This work is utilising the concept of an “ecotype” is characterising the sequence difference, gene expression differences and physiological differences of various Symbiodinium strains under different conditions. This information will determine the ecological relevance of different Symbiodinium strains to the intact coral-algal holobiont.
Available research projects within Leggat Laboratory:
There are a variety of projects currently available within the Leggat laboratory for national and international research students (Hons, MSc and PhD candidates). Research projects will combine molecular biology, protein chemistry, physiology and ecological components to investigate the above listed research interests within the laboratory. Please contact Bill Leggat to discuss the available options.
- Ainsworth, T.D., Heron, S., Ortiz, J.C., Grech, A., Ogawa, D., Eakin, M., Mumby, M., Leggat, W. (2016) Climate change disables coral bleaching protection on the Great Barrier Reef. Science 352:338-342 (I.F. = 33.6)
- Hernandez-Agreda, A., Leggat, W., Bongaerts P, Ainsworth, T.D. (2016) The Microbial signature provides insight into the mechanistic basis of coral success across reef habitats. mBio 7:e00560-16 (I.F. = 6.8)
- Gierz, S., Gordon, B. Leggat, W. (2016) Integral light-harvesting complex expression in Symbiodinium within the coral Acropora aspera under thermal stress. Scientific Reports 6:25081
- Veilleux, H.D., Ryu, T., Donelson, J.M., van Herwerden, L., Seridi, Y., Berumen, M.L., Leggat, W., Ravasi, T., Munday, P. (2015) Molecular Processes of transgenerational acclimation to a warming ocean. Nature Climate Change 5 (12), 1074-1078 (I.F. = 15.3)
- Ainsworth T.D., Bridge T, Torda G, Raina, JB, Gates, R, Padilla-Gamino J, Smith C, Woosley E, Krausee L, Zakrzewski M, Bongaerts P, Spalding H, Bourne D, Hoegh-Guldberg O, Leggat W (2015) The coral core microbiome identifies rare bacterial taxa as ubiquitous endosymbionts. The ISME Journal 9, 2261–2274 (I.F. = 9.3)
- Van de Water, J., Ainsworth, T.D., Leggat, W., Bourne, D., Willis, B., van Oppen, M. (2015) The coral immune response facilitates protection against microbes during tissue regeneration. Molecular Ecology 24 (13), 3390-3404 (I.F. = 5.8)
- Krueger, T., Hawkins, T.D., Becker, S., Pontasch, S., Dove, S., Hoegh-Guldberg, O., Leggat, W., Fisher, P.L., Davy, S.K. (2015) Differential coral bleaching – Contrasting the activity and response of enzymatic antioxidants in symbiotic partners under thermal stress. Comparative Biochemistry and Physiology (Part A) 190:15-25 (I.F. = 2.0)
- Voolstra, C.R., Miller, D.J., Ragan, M., Hoffmann, A., Hoegh-Guldberg, O., Bourne, D., Ball, E., Ying, H., Foret, S., Takahashi, S., Weynberg, K.D., van Oppen, M.J.H., Morrow, K., Xin Chan, C., Rosic, N., Leggat, W., Sprungala, S., Imelfort, M., Tyson, G.W., Kassahn, K., Lundgren, P., Beeden, R., Ravasi, T., Berumen, M., Abel, E., Fyffe, T. (2015) The ReFuGe 2020 Consortium – Using “omics” approaches to explore the adaptability and resilience of coral holobionts to environmental change. Frontiers in Marine Science. 2:68
- Krueger, T., Fisher, P.L., Becker, S., Pontasch, S., Dove, S., Hoegh-Guldberg, O., Leggat, W., Davy, S.K. (2015) Transcriptomic characterisation of the enzymatic antioxidants FeSOD, MnSOD, APX and KatG in the dinoflagellate Symbiodinium. BMC Evolutionary Biology 15:1-48 (I.F. = 3.4)
- Ainsworth, T.D., Knack, B., Ukani, L. Seneca, F., Weiss, Y., Leggat, W. (2015) In situ hybridisation detects pro-apoptotic gene expression in apparently healthy regions of white syndrome-affected coral. Diseases of aquatic organisms. 117:155-163 (I.F. = 1.6)
- van de Water, J, Leggat, W, Bourne, B, van Oppen, M, Willis, W., Ainsworth, T. (2015) Elevated seawater temperatures have limited impact on the coral immune response following physical damage. Hydrobiologia DOI 10.1007/s10750-015-2243-z (I.F. = 2.4)