Dr David Welsh

Dr Dave WelshBSc (Hons), PhD

Senior Lecturer, Griffith School of Environment
Research Member, Australian Rivers Institute

Contact details for Dr David Welsh

Research Expertise

My research covers a wide range of areas in microbial ecology and applied microbiology, as well as more general ecosystem ecology. Research areas of specific interest include:

Bacterial biogeochemistry

The study of the bacterial populations and processes, involved in organic matter turnover and the major elemental (C, N, P, S, Fe, etc) cycles in aquatic ecosystems. Particular research interests include the effects of seagrass roots and animal burrows in providing micro-niches for specific bacterial population in otherwise inhibitory sediment environments and the role of microbial processes in buffering ecosystems against eutrophication processes.

Microbial symbioses

Bacteria form a wide range of symbioses with both plants and animals, this research theme addresses both the specific interactions between the symbiotic partners and the influences of these symbioses on ecosystem nutrient cycles. Symbioses of particular interest are:

  • The associative symbiosis between seagrasses and nitrogen-fixing sulfate reducing bacteria in the rhizosphere.
  • The endo and ectosymbioses between chemautotrophic sulfur oxidising bacteria and benthic marine invertebrates.
  • Symbioses of photosynthetic (zooanthellate) marine invertebrates, and nitrogen fixing and ammonium oxidising bacteria, and their roles in N-assimilation.
  • The evolution of new symbioses between introduced legume weeds and native nitrogen-fixing bacteria.

Microbial based assays to assess water quality

Research aims at developing novel respiration based bioassays utilising microbial biocatalysts to assess the organic matter loads and/or toxicity of waste and treated waste waters and to ultimately identify the class(es) of toxicants present in the water. The development of assays based on the same principles to evaluate the metabolic status and capacity of the activated sewage sludges employed to treat wastewaters.

Publications

Review articles in international peer reviewed journals

  • Welsh, D.T. (2003) It’s a dirty job but someone has to do it: The role of marine benthic macrofauna in organic matter turnover and nutrient recycling to the water column. Chemistry and Ecology 19, 321-342.
  • Welsh, D.T. (2000). Nitrogen fixation in seagrass meadows: Regulation, plant-bacteria interactions and significance to primary productivity. Ecology Letters. 3: 58-72.
  • Welsh, D.T. (2000). The ecological significance of compatible solute accumulation: From single cells to global climate. FEMS Microbiology Reviews. 24: 263-290.
  • Welsh, D.T., Viaroli, P., Hamilton, W.D. & Lenton, T.M. (1999). Is DMSP synthesis in Chlorophycean macro-algae linked to aerial dispersal. Ethology, Ecology and Evolution. 11: 265-278.

Research Articles in peer reviewed international journals.

  • Dunn, R.J.K., Ali, A., Lemckert, C.J., Teasdale, P.R., Welsh, D.T. In Press). Short0term variability of physico-chemical parameters and the estimated transport of filterable nutrients and chlorophyll a in the urbanised Coombabah Creek system, Australia. Journal of Coastal Research
  • Dunn R.J.K., Lemckert, C.J., Teasdale, P.R., Welsh, D.T. (2007). Distribution of nutrients in surface and sub-surface sediments of Coombabah Lake, southern Moreton Bay (Australia). Marine Pollution Bulletin, Marine Pollution Bulletin 54, 602-625
  • Nizzoli, D. Welsh, D.T., Fano, E.A. & Viaroli, P. (2006) Impact of clam and mussel (Tapes philippinarum and Mytilus galloprovincialis) farming on benthic metabolism and nitrogen cycling with emphasis on nitrate reduction pathways. Marine Ecology Progress Series 315, 151-165.
  • Lee, SY., Dunn, R., Young, R.A., Connolly, R., Dale, P., Dehayr, R., Lemckert, C., McKinnon, S., Powell, B. Welsh, D.T. (2006)Impact of urbanisation on coastal wetland structure and function. Austral Ecology 39, 149-163.
  • Nizzoli, D., Welsh D.T., Bartoli, M. & Viaroli, P. (2005). Impacts of mussel (Mytilus galloprovincialis) farming on oxygen consumption and nutrient recycling in a eutrophic coastal lagoon. Hydrobiologia 550, 183-198.
  • Viaroli, P., Bartoli, M., Giordani, G., Magni, P. & >Welsh, D.T. (2004). Biogeochemical indicators as tools for assessing sediment quality/vulnerability in transitional aquatic ecosystems. Aquatic Conservation.: Marine and Freshwater Ecosystems 14, S19-S29.
  • Welsh, D.T. & Castaldelli, G. (2004). Bacterial nitrification activity directly associated with isolated benthic marine animals. Marine Biology 144, 1029-1037.
  • Castadelli, G., Welsh, D.T., Flachi, G., Zucchini, G., Colombo, G., Rossi, R. & Fano. E.A. (2003). Decomposition dynamics of the bloom forming macroalga Ulva rigida C. Agardh determined using a 14C-carbon radiotracer technique. Aquatic Botany. 75, 111-122.
  • Castadelli, G., Mantovani, S., Welsh, D.T., Rossi, R., Mistri, M. & Fano, E.A. (2003). Impact of commercial clam harvesting on water column and sediment physicochemical characteristics and macrobenthic community structure in a lagoon (Sacca di Goro) of the Po River Delta. Chemistry and Ecology 19, 161-171.
  • de Wit, R., Stal, L.J., Lomstein, B.A., Herbert, R.A., van Gemerden, H., Viaroli, P., Cecherelli, V-U., Rodriguez-Valera, F., Bartoli, M., Giordani, G., Azzoni, R., Schaub, B., Welsh, D.T., Donnelly, A., Cifuentes, A., Antom, J., Finster, F., Nielsen, L.B., Jensen, A-G.U., Neubauer, A.T., Colangelo, M.A. & Heijs, S. (2001). "ROBUST: The Role of Buffering capacities in Stabilising coastal lagoon ecosystems". Continental Shelf Research 21, 2021-2041.
  • Nizzoli, D., Castadelli, G., Bartoli, M., Welsh, D.T., Arriaga Gomez, P., Fano, E. & Viaroli, P. (2002). Benthic fluxes of dissolved inorganic nitrogen in a coastal lagoon of the Northern Adriatic Sea: An interpretation of spatial variability based on sediment features and infauna activity. Marine Ecology. 23, Supplement 1, 297-306.
  • Azzoni, R., Giordani, G., Bartoli, M., Welsh, D.T. & Viaroli, P. (2001). Iron, sulphur and phosphorus cycling in the rhizosphere sediments of a eutrophic Ruppia cirrhosa  meadow of the valle Smarlacca, Italy. Journal of Sea Research 45: 15-26.
  • Nielsen, L.B., Finster, K., Welsh, D.T., Donelly, A.P., Herbert, R.A., de Wit, R. & Lomstein, B.A. (2001). Sulfate reduction and nitrogen fixation rates associated with roots, rhizomes and sediments from Zostera noltii and Spartina stricta meadows. Environmental Microbiology 3:63-71.
  • Welsh, D.T.& Bourguès, S. (2001). Regulation of nitrogen fixation in intertidal seagrass meadows by light, nitrogen and carbon sources: Nitrogen fixation as a simple measure of eutrophication status. Atti della Associazione Italiana di Oceanologia e Limnologia. 14: 99-108.
  • Welsh, D.T., Castadelli, G., Bartoli, M., Poli, D., de Wit, R., Careri, M. & Viaroli, P. (2001). Denitrification in an intertidal seagrass meadow, a comparison of 15N-isotope and acetylene block techniques; Dissimilatory nitrate reduction to ammonium as a source of N2O. Marine Biology. 139: 1029-1036.
  • Bartoli, M., Nizzoli, D., Welsh, D.T. & Viaroli, P. (2000). Influence of sediment recolonisation by the polycheate worm Neries succinea on oxygen and nitrogen fluxes, and denitrification rates; A mesocosm simulation. Hydrobiologia. 431: 165-174.
  • Welsh, D.T., Bartoli, M., Nizzoli, D., Castadelli, G., Riou, S.A. & Viaroli, P. (2000). Denitrification, nitrogen fixation, community primary productivity and inorganic-N and oxygen fluxes in an intertidal Zostera noltii meadow. Marine Ecology Progress Series 208:51-65.
  • Welsh, D.T. & Herbert, R.A. (1999). Osmotically induced intracellular trehalose, but not glycine betaine accumulation promotes desiccation tolerance in Escherichia coli. FEMS Microbiology Letters. 174: 57-63.
  • Welsh, D.T., Bartoli, M., Riou, S. & Benatti, M. (1999). Seasonal variations in community primary productivity, inorganic nitrogen fluxes and denitrification rates in seagrass meadows of differing eutrophication status. Atti della Associazione Italiana di Oceanologia e Limnologia. 13: 65-74.
  • Nizzoli, D. & Welsh, D.T. (1999). Influence of the polycheate worm Nereis succinea on fluxes of oxygen, inorganic and organic nitrogen and rates of denitrification and coupled nitrification - denitrification in experimental mesocosms. Atti della Associazione Italiana di Oceanologia e Limnologia. 13: 319-328.
  • Donelly, A.P., Finster, K., Lomstein, B., Welsh, D.T., Giordani, G. & Herbert, R.A. (1998). Bacterial interactions in the rhizosphere of seagrass communities in shallow coastal lagoons. Journal of Applied Microbiology Supplement. 85:VII.
  • Welsh, D.T., Guyoneaud, R. & Caumette, P. (1998). Sugar catabolism by purple sulfur  and nonsulfur bacteria. Canadian Journal of Microbiology. 44: 974-979.
  • Welsh, D.T., Bourguès, S., de Wit, R. & Auby, I. (1997). Effect of plant photosynthesis, carbon sources and ammonium availability on nitrogen fixation rates in the rhizosphere of Zostera noltii. Aquatic Microbial Ecology. 12: 285-290.
  • Welsh, D.T., Bourguès, S., de Wit R. & Herbert, R.A. (1996). Seasonal variations in nitrogen fixation (acetylene reduction) and sulphate reduction rates in the rhizosphere of Zostera noltii: Nitrogen fixation by sulphate reducing bacteria. Marine Biology. 125: 619-628.
  • Welsh, D.T., Wellsbury, P.K., Bourguès, S., de Wit, R. & Herbert, R.A. (1996). Relationship between porewater organic carbon content, sulphate reduction and nitrogen fixation (acetylene reduction) in the rhizosphere of Zostera noltii. Hydrobiologia. 329: 175-183.
  • Welsh, D.T., Bourguès, S., de Wit, R. & Herbert, R.A. (1996). Seasonal variations in rates of heterotrophic nitrogen fixation (acetylene reduction) in Zostera noltii meadows and uncolonised sediments of the Bassin d'Arcachon, south-west France. Hydrobiologia. 329:161-174.
  • Welsh, D.T., Lindsay, Y.E., Caumette, P., Herbert, R.A. & Hannan, J. (1996). Identification of trehalose and glycine betaine as compatible solutes in the moderately halophilic sulphate reducing bacterium Desulfovibrio halophilus. FEMS Microbiology Letters. 140: 203-207.
  • Welsh, D.T. & Herbert, R.A. (1995). A glycine betaine transport system in a halotolerant Chromatium species. FEMS Microbiology Letters. 125:27-32.
  • Welsh, D.T. & Herbert, R.A. (1993). Identification of organic solutes accumulated by purple and green sulfur bacteria during osmotic stress using natural abundance 13C nuclear magnetic resonance spectroscopy. FEMS Microbiology Ecology. 13: 145-150.
  • Welsh, D.T., & Herbert, R.A. (1993). Osmoadaptation of Thiocapsa rosepersicina OP1 in batch and continuous culture: Accumulation of K+ and sucrose in response to osmotic stress. FEMS Microbiology Ecology. 13: 151-158.
  • Welsh, D.T., Reed, R.H. & Herbert, R.A. (1991). The role of trehalose in the osmoadaptation of Escherichia coli NCIB 9484: Interaction of trehalose, K+ and glutamate during osmoadaptation in continuous culture. Journal of General Microbiology. 137: 745-750.

Chapters in peer reviewed books and congress proceedings.

  • Nizzoli, D., Welsh, D.T., Bartoli, M. & Viaroli, P. (2001) Effetti sull’alevamento di Mytilus galloprovincialis sul consumo di qssigeno e sui flussi di nutrenti in un ambiente lagunare eutrofico. Congresso Nazionale della Società Italiana di Ecologa. Atti SITE 25 (In Italian).
  • Azzoni, R., Giordani, G., Bartoli, M., Welsh, D.T. & Viaroli, P. (2000). Crescita e produttività di Ruppia cirrhosa  in relazione ai cicli sedimentari di zolfo, ferro e fosforo in una laguna eutrofica (Valle Smarlacca, Valli Comacchio). Proceedings of the 9th Congress of the "Società Italiana di Ecologia" S.IT.E. Atti 20 pp.47-56. (In italian).
  • Caumette, P., Materon, R., Welsh, D.T., Herbert, R.A. & de Wit, R. (1999). Ecology and osmoadaptation of halophilic Chromatiaceae in hypersaline environments. pp. 707-713. In: The Phototrophic Prokaryotes. Edited by G.A. Peschek, W. Loffelhardt & G. Schmetterer. Academic/Plenum Publishing, New York.
  • Herbert, R.A. & Welsh, D.T. (1994). Establishment of phototrophic sulphur bacteria in microbial mat ecosystems. pp. 51-60. In: Microbial Mats. Structure, developement and environmental significance. Edited by L.J. Stal & P. Caumette. Springer-Verlag, Berlin.
  • Welsh, D.T. (1994). Colonisation and early development of microbial mat communities. pp. 131-132. In: Microbial Mats. Structure, development and environmental significance. Edited by L.J. Stal & P. Caumette. Springer-Verlag, Berlin.

Patents

  • Tunnacliffe, A.G., Welsh, D.T., Roser B, J., Dhaliwal, K.S. & Colaco, C. (1996). Bacterial Drying. PCT patent application WO9824882A1.

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