Dr. Daniel Thornton

Bio

Dr. Thornton is a biological oceanographer interested in marine ecology and biogeochemistry.  His research focuses on the role of marine microorganisms in the global carbon and nitrogen cycles.  The long-term objectives of Dr. Thornton’s research are (1) to understand the role of exopolymers (EPS) produced by microorganisms in marine ecosystem function and carbon biogeochemistry; (2) to develop a mechanistic understanding of the ecosystem processes affecting nitrogen cycling in the coastal ocean.  A better understanding of the microbial ecology of nitrogen and carbon cycling in both pristine and altered marine habitats will enhance our understanding of both biogeochemical cycles and marine ecosystems.

Dr. Thornton combines field descriptions of natural systems with laboratory and field experimentation. He generally works in the coastal ocean and has conducted field work in the United States (North Inlet in South Carolina, and the Gulf of Mexico), Europe (Estuaries in the United Kingdom and Denmark, the Adriatic Sea), Belize (mangrove islands), and Indonesia (coral reefs).  Much of his research includes the ecology and physiology of diatoms, which are an incredibly successful group of primary producers in the ocean.

Research Interests

Biogeochemistry of exoploymers:  Exopolymers or extracellular polymeric substances (EPS) are large molecules (e.g. polysaccharides) that are produced by microorganisms in the ocean.  In terms of organic carbon, the amount of EPS in the ocean is estimated to be many times that of living marine organisms.  The sticky properties of EPS means that they play a central role in the transport and transformation of organic carbon in the marine environment, and consequently, the carbon cycle.

Ecology and physiology of phytoplankton and microphytobenthos:  Approximately half the carbon fixed by photosynthesis each year on Earth is fixed by phytoplankton.  This organic carbon supports almost all food webs in the ocean.   There is a need to understand the basic ecology and physiology of this diverse group of important organisms, as well as how they will respond to climate change such as warming of the surface ocean and ocean acidification.

Nitrogen cycling in the coastal ocean:  Approximately half the reactive nitrogen (Nr) entering ecosystems each year comes from human activity.   There is a pressing need to understand the effect of this excess nitrogen on ecosystem function and biogeochemistry.

Biology and biogeochemistry across the air-sea interface:   The ocean and atmosphere interact to affect weather and climate on Earth.  There is an increasing interest in both the role of gases and aerosol produced by marine microorganisms in atmospheric processes, such as cloud formation.

Projects

• Effect of temperature on the production of expolymers (EPS) by planktonic diatoms.
• Evaluation of LISST instruments to monitor for harmful algal blooms (HABs) in Texas coastal waters.
• Nitrous oxide production in the Gulf of Mexico hypoxic zone.
• Factors affecting the production and losses of carbohydrates from sediments dominated by microphytobenthos.
• Marine biogenic aerosols as cloud condensation nuclei over the Pacific Ocean.

Experience

• 2010-present: Associate Professor, Department of Oceanography, Texas A&M University
• 2004 - 2010: Assistant Professor, Department of Oceanography, Texas A&M University
• 2003: Research Fellow, Wrigley Institute for Environmental Studies, University of Southern California
• 2000 - 2002: Research Fellow, Ecology Centre, University of Sunderland, UK
• 1996 - 1999: Senior Research Officer, Department of Biological Sciences, University of Essex, UK

Awards

• 2008   Texas A&M Association of Former Students - College Level Teaching Award
• 2007   Visiting Scientist Award – Baruch Marine Field Laboratory

Publications

1. Thornton DCO, Kopac SM, Long RA (2010) Production and enzymatic hydrolysis of carbohydrates in intertidal sediment.   Aquatic Microbial Ecology 60: 109-125
2. Hiranuma N, Brooks SD, Thornton DCO, Auvermann BW (2010) Atmospheric ammonia mixing ratios at an open-air cattle feeding facility.  Journal of the Air & Waste Management Association 60: 210 – 218.  DOI:10.3155/1047-3289.60.2.210
3. Thornton DCO (2009)  Spatiotemporal distribution of dissolved acidic polysaccharides (dAPS) in a tidal estuary. Limnology and Oceanography 54: 1449-1460
4. Thornton DCO (2009)   Effect of low pH on carbohydrate production by a marine planktonic diatom (Chaetoceros muelleri). Research Letters in Ecology, Article ID 105901, DOI:10.1155/2009/105901
5. Thornton DCO, Visser LA (2009) Measurement of acid polysaccharides (APS) associated with microphytobenthos in salt marsh sediments. Aquatic Microbial Ecology 54: 185-198
6. Thornton DCO, Fejes EM, DiMarco SF, Clancy KM (2007) Measurement of acid polysaccharides (APS) in marine and freshwater samples using alcian blue. Limnology and Oceanography: Methods 5: 73-87
7. Thornton DCO, Dong LF, Underwood GJC, Nedwell DB (2007) Sediment-water nutrient exchange and nitrogen budgets in the Colne Estuary. Marine Ecology Progress Series 337: 63-77
8. Patel D, Thake B, Thornton DCO (2005)    Effect of light and turbulent mixing on the growth of Skeletonema costatum (Bacillariophyceae).   Marine Biology 146: 633-644
9. Thornton DCO (2004)   Formation of transparent exopolymeric particles (TEP) from macroalgal detritus.  Marine Ecology Progress Series 282: 1-12
10. Thornton DCO (2002)   Diatom aggregation in the sea: mechanisms and ecological implications. European Journal of Phycology  37:149-161
11. Thornton DCO, Dong LF, Underwood GJC, Nedwell DB (2002)   Factors affecting microphytobenthic biomass, species composition and production in the Colne estuary (UK). Aquatic Microbial Ecology 27:285-300
12. Dong LF, Nedwell DB, Underwood GJC, Thornton DCO, Rusmuna I  (2002) Nitrous oxide formation in estuaries: the central role of nitrite. Applied and Environmental Microbiology 68:1240-1249
13. Thornton DCO (2002) Individuals, clones or groups? Phytoplankton behaviour and units of selection.   Ethology, Ecology and Evolution 14:165-173
14. Dalsgaard T (Editor), Nielsen LP, Brotas V, Viaroli P, Underwood G, Nedwell DB, Sundbäck K, Rysgaard S, Miles A, Bartoli M, Dong LF, Thornton DCO, Ottosen LDM, Castaldelli G, Risgaard-Petersen N.  (2000)   Protocol handbook for NICE - Nitrogen Cycling in Estuaries: a project under the EU research programme: Marine Science and Technology (MAST III).   National Environmental Research Institute, Silkeborg, Denmark.  62pp
15. Dong LF, Thornton DCO, Underwood GJC, Nedwell DB (2000)   Denitrification in the sediments of the Colne estuary, England. Marine Ecology Progress Series 203: 109-122
16. Thornton DCO, Underwood GJC, Nedwell DB (1999) Effect of light and emersion period on the exchange of ammonium across the estuarine sediment-water interface.    Marine Ecology Progress Series 184: 11-20
17. Thornton DCO, Santillo D, Thake B (1999)   Prediction of sporadic mucilaginous algal blooms in the Northern Adriatic Sea.  Marine Pollution Bulletin 38(10): 891-898
18. Thornton DCO (1999)   Phytoplankton mucilage in coastal waters: A dispersal mechanism in a front dominated system?   Ethology Ecology and Evolution 11(2): 179-185
19. Thornton DCO, Thake B (1998)   Effect of temperature on the aggregation of Skeletonema costatum (Bacillariophyceae) and the implication for carbon flux in coastal waters   Marine Ecology Progress Series 174: 223-237
20. Chiappori A, Balostro R, Thake B, Santillo D, Thornton D, Patel D,   (1995).  The Adriatic Sea and coastal resources; a management and pollution control study.   In: Coastal Ocean Space Utilization III.   Edited by N. D. Croce, S. Connell and R. Abel.  pp 331-344.   E & FN Spon, Chapman and Hall, London