Earth and Environmental Sciences (SEES)

Marine Biogeochemistry and Ecosystem Research

Staff: Gary Fones & Michelle Hale

Gary Fones

Main Research Themes:

• Sediment and water column trace metal and nutrient biogoechemistry
• Benthic-Pelagic biogeochemical coupling
• Iron cycling and speciation in High Nitrate Low Chlorophyll (HNLC) regions
• Submarine diagenesis of tephra
• Development of in situ passive samplers for water column and sediments
• Copper toxicity and speciation in estuaries and harbours

Recently completed and Current Research Projects:

Benthic supply of iron to the ocean

Main collaborators: Prof Peter Statham (National Oceanography Centre, Southampton)

The marine biogeochemistry of iron is complex, but nonetheless it is clear that the element is essential to the metabolic functioning of a wide range of micro-organisms.

Supply of Fe to the ocean and organisms is thus of global importance as regards primary production, and this is particularly so in high-nutrient low-chlorophyll (HNLC) zones where iron has a major impact on the species of micro-organism present, and productivity. It has been hypothesised that sediments may be an important source of iron to such systems. Indeed amidst the HNLC "deserts" of the southern ocean are areas of relatively high productivity associated with island systems (e.g. Crozet, Kerguelen), that may reflect sedimentary inputs of Fe. Here we propose a detailed investigation of the forms and concentration of Fe and Fe ligands in waters around Crozet in order to identify if sediments are a significant source of Fe. The low background iron concentrations make this an ideal area to trace benthic sources of Fe (using natural Ra isotopes), and to follow changes in the nature of ligand and colloidal forms. The work will provide information on a potentially globally relevant process, as any such sediment inputs will be importatnt in a wide range of marine regimes. The work is novel and timely and will provide an important new dimension to our understanding of processes influencing the ocean biogeochemistry of Fe.

Impact of early alteration of volcanic ash on global biogeochemical cycles

Main collaborators: Prof Martin Palmer, Dr Damon Teagle, Dr Rachel Mills (National Oceanography Centre, Southampton)

Most of the world's volcanoes are close to the oceans, and much of the volcanic material they erupt is rapidly transported into the sea. This material is highly reactive and undergoes rapid alteration when exposed to seawater. Preliminary studies suggest that the extent of alteration is large enough to play a major role in controlling the chemical composition of the oceans. In addition, alteration of fresh volcanic material may influence biogeochemical cycles in a manner that exerts a strong control on the Earth's climate.

The volcano on Montserrat has been active since 1995 and has deposited thick layers of volcanic ash onto the surrounding sea floor. We are conducting a 14 day cruise around the Caribbean island of Montserrat, where we will take cores from the sea floor and study the changes that take place in the ash after it enters the oceans. In addition, we will collect samples of ash from the volcano and carry out laboratory-based alteration experiments.

Testing the chemical calibration of Sediment Profile Imagery (SPI) with novel in-situ pore water gel probe techniques: a proof of concept study

Main collaborators: Dr Ruth Parker (Cefas) and Dr Martin Solan (University of Aberdeen)

Sediment Profile Imagery (SPI) has been used recently to look at the relationship between benthic communities and sediment.

However the SPI image has not really been calibrated with respect to the sediment redox and sediment biogeochemistry.

This proof of concept study aims to use the in-situ technique of DET and DGT gel probes to undertake the first colour/chemical calibration of SPI images in order to determine high-spatial resolution redox sensitive features in a biological context relating to aRPD (apparent redox potential discontinuity) and bioturbation.

Iron Biogeochemistry in the High Lattitude North Atlantic

Main collaborators: Prof Eric Achterbery, Dr Richard Sanders and Dr Mark Moor (NOCS); Prof Tim Jickells and Alex Backer (UEA); Prof Rick Williams (University of Liverpool) and Prof Richard Geider (University of Essex)

The concentration of carbon dioxide has increased significantly since the start of the industrial revolution as a result of burning of fossil fuels and deforestation.

Carbon dioxide influences the climate on earth and its concentration is now so high that the earth's atmosphere is warming and the weather is becoming more extreme. Recently, it has been discovered that the phytoplankton in many regions of the world's oceans are lacking Fe. For example, in the Southern Ocean the growth of the phytoplankton cells is limited by very low Fe concentrations. Therefore, the phytoplankton in this ocean does not remove as much carbon dioxide from the atmosphere as they could do under ideal conditions. Many people think that the North Atlantic Ocean received enough Fe through dust transport from the Sahara. However, recent experiments have shown that even in the North Atlantic phytoplankton cells may be lacking Fe.

In this proposed study, we want to study whether Fe is limiting phytoplankton growth in the North Atlantic at higher latitudes (>60 N). To do this study, we will take part in 3 research cruises and take samples of water, sedimenting material, and atmospheric dust and rain. We will analyse Fe and nutrients in the samples and calculate the supply ratios of Fe to N, P, C to the surface oceans, and their ratios in sedimenting material. We will use models to aid us with the calculations for the oceanic transfers of these elements. If the phytoplankton are Fe limited in the high latitude North Atlantic then it will be because the amount of Fe they get in relation to other nutrients is too low. We will also directly investigate whether Fe is limiting the growth of phytoplankton in water samples from the high latitude North Atlantic.

To find this out, we will grow phytoplankton cells taken from the surface ocean in transparent bottles on the deck of the ship. We will add Fe to some bottles, whereas other bottles will receive no added Fe at all. The growth and physiological state of the phytoplankton will be determined using a number of measurements, such as pigment (chlorophyll a) concentrations. These measurements will show us whether the bottles with added Fe show a higher number of phytoplankton cells and a higher growth, compared with the bottles to which we added no Fe.

The results of the proposed project will provide us with a better understanding of the role that nutrients like Fe play in the growth of phytoplankton cells in the ocean. The gathered data will help the computer modellers to design improved climate models that will allow us to better predict climate change over the next 100s of years.

Sediment-Water Column Exchange of Nutrients in Coastal and Shelf-Sea Waters

Main collaborators: Prof Peter Statham, Prof Carl Amos and Dr Boris Kelly-Gerreyn (National Oceanography Centre, Southampton); Dr Ruth Parker and Dr John Aldridge (Centre for Environment, Fisheries and Aquaculture Science - Cefas) and Dr Kevin Black (Partrac Ltd).

Shelf seas are globally important sinks for both nitrogen and carbon because approximately one third of global marine primary production takes place in these environments. Coastal and shelf-seas of the northern temperate latitudes, such as the North Sea, experience intense phytoplankton blooms in spring fuelled by macronutrients (N, P and Si) in the water column.

The shallow nature of shelf seas enables up to 50% of the total phytoplankton biomass produced in the water column to be cycled through the sediments, where this particulate organic carbon in mineralised. This mineralization enriches sediment pore waters with nutrients thus evoking a diffusive flux to the overlying water column.

However, transport processes other than diffusion often dominate in coastal and shelf sea sediments. These include advection and resuspension which may deliver nutrients to the overlying water many times faster than diffusion. Resuspension is particularly widespread owing to causes both natural - strong winds, waves, tidal currents and biological activity - and anthropogenic - trawling and dredging.

The outcome these advective and resuspension events have on nutrient fluxes to the overlying water and their subsequent impact on water column chemistry and primary production remains unclear. This program of research aims to elucidate the effects of resuspension and pore-water advection on sediment water-column nutrient and carbon exchange using both novel in-situ and laboratory based experiments.

Research funding sources:

2008: Natural Environmental Research Council (NERC), UK. "Sediment-Water Column Exchange of Nutrients in Coastal and Shelf-Sea Waters" (NE/F003293/1). £188,742.13 - 41 months. Fones, Principal Investigator.

2007: Natural Environmental Research Council (NERC), UK. "Iron Biogeochemistry in the High Lititude North Atlantic" (NE/E006833/1). £21,178.06 - 43 months. Fones, Co-PI.

2007: Natural Envrionmental Research Council (NERC), UK. CONNECT A - "Testing the chemical calibration of Sediment Profile Imagery (SPI) with novel in-situ pore water gel probe techniques: a proof of concept study" (NE/F523285/1) £4,955.41 - 6 months. Fones, Principal Investigator.

Recent Publications:

• Bennett S. A., Achterberg E. P., Connelly D. P., Statharn P. J., Fones G. R., and Gernian C. R. (2008) The distribution and stabilisation of dissolved Fe in deep-sea hydrothermal plumes. Earth and Planetary Science Letters 270 (3-4), 157-167.

• Charette M.A., Gonneea M. E., Morris P. J., Statham P., Fones G., Planquette H., Slater I., and Garabato A. N. (2007) Radium isotopes as tracers of iron sources fueling a Southern Ocean phytoplankton bloom. Deep-Sea Research Part Ii - Topical Studies in Oceanography 54, 1989-1998.

• Planquette H., Statham P.J., Fones G. R., Charette M. A., Moore C. M., Salter I., Nedelec F. H., Taylor S. L., French N., Baker A. R., Mahowald N., and Jickells T. D. (2007) Dissolved iron in the vicinity of the Crozet Islands, Southern Ocean. Deep-Sea Research Part Ii - Topical Studies in Oceanography 54, 1999-2019.

• Fones G. R., Davison W., and Hamilton-Taylor J. (2004) The fine-scale remobilization of metals in the surface sediment of the North-East Atlantic. Continental Shelf Research 24 (13-14), 1485-1504.

• Wei L. P., Donat J. R., Fones G. R., and Ahner B. A. (2003) Interactions between Cd, and Cu, and Zn influence particulate phytochelatin concentrations in marine phytoplankton: Laboratory results and preliminary field data. Environmental Science & Technology 37(16), 3609-3618.

• Zeng H. H., Thompson R. B., Maliwal B. P., Fones G. R., Moffett J. W., and Fierke C. A. (2003) Real-time determination of picomolar free Cu(II) in seawater using a fluorescence based fiber optic biosensor. Analytical Chemistry 75(24), 6807-6812.

• Fones G. R., Davison W., Holby O., Jorgensen B. B., and Thamdrup B. (2001) High-resolution metal gradients measured by in situ DGT/DET deployment in Black Sea sediments using an autonomous benthic lander. Limnology and Oceanography 46(4), 982-988.

Michelle Hale

Main Research Themes:

Microbial foodwebs are ecologically and biogeochemically important to the cycling of energy and materials in the ocean. The factors that control the growth and loss rates of bacterioplankton and phytoplankton can, and do, substantially differ in different marine environments. Growth rates may be limited by availability of nutrients (e.g. dissolved organic matter and/or inorganic nutrients, including iron), or temperature. In contrast, changes in standing stocks are controlled by the balance of concurrent growth and loss processes, where the latter includes grazing and viral lysis. Each of the above factors may exert an influence over growth, production and loss over different temporal and spatial scales. My research seeks to understand the spatial and seasonal variation in microbial foodweb dynamics and community composition in different biogeochemical provinces of the North Atlantic and Arctic Oceans.

My main research interests are:

• The role of microbial trophic pathways in regulating the cycling of biogenic carbon and sulfur
• Microzooplankton herbivory and bacterivory
• Regulation of growth and loss processes of marine bacteria in constrasting biogeochemical provinces
• Effects of grazing and nutrient limitation on microbial community structure
• Importance of microbial diversity to ecosystem function in marine systems

Recently Completed and Current Research Projects:

Canadian Surface Ocean Lower Atmosphere Study (C-SOLAS) Research Network)

Main collaborators: Dr. Richard Rivkin and Ms. Kimberley Keats (Memorial University of Newfoundland, Canada); Dr. M. Robin Anderson, Dr. William Li and Dr. Michael Scarratt (Department of Fisheries and Oceans, Canada); and Dr. Maurice Levasseur (Universite Laval).

The C-SOLAS research network is funded by the Canadian Natural Science and Engineering Research Council (NSERC) and Canadian Association for Climate and Atmospheric Sciences (CFCAS), to establish an integrated network of atmospheric and marine-research specialists. Together, we examine the key interactions of the marine biochemical system and the atmosphere and the impact of these interactions on climate change. I was involved in 2 field programs, for which data are currently being analysed and prepared for publication, and am currently preparing for a research expedition to the Arctic in September 2008, as an international collaborator on the program.

• Subarctic Ecosystem Response to Iron Enrichment Study (SERIES) Iron Enrichment Experiment (2002): Response of bacteria, picophytoplankton, nanophytoplankton, and microzooplankton to a mesoscale in situ iron enrichment experiment in the NE subarctic Pacific
• Study of Air-Sea Biogeochemical Interactions in the Northwestern Atlantic (SABINA) (2003): Seasonal variations in microbial dynamics in different biogeochemical provinces in the NW Atlantic
• Artic SOLAS (2008): Ocean sulfur production and aerosol dynamics in a changing Arctic.

Atlantic Meridional Transect (AMT) Program

Main collaborators: Dr. Matt Mills (Stanford University, USA); Dr. Glen Tarran and Dr. Elaine Fileman (Plymouth Marine Laboratory); Dr. Dave Sugget and Dr. Richard Geider (University of Essex); Dr. Mark Moore (National Oceanography Centre); and others.

The Atlantic Meridional Transect Programme (AMT) is a UK National Environment Research Council (NERC) funded project which aims to quantify the nature and causes of ecological and biogeochemical variability in the planktonic ecosystems of the Atlantic Ocean, and the effects of this variability on the biological carbon pump and on air-sea exchange of radiatively active gases and aerosols. The AMT programme undertakes biological, chemical and physical oceanographic research during the annual return passage of the RRS James Clark Ross between the UK and the Falkland Islands or the RRS Discovery between the UK and Cape Town, a distance of up to 13,500 km. This transect crosses a range of ecosystems from sub-polar to tropical and from euphotic shelf seas and upwelling systems, to oligotrophic mid-ocean gyres. I participated in 2 AMT expeditions (AMT16 & AMT17) on the RRS Discovery, running experiments to determine the nutrient regulation of bacterial growth and microzooplankton herbivory and bacterivory for which data are currently being analysed and prepared for publication.

Research Funding Sources:

2008: Royal Society, UK. "The effect of Arctic ice cover on microzooplankton herbivory and bacterivory". £12,884, 12 months. Hale, Principal Investigator.

• Hale, M. S. & Rivkin, R. B. (2007). Interpreting the results of mesoscale iron enrichment experiments: Caveats and lessons from limnology and coastal ecology. Limnology and Oceanography, 52, 912-916.
• Hale, M. S. , Rivkin, R. B., Matthews, P., Agawin, N. S. R, Li W. K. W. (2006). Microbial response to a mesoscale iron enrichment in the NE subarctic Pacific: Heterotrophic bacterial processes. Deep Sea Research II, 53, 2231-2247.
• Agawin, N. S. R, Hale, M. S., Rivkin, R. B., Matthew,s P., Li, W. K. W. Microbial response to a mesoscale iron enrichment in the NE subarctic Pacific: Bacterial community structure. Deep Sea Research II, 53, 2248-2267.
• Levasseur, M., Scarratt, M. G., Michaud, S., Merzouk, A., Wong, C. S., Arychuk, M., Richardson, W., Rivkin, R. B., Hale, M. S., Wong, E., Marchetti, A., Kiyosawa, H. DMSP and DMS dynamics during a mesoscale iron fertilization experiment in the Northeast Pacific. Part I. Temporal and vertical distributions. Deep Sea Research II , 53, 2353-2369.
• Merzouk, A., Levasseur, M., Scarratt, M. G., Michaud, S., Rivkin, R. B., Hale, M. S., Kiene, R., Price, N., Li, W. K. W.  DMSP and DMS dynamics during a mesoscale iron fertilisation experiment in the Northeast Pacific. Part II. Bacterial cycling. Deep Sea Research II, 53, 2370-2383.
• Scarratt, M. G., Marchetti, A., Hale, M. S., Rivkin, R. B., Michaud, S., Matthews, P., Levasseur, M., Sherry, N., Merzouk, A., Li, W. K. W., Kiyosawa, H., Tsuda, A. Assessing the microbial response to iron enrichment in the Subarctic Northeast: Do microcosms represent the in situ response? Deep Sea Research II, 53, 2182-2200.
• Hale, M. S. & Rivkin, R. B. (2006). Comment on ?Nature of Phosphorous Limitation in the Ultraoligotrophic Eastern Mediterranean?. Science, 312 , 1748.
• Boyd, P. W., Law, C. S., Wong, C. S., Nojiri, Y., Tsuda, A., Levasseur, M., Takeda, S., Rivkin, R., Harrison, P. J., Strzepek, R., Gower, J., McKay, M., Abraham, E., Arychuk, M., Barwell-Clarke, J., Crawford, W., Crawford, D., Hale, M., Harada, K., Johnson, K., Kiyosawa, H., Kudo, I., Marchetti, A., Miller, W., Needoba, J., Nishioka, J., Ogawa, H., Page, J., Robert, M., Saito, H., Sastri, A., Sherry, N., Soutar, T., Sutherland, N., Taira, Y., Whitney, F., Wong, S. K., Yoshimura, T. (2004). The decline and fate of an iron-induced subarctic phytoplankton bloom. Nature 428(6982), 549-53.
• Hale, M. S., & Mitchell, J. G. (2002). Effects of particle size, flow velocity, and cell surface microtopography on the motion of submicrometer particles over diatoms.  Nano Letters 2(6), 657-663.
• Hale, M. S., & Mitchell, J. G. (2001). Motion of small colloids dominated by Brownian motion near cell and micro-fabricated surfaces.  Nano Letters 1(11), 617-623.
• Hale, M. S., & Mitchell JG 2001. The functional morphology of diatom frustule microstructures: Hydrodynamic control of Brownian particle diffusion and advection.  Aquatic Microbial Ecology 24(3), 287-295.
• Hale, M. S., & Mitchell, J. G. 1997. Sea surface microlayer and bacterioneuston spreading dynamics.  Marine Ecology Progress Series 147, 269-276.
• Hale, M. S., & Mitchell, J. G. 1995. CLOD spreading in the sea surface microlayer.  Science 270, 897.