Mark Wells, Ph.D.

Contact Information

Phone: 207. 581.4322

CV: Link to Wells CV


201 Libby Hall
Orono, ME  04469-5741


Ph.D. University of Maine

Research Interests

Marine dissolved organic matter (DOM) is one of the largest reservoirs of organic carbon on the earth’s surface. Colored, or chromophoric organic matter (CDOM) is a variable component of the total DOM which interferes significantly with light propagation in surface and deep waters and greatly complicates the interpretation of remote sensing data. More importantly, the abundance and spectral characteristics of CDOM varies unpredictably over both temporal and spatial scales independently of traditional parameters (e.g. chl a, cell numbers, DOC, etc.). As a result, it is not possible to definitively correct remote sensing data for optical interferences arising from CDOM. Recent work in an adjacent oceanographic field has demonstrated that a major fraction (30-60%) of bulk marine DOM is colloidal (> 1 kDa) in nature, and preliminary evidence suggests that the optical signature of this organic colloidal matter differs markedly from the bulk CDOM. In addition, the colloidal organic fraction appears to cycle more rapidly than truly soluble organic matter. My working hypothesis is that a major part of the highly variable CDOM signal in surface waters can be explained mechanistically by short term fluctuations in the composition and cycling dynamics of colloidal CDOM. The two primary goals for this project are: 1) measure the optical signature of marine colloidal matter in nearshore waters and determine the extent to which this signature changes in response to biological activity (the source and likely sink of marine colloids), and 2) determine the extent to which photochemical processes differentially affect the optical characteristics and residence time of soluble and colloidal CDOM in seawater. The work proposed here takes the first critical steps towards physically teasing apart marine CDOM components to better explain their nature and cycling in seawater.


  • Trainer, V.L., Hickey, B.M., Lessard, E.J., Cochlan, W. P., Trick, C.G., Wells, M.L., MacFadyen, A., Moore, S. K. (2009) Variability of Pseudo-nitzschia and domoic acid in the Juan de Fuca eddy region and its adjacent shelves. Limnology and Oceanography 54:289-308.For more information: Download file (PDF)
  • Pickell, L., Wells, M.L., Trick, C.G., and Cochlan, W. P. (2009) A sea-going continous culture system for investigating phytoplankton response to macro- and micronutrient (trace metal) manipulations. Limnology and Oceanography Methods 7:21-32For more information: Download file (PDF)
  • Floge, S. A., Hardy, K.R., Boss, E. and Wells, M.L. (2009) Analytical intercomparision between Type I and Type II long pathlength liquid core waveguides for the measurement of chromophoric dissolved organic matter (CDOM). Limnology and Oceanography Methods 7:260-268.For more information: Download file (PDF)
  • Roy, E., Jiang, C.,Wells, M.L., and Tripp, C. (2008) Determining subnanomolar iron concentrations in oceanic seawater using siderophore-modified film analyzed by infrared spectroscopy. Analytical Chemistry 80:4689-4695.For more information: Download file (PDF)
  • Roy, E. and Wells, M.L. (2008) The Persistence of Fe(II) in Surface Waters of the Western Subarctic Pacific. Limnology and Oceanography 53:89-98.For more information: Download file (PDF)
  • Orcutt, K., Gunderson K., Wells, M.L., Poulton, N., Sieracki, M.E. and Smith, G.J. (2008) Lighting up phytoplankton cells with quantum dots. Limnology and Oceanography Methods 6:653-658For more information: Download file (PDF)
  • Tsuda A. et al. (2007) Evidence for the grazing hypothesis: Grazing reduces phytoplankton responses of the HNLC ecosystem to iron enrichment in the western subarctic Pacific (SEEDS II). Journal of Oceanography 63:983-984.
  • Floge, S.A. and Wells, M.L. (2007). Variation in Colloidal Chromophoric Dissolved Organic Matter in the Damariscotta Estuary, Maine. Limnology and Oceanography, 52:32-45.
  • Orcutt, K.M. and Wells, M.L. (2007). A Liposome-Based Nanodevice for Sequestering Siderophore-Bound Iron. J. of Membrane Science, 288:247-254.
  • Yoshimura, T., Nishioka, J., Saito, H., Takeda, S., Tsuda, A. and Wells, M.L. (2006). Distributions of Particulate and Dissolved Organic and Inorganic Phosphorous in North Pacific Surface Waters. Marine Chemistry, 103:112-121 .
  • Boehme, J. and Wells, M.L. (2006). Fluorescence Variability of Marine and Terrestrial Colloids: Examining Size Fractions of Chromophoric Dissolved Organic Matter in the Damariscotta River Estuary. Marine Chemistry, 101:95-103 .
  • Wells, M.L., Trick, C.G., Cochlan, W.P., Hughes, M.P., and Trainer, V. L. (2005). Domoic acid: The Synergy of Iron, Copper, and the Toxicity of Diatoms. Limnology and Oceanography 50(6), 1908–1917
  • Wells, M.L., (2004). The Colloidal Size Spectrum of CDOM in the Coastal Region of the Mississippi Plume Using Flow Field-Flow Fractionation. Marine Chemistry 89:89-102.
  • Chen, R.F. et al., (2004). Chromophoric Dissolved Organic Matter (CDOM) Source Characterization in the Louisiana Bight. Marine Chemistry 89:257-272.
  • Wells, M. L. and Trick, C. G. (2004) Controlling Iron Availability to Phytoplankton in Iron-Replete Coastal Waters. Marine Chemistry 86: 1-13.
  • Wells, M. L., (2003). The Lower Limit of Iron Enrichment Required to Initiate Diatom Blooms in HNLC waters. Marine Chemistry 82: 101-114
  • Bates, S.S., C. Léger, M.L. Wells, and K. Hardy. (2003). Photodegradation of Domoic acid, p. 30-35. In: S.S. Bates [ed.] Proceedings of the Eighth Canadian Workshop on Harmful Marine Algae. Can. Tech. Rep. Fish. Aquat. Sci. 2498
  • Ward, B.B., Granger, J., Maldonado, M.T. and Wells, M.L., (2003). What Limits Bacterial Production in the Suboxic Region of Permantly Ice-covered Lake Bonney, Antarctica. Aquatic Microbial Ecology 31: 33-47.
  • Wells, M. L., (2002). Marine colloids and trace metals. In Biogeochemistry of Marine Dissolved Organic Matter. Elsevier Science, USA. Pp. 367-404
  • Maldonado, M.T., M.P. Hughes, E. L. Rue, and M. L. Wells. (2002). The effect of Fe and Cu on growth and domoic acid production by Pseudo-nitzschia multiseries and Pseudo-nitzschia australis. Limnol. Oceanogr. 47:515-526.
  • Maldonado, M.T., M.P. Hughes, E. L. Rue, and M. L. Wells. (2002). The Effect of Fe and Cu on Growth and Domoic Acid Production by Pseudo-nitzschia multiseries and Pseudo-nitzschia australis. Limnology and Oceanography 47:515-526.
  • Wells, M. L., G. J. Smith, and K. W. Bruland. (2000). The distribution of colloidal and particulate bioactive metals in Narragansett Bay, RI. Mar. Chem. 71:143-163
  • Limnology and Oceanography
    Wells, M. L. (1999). Manipulating iron availability in nearshore waters. Limnology and Oceanography 44:1002-1008.
  • Wells, M. L., Vallis, G and Silver, E. (1999). Influence of tectonic processes in Papua New Guinea on past productivity in the eastern equatorial Pacific Ocean. Nature, 398:601-604.
  • Marine Chemistry
    Wells, M. L.and Bruland, K. W. 1998. An improved method for rapid preconcentration and determination of bioactive trace metals in seawater using solid phase extraction and high resolution inductively coupled plasma mass spectrometry. Mar. Chem. 63:145-153.
  • Marine Chemistry
    Wells, M. L., P. B. Kozelka, and K. W. Bruland. 1998. The complexation of “dissolved” Cu, Zn, Cd, and Pb by soluble and colloidal organic matter in Narragansett Bay, RI. Mar. Chem., 62:203-217.
  • Nature
    Wells, M. L. 1998. Marine colloids: a neglected dimension. News and Views, Nature 391:530-531.
  • Marine Chemistry
    Buesseler, K. O. et al.. 1996. An intercomparison of cross-flow filtration techniques used for sampling marine colloids: overview and organic carbon results. Mar. Chem., 55:1-31.
  • Marine Chemistry Special Issue
    Marine Chemistry Special Issue. 1995. The Chemistry of Iron in Seawater and its Interaction with Phytoplankton. Co-Guest Editors K.W. Bruland and M. L. Wells. Volume 50: 1-241
  • Limnology and Oceanography
    Wells, M. L., Price, N. M., and Bruland, K. W. 1994. Iron limitation and the Cyanobacterium Synechococcus in equatorial Pacific waters. Limnol. Oceanogr., 39:1481-1486.
  • Nature
    Wells, M. L., 1994. Pumping Iron in the Pacific. News and Views, Nature 368:295-296.
  • Limnology and Oceanography
    Wells, M. L. and Goldberg, E. D. 1994. The distribution of colloids in the North Atlantic and Southern Oceans. Limnol. Oceanogr. 39:286-302.
  • Marine Chemistry
    Wells, M. L. and Goldberg, E. D. 1993. Colloid aggregation in seawater. Mar. Chem., 41:353-358.
  • Marine Chemistry
    Wells, M. L. and Goldberg, E. D., 1992. Marine sub-micron particles. Mar. Chem., 40:5-18.
  • Marine Ecology Progress Series
    Kepkay. P. and Wells, M. L.. 1992 Dissolved organic carbon north Atlantic surface waters. Mar. Ecol. Prog. Ser., 80:275-283.
  • Deep-Sea Research
    Longhurst, A. R., Koike, L., Li, W., Rodriguez, J., Dickie, P., Kepkay, P., Partensky, F., Bautista, B., Ruiz, J., Wells, M. L. and Bird, D., 1992. Sub-micron particles in north-west Atlantic shelf water. Deep-Sea Res., Rapid Response Paper, 39:1-7.
  • Nature
    Wells, M. L. and Goldberg, E. D., 1991. Small colloids in seawater. Nature 353:342-344.
  • Nature
    Wells, M. L., Mayer, L. M., Donard, O. F. X., de Souza Sierra, M. M. and Ackleson, S. G., 1991. The photolysis of colloidal iron and its significance in the ocean. Nature 353:248-250.
  • Deep-Sea Research
    Wells, M. L. and Mayer, L. M., 1991. The photoconversion of colloidal iron oxyhydroxides in seawater. Deep-Sea Res., Rapid Response Paper, 38:1379-1395.
  • Marine Chemistry
    Wells, M. L., Mayer, L. M. and Guillard, R. R. L., 1991. A chemical method for estimating the availability of iron to phytoplankton in seawater, 1991. Mar. Chem., 33:23-40.
  • Marine Ecology Progress Series
    Wells, M. L., Mayer, L. M and Guillard, R. R. L., 1991. Evaluation of Fe as a triggering factor for red tide blooms. Mar. Ecol. Prog. Ser., 69:93-102.
  • Biological Oceanography
    Wells, M. L., 1991. The availability of iron in seawater: A perspective. Biol. Oceanogr., 6:463-476.
  • Marine Chemistry
    Wells, M. L. and Mayer, L. M., 1991. Variations in the chemical lability of Fe in estuarine, coastal and shelf waters and its implications for phytoplankton. Mar. Chem., 32:195-210.
  • Journal of Marine Research
    Wells, M. L., Zorkin, N. G. and Lewis, A. G., 1983. The role of colloid chemistry in providing a source of iron to phytoplankton. J. Mar. Res., 41:731-746.