Research interests:

Researchers in the laboratories of M. G. Hadfield have long had as their core theme the processes that occur when planktonic larvae of diverse marine invertebrate animals settle to the benthos and undergo the complex developmental processes of metamorphosis. Larvae of different species are known to respond to either dissolved or surface-bound cues to settlement and metamorphosis. In the Hadfield labs, these cues are investigated in terms of the developmental processes that they actually induce; the stimulatory cues are thus investigated as chemical ligands with specific receptors on the outer surfaces of larvae. Binding of ligand with receptors produces a cascade of behavioral and morphogenetic processes, which result in the profound morphological and physiological alterations that are summarized as metamorphosis.

Using especially a widely distributed tropical marine slug, Phestilla sibogae, and a common warm-water fouling organism, the tube worm Hydroides elegans, graduate student and postdoctoral researchers have collaborated with the P.I. to study the nature of the external cues, the site of their perception, the nature of receptor mechanisms, the role of the nervous system in promulgating the morphogenetic signal, and, most recently, the molecular events of metamorphic activation.

Other projects under investigation are related to the above, including: the mechanisms of invasion of a barnacle species, native to the Caribbean Sea, that first appeared in Hawaii in the last 10-20 years. The role played by larval recruitment and survival in successful marine invasions is a particular focus of this work. Additionally, in collaboration with Dr. Celia Smith of the U.H. Botany Department, some research in the Hadfield labs has sought better understanding of the mechanisms by which most tropical marine algae avoid the recruitment of sessile invertebrates to their surfaces, Drs. Hadfield and Smith also collaborate with U.S. Naval scientists in testing, in a tropical marine setting, the latest generation of marine coatings in resisting firm attachment by marine fouling organisms such as the barnacles and tube worms mentioned above.

Because invertebrate larvae, mostly in the range of 50 to 300 microns in diameter, have proven to be too small for effective use of intracellular nervous recording techniques, research in the Hadfield labs has broadened, in recent years, to include investigation of mechanisms and pathways of chemical perception in adults of Phestilla sibogae. They to carry out this effort, the lab has an excellent neurophysiology "rig" plus excellent microelectrode puller, recording instruments, micromanipulators, and other necessary equipment.

Another interest of Professor Hadfield is the conservation biology of a large group of tree snails unique to Hawaii. This work is described on another web site: http://www2.hawaii.edu/~zoology/graduate/faculty/hadfield.htm#top

Dr. Hadfield is lead Principal Investigator on a National Science Foundation training grant in the Undergraduate Mentoring in Environmental Biology (http://www2.pbrc.hawaii.edu/umeb/), which brings 7 - 10 Pacific Island undergraduates, mostly from community colleges in American Samoa and Micronesia, to the University of Hawaii for ten-week summer internships in environmental biology.  Three or four of these students are supported for year-round internships as they complete four-year degrees at the University of Hawaii at Manoa.  Since 2000, more than 50 Pacific Islanders have participated in this program, gone on to baccalaureate institutions and taken jobs critical for environmental conservation and natural resources management in their island groups.

Recent Publications:

• Strother, J.A., Reidenbach, M.A., Koseff, J.R., Hadfield, M.G., and Koehl, M.A.R.  Individual-based model of larval transport to coral reefs in turbulent, wave-driven flow: Effects of behavioral responses to dissolved settlement cues.  Marine Ecology Progress Series (accepted, in revision).
• Zabin, C.J., Zardus, J., Pitombo, F.B., Fread, V., and Hadfield, M.G. 2006. A tale of three seas: consistency of natural history traits in a Caribbean-Atlantic barnacle introduced to Hawaii . Biological Invasions (in press).
• Miles, C.M., Hadfield, M.G., and Wayne, M.L. 2006. Estimates of heritibility for egg size in the serpulid polychaete Hydroides elegans. Marine Ecology Progress Series (in press).
• Faucci, A., Toonen, R.J., and Hadfield, M.G. 2006. Host shift and speciation in a coral-feeding nudibranch. Proceeding of the Royal Society of London, B (in press).
• Shikuma, N.J. and Hadfield, M.G  2006. Temporal variation of an initial marine biofilm community and effects on larval settlement and metamorphosis of the tubeworm Hydroides elegans.  Biofilms (in press).
• Holland , B.S. and Hadfield, M.G.  2006. Molecular Systematics of the Endangered Oahu Tree Snail Achatinella mustelina (Mighels, 1845): Synonymization of Subspecies and Estimation of Gene Flow Between Chiral Morphs. Pacific Science (in press).
• Hadfield, M.G., Faucci, A., and Koehl, M.A.R. 2006. Measuring recruitment of minute larvae in a complex field environment: the corallivorous nudibranch Phestilla sibogae (Bergh).  Journal of Experimental Marine Biology and Ecology, 338: 57 - 72.
• Buckland-Nicks, J. and Hadfield, M.G. 2005.  Spermatogenesis in Serpulorbis (Mollusca: Vermetoidea) and its implications for phylogeny of gastropods.  Journal of Invertebrate Reproduction and Development,  48(1-3): 171 – 184.
• Zardus, J.G. and Hadfield, M.G. 2005. Population history of the Atlantic barnacle Chthamalus proteus and the genetic origins of its introduction to the Pacific.  Molecular Ecology, 14: 3719-3733.
• Zardus, J.D. and Hadfield, M.G. 2004. Larval development and complemental males in Chelonibia testudinaria, a barnacle commensal with sea turtles.  Journal of Crustacean Biology, 24(3): 409-421.
• Hadfield, M.G. and Koehl, M.A.R. 2004. Rapid behavioral responses of an invertebrate larva to dissolved settlement cue. Biol. Bull., 207:28-43.
• Koehl, M.A.R. and Hadfield, M.G. 2004.  Soluble settlement cue in slowly moving water within coral reefs induces larval adhesion to surfaces.  Journal of Marine Systems, 49: 75-88.
• Hadfield, M.G., Holland, B.S., and Olival, K.J. 2004. Contributions of ex situ propagation and molecular genetics to conservation of Hawaiian tree snails.  Experimental Approaches to Conservation Biology, M. Gordon and S. Bartol , eds. University of California Press. Pp. 16 – 34.
• Holland , B.S. and Hadfield, M.G. 2004.  Origin and diversification of endemic Hawaiian tree snails (Achatinellidae: Achatinellinae) based on molecular evidence.  Molecular Phylogeny and Evolution, 32:588-600.
• Croll, R.P., Boudko, D.Y., Pires, A., and Hadfield, M.G. 2003.  Transmitter contents of cells and fibers in the cephalic sensory organs of the gastropod mollusc Phestilla sibogae.  Cell and Tissue Research, 314: 437-448.
• Walters, L.J., Smith, C.M., and Hadfield, M.G. 2003. Recruitment of sessile marine invertebrates on Hawaiian macrophytes: Do pre-settlement or post-settlement processes keep plants free from fouling? Bull. Mar. Sci., 72(3):813-839.
• Huang, S. and Hadfield, M.G. 2003. Composition and density of bacterial biofilms affect metamorphosis of the polychaete Hydroides elegans. Marine Ecology Progress Series, 260:161-172.
• Pettengill, J.G., Hadfield, M.G., Schug, M.D., and Wendt, D.E. 2003. Characterization of six polymorphic microsatellites for the polychaete tubeworm Hydroides elegans and cross-species amplification in the congener Hydroides hexagonus. Molecular Ecology Notes, 3(3): 369-371.
• Carpizo-Ituarte, E. J. and Hadfield, M.G. 2003. Transcription and translation inhibitors permit metamorphosis up to radiole formation in the serpulid polychaete Hydroides elegans Haswell. Biol. Bull., 204:114-125.
• Walters, L.J., Smith, C.M., and Hadfield. M.G. 2002. Recruitment of sessile marine invertebrates on Hawaiian macrophytes; do pre-settlement or post-settlement processes keep plants free from fouling? Bull. Mar. Sci., 72(3): 813-839.
• Hofmann, D. K. and Hadfield, M.G. 2002. Hemaphroditism, gonochorism, and asexual reproduction in Cassiopea sp. - an immigrant in the islands of Hawai'i. J. Invert. Reproduction & Development, 41:215-221.
• Zabin, C. and Hadfield, M.G. 2002. Do locals rule? Interactions between native intertidal animals and a Caribbean barnacle in Hawai'i. Pacific Science, 56:235-236.
• Holland. B.S. and Hadfield, M.G. 2002. Islands within an island: Phylogeography and conservation genetics of the endangered Hawaiian tree snail Achatinella mustelina. Molecular Ecology, 11:365-376.
• Hadfield, M.G., Carpizo-Ituarte, E.J., Del Carmen, K., and Nedved, B.T. 2001. Metamorphic competence, a major adative convergence in marine invertebrate larvae. American Zoologist, 41:1123-1131.
• Croll, R. P., Boudko, D.Y., and Hadfield, M.G. 2001. Histochemical survey of transmitters in the central ganglia of the gastropod mollusc Phestilla sibogae. Cell and Tissue Research, 305:417-432.
• Hickman, C. S. and Hadfield, M.G. 2001. Larval muscle contraction fails to produce torsion in a trochoidean gastropod. Biological Bulletin, 200:257-260.
• Hadfield, M. G. 2001. Hemichordata. In, "Atlas of Marine Invertebrate Larvae," C. M. Young, M. E. Rice and M. Sewell, eds. Academic Press, 553-564.
• Hadfield, M. G. and Paul, V.J. 2001. Natural chemical cues for settlement and metamorphosis of marine invertebrate larvae. In, "Marine Chemical Ecology," J. B. McClintock and W. Baker, eds. CRC Press, 431-461.
• Leise, E.M. and Hadfield, M.G. 2000. An inducer of molluscan metamorphosis tranforms activity patterns in a larval nervous system. Biological Bulletin, 199:241-250.
• Hadfield, M. G. 2000. Why and how marine invertebrate larvae metamorphose so fast. Seminars in Cell and Developmental Biology, 11(6):437-443.
• Thacker, R. and Hadfield, M.G. 2000. Mitochondrial phylogeny of extant Hawaiian tree snails (Achatinellinae). Molecular Phylogenetics and Evolution, 16:263-270.
• Pires, A., Croll, R.P., and Hadfield, M.G. 2000. Catecholamines modulate metamorphosis in the opisthobranch gastropod Phestilla sibogae. Biological Bulletin, 198(3):319-331.
• Hadfield, M. G., Meleshkevitch, E., and Boudko, D. 2000. The apical sensory organ of a gastropod veliger is a receptor for settlement cues. Biological Bulletin, 198(1):67-76.

hadfield@hawaii.edu