Michael G. Hadfield

PhD Stanford (Biological Sciences), 1968

Professor, Department of Zoology
Director, Kewalo Marine Laboratory

Department of Zoology, University of Hawai`i
2538 McCarthy Mall, Edmondson 152
Honolulu, HI 96822
hadfield@hawaii.edu
www.kewalo.hawaii.edu

Chemical signaling; Hawaiian tree snails

[publications] [graduate students]
Chemical Signaling in Marine Invertebrates
Chemical signaling is of paramount importance to all animals, but especially to those living in the sea: cells chemically signal to each other in development and regulation; chemical signals warn of predators and provide cues to food; and pelagic larvae are induced to settle in appropriate sites by chemical cues. We focus our research on two aspects of chemical signaling in marine invertebrates: chemoreception and metamorphic induction. Employing nearly all of the methods and approaches of neurophysiology and molecular biology, we are studying the chemosensory mechanisms of marine slugs, with a special emphasis on finding and characterizing the major gene family that specifies chemoreceptor proteins. Metamorphosis in larvae of many invertebrates depends on external chemical signals. We study the chemical nature of a highly specific inducer from prey coral of the sea slug Phestilla sibogae, and a complex substance from bacterial films that induces metamorphosis in the small fouling worm Hydroides elegans, as well as the signal-transduction mechanisms in these larvae. The latter work has led us to a major interest on the composition of marine biofilms, and thus on the interactions between marine microorganisms and developing marine animals, especially at the time of larval recruitment.
Conservation and Evolutionary Biology of Hawaiian Tree Snails
Among the spectacular endemic evolutionary radiations for which Hawai'i is famous is that of the terrestrial and arboreal snails. These snails are famous for both their high rates of speciation and, more recently, their disastrously high extinction rates. We study, in the field and the laboratory, the demography and conservation biology of a single family of endemic Hawaiian snails, the Achatinellidae. These snails have suffered from habitat alteration and outright destruction and from introduced predators. The field studies provide models for determining demographic patterns and analyzing causes of mortality of terrestrial invertebrates in their natural habitat, and they reveal much about the mechanisms of evolution in these snails. Our captive propagation effort now includes five Achatinella species. Currently we are studying microsatellite DNA sequences to compare genetic identities of individual snails, analyze the degree of inbreeding in very small, remnant field populations, and devise breeding plans for captive-rearing.
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Representative publications

Hadway LJ, Hadfield MG. 1999. Conservation status of tree snail species in the genus Partulina (Achatinellinae) on the island of Hawai'i: a modern and historical perspective. Pac Sci 53:1-14.

Carpizo-Ituarte E, Hadfield MG. 1998. Stimulation of metamorphosis in the polychaete Hydroides elegans Haswell (Serpulidae). Biol Bull 194:14-24.

Hadfield MG. 1997. The D.P. Wilson lecture: research on settlement and metamorphosis of marine invertebrate larvae: past, present and future. Biofouling 12:9-29.

Hadfield MG, Strathmann MF, Strathmann RR. 1997. Ciliary currents of non-feeding veligers in ancient clades of gastropods. Invert Biol 116:313-321.

Hadfield MG, Strathmann MF. 1996. Variability, flexibility and plasticity in life histories of marine invertebrates. Oceanol Acta 19:313-321

Hadfield MG, Miller SE, Carwile AH. 1993. Decimation of endemic Hawaiian tree snails by alien predators. Am Zool 33:610-622.

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Current students

Kim Del Carmen (PhD)
sea slug metamorphosis
Brian Nedved (PhD)
neurogenesis in polychaete worm
Barry Smith (PhD)
Guam tree snail population biology
Chela Zabin (PhD)
effects of marine invasive species
Shuyi Huang (MS)
bacteria and marine invertebrate settlement
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Last update: 15 December 1999
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The University of Hawai`i is an Equal Opportunity/Affirmative Action Institution.