Coral larvae conservation: Physiology and reproduction q M. Hagedorn a,b, * , R. Pan a , E.F. Cox b , L. Hollingsworth b , D. Krupp b , T.D. Lewis b , J.C. Leong b , P. Mazur c , W.F. Rall d,1 , D.R. MacFarlane e , G. Fahy f , F.W. Kleinhans g a Department of Reproductive Sciences, Smithsonian National Zoological Park, Washington, DC 20008, USA b Hawaii Institute of Marine Biology, University of Hawaii, Kaneohe, HI 96744, USA c Department of Biochemistry and Molecular and Cellular Biology, University of Tennessee, Knoxville, TN 37996, USA d Division of Veterinary Resources, Office of Research Service, National Institutes of Health, Bethesda, MD 20892-5590, USA e School of Chemistry, Monash University, Clayton, Vic. 3800, Australia f 21st Century Medicine, Inc., 10844 Edison Court, Cucamonga, CA 91730, USA g Department of Physics, Indiana University–Purdue University Indianapolis, Indianapolis, IN 46202, USA Received 5 August 2005; accepted 13 September 2005 Available online 6 December 2005 Abstract Coral species throughout the worldÕs oceans are facing severe environmental pressures. We are interested in con- serving coral larvae by means of cryopreservation, but little is known about their cellular physiology or cryobiology. These experiments examined cryoprotectant toxicity, dry weight, water and cryoprotectant permeability using cold and radiolabeled glycerol, spontaneous ice nucleation temperatures, chilling sensitivity, and settlement of coral larvae. Our two test species of coral larvae, Pocillopora damicornis (lace coral), and Fungia scutaria (mushroom coral) demonstrat- ed a wide tolerance to cryoprotectants. Computer-aided morphometry determined that F. scutaria larvae were smaller than P. damicornis larvae. The average dry weight for P. damicornis was 24.5%, while that for F. scutaria was 17%, yielding osmotically inactive volumes (V b ) of 0.22 and 0.15, respectively. The larvae from both species demonstrated radiolabeled glycerol uptake over time, suggesting they were permeable to the glycerol. Parameter fitting of the F. scu- taria larvae data yielded a water permeability P2 lm/min/atm and a cryoprotectant permeability = 2.3 · 10 4 cm/min while modeling indicated that glycerol reached 90% of final concentration in the larvae within 25 min. The spontane- ous ice nucleation temperature for F. scutaria larvae in filtered seawater was 37.8 ± 1.4 °C. However, when F. scu- taria larvae were chilled from room temperature to 11 °C at various rates, they exhibited 100% mortality. When instantly cooled from room temperature to test temperatures, they showed damage below 10 °C. These data suggest that they are sensitive to both the rate of chilling and the absolute temperature, and indicate that vitrification may 0011-2240/$ - see front matter Ó 2005 Elsevier Inc. All rights reserved. doi:10.1016/j.cryobiol.2005.09.008 q This work was supported by a grant to M.H. from the Friends of the National Zoo, and to L.H. from grants from the Hawaii State Biomedical Research Infrastructure Network Summer Research Scholarship (HS-BRIN; NIH/NCRR Grant RR-16467), an NSF-REU fellowship from the University of Hawaii Sea Grant Marine Science Undergraduate Research Fellowship program (NSF REU Grant 0243600) and by the University of Hawaii Investing in Multidisciplinary University Activities through Hawaii EPSCoR program (NSF RII Grant 0237065). * Corresponding author. Fax: +1 808 236 7417. E-mail address: hagedornm@si.edu (M. Hagedorn). 1 This author contributed to this paper in his personal capacity. The views expressed are his own and do not necessarily represent the views of the National Institutes of Health or the United States Government. Cryobiology 52 (2006) 33–47 www.elsevier.com/locate/ycryo