DAO 87:67-78 (2009)  -  doi:10.3354/dao02088

Immune defenses of healthy, bleached and diseased Montastraea faveolata during a natural bleaching event

Laura D. Mydlarz1,*, Courtney S. Couch2, Ernesto Weil3, Garriet Smith4, C. Drew Harvell2

1Department of Biology, University of Texas at Arlington, Arlington, Texas 76019, USA
2Department of Ecology and Evolutionary Biology, Corson Hall, Cornell University, Ithaca, New York 33431, USA
3Department of Marine Sciences, University of Puerto Rico, PO Box 908, Lajas 00667, Puerto Rico
4Department of Biology and Geology, University of South Carolina Aiken, 471 University Parkway, Aiken, South Carolina 29801, USA

ABSTRACT: One prominent hypothesis regarding climate change and scleractinian corals is that thermal stress compromises immune competence. To test this hypothesis we tracked how the immune defenses of bleached, apparently healthy and yellow band disease (YBD) diseased Montastraea faveolata colonies varied with natural thermal stress in southwestern Puerto Rico. Colonies were monitored for 21 mo from the peak of the bleaching event in October 2005 to August 2007. Since sea surface temperature was significantly higher in summer and fall 2005 than 2006, year of collection was used as a proxy for temperature stress, and colony fragments collected in 2005 were compared with those collected in 2006. Mortality rate was high (43% overall) and all colonies (except one) either died or became infected with YBD by August 2007. YBD-infected tissue did not bleach (i.e. expel zooxanthellae) during the 2005 bleaching event, even when healthy tissue of these colonies bleached. Immune activity was assayed by measuring prophenoloxidase (PPO), peroxidase (POX), lysozyme-like (LYS) and antibacterial (AB) activity. Immune activity was variable between all coral samples, but there was a significant elevation of PPO activity in bleached colonies collected in 2005 relative to apparently healthy and YBD-diseased corals in 2006. In YBD-diseased colonies, LYS and AB activity were elevated in both healthy and infected tissue, indicating a systemic response; activity levels in these colonies were higher compared to those that appeared healthy. In both these immune parameters, there was a trend for suppression of activity in corals that were bleached in 2005. These data, while complicated by between-genet variability, illustrate the complex interaction between disease and temperature stress on immune function.

KEY WORDS: Coral bleaching · Montastraea faveolata · Yellow band disease · Prophenoloxidase · Peroxidase · Antibacterial activity

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Cite this article as: Mydlarz LD, Couch CS, Weil E, Smith G, Harvell CD (2009) Immune defenses of healthy, bleached and diseased Montastraea faveolata during a natural bleaching event. Dis Aquat Org 87:67-78

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