research
Project Background
Abalone are ecologically important inhabitants of the intertidal and nearshore subtidal, marine habitat, providing key revenue for coastal communities from sport fishers in northern California (CA) and recreational diving enthusiasts throughout the state. In addition, five of the eight CA abalone species once supported a commercial fishery and several species are being cultured for commercial or restoration purposes in the state. All species within CA are in severe decline; the white abalone (H. sorenseni) is Endangered and four others are federal Species of Concern. The black abalone (Haliotis cracherodii), one of the four federal Species of Concern, is now a Candidate for protection by the Endangered Species Act as Threatened or Endangered. Withering syndrome (WS) is a catastrophic bacterial disease of abalone resulting in losses of up to 99 percent. WS has also profoundly impacted captive rearing of the endangered white abalone and seasonally hinders red abalone (H. rufescens) aquaculture in California. The causative agent, a Rickettsiales-like Prokaryote (RLP) and other factors influencing WS expression (i.e. temperature, food availability) have been well documented; climatic variation (especially temperature) was recently shown to induce profound changes in the host-parasite relationship between abalone and the WS-bacterium resulting in high losses of abalone (Braid et al. 2005, Vilchis et al. 2005). Recent data indicate that susceptibility to WS varies among species (Friedman, unpubl. data). In addition, mortality patterns and quantitative real-time PCR (Q-PCR) analyses of RLP loads released by progeny from WS-exposed vs. WS-naïve populations of black abalone suggest that abalone develop resistance or increased tolerance to WS. The host defense mechanisms involved in this important trait have yet to be elucidated. A better understanding of the host-parasite (abalone-RLP) interaction and physiological processes associated with increased abalone survival will provide crucial information for effective management, conservation and restoration of abalone in CA.
Collaborators: Carolyn Friedman and Glenn VanBlaricom
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Disease-Resistant Black Abalone Discovered
November 5, 2007
Contact: Christina S. Johnson, California Sea Grant, 858-822-5334, csjohnson@ucsd.edu
Biologists have discovered that black abalone on San Nicolas Island in the Santa Barbara Channel are more resistant to the deadly bacterial disease known as withering syndrome than abalone on the mainland. The discovery may help save these now rare intertidal mollusks from extinction, as scientists hope to soon breed these animals in captivity for release in the wild.
San Nicolas Island has been the site of several severe outbreaks of withering syndrome, said Carolyn Friedman, a professor at the School of Aquatic and Fishery Sciences at the University of Washington in Seattle, explaining the island abalones’ hardiness ..........
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Related References
Int J Syst Evol Microbiol. 2000 Mar;50 Pt 2:847-55. Freidman et al
'Candidatus Xenohaliotis californiensis', a newly described pathogen of abalone, Haliotis spp., along the west coast of North America.
'Candidatus Xenohaliotis californiensis', a newly described pathogen of abalone, Haliotis spp., along the west coast of North America.
Taxonomy of RLP via NCBI
Disease resistance in abalone: Understanding genetic mechanisms and the influence of thermal stress