Nov 9, 2010

Temperature Affects Marine Vibrio Bacteria

Vibrio is a genus of marine bacteria found in clams, shellfish, corals, Syngnathids, and Cholera in humans (There are even benign species such as Vibrio Fischeri responsible for bioluminescence in some species of squid and fish). Vibrio cholerae infects humans, Vibrio coralliilyticus infects certain stony corals, and Vibrio spp. infect seahorses and other Syngnathids. The preferred temperature range for growth and the temperature at which virulence increases of each of these three infectious Vibrio species is strikingly similar.

The optimal temperature for Vibrio cholerae survivability and abundance is between 68°F and 86°F. Scientists fear that global warming trends may steadily increase the number of Cholera outbreak cases. It is not surprising that Vibrio coralliilyticus and the Syngnathid-specific strains of Vibrio spp. also favor temperature conditions between 68°F and 86°F.

The Magic Numbers

The recent findings of researchers at the Hollings Marine Laboratory in Charleston, South Carolina reported by CORAL magazine (Jan/Feb 2010) show that infectious strains of Vibrio coralliilyticus linked to coral-bleaching events of small polyp stony corals are temperature dependent. Similar to the Vibrio spp. strains that infect seahorses, Vibrio coralliilyticus does not normally cause disease in healthy coral specimens at a temperature of 75°F, but becomes pathogenic at higher temperatures. Temperatures above 80°F increase the acceleration and severity of the infection.

Not much research has been done on the Syngnathid-specific strains of Vibrio, but for years seahorse aquarists have noticed a correlation between high temperatures and Vibrio bacterial infections in their pets. In the book Working Notes – A Guide to Seahorse Diseases pathologist Martin Belli M.D. writes that strains of Vibrio found to affect seahorses did not grow well in a lab at temperatures lower than 64°F. members have long advocated seahorse aquarium temperatures no higher than 74°F because Vibrio becomes more aggressive and virulent at higher temperatures. Temperatures in the low 80's seem to increase number of cases, rate of infection, and chance of death.

MORE ON VIBRIO from Felicia's Aquarium Adventures:

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