Invincible Black Abalone

29 12 2012
Pre-disease black abalone population on San Nicolas Island (G. VanBlaricom)

Pre-disease black abalone population on San Nicolas Island (G. VanBlaricom)

When I first began this blog, I introduced withering syndrome and it’s devastating effect on black abalone populations in Southern California.  The effect of the disease on the populations on San Nicolas Island is the equivalent of wiping out all the people in the world except for the populations in the US, Indonesia, and Brazil.  Only three of the most densely populated countries out of the total 242 countries in the world manage to survive.  It’s a little sobering when you think of it that way.  If you break it down so populations are evenly lost among each country, only the populations in Washington and Idaho would survive in the United States (I’m in Washington, so I’m happy I survive the fake apocalypse).  I’m not stating the statistics in the manner to convince everyone to move to the northwest, even though it’s the best place to live, I’m just trying to paint a picture of how the US would look if only 1% of the population survived.  Out of the 315,077,987 people in the US, only approximately 3 million make it.

 

Then, imagine among the people dodging the zombies in the apocalypse (I’ve been watching a lot of Walking Dead, so that’s the only apocalypse scenario I can picture right now), there is a group of individuals resistant to the brain-eating bacteria!  And they’re found on San Nicolas Island.

 

Disease-resistant black abalone discovered on US island

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 molluscs from extinction, as scientists hope to soon breed these animals in captivity for release in the wild.

According to Carolyn Friedman, from the School of Aquatic and Fishery Sciences at the University of Washington in Seattle, San Nicolas Island has been the site of several severe outbreaks of withering syndrome. The present population appears to be the descendants of that 1% of the population that survived the onslaught.

Friedman and her colleague on the California Sea Grant project, Steven Roberts, also at the University of Washington, are now trying to identify which genes are responsible for resistance and the mechanisms by which this resistance is conferred. This work includes studying differences in gene expression between island black abalone and those from Carmel in Monterey, as the animals are subjected to high loads of the withering syndrome pathogen.

Withering syndrome, which causes severe atrophy of the animal’s foot muscle and is caused by a water-borne pathogen excreted in abalone faeces, occurs in relatively warm water, such as those found in the Santa Barbara Channel. Until recently, waters off the more northerly Carmel have been too cold to trigger outbreaks. As a result, abalone in Carmel have little natural protection against the disease.

Source: California Sea Grant

Anonymous.  2008.  Disease-resistant black abalone discovered on US island.  Marine Pollution Bulletin, 56(1): 7

 

Super Black Abalone (B. Blaud)

Super Black Abalone (B. Blaud)

Beginning in 2001, isolated populations on San Nicolas Island began to increase, so Dr. Friedman hypothesized that there may be disease resistant animals.  My very first trip to the island in 2004 was to collect animals and bring them back to UW to test this hypothesis.  The exposure of naïve (uncontaminated, un-diseased) black abalone from Carmel and comparing the rate of mortality to infected animals from San Nicolas Island indicated that San Nicolas Island black abalone are, in fact, resistant to the disease.  It’s a snail…it’s a rock…it’s SUPER BLACK ABALONE!  Yeah, I’m a dork.

 

But the story doesn’t end here.  Continuing this work, Dr. Friedman and PhD student Lisa Crosson investigated which genes were potentially responsible for the disease resistance in black abalone populations, and in doing so, made a surprising discovery.  But that is a story for another time…