Many pathogens, but temperature tips the scale

Today we heard about many pathogen infections from around the globe that included different domains and kingdoms. One fungal infection, one polychaete worm, and two bacterial infections. Three of these involved different species of abalone as a primary host and one involved the infamous Pacific oyster, C. gigas.

While they occurred on different continents, temperature was the key in triggering the spread in of these diseases. In each case, the pathogen was either detectable and/or caused obvious malformities.

The most intriguing case was the Sabellid Polychaete, which infests various gastropods. The example focused on was farmed abalone (Haliotis midae), however it does also infests Tegula and less so limpets. Some facts that make this case cool was that it had been recently brought in from South Africa to the West Coast of the US. Infestation signs were noticeable, as the Sabellid causes the shell to build up and deform.


Sabellid worms build, secrete a mucus tube, and modify the edge of the shell. Another cool fact: they’re functional hermaphrodites. It takes 1 to cause an outbreak, Kuris & Culver (1999) – YIKES!

Also, reproduction increases above 16C, cooler temps also allow infestation to occur, but less so. (It can still reproduce 11C, but much less.)
Eventually, the Sabellids were established in the wild in Tegula funebralis, due to ignorant practices of one hatchery. This oversight allowed 17,000 viable worms/day escape through the effluent and into the open ocean.


Luckily this worm doesn’t move far, and the efforts of Carolynn Culver’s work at UCSB removed 1.6 million viable gastropod hosts. The team continued to remove viable hosts and eventually continuous monitoring showed that the Sabellid was irradiated.
Image credits: Kuris & Culver (1999), Invertebrate Biology

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