We’ve got some marauding diseases on the loose in the U.S. and in oceans around the world. Many of them leave a path of destruction in their wake. Some are heading for the border…
I was writing down my own “most wanted” list in preparation for a lecture the other day when I realized I could crowd-source the list from the audience of undergraduates. While there are marine diseases that maintain a low profile despite wreaking havoc on wildlife populations, the worst ones should be notorious.
So what do Cornell undergraduates think of when they hear the phrase “marine disease”?
1. Sea Star Wasting Disease
This was not a shock. SSWD is unprecedented in scale, affecting around 20 species of asteroids and causing mass mortality. The sea star pictured below, Pisaster ochraceus, is just one of these species. Sick sea stars display twisting, white lesions, and even arms that walk away from their bodies.
Given the role that sea stars play in the ocean, many ecologists worry that removing sea stars via this mass mortality event will have rippling effects throughout the ecosystem. Cornell microbiologist Ian Hewson has linked the disease to densovirus and is posting updates on his experiments on his blog. I recently worked with other graduate students to study the immune response to SSWD. Resistance may be the last resort.
Sea star wasting affects many species of asteroids, including the iconic Pisaster ochraceus of the Pacific NW.
2. Oyster Dermo and MSX
The student who volunteered this answer astutely named both diseases together. Both Dermo and MSX affect oysters in the U.S., sometimes simultaneously. This is of interest to me given my own work on coral coinfection. Additionally, Dermo and MSX are some of the most commercially important marine diseases in the U.S. Both are caused by protists and have been linked to salinity and temperature conditions. Luckily, there is evidence that oysters are developing resistance to disease.
3. Eelgrass Wasting Disease
This was a great answer, but was likely influenced by the fact that students know more about work by Cornell researchers. Still, this might be one of the most important emerging epizootics for U.S. marine ecosystems and resources. Eelgrass beds provide habitat, prevent erosion, and filter runoff. Historically, wasting disease has affected eelgrass in the North Atlantic, Mediterranean, and the Pacific NW. It is caused by the spindle-shaped protist, Labyrinthula zosterae, a relative of the the labyrinthulid protist I study in sea fans.
4. Coral Bleaching
This is not a disease, but it presents a “teachable moment”. Bleaching is not a disease to me because it’s usually not caused by a pathogen. However, it’s certainly very damaging - and this was a very timely answer given the unseasonably warm waters in the Pacific. NOAA has recently declared the 3rd global coral bleaching event and expects widespread damage to coral reefs.
This list is diverse, but it leaves out some major players. I’ve included a few in the table below.
I mostly agree with the undergraduates and I think they’ve pointed out well-known, notorious marine diseases. However, it’s hard to say which are the most important. Even a few years ago, no one would have put sea star wasting disease on this list and now it’s one of the worst we’ve ever seen…
What would you include? Feel free to add a comment to enhance this crowd-sourced “most wanted” list.