Dissolving starfish in the Puget Sound

[Roko]

Likewise, up in Vancouver BC, my rather non-scientific observation is that it began with Sunflower Starfish and Morning Sun Stars (which had apparently been experiencing a population surge in recent years). After a month or so, when most of those starfish were little more than a "goo" on the bottom, I observed Giant Pink stars beginning to waste away. I've heard mention of it effecting Ochre Starfish, but haven't seen any wasting away myself. (Granted, in late stages, it's impossible to identify what is what). I've still seen Ochres around, but seemingly nowhere near as many as before.. Could be a cognitive bias on that part.

An interesting note is that species that tend to congregate (from what I've observed), such as the Sunflowers and Morning Stars, wasted away first, while other species that don't congregate are either unaffected, or were struck later (such as the Giant Pink star case). Of course, that is only a single data-point, so it would be interesting to hear if others have corroborating or conflicting observations.

Some Giant Pink Stars at Porteau:



I've been blogging some photos/observations of what I've seen up in Vancouver as well: Starfish Die-Off | dive.roko.ca

 

[DiverLaura]

From this weekend at Cove 1

[video=vimeo;80181246]http://vimeo.com/80181246[/video]

 

[Peter Guy]

You can be sure that marine biologists up and down the coast are trying to figure this out. It is my understanding that they are in contact with one another up and down the coast.

 

[bluejaykaren]

Starfish are much more sensitive to change of acidity. A slight, even gradual change will cause them to die when nothing else is affected. It would be my first suspect.

 

[TSandM]

It would be interesting to collect water samples in the "death zone" and where the starfish seem to be doing better, and see if there is a noticeable difference in pH.

 

[drbill]

I noticed Lynne said the starfish populations had been booming recently. This could add additional credence to the disease theory since high population densities might facilitate disease transmission.

 

[DiverLaura]

I noticed Lynne said the starfish populations had been booming recently. This could add additional credence to the disease theory since high population densities might facilitate disease transmission.

The starfish boom was mentioned up in Howe Sound. I can look back at video, but at the sites i've surveyed for dead vs. living, looking back at footage from earlier in the year, pre-disease starfish numbers did not seem out of the ordinary.

I have not seen a site down here overrun by sunflower stars like the images from BC.

 

[drbill]

I'm curious.... since bat stars (Asterina miniata) often scavenge on dead critters and I've seen images of them consuming the remains of wasted sea stars, is there any indication that the bat stars subsequently waste away? This might add credence to the disease theory.

 

[Peter_C]

I saw tons of dead and rotting stars yesterday at Point Lobos, but can remember seeing any bat starts falling apart, although I will admit to looking more for living creatures to show my friends.

 

[Hank49]

Bioassays.
Stars from your area need to be sent to a lab where they have healthy stars in tanks from another area that are known to be healthy.
Feed tissue from your sick ones to ones like the bat stars that eat others. If they get sick and die quickly, it's likely a pathogen rather than environment.

Get water from where you see a lot of dead ones. Send to lab. Put healthy stars from other place in that water. If they die in your water and not the controls…likely environmental? But I would think if an environmental factor such as pH was killing at this scale, other animals would be affected also.

You must do controls with each bioassay.

The problem with determining the problem with the stars is time and money. No one eats stars or has a big investment in them so even the universities that do this type of work won't do it for free. It's going to be in the thousands of dollars for proper bioassays and virus testing. Developing markers for PCR can take a couple years.

From what I know with shrimp viruses, depending on whether it's an RNA or a DNA virus, you will have survivors and their offspring will have a higher number of resistant offspring. Within a couple years it will only be a memory of the dead stars. Other viruses are more virulent though and it's hard to get resistance. But nature has a way. It's not in a pathogen's best interest to kill all its hosts.

I'm no marine epidemiologist but I have worked with shrimp viruses for 25 years or so and know a bit of the history.