The Ecologist Who Threw Starfish | Hacker News Reader

The Ecologist Who Threw Starfish

nautil.us

63 pointsdnetesn9 comments

Robert Paine showed the importance of predators in maintaining an ecosystem. The same effects are occurring at scale across the entire California coast right now. Massive numbers of Sea stars (starfish) have died[1] due to "Sea star wasting disease"[2] which is caused by Sea Star Associated Densovirus (SSaDV)[3].

No sea stars causes huge numbers of sea urchins which causes the disappearance of kelp forests. My favorite kelp forest to scuba dive in the Monterey Bay is now an urchin barren[4]. No fish, no sea otters, just sea urchins. I was there a month ago and it is gone.

[1]: http://news.nationalgeographic.com/2015/03/150401-urchins-se...

[2]: https://en.wikipedia.org/wiki/Sea_star_wasting_disease

[3]: http://phys.org/news/2014-11-densovirus-devastating-sea-star...

[4]: https://en.wikipedia.org/wiki/Urchin_barren

Unfortunately there is a glaring omission in the article.

Did he throw them like a frisbee, boomerang, baseball? some other way?

Disappointing to say the least.

Watch the video

How quickly did the starfish return? He only removed them every other week. How many needed to be removed each time? If he had to remove a similar number each week as he did on the first, the message is that the removal isn't effective. If they were coming back within days/hours his results might be coincidental. Shorelines are dynamic places. Even with a control area a few meters away, he might have been witness to a natural change at that location.

Also, pity the poor animals on the sharp end of "kick it and see" experimentation. This is not something to be applied to what my land use prof called "cute cuddly megafauna".

Did you actually read the whole article? That was just the first experiment. The keystone species hypothesis has been confirmed time and time again all across the globe, and it's a widely-accepted theory these days (to the extent where I, someone who's never studied ecology, already knew the theory and was surprised that it was developed so recently and was controversial when it was proposed).

I don't debate the keystone species concept, just the methodology of this particular experiment. If this was new science today, I'd probably be on the side of people ripping it apart and dismissing any results as untrustworthy.

If you want all the details, maybe you should read the actual study before criticizing someone who did a good study, but you're too lazy to realize it.

> How quickly did the starfish return?

From wikipedia:

> Most starfish cannot move quickly, a typical speed being that of the leather star (Dermasterias imbricata), which can manage just 15 cm (6 in) in a minute.

So if they managed to spend all their time moving, none of their time feeding, and moved only in a straight line, and never fatigued, they'd move 1.5km in a week. But even if his intervention wasn't completely successful, how do you propose to explain the variation between experimental and control treatments?

I don't suggest that the thrown starfish are returning, but perhaps that others nearby might be moving into the test area. But it would have been interesting to tag them and see if they were in fact coming home

The use of a nearby control, or for that matter any control, is based on the assumption that absent the differential treatment there should be no observed change. I'd say that in selecting a pair of control and experimental areas one should first monitor them over a significant period of time to establish that they are stable or at least similar enough. Otherwise a change that was inevitable in one but not the other will appear to have been the result of the experiment.

I'd want to see more samples and some sort of region-wide survey to establish whether the baseline populations are in flux region-wide.

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