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Monday, August 9, 2010

Knee-jerk hypothesis Monday

Happy Monday all ya'll.

Today, I would like to share a haiku about coffee that I am making up on the spot:

Black coffee tastes great,
Makes me cheerful, and keeps me
 From killing people 

FYI - while I was only innocently counting the syllables on my fingers, I have found that if you mutter "" while staring at your moving fingers, your co-workers will leave you alone.

Lots of interesting news has accumulated over the past few days.

Let's start off with something that should make everyone happy: the Fraser river sockeye returns are strong so far. First Nations fisheries and recreational fishermen are getting in on the action, and the commercial fishery has opened for the first time since 2006. It is doubtful that anyone is giddy, of course - all of this is going on in the shadow of last year's epic collapse, after all. Still, the important early summer run is now projected at 1.6 million - more than double the preseason projection. One potential bit of trouble looms for the returning salmon, however: water temperatures in the Fraser are more than one degree higher than normal and are approaching levels known to impede migration and cause mortality.

Warming water is, of course, one of the climate change effects that is expected to present significant trouble to marine organisms. Recent research out of the University of British Columbia shows that at least one kind of fish may be capable of handling severe temperature changes: sticklebacks taken from marine waters, which are adapted to a narrow range of temperatures, needed only three generations to become as cold-tolerant as their freshwater cousins. The report's authors found that the third generation of previously-marine sticklebacks were able to handle waters 2.5 degrees C colder than the original generation, representing extremely rapid evolution. The authors caution that the results cannot, for many reasons, be taken to suggest that other species may be able to evolve as rapidly to warming water.

While the authors of the stickleback report attribute the stickleback's capacity for rapid evolution to the species' genetic diversity, the authors of a recent paper from another set of B.C.-based scientists - this time based at the University of Victoria - report that their review of existing literature shows that  coral reefs in protected areas are less resilient to the bleaching effects of warming water, compared to reefs in areas that are not protected. This despite the tendency of protected reefs to have greater species diversity than non-protected reefs. In the non-protected areas, fast-growing, stress-resistant 'weedy' corals dominate, whereas protected areas harbor corals that are not tolerant of stress. The authors report that proportionally more of the protected reefs are damaged by bleaching, presumably because the protected reefs contain species that are sensitive to disturbance while the non-protected reefs have had their sensitive species helpfully removed by various human activities.

The results of the coral reef paper seem to be a surprise, because diversity is generally believed to make species and/or ecosystems more resilient to change. This relationship was recently demonstrated in a recent and well-publicized study that I just haven't gotten around to mentioning yet - a group of scientists, most of whom hail from the University of Washington, studied the famed Bristol Bay sockeye salmon complex and found that the genetic and behavioral diversity of the hundreds of distinct sockeye populations buffered the overall Bristol Bay sockeye complex against the effects of population-level variations. In other words: because there are hundreds of different populations, with different traits, in the Bristol Bay sockeye complex, whenever some populations are not well-adapted to a change in conditions and are therefore reduced in number, other populations are likely to rather enjoy the new conditions and thrive as a result. The authors of this study calculated that if the Bristol Bay sockeye all belonged to the same population, the fishery would close ten times more often than it does. The authors are pretty clear: the stability of this fishery over the years owes a lot to the diversity within the sockeye themselves.

So which is it? Does diversity lead to stability in the face of change, as the stickleback and sockeye studies seem to demonstrate? Or does it sometime lead to less stability, as the coral reef study seems to suggest? (it's worth pointing out that the two fish studies deal with genetic diversity within a species, whereas the coral reef study likely deals with coral species diversity).

Well, allow me to unleash installment #1 of JD's On-The-Spot Hypothesis That I'll Never Test:

I, JD, operating from a position of total naivete and unwillingness to do the legwork, hereby hypothesize that the 'weedy' corals that apparently fare better against bleaching do so because they have access to more-diverse symbiotic algae, relative to that associated with the less stress-resistant coral species found in protected areas. In other words, the coral study appears to show that coral reefs with less coral species diversity do better against bleaching - but I'm saying that those unprotected reefs do better because their 'weedy' corals actually have access to more diversity in their symbiotic algae, and it is the diversity in the symbiotic algae that makes them more resilient to bleaching.

Is there anyone who reads this who knows what they're talking about and would care to take a whack at this stupid idea?

1 comment:

  1. John, I just wrote a long and learned response to your hypothesis, which was unfortunately erased when I signed into google groups to post. Suffice it to say it would have changed the course of scientific thinking on this topic.

    Long live the knee-jerk hypothesis!