Squid, Wolves, And Global Warming
    By Danna Staaf | November 16th 2009 08:10 PM | 9 comments | Print | E-mail | Track Comments
    About Danna

    Cephalopods have been rocking my world since I was in grade school. I pursued them through a BA in marine biology at the University of California...

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    The Associated Press, that bastion of scientific knowledge, shares with us a list of "pests that are benefiting or could benefit from global warming", starting with:
    _Ticks that transmit Lyme disease are spreading northward into Sweden and Canada, once too cold for them.
    _Giant Humboldt squid have reached waters as far north as British Columbia,
    threatening fisheries along much of the western North American coast.
    Do they always use underscores as bullets? Anyway, it's nice to see my study organism make the top five, er, six. But in my opinion, when people ask about the squid range expansion--"Is it global warming?"--the only scientifically rigorous answer is "Maybe."

    Clear-cut cases of range expansions and invasions due to rising temperatures certainly exist. But with our currently limited knowledge, the Humboldt squid isn't among them. The range expansion is itself a documented definite, but we're still trying to figure out the cause(s). By "trying," I mean my colleages are gathering and crunching data every day--catching squid, downloading information from satellites, and running statistical analyses. It's an active, exciting research area precisely because we don't have the answer yet.

    At this weekend's meeting of the Western Society of Naturalists, a great many excellent talks addressed climate change impacts, from the individual organism to the ecosystem. But there was also an awareness of the need not to turn climate change into a scapegoat for all ecological disasters. One speaker in particular cautioned that we must be certain that the impacts we ascribe to climate change aren't caused by some other disruptive factor--of which there are many. Amid a frenzy of climate-change activism, one mustn't yield to the temptation to cry wolf!

    Speaking of wolves, one of humanity's most pervasive impacts on the planet is the reduction or complete elimination of large animals, particularly predators. The gray wolf once ranged throughout North America. Now, as the result of widespread extermination efforts, it's almost completely gone from Mexico and the continental US.

    Setting aside aesthetic appreciation, why should anyone care? Here's one reason:

    Wolves eat deer. In the absence of wolves, deer populations explode. With the sudden abundance of deer, ticks have a field day. With the proliferation of ticks comes an outbreak of Lyme disease.

    Is it really that simple? Probably not. And climate change could have a big effect, too. But it's not necessarily the whole story.

    Similarly, the Humboldt squid invasion (see, I am bringing it back to squid!) could be influenced by both direct (overfishing of squid predators) and indirect (climate change) ecosystem changes.

    So, maybe the lesson is to cry "wolf!" and "fire!" at the same time?

    Or maybe I just wanted an excuse to post this awesome painting by Michelle Miron:


    What is their basis for classifying the Giant Humboldt Squid as a "pest"?
    Robert H. Olley / Quondam Physics Department / University of Reading / England
    My guess is the 'pests' definition comes from the squid habits of always stealing the TV remote, leaving the refrigerator door open after getting a beer, and forgetting to fuel up the car when they use it.

    Oh, okay, it probably comes from their statement that squid 'threaten fisheries'.  Sadly, I think 'pest' too often means "something we can't eat", with possibly an additional "and isn't cute".  Which totally ignores any real role they may have in the ecosystem.

    For example, some ranchers deem wolves 'pests' because they affect the rancher's livelihood if they kill sheep.  However, as Danna's article notes, wolves surpress the deer population and thus have a useful role.  So the word 'pest' is way too broad to have any useful meaning.

    Alex, next door at the Daytime Astronomer
    Danna Staaf
    Well said! I mean, in addition to leaving the gas tank empty, they are voracious predators, so the concern that they might be eating significant quantities of "our" fish is quite reasonable.

    In this case, though, the "pest" is itself edible. There's already talk of implementing "pest control." in the form of aggressively fishing Humboldts out of northern waters.

    I think I'd say "invasive" is biological terminology, while "pest" is socio-economic.
    The term "pest" is an anti scientific conception. It has absolutely nothing to do with evolution or ecology.

    Real science would tell you that evolution doesn't care about the lifestyle of its creatures, or how they affect other creatures. They are all just beings trying to spread their genetic materials.

    It is the Gaia worshipers who tell us that some life is more equal than others.

    Fossil Huntress
    A whack (and I do feel compelled to use the hard scientific terms here) of Humboldt squid washed up on the shores of Port Hardy recently. Tis true.

    Anyone whose been to this north island community will be sure to tell you it was not global warming that drove the charge but news of $2.00 pints and smoked salmon appies. As a cephalopod researcher, you'll surely confirm that the red devils known as Dosidicus gigas are aggressive drinkers who lose their minds at the first taste of fresh salmon especially when paired with the almighty brew. 

    Another great piece, Danna.
    Danna Staaf
    Thanks! I like whack as a collective noun, although for some reason I feel it might be more appropriately applied to moles...
    Nice pack of info

    Re: collective nouns - shouldn't it be a pod of cephaloes?

    To return to a more sane mode of ratiocination:
     is it possible that there is a connection between warmer waters and cephalopod chromatophoric communication?  My understanding of cephalopod chromatophores is that they are somewhat temperature sensitive.  If it is a given that squid language and breeding behaviour are strongly inter-related, and that the visual language is temperature sensitive, then water temperatures will have a predictable effect in delimiting habitats.  If any current habitats were once cool enough to inhibit, even moderately, squid mating communications, then that would suggest a link between current distributions and global warming.

    Are Humboldt squid migratory, like cuttlefish?  Researchers have found a positive correlation between relative abundance of cuttlefish and sea surface temperatures.  Could this have any bearing on your research?
    Danna Staaf
    Thanks for your thoughts! Cephalopod chromatophores are controlled by muscles and nerves, so I don't think they are any more or less sensitive to temperature than all of the other muscles and nerves in the cephalopod body. I would expect the major effect of temperature to be on metabolism and growth, not communication, but I would certainly be intrigued by any evidence to the contrary!

    We do think that Humboldt squid may be migratory, but exactly where and how far they go hasn't been fully established. I appreciate the cuttlefish article, it is indeed relevant, although the authors do emphasize that: "Local abundance shows a positive correlation with SST, although it is difficult to determine if this reflects any causal link." Always tricky, looking at correlations!