Re: NANFA-L-- Sculpin temperature tolerance

Lori Austin (providentaustin at yahoo.com)
Thu, 15 Sep 2005 18:03:21 -0700 (PDT)

Michael,

Nice find. Probably a combination of "local conditions and tolerance" and what Gerald indicated about groundwater patches. Most of my favorite riffles on the Little Muskingum River are but a trickle with patches of isolated pools. Some of these pools are toasty while others feel icy cold. Like Gerald mentioned, sculpins found in the warmwater streams are likely honing in on these cooler areas. But, in alignment with your find...a sculpin from the Mad River (cold water) may not due as well as my sculpin from Big Darby (warmwater). Another example ... "latitude"...Becker..Fishes of Wisconsin (northern distribution)..he makes note of a population of lake dwelling mottled sculpin that inhabit the shoreline where temp. rarely exceeds 82.(? I don't have the book in front of me) I take that to mean that at some point this northern population may be exposed to "the high end" and continues to survive.

However, now with all this talk my 78 degree sculpin refused his first earthworm today. ??

(PS - This is my last email under "Lori", I will work on getting my own later on tonight)


Michael Sandel <kwksand at yahoo.com> wrote:
Hey Todd and others,

This information was posted by Dave Neely in 1997. The species are probably comparable in adaptability, but individual gene expression is controlled by local conditions. i.e.- an individual raised in a warm stream is probably more heat tolerant than an individual from a cold stream, regardless of latitude or species.

Steve Walsh et al. (1997) examined the thermal tolerance and metabolism of
several sculpin taxa from the SE US.

Sculpins were held at stepped acclimation temperatures of 10, 15, 20, and 25
deg C for between 2-72 weeks, then tested for critical thermal maxima
(defined as the temp at which fish would not right themselves after being
flipped over), and metabolic rates.

They did not find intraspecific differences in thermal tolerance between
Tallapoosa sculpin, banded sculpin, Ozark sculpins, or "mottled sculpin"
(they used "smoky sculpins" from the upper Etowah). Pygmy sculpins and
mottled sculpins had lower critical thermal maxima than all other taxa
examined. All species examined exhibited significant differences in
temperature tolerance across acclimation temperatures, suggesting that
localized populations which are used to high temps would be more able to
withstand such conditions in aquaria.

The complete citation for those interested parties is:
Walsh, SJ, DC Haney, and CM Timmerman. 1997. Variation in thermal tolerance
and routine metabolism among spring and stream-dwelling freshwater sculpins
(Teleostei: Cottidae) of the southeastern United States. Ecology of
Freshwater Fish 1997(6):84-94.

best,
Dave
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