>I've written before about the creek that flows through my back
>yard, and how it dried up completely this year. Now we've had
>about 2 weeks worth of rain, and the creek is flowing again. Just
>this afternoon I netted a 4" creek chubsucker near my house. I
>wonder where he was hiding all this time? In a deep pool far
>downstream, or in a crawdad burrow?
Geesh...doesn't anybody read American Currents? :-(
The Spring 1999 issue contained this Riffles entry:
Deep pools may be source habitats for riffle fishes
A population study of the Ouachita madtom (Noturus lachneri) has led researchers
to hypothesize that the large, deep pools in which fishes congregate during
droughts are critical "source habitats" for the entire stream. Working in three
Arkansas streams during August, the researchers counted the numbers of madtoms
(and associated fishes) in shallow, drying riffles, and the numbers in the
deeper pools that did not dry out. They found that substantial numbers of fishes
did not seek deeper waters as riffles dried up; instead, they remained behind
and died, some from desiccation, others from predation (e.g., cottonmouth
snakes). Since these sections of streams were then recolonized during the rainy
months of fall, the researchers conclude that the fishes that do seek the deeper
pools are the reproductive source for the entire stream. The researchers warn
that land management practices that increase the sediment load may decrease pool
depth, thereby reducing the source habitat for riffle dwellers. (Source: Copeia,
1998, no. 4)
Chris Scharpf
Baltimore
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