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Subtle Pollution Evidence In The Tallapoosa River, Alabama

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#1 Guest_fundulus_*

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Posted 14 July 2008 - 08:16 PM

Our stippled studfish (Fundulus bifax) project went out last Friday on a swing through streams in the southern tier of Cleburne County, Alabama, SE of Anniston near the Georgia line. This is in the Tallapoosa River drainage that begins in Georgia and runs SW through Alabama. This area is apparently a gap in the known distribution of stippled studfish, which we and others have found downstream in several Alabama counties and their former range upstream in Georgia where they haven't been seen in ten years or more. We hit six creek systems in all that day, and found no stippled studfish although we found other interesting species like bandfin shiners (Luxilus zonistius) and streamline chubs (Hybopsis dissimilis). What we've found to date is that stippleds are very particular in their preferred habitat, which is sandy substrate in very clear, clean water with no nutrient overload and thus no significant algae. The species has been found in the Tallapoosa River on occasion, which in principle could work as a connecting stream between all of the tributaries where we've found stippled studfish to date. And on Friday we sampled the Tallapoosa itself for the first time, since we found a site with easy access and wadable water.

The knock on the Tallapoosa coming out of Georgia is that it's eutrophic, and only loses that nutrient load further downstream after the river runs through a reservoir in Wedowee, Randolph County. So it was interesting to see a site on the eutrophic stretch of the Tallapoosa. The water was clear, but heavy growths of algae were found on the substrate even in areas of heavier current. This stretch of the river couldn't support a breeding population of stippled studfish, since the species requires very clean sand in which to deposit eggs and allow the eggs to develop and hatch (Joe Scanlan described this breeding strategy in a recent article in American Currents). If this is true of this stretch of the river, and I'd guess that it is, that means the Tallapoosa itself can't sustain stippled studfish except in the sense of an occasional connecting path between such tributaries as can still support breeding populations. And this implies increasing genetic isolation of these isolated populations over time.

Anyway, here are two photos of the Tallapoosa River where it's crossed by Highway 46. A public boat ramp next to the bridge allows free access. Notice the dark greenish blobs on the substrate in the photos, which result in a whole bunch of green hair algae in the net if you pull a seine through it. So the river looks good at first, and we netted lots of fish from it, especially centrarchids, but the river has been significantly altered by sustained nutrient overload.


#2 Guest_fundulus_*

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Posted 16 July 2008 - 03:23 PM

A correction: the Hybopsis species we found was the lined chub, H. linneapunctata rather than H. dissimilis. Hopefully no one got too excited about that...

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