Wednesday, October 19, 2011

Fall in the Spring

It's fall... which means time for a little spring work. This past week was our annual habitat and fish monitoring at Colvard Spring in north Georgia with our awesome friends at the Conasauga River Alliance, Georgia Department of Natural Resources, and the Nature Conservancy. And since the weather stayed warm, we also got to work on our underwater photography skills! Here are a few pictures from our trip:

Coldwater darters (Etheostoma ditrema) are shy, but seem be responding well to changes in vegetation type and abundance. 

In our fish sampling yesterday, we caught 464 darters--more than we've seen in Colvard Spring before!

Silt is still thick in some parts of the spring...

but is replaced by slightly coarser particles where spring upwellings blow the fine silt away...

 or around the bases of some of the clumps of vegetation (here, a Ludwigia sp.). A mix of stonerollers (Campostoma oligolepis), creek chubs (Semotilus atromaculatus), and orangeside dace (Rhinichthys obtusus) are milling about in the foreground.

One notable change this fall has been an increase in filamentous algae; here it's growing on muskgrass (Chara), sticks, and exposed rock. The floating clumps at the surface are algal mats that have floated free and are decaying.

The algae can look almost otherworldly... The small fish near the surface are western mosquitofish (Gambusia affinis), which are the most abundant fish species in the spring.

A happy TNACI team at the end of a long field day.  If you'd like to see more pictures from our field work at Colvard, check out our Facebook photo album!

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