South Atlantic Water Science Center - Georgia
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The Apalachicola-Chattahoochee-Flint (ACF) River National Water Quality Assessment (NAWQA) Program
ACF Study Design: Surface Water Biological sites
Biological samples were collected at least once a year at each of the indicator sites and at their respective comparison sites, and a measure of terrestrial and in-stream habitat made once during the period of study. The most intensive sampling effort was conducted at the six indicator sites. A stream reach 6-10 times as long as the average width that contained replicate examples of the various habitats (i.e. pools, riffles, overhangs, submerged logs) was defined. As cross-sectional areas for sampling were identified, care was taken to minimize disturbance of the cross section. Individual quantitative samples of macroinvertebrates and benthic algae were collected from potentially rich habitats such as cobble and gravel substrates in riffles, and depositional areas such as sand and mud in pools. Qualitative samples were collected from these same habitats and, additionally, from other habitats such as the surfaces of living or dead vegetation, root and leaf mats, and overhanging banks in an attempt to provide data on relative abundance, and to better define a complete species list. Fish were collected using techniques such as electroshocking, seines, dip nets, or combinations of these techniques that provided the most representative sample of the fish community. Measurements of in-stream habitat included stream width, depth, and velocity; size and distribution of substrates; amount and type of submerged and emergent vegetation; and estimates of the percent of pools and riffles. Measurements of terrestrial habitat included bank slope and stability; vegetation type, size, and density; and percent of cover overhanging the stream. A less intensive sampling effort was performed at the comparison sites to conserve funds and human resources. Priority was placed on the collection of a representative sample of the fish community; single, qualitative/semiquantitative samples of macroinvertebrates and benthic algae, and measurements of in-stream habitat.