Cullman County SWCD Conducts Biology Field Trip at Wallace State

by Johnny Grantham, Cullman County Soil and Water Conservation District, Cullman, AL

In March, Cullman County Soil and Water Conservation District Water Quality Technician Bob Keefe took Mrs. Connie Brien’s Wallace State College Biology 101 class on a field trip to Thacker Creek, in southern Cullman County, to conduct a bio-assessment survey of the creek. The purpose of this trip was to show the students some of the "critters" that inhabit our aquatic ecosystems in this area and how they can help us assess the purity of the water in which they are found. The bio-assessment concentrated on macro-invertebrates; organisms without backbones  which are visible to the naked eye, such as various insect larvae (stone fly, mayfly, dragonfly, etc), snails, crayfish, mussels, and worms.

The first hour was spent in Mrs. Brien’s classroom covering some basic stream dynamic information, "critter" identification and classification procedures, and the sampling method to be used. Then the class traveled about 10 minutes from the college to Thacker Creek and spent the next two hours catching and classifying macro-invertebrates.

The class broke up into three groups each with a kick net and began to sample the riffle areas where the macro-invertebrates are generally found. One or two students held the net firmly on the creek bed while another went upstream and gently kicked the creek bed above the net to discharge the macro-invertebrates from the rocks and float them into the net. Our goal was to collect at least 100 critters to identify and categorize.

Once the critters were collected in the nets, the students took forceps and picked them out one by one and put them into one of three water filled containers labeled 1, 2, or 3, based on a classification system which assesses each individual species’ tolerance to pollution. When all the macro-invertebrates had been removed and categorized, additional samples were taken until the desired number was reached. Then the critters in each container were counted by taxa, or similar species, and the information run through a matrix which gave the creek a Stream Quality Assessment rating of Poor, Fair, Good, or Excellent depending on the type and quantity of macro-invertebrates sampled.

The students ended up collecting 132 macro-invertebrates from 9 different taxa. Over 100 individuals were stonefly and mayfly larvae taxa which fall in Category 1, but the highest number of different taxa were found in Category 2. This resulted in a Stream Quality Assessment Rating of Good.  In the past Thacker Creek jad been listed by the US Environmental Protection Agency as an impaired creek (303d), but this survey confirms that it has been cleaned up and is in pretty good condition today.

This was an excellent practical learning experience for the class.  Both the students and Mrs. Brien were happy with the outcome and expressed hope that this can be an ongoing part of their biology education program at Wallace State College.

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