Macroinvertebrates are animals without a backbone that can be seen with the naked eye. These bottom-dwelling animals include crustaceans and worms but most are aquatic insects. Beetles, caddis flies, stoneflies, mayflies, hellgrammites, dragonflies, true flies, and some moths are among the groups of insects represented in streams. Macros are an important link in the food web between the producers (leaves, algae) and higher consumers such as fish. Virtual Stream Macroinvertebrate Investigation (You might want to make brief notes as you read through the power point. You do NOT have time to write every word!!)    

Common Stream Macroinvertebrates Macroinvertebrates are often used as one of the primary indicators of water quality. Some macroinvertebrates, such as stoneflies, mayflies and water pennies, require a high level of dissolved oxygen and their abundance is an indication of good water quality. Other macroinvertebrates can survive at a lower dissolved oxygen level because they can come to the surface to get oxygen through a breathing or "snorkel" tube or carry a bubble of air with them around their bodies or under their wings. Several species of macroinvertebrates are indicative of water systems with lower dissolved oxygen levels and include aquatic worms and leeches. Lower dissolved oxygen levels are often associated with polluted waters while higher levels indicate good quality water.

Organisms are collected, sorted and counted. The identity and classification of each type of organism is used to deteremine water quality.

Why are macroinvertebrates good indicators of water quality? There are several reasons why macroinvertebrates are used as water quality indicators: They are sensitive to changes in the ecosystem. Many live in an aquatic ecosystem for over a year. They cannot escape changes in the water quality. They can be collected very easily from most aquatic systems with inexpensive or homemade equipment.

Macroinvertebrate Water Quality classification Class I Pollution intolerant : These organism are highly sensitive to pollution and lower dissolved oxygen (dO2) levels Class II Somewhat pollution tolerant: These organisms will be found in clean and slightly polluted waters. Class III Pollution tolerant: These organisms will be found in polluted, as well as clean aquatic ecosystems Macroinvertebrates are divided into three classes based on their tolerance for low levels of dissolved oxygen and pollutants within their aquatic environment. Class one (I) organisms are highly sensitive to low levels of oxygen, class two (II) organisms are somewhat sensitive and class three (II) organisms can survive low levels of oxygen. A healthy aquatic environment will contain organisms in all three classes while a oxygen depleted polluted aquatic environment will only have organisms in the class three category.

The organisms and the numbers of each that were collected are in the following pictures. Not all the organisms listed in the data table will be found in the “virtual stream”. Use online keys from various websites (links found on next slide) to identify the organisms found in the “virtual stream”. You may also use any other online resources to identify the organisms. After you identify each organism, fill in the data table and calculate the biotic value for each organism and then calculate the total biotic value for the virtual stream. Use the total biotic value and infer the water quality of our “stream”. The organisms in this power point were found in a small section of WWCHS’s “virtual stream”. A representative of each of the organism is shown and the number of each type of organism collected was recorded.

Links to several online identification keys/websites http://www.stroudcenter.org/education/MacroKeyPage1.shtm http://vitalsignsme.org/macroinvertebrates http://www.bae.ncsu.edu/programs/extension/wqg/srp/taxonomy/dichotomous_key.pdf

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Class I Biotic Value Number found Total biotic value Class II Class III Biotic value Stonefly 10 Beetle larva 8 Midgefly larva 5 Mayfly Sowbug Snails 4 Dobsonfly larva Scud 6 Leech 2 Caddisfly larva Clams, mussels Aquatic worms Riffle beetle Crayfish Water penny Cranefly larva Dragonfly nymph Damselfly nymph Black fly larva Total value

Calculating Biotic Value – Show all you calculations and NO CALCULATORS Total Biotic value = biotic value x # of organisms Total = sum of biotic values for each class Biotic index = total / 10 Divide by 10 because this is the highest biotic value obtained by macroinvertebrates Biotic Index/Water Quality >70 Excellent 60-79 Good 40-59 Fair <40 Poor

Conclusions: Answer each question in complete sentences on the back of your data table. Use DATA when appropriate What is the overall water quality of our virtual stream? Give 3 reasons macroinvertebrates are good indicators of water quality? How are macroinvertebrates collected? Would you expect to find organisms from each class of macroinvertebrates in a body of water with good quality? Explain why or why not. Would you expect to find organisms from each class of macroinvertebrates in a body of water with poor quality? Explain why or why not. Predict at least 3 specific macroinvertebrates that you might find if you sampled the following aquatic environments: Fast moving moutnain stream in a National Forest River near a sewage treatment plant Shallow slow moving stream that runs through a city neighborhood