Hester-Dendy Collection Plate Lab

Before you start, it will be helpful for you to know what a macroinvertebrate (pronounced mack-row-in-VERT-ah-brate) is. A macroinvertebrate is a small organism that does not have a backbone. You do not need a microscope to see one; they are large enough to see with the naked eye. The variety and the quantity of macroinvertrebrates in a given area can tell scientists a lot about the health of that water body-whether it is polluted or not. Their varied life spans (they live from a few months to many years) are long enough to evaluate the full effects of pollution on them, yet short enough for populations to respond relatively quickly to water quality changes. As an added bonus, macroinvertebrates can help scientists pinpoint polluted areas because they do not move around much, and can't escape to cleaner water.

Hester-Dendy sampler A Hester-Dendy sampler is a fancy word for “bug hotel.” Aquatic macroinvertebrates will colonize the spaces between the rough-textured plates of the sampler. Anchor the sampler to the bottom of the stream or suspend in the water column (different placements will attract different populations). Allow at least 4 weeks to attract a sizable population. Wrap a fine mesh bag around the sampler when you remove it to investigate. This will catch any macros that float off of the squares. Also, remember to flag your sampler so you can find it later.

Materials - Minimum of 4 large plates (made of wood, cement, unglazed porcelain or anything rough and durable) no more than 10 cm square and 3 cm thick. - 1 eye bolt 6 in long - 20 washers - 2 nuts - drill

Directions 1. Drill a hole through the middle of each plate the size of your eye bolt and washers. 2. Stack plates on the eyebolt and separate with washers. Place larger plates on bottom. Using the washers, vary the space between plates to provide for different habitats. 3. Secure the plates in place with a nut. Hester- Dendy Collection Plate Prelab Questions

1. What type of material were your HD plates made of? (3-ply plywood, 1x4 pine, pressure treated wood, etc)

2. Do you think the material you used will affect the types of animals you collect? Why?

3. What was the space in between your HD plates in mm?

4. Do you think the distance between your plates will affect what type of animals you collect? Why?

5. What were the dimensions of each your HD plates (Length x Width x Height)?

6. What is the total surface area of your Hester-Dendy collection plate in cm? Hint: To find the outside area of your plates you need to add up the area of each of the plate sides for each of the plates.

7. What do you think scientists use Hester-Dendy plates for?