Kelly Manktelow: Macro-invertebrate collection using Hester-dendy

Measuring depth at the location of a Hester-dendy

On August 1, Jesse Bolli and myself set out a total of 14 Hester-dendy samplers in Cub Creek. They were placed at two different sites, with 7 being placed at each site. A Hester-dendy is a sampler made of 7 tempered masonite plates on a long bolt with some sort of spacer between the plates and a wing nut at the end of the bolt (see photos below). These are used to collect macro-invertebrates in steams with a silty substrate. If Cub Creek had a rocky substrate then it would be possible to collect the macro-invertebrates from simply turning over the rocks, but the lack of rocks then requires the use of the Hester-dendy sampler to provide a living space. The Hester-dendy sampler is placed it the stream for a month to allow the macro-invertebrates time to take up residence on them before they are collected. Water Quality data including depth at each placement site, along with pH, conductivity, turbidity, dissolved oxygen and temperature were taken when the Hester-dendy samplers were deployed on Aug. 1 and when they were collected on Aug 30. Water samples were also collected and used to test the level of e.coli. The e.coli test is performed by placing 1ml of the water sample on petrifilm and placing in a moist incubator for 24 hours.

On August 31, I set out with Ranger Jesse Bolli and SCA Molly Watters to collect the Hester-dendy samplers. We placed each Hester-dendy in a container, along with some of the creek water and transported them back to the maintenance area at the monument. Once we collected all 14 and took water quality data at all of the sites (except one, since the water level of Cub Creek dropped and left the Hester-dendy out of the water) we could take them apart and collect the macro-invertebrates into containers. The method used to collect the macro-invertebrates required one person to work on only one site's Hester-dendy at a time. We would place a sieve in a bucket and pour the water from the container and the hester-dendy into it. We then unscrewed the wing nut holding the plates together and using water pressure and soft brushes rinsed all macro-invertebrates into the sieve. After removing as much detritus as possible we were ultimately left with all of the macro-invertebrates that were living at that site in the sieve. They were then placed in a bottle, filled with alcohol and labeled with the site ID and date. These bottles will be shipped to the Heartland Monitoring Network for identification and this info along with the water quality data collected at the sites can then be used to help determine how healthy Cub Creek is.
For more information about the Heartland Monitoring Network please visit: http://science.nature.nps.gov/im/units/htln/