Bioassessment at South Skunk River

Communications Assistant Bryce Garman and Conservation staff, Sara Carmichael, Brandon Clough, and Jacob Reischauer, along with staff from the State Hygienic Lab, conducted a bioassessment on the South Skunk River at the Osheim Prairie and Slough Preserve. This 3-4-hour process gives us a better understanding of the health of our waterbodies.

We began the morning by taking a short hike through Osheim Prairie to get to the area of the South Skunk that we were assessing. After arriving at the location, the first thing the State Hygienist staff did was collect water samples to test. They are testing for things such as nitrates, phosphates, and dissolved oxygen.

We then began the hunt for Benthic Macroinvertebrates (aka bugs even though Brandon will say they aren't bugs). Identifying species that are in the South Skunk helps in determining the quality of the stream. We found a mixture of pollution tolerant and pollution intolerant species. Pollution tolerant means they can live in a waterbody with lower water quality standards. These would be species such as bloodworms or leeches. Pollution intolerant means the opposite and those consist of species such as mayfly and stonefly larvae. We collected samples along the vegetative banks and through the riffles and woody debrief debris to complete the full sample.

The most exciting part of the day - fish collection (aka fish shocking). We split up into two groups. Two people carried the electrical backpacks and shocked the fish, while two others followed with a net to catch them, and then two others carried buckets to hold the fish. I was indeed a bucket holder! We began walking upstream, shocking the fish in our path, so we could count the number of each species. At the conclusion of the section of stream, we counted over 100 fish and around 18 different species.

The last part of the day consisted of studying the physical habitat of the stream. We started downstream and moved upstream, taking ten different transects. A transect is a line or path that is used to make standardized observations and measurements of a landscape. We were looking at bank vegetation, what the substrate (bottom of river) is made of, depth of water, and how much sunlight penetrates through the trees to the water.

Bioassessments in the county are completed once a year and all data is analyzed at the State Hygienic Lab. Results of the macroinvertebrate samples, fish samples, and water samples will be available later this winter. To see previous bioassessments in the county, or throughout the state, visit the BioNET website through the Iowa Department of Natural Resources.