Stonefly Search 2015 Wrap Up
A Surprisingly Pleasant January Day
You never know what a Michigan January will bring; last year HRWC was forced to cancel the Stonefly Search because of sub-zero temperatures and blizzard conditions. But this year, on January 17, 125 intrepid volunteers enjoyed bright sunshine and 30 degree weather as they spread across the Huron River watershed. They were in search of stoneflies, which are only found in clean and healthy streams. Everyone made it back safe, and not a single leaky wader was reported! Overall, it was a great success!
The results are in, and are given in this pdf report.
What We Found
1. Usually when we look at the data after an aquatic bug search, we see that some sites do better than normal, some sites do worse, but most sites stay the same. This was a strange year because while most sites stayed the same, several did worse than normal, and none did better. Overall, the count of stonefly families was down about 10% from our last sampling event (2013). There is no clear explanation for this; weather conditions were great and the ice wasn’t any thicker than other year. We will start to be concerned if we continue to see this happen year after year. However, there is always natural variation in the data and collecting and this year will likely not be the start of a downward trend in terms of the overall sampling.
2. That being said, there are specific locations that have shown long-term degradation. For example, Honey Creek in Ann Arbor. The team searching for stoneflies in Honey Creek at Wagner were unable to find stoneflies. This site has been sampled 14 times since 1995, and this is the first time that stoneflies could not be found. This is a site with lots of turbulent highly oxygenated water and should be a great place for stoneflies. Taken in isolation, the absence of the stoneflies at Wagner Road would not be concerning given that this is a single sample. However, two upstream Honey Creek Adopt-a-Stream sites used to have stoneflies but haven’t in years. Stoneflies haven’t been seen in Honey Creek at Jackson Road since 2008; they haven’t been at Honey Creek at Pratt Road since 2003. All of the pieces combined indicates that the overall quality of Honey Creek is degrading over the last decade.
3. Davis Creek at Pontiac Trail is another location where the stonefly population has dropped over time. This change is concerning because it happened slowly over the last ten years and our spring and fall samples show a very similar pattern. In the early 2000s we regularly found one or two stonefly families at the creek, but they started to drop off and now have not been found since 2009.
4. All this doom and gloom needs to be put in perspective, though. Remember, most of the sites we visited were as healthy as ever. Of the 61 Adopt-a-Stream sites that HRWC uses to assess the overall water quality of the watershed, stoneflies are regularly found at 38 of them. In other words, 62% of our watershed has very high water quality and habitat. This agrees with recent analyses of other HRWC data, showing that 66% of the watershed was good to very high quality, 28% was fair to good, and 7% was highly impacted (2014 State of the Huron)
Next on the horizon!
Interested in doing more with our macroinvertebrate searches? Think about becoming a trained leader or collector by coming to the next training on March 29. This is an extremely important job because every team needs both a trained leader and collector, and we often do not have enough to meet the demand. Sign up for the training!
