An Ecosystem Approach to Pollution

This summer my research team and I explored the possibility of restoring Wild Rice in the Red Cedar watershed.  We dove into this topic because aquatic vegetation has the potential to change phosphorus dynamics in the water, possibly locking up some of the excess nutrients—those same nutrients that cause the toxic cyanobacteria blooms each summer.

One of our Wild Rice study sites

 Aquatic plants have a complex relationship with phosphorus: they take it up during the summer months when cyanobacteria blooms are most problematic; slow water velocity, allowing for nutrients to settle into the sediment; and hold sediment, along with the nutrients in it, in place with their roots.  Essentially, plants shape their environment and have the potential to help regulate nutrient levels in the water column.

We choose to focus on Wild Rice because it is a native plant which is historically significant to the area.  According to literature from the beginning of the 20^th century, Wild Rice once flourished in the Red Cedar Watershed.  During that time, the plant was an important food source for Native Americans.  Today, Wild Rice is still harvested each fall in Minnesota and parts of Wisconsin.  In an age where people are becoming more mindful of local food, having a native grain as part of the ecosystem is an exciting prospect.  Beyond human use, Wild Rice is also important for the ecosystem since it offers a food source for wildlife.

Today, Wild Rice is no longer common in the area, so our research focused on assessing the barriers and possibilities of restoration in the Red Cedar Watershed.  We hoped to identify factors which would be useful for successful re-seeding efforts.  To do this, we studied five wild Rice sites in the surrounding counties.  One site was in the Watershed, while the others were in adjacent watersheds.  We investigated some of the environmental conditions in the rice beds in addition to the adjacent land use.  Our aim was to decipher why Wild Rice grows there and not here.

Although our study and the literature on Wild Rice did not definitively identify why Wild Rice is no longer present in the watershed, we have some clues.  The plant’s decline likely results from a myriad of inter-related factors.  It boils down to human impacts on the landscape.  Damming of the rivers, wave disturbance from boats, invasive species and shoreline degradation are key suspects.  In addition, climate change will likely have a devastating effect on the species; with increased frequency and severity of storms, we can expect more Wild Rice to be uprooted from wind and flooding.

  Despite these concerns, I am still optimistic about restoration efforts in the Red Cedar Watershed.  Two of the sites we assessed were attached to nutrient rich eutrophic lakes.  We also found highest density of Wild Rice in organic rich river muck.  This suggests that Wild Rice can tolerate high levels of nutrients, like what we see in the Red Cedar Watershed.

 Nevertheless, there are still limitations with reestablishment here.  The dams which create Lakes Tainter and Menomin hold water levels at an artificially constant level.  Wild Rice may do better with a slight seasonal draw down during the winter months, this would provide the plant a competitive advantage over native perennials like cattails which need year-round saturation.  However, far more research would have to be done to understand how to best manage dams for the entire aquatic ecosystem.  It would be foolish to draw down dams and kill off aquatic perennials before we have a reseeded Wild Rice bed to take its place.  Previous researchers have also found that Wild Rice is sensitive to waves.  Waves from motor boats could potentially uproot stalks during their summer growth.  This issue could be resolved with no wake zones to protect shoreline vegetation.  Researchers have also shown that Wild Rice is sensitive to land use and does not do well in areas of higher urban development.  Although the Red Cedar watershed does not have a large proportion of urban areas, precautions can still be taken to ensure that development is as low impact as possible.  Good shoreline zoning and development regulations are tools which could be used to protect sensitive aquatic plants like Wild Rice.

Ultimately, we have scratched the surface on the dynamics at play in a Wild Rice ecosystem.  Further research is needed to truly understand what restoring Wild Rice in the Red Cedar Watershed might look like.  If I have learned one thing this summer, it is that natural ecosystems are incredibly complex.  Relationships are not linear, but instead interwoven and compounding.  It is this inter-relatedness that makes losing one species on the landscape so damaging; it is truly a loss to the entire ecosystem, upsetting the natural balance.

Therefore, I believe that restoring native ecosystems has great potential in mitigating the phosphorus problem; an ecosystem in balance has greater resilience and is better able to adapt to exterior changes such as excess phosphorus loading.  Wild Rice is by no means the answer to the problem, and more research needs to be done on the nutrient cycling of the plant, however, I think that ecosystem restoration is one of a suite of solutions which together can make the watershed more beautiful and vibrant.  

We need to take a holistic, long term approach to this problem.  This means both reducing the initial phosphorus inputs that are added through runoff and erosion and dealing with the legacy phosphorus that has accumulated from years of inputs.  One of the most difficult components of this problem is that it is not a quick fix, we cannot simply “solve” it and move on.  Instead we have to adapt our mindset about the lakes; the cyanobacteria is not a problem we have to fix, rather the lakes are a resource we should protect and take care of.