Eutrophication – Growing of Plants At the Wrong place

 

What Is Eutrophication?

Hello Foodies! Today’s topic is on eutrophication, which refers to an excess run-off of nutrients into a lake or body of water. These run-offs often contain high levels of nutrients, especially from diffuse sources, such as animal waste products and fertilizers. As a result, these rich nutrients, especially nitrates and phosphates allow for large amounts of plant and algae growth in the body of water (Ansari et al., 2010). This is done so as nitrates and phosphates increase the otherwise limiting level of nutrients in the body of water, which helps these plants absorb nutrients and improve the efficiency of photosynthesis (Chislock et al, 2013).

These large blooms in plants and algae often inhibit light penetration, thus reducing the growth or even causing mass die out of underwater plant lives. In other cases, these limited amounts of light can also affect predatory species which rely on sunlight to catch prey. Furthermore, harmful algae blooms and plants coupled with higher efficiency in photosynthesis can deplete dissolved carbon, competing with the original plant ecosystems. Moreover, when these dense algae bloom die, it can lead to mass decomposition, therefore leading to mass depletion of oxygen. Thus, this depletion of oxygen can lead to mass die outs in the area, creating a ‘dead zone’.

Furthermore, depending on the species of algae, some blooms can produce toxins, which not only affects the ecosystem as large amounts of the toxin is released due to eutrophication, but also decreases water quality. Often, these toxins cause the water to be unsuitable for consumption and for activity. Furthermore, the growth of phytoplanktons can also cause bad smells and harm water quality. Thus, these decreases in water quality can cause a big problem, especially when the water is consumed by humans as it can pose a large risk to human health (Chislock et al., 2013). Thus, often these waters have to undergo expensive water treatment before it can be consumed.

Case Study: Lake Erie, Ohio (United States)

Lake Erie, Ohio United States: Eutrophication

In this case study, we will take a look at Lake Erie, one of the five great lakes in North America. With the boom in agriculture after the 1970s, many farms transformed from small to industrial-sized. As such, many farmers in the area have employed more fertilizers, which was washed out during the frequent storms, into Lake Erie. As such, over 80% of the nutrients run-off into Lake Erie can be credited to agricultural runoffs from nearby farms.

Ever since the 1990s, a bloom has been prevalent in Lake Erie, especially during summer. With our earth warming due to climate change, these blooms tend to last longer and spread further across the lake. Furthermore, the cyanobacteria that were allowed to thrive during eutrophication have also decreased water quality. As such, many residents in Toledo, Ohio were advised to avoid the consumption of the water entirely, as the toxicity of the polluted water will only increase when boiled. Thus, raising high levels of health implications in the city.

Looking at the bigger picture, Eutrophication does not only take place in a single water-body but rather implicates areas further downstream as well. In the US, eutrophication not only takes place in freshwater lakes but also off the coast as well. As seen as the “red tide”, toxic algae blooms in the sea have the ability to wipe out the ecosystems and release toxic into both the air and water. Therefore, showing how nutrients can cause eutrophication not just nearby to the source but even as far away as the ocean (Hance, 2020). 

For more information on US Eutrophication, the guardian has a really nice article regarding this here 

Potential Improvement Techniques

As eutrophication is often due to human factors, it is important that better management of the use of nutrients is applied. I have mentioned these management methods in my pollution blog under the fertilizer pollution posts so in this post, we will discuss how we are able to further manage the rate of eutrophication.

Apart from minimizing nutrients flow into rivers and lakes through the reduction of fertilizer use, another method adopted is flow manipulation. As eutrophication is often a major problem during the hot summer months, the flow control of these nutrients can direct water that might cause eutrophication elsewhere, to eliminate nutrients released into water bodies (Tekile et al., 2015). This redirection can allow water to be treated, which reduces the chances of eutrophication after the water is released. Thus, giving us more control over the rate of eutrophication.

Conclusion:

In conclusion, eutrophication is a serious pollution problem with nutrients as its main source of pollutants. These pollutants tend to be diffuse-source pollution, where its impact can be felt far away, as seen in the case study, where harmful algae blooms can be located at the coast rather than further inland where the farm is located. Eutrophication also heavily affects water quality, as the growth and death of algae blooms and cyanobacteria release toxins into the water. Therefore posing a health risk when this water is consumed. 

It is important to know the source of eutrophication, as it helps us identify management techniques that allow us to reduce the impact and extent of eutrophication. However, as the main source of nutrients often comes from the use of fertilizers in agriculture, the management of the use of fertilizers is therefore essential in reducing the eutrophication of water bodies. Even though there are alternate techniques used to reduce the impacts, these flow manipulation techniques tend to be expensive and cause pollution and destruction of ecosystems in their development. Thus, it is imperative that we educate the farmers on what and how eutrophication comes about, their impacts, and how they can limit its growth. 

That brings us to the end of the first segment of agriculture. Till we meet again!

 

Detective Out,

Wen Hong

References

Ansari, A. A., Singh, G. S., Lanza, G. R., & Rast, W. (2010). Eutrophication: Causes, consequences and control. Springer Science & Business Media.

Chislock, M. F., Doster, E., ZItomer, R. A., & Wilson, A. E. (2013). Eutrophication: Causes, consequences, and controls in aquatic ecosystems. Nature. https://www.nature.com/scitable/knowledge/library/eutrophication-causes-consequences-and-controls-in-aquatic-102364466/

Hance, J. (2020, January 8). Lethal algae blooms – an ecosystem out of balance. the Guardian. https://www.theguardian.com/environment/2020/jan/04/lethal-algae-blooms-an-ecosystem-out-of-balance

Tekile, A., Kim, I., & Kim, J. (2015). Mini-review on river eutrophication and bottom improvement techniques, with special emphasis on the Nakdong river. Journal of Environmental Sciences, 30, 113-121. https://doi.org/10.1016/j.jes.2014.10.014

USGS. (2019, March 2). Nutrients and eutrophication. USGS.gov | Science for a changing world. https://www.usgs.gov/mission-areas/water-resources/science/nutrients-and-eutrophication?qt-science_center_objects=0#qt-science_center_objects

Pictures Obtained from:

https://www.nytimes.com/interactive/2017/10/03/science/earth/lake-erie.html

https://www.open.edu/openlearn/nature-environment/environmental-studies/eutrophication/content-section-0?active-tab=description-tab