Understanding Harmful Algal Blooms and their effects on our health, Gulf of Mexico

 What are algal blooms?

Algae is an aquatic microorganism found in all bodies of water, it appears as green, brown, or red depending on the type (National Institute of Environmental Health Sciences (NIEHS), 2021). Like plants, they contain chlorophyll and photosynthesize using sunlight as energy. Algae and Cyanobacteria (blue-green algae) are important microorganisms since they produce more oxygen than the land plants. In addition, algae form the foundation of aquatic food webs supporting a wide range of animals. An acceptable amount of algae is always present in water and it is used to gauge the health of the stream or body of water since it responds to changes in the environment (mywaterquality.ca.gov, 2017).

Algal blooms are excessive or rapid growth of the algae which can form a thick, foamy, or slimy layer on the surface of water. It smells bad, discolors the water and makes fish taste bad. This discourages people from drinking tap water and visiting beaches. The harmful algal blooms (HABs) also produce toxins and harm humans, animals and the environment by blocking sunlight, depleting the oxygen in the water and releasing harmful gases (Centers for Disease Control (CDC), 2022).

(EPA, 2022)

What are the causes of Algal Blooms?

Algal blooms are caused by many factors like: levels of nutrients, temperature of water, water flow and conditions.

The excessive use of fertilizers by farmers and home gardeners leads to overgrowth of algal blooms. The diagram on left helps to explain how runoff is carried into bodies of water. It is important to understand that all water runoff eventually drains into bodies of freshwater or ocean, thus any pesticides and fertilizers are carried along with it. High levels of nutrients like nitrogen and phosphorus come from: fertilizers used by farmers/home lawns, sewage from people and animals, runoff from cities and industrial waste and cause nutrient pollution in water. Which can lead to excessive growth of the algae.

                       (Researchgate, California, n.d.)

Temperature of water directly affects the growth of algae, warm temperatures increase the growth. Climate change can increase the growth of HABs, and cause blooms to occur more often and be more severe (CDC, 2021).

When water flow is low and water moves slowly such as during drought conditions, it can also lead to a rapid growth of algae in the standing water. Similarly, the conditions of the water can also cause more growth, such as clear water lets sun easily shine through the water and helps the algae grow. 

Prevalence of Algal Blooms

Algal blooms occur all over the U.S., usually during summer months. The occurrence of algal blooms has been increasing due to an increase in temperatures and nutrients from run-off (Lavery et al., 2021).The numbers and effects are expected to grow as the extent of occurrence continues to increase.  Some of the prominent algal blooms occur in the Chesapeake Bay in the northeast, Puget Sound area in the pacific northwest, and the Mississippi River Basin that empties into the Gulf of Mexico region (NIEHS, 2021). 

                                            (EPA, 2022)

It is a serious nutrient pollution issue that pollutes the drinking water supply, air and the environment. While the complete extent of the effects on health are yet unknown, 321 harmful algal blooms (HAB) related emergency room visits were reported for 2017-2019 (Lavery et al., 2021). The majority of these cases occurred during the summer months, and a large number of cases occurred due to a red tide algal bloom bloom event in the Gulf of Mexico during 2018.

(Roberts et al., 2020)

The One Health Harmful Algal Bloom System (OHHABS) was established in 2016, it is a voluntary reporting system available to state health departments. It collects data on human illnesses, animal illnesses, and environmental impact to help CDC and partners understand HABs and prevent human/animal illness caused by them (CDC, 2021). OHHABS reported 63 human illness and 367 animal illnesses in the most recent year, 2019. They also tested the HAB events for toxins, and reported that toxins were found in 53% of the events. The infographic below summarizes the data for 2019. 

 

                        (CDC, 2021)

How Algal Blooms affect our health, animal health, and the environmental impact

HABs can produce toxins which are harmful to human health and aquatic life. People, pets, aquatic animals can become exposed to the toxins by: drinking the water, eating the fish, swimming, and breathing the air from a HAB (NIEHS, 2021). The toxins are not killed by boiling the water, and cooking the seafood. Thus, it is important to not risk eating and swimming in a body of water that has blooms. The HABs specifically found in salt water can cause serious health effects like paralytic shellfish poisoning and lead to paralysis, vomiting, diarrhea, confusion, seizures, permanent short-term memory loss or death when consumed at high levels. Fresh water HABs that occur in lakes and drinking water sources contain liver toxins that can cause gastrointestinal illness and result in damage to the liver (NIEHS, 2021). Children and elderly people can be more susceptible to HAB toxins. Populations living in coastal areas that rely mainly on seafood diet are at risk of long-term health effects of low level exposures to HAB toxins. These long-term effects are now being studies by scientists since neurotoxic chemicals released by the HABs can damage brain function over time(NIEHS, 2021).

Algal blooms cause a thick layer of green or red on the surface of water and impact clear water. This leads to low penetration of light in the water and impacts organisms that live deep in the water. When the excessive amount of algae in a bloom dies, it uses up the oxygen in the water. The aquatic animals like fish die as a result of this lack of oxygen. These areas with low oxygen levels are called dead zones in ocean, the largest dead zone occurs in the Gulf of Mexico every year during summer (NIEHS, 2021).  

HABs have economic impacts as well as environmental impacts. The drinking water sources become contaminated and cleaning costs increase tremendously (EPA, 2021). The fisheries lose huge amounts of revenue when they are closed due to HABs. Property values are impacted if HABs are a common occurrence for the water front properties (EPA, 2021). 

There is a link between the issues of HABs, climate change, safe water, and food sources. Warming temperatures due to climate change increase the occurrence of HABs, which can harm the drinking water as well as seafood. Our interactions with the environment are leading to these serious issues with sources of water and food. There is an urgent need to reduce our carbon emissions as well as the nutrient runoff by limiting the use of chemical fertilizers to lower the impact on our environment.

   

References

California, S. of. (n.d.). Why are algae important? EcoSystem Health - Streams. Retrieved July 22, 2022, from https://mywaterquality.ca.gov/eco_health/streams/algae.html

Centers for Disease Control and Prevention. (2022, February 28). Causes and ecosystem impacts. Centers for Disease Control and Prevention. Retrieved July 22, 2022, from https://www.cdc.gov/habs/environment.html

Environmental Protection Agency. (2022). EPA. Retrieved July 22, 2022, from https://www.epa.gov/nutrientpollution/issue

Lavery, A., Backer, L., & Daniel, J. (2021). Evaluation of Electronic Health Records to Monitor Illness From Harmful Algal Bloom Exposure in the United States. Journal of Environmental Health, 83(9), 8+.

Roberts, V. A., Vigar, M., Backer, L., Veytsel, G. E., Hilborn, E. D., Hamelin, E. I., Vanden Esschert, K. L., Lively, J. Y., Cope, J. R., Hlavsa, M. C., & Yoder, J. S. (2020). Surveillance for harmful algal bloom events and associated human and animal illnesses — one health harmful algal bloom system, United States, 2016–2018. MMWR. Morbidity and Mortality Weekly Report, 69(50), 1889–1894. https://doi.org/10.15585/mmwr.mm6950a2

U.S. Department of Health and Human Services. (n.d.). Algal blooms. National Institute of Environmental Health Sciences. Retrieved July 22, 2022, from https://www.niehs.nih.gov/health/topics/agents/algal-blooms/index.cfm

Discussion Question: 

What are some ways that we can make a positive impact and reduce nutrient pollution in bodies of water?