Nutrient Pollution: Solutions for the Indian River Lagoon
Nutrient pollution is a type of water pollution in which
excessive amounts of nutrients, mainly nitrogen, and phosphorus, enter
waterways. Nutrient pollution is the main cause of eutrophication. Eutrophication
refers to the growth of algal blooms caused by excess nutrients in a body of
water. These algal blooms block sunlight from reaching plant life at the bottom
of the waterway, causing them to die off. Once the excess nutrients are
exhausted, the algae die, sink to the bottom, and decompose in a process that
depletes the amount of dissolved oxygen in the water. Marine life suffocates
due to the lack of dissolved oxygen, in an event commonly referred to as a fish
kill. The decayed material leads to more nutrients, feeds more algal blooms,
causes less oxygen, and more die off, creating a feedback loop.
Sources of Excess Nitrogen and Phosphorus
Many factors play a part in nutrient pollution of waterways.
Sources of excess nutrients can be either point or non-point. Agricultural,
municipal, residential, and fossil fuel sources, as well as legacy sediments,
all contribute to the issue (U.S. Environmental Protection Agency, 2019).
Agricultural
Nitrogen and phosphorus are essential to plant growth and
are added to crops, in the form of fertilizers, often to excess. Nutrients are
also present in animal manure. When these nutrients are in excess, they can run
off into surface waters.
Municipal
Aging and poorly operating wastewater treatment facilities
can discharge nutrients into waterways.
Residential
Fertilizers applied to lawns, pet waste, some soaps, and
yard waste contain nitrogen or phosphorus. These excess nutrients can runoff
into storm drains, eventually making their way into local waterways. Leaking
and improperly maintained septic tanks also release nutrients.
Fossil Fuels
Power plants, automobiles, and other industrial sources
release nitrogen into the air (U.S. EPA, 2019). This excess nitrogen can return
to the ground through rainwater.
Muck
Build-up of decomposed material, known as muck, releases
legacy loads of nutrients into a waterway when the bottom is disturbed by
weather, marine life, or human recreational activity.
Effects on the Indian River Lagoon
The Indian River Lagoon (IRL) is an estuary situated on 40%
of the east coast of Florida (IRL National Estuary Program, 2020). Home to over
4,300 species, the Indian River Lagoon is one of the most biodiverse estuaries
in North America (Harbor Branch, n.d.). According to the IRL National Estuary
Program (2020), “Fifty-three species of threatened or endangered animals live
within the lagoon’s watershed, with Merritt Island National Wildlife Refuge
alone containing more than any other national wildlife refuge in the U.S.”
(para. 4). Lake Okeechobee, Florida’s largest lake, is connected to the Indian
River Lagoon by the C-44 Canal and the St. Lucie River. During periods of heavy
rainfall, nutrient-rich water is released from Lake Okeechobee, making its way
into the south Indian River Lagoon and the Atlantic Ocean.
Harmful Algal Blooms
The St. Lucie River is affected by blue-green algae
(cyanobacteria) when water is discharged from Lake Okeechobee, resulting in
harmful algal blooms (HABs) in 2013 and 2016. In 2018, a blue-green algal bloom
was detected in the Indian River Lagoon after one of the Lake Okeechobee
discharges (Treadway, 2018).
In 2011, a green algal bloom (chlorophyta) killed 50 square
miles of seagrass in the Indian River Lagoon (Waymer, 2018). Between the 2011
green algal bloom and a 2012 brown algal bloom (Aureoumbra lagunensis), over
47,000 acres of seagrass was lost (Waymer, 2018). Brown algal blooms, also
known as brown tide, resulted in a massive fish kill in 2016 and another
smaller fish kill in 2018.
Red tide (Karenia brevis), a harmful algal bloom usually
found in ocean waters, was detected in 2018 at low levels near ocean inlets in
the Indian River Lagoon (Hodges, 2018).
Effects on Human Quality of Life and the Economy
Nutrient pollution and, more specifically, harmful algal
blooms have caused significant effects not only to the environment, but also
human quality of life and the local economy. Red tide (Karenia brevis) produces
brevetoxins that cause respiratory illness and irritation of the skin and eyes
in humans, in addition to death in some marine life (Florida Department of
Health, 2019). Blue-green algal blooms (cyanobacteria) produce cyanotoxins that
cause skin rash, sore throat, headache, nausea, vomiting, diarrhea, and
pneumonia in humans (U.S. EPA, 2019). Economic impacts have been experienced in
recreational and commercial fishing, real estate, resource management, and the
tourism industry. In 2016, 54 businesses reported economic damage related to
harmful algal blooms in central and South Florida (Turner, 2016). Future
impacts to the local economy are predicted. According to Hazen and Sawyer
(2020), “as the environmental quality of the Indian River Lagoon deteriorates,
so too will its economic value” (sec. 2). Finally, waterfront property values
are expected to decrease by 25% in the next five years if the lagoon is not
restored (Tetra Tech, Inc. & Closewaters, LLC, 2020).
Societal and Political Reactions
Ecological decline of the Indian River Lagoon generates
public concern. Economic impacts in particular drive societal awareness.
Environmental movements, protests, ad campaigns, and organizations, such as the
Marine Resources Council, the Save Our Indian River Lagoon Citizen Oversight
Committee, and Captains for Clean Water, are examples of societal reaction to
the issue. Public and economic pressure drives political involvement. In 2016,
residents of Brevard County (holding the largest portion of the lagoon) voted
to raise sales tax by a half-cent for 10 years, totaling approximately $494
million for the Save Our Indian River Lagoon (SOIRL) Trust Fund to be used for
lagoon restoration. This year on March 10, Brevard County commissioners voted
on an updated plan to assign an additional $55.5 million to restoration
projects (Berman, 2020).
Solutions
Decades of nutrient pollution in the Indian River Lagoon
will likely take decades to remediate. Loss of the Indian River Lagoon would be
devastating to the 4,300 species, including 53 threatened or endangered, that
reside there (IRL National Estuary Program, 2020). Possible solutions to
restore water quality to the IRL include oyster bars, muck removal, mangrove
planting, biochar filtration, and monitoring total maximum daily loads (TMDLs).
Oyster Bars
Oysters are filter feeders, filtering about 50 gallons of
water per day. As the oyster filters water to feed, nitrogen is absorbed into
its shell and tissue. Nitrogen is then removed by denitrification or by
harvesting the oysters. Denitrification is a process by which nitrogen is
converted into its gaseous state and released into the air (Bernhard, 2010).
Unfortunately, the effects can be localized. However, this solution can also
help prevent soil erosion and promote seagrass growth (Tetra Tech, Inc. and
Closewaters, LLC, 2020). Oyster bars are sustainable because of its use of
natural processes of filtering water. Juvenile oysters also propagate on top of
old oyster shells. This solution is currently being implemented by various
parties.
Muck Removal
Muck, containing legacy loads of nutrients, can be removed
from the bottom of the Indian River Lagoon for immediate results (Tetra Tech,
Inc. & Closewaters, LLC, 2020). This solution uses pumps to siphon muck
from the bottom of the lagoon. Muck dredging is currently being implemented
using money allocated from the SOIRL Trust Fund.
Mangrove Planting
Three
species of mangroves are native to the Indian River Lagoon: red, black, and
white. These mangroves are essential components of the lagoon, providing food
and habitat to many land and marine organisms as well as help to stabilize
sediments and prevent shoreline erosion. Mangroves can uptake nutrients through
the roots which grow out of the water. However, it should be noted that
according to Agraz-Hernández et al. (2018), continuous inflows of nutrients
could diminish mangroves capability to absorb nutrients. Mangrove planting is
currently being accomplished by the Marine Resources Council.
Biochar Filtration
Biochar is made from burning organic material from
agricultural and other wastes with access to very little oxygen. Biochar has a
large surface area and is highly porous and can adsorb excess nutrients passing
over it (Vikrant et al., 2018). After filtering nutrients from the water, the
used biochar has the potential to be reused as fertilizer. Large-scale
production of biochar is expensive, however as a small-scale restoration
project, this solution could be implemented quickly and relatively
inexpensively.
Total Maximum Daily Loads (TMDLs)
Each
state is required by the Clean Water Act to submit a list of impaired and threatened
waters and set priorities to develop total maximum daily loads of pollutants. Defined
by the EPA (2018), “a TMDL is the calculation of the maximum amount of a
pollutant allowed to enter a waterbody so that the waterbody will meet and continue
to meet water quality standards for that particular pollutant” (para. 1). The
process to set TMDLs is tedious and expensive. Unfortunately, most states do
not have enough money or personnel to monitor a large percentage of waterways enough
to find problems (Manuel, 2014).
Personal Impact
Many factors contribute to nutrient pollution of the Indian
River Lagoon. Fertilizer use, leaking septic systems, and stormwater runoff are
some individual sources of excess nutrient loads. To reduce contributing to the
issue, you can discontinue the use of fertilizer on residential lawns. Ensure adherence
to the Brevard County fertilizer ban from June 1 through September 30. Another
option is to gradually replace your lawn with Florida-native plants, trees, and
grasses that require much less maintenance. Additionally, ensure that all grass
clippings are blown off the street and back into your yard. Rain barrels can be
used to collect rainwater; this creates less runoff and the collected rain can
be used to water plants. Encourage others to follow these basic steps, advocate
for lagoon restoration at county commission meetings, and volunteer with local
non-profit organizations that work to improve the health of the lagoon.
References
United States
Environmental Protection Agency. (2019, February 4). Nutrient pollution:
Sources and solutions. Retrieved from https://www.epa.gov/nutrientpollution/sources-and-solutions
Indian River
Lagoon National Estuary Program. (2020). Importance. One Lagoon.
https://onelagoon.org/importance/
Harbor Branch
Oceanographic Institute. (n.d.). Indian River Lagoon – Facts & figures.
Florida Atlantic University.
https://www.fau.edu/hboi/irlo/docs/IRL.Fact.Sheet.pdf
Indian River
Lagoon National Estuary Program. (2020). Living resources. One Lagoon.
https://onelagoon.org/living-resources/
Treadway, T.
(2018, July 20). Toxic blue-green algae returns to St. Lucie River; bloom
now seen in Indian River Lagoon. TcPalm. https://www.tcpalm.com/story/news/local/indian-river-lagoon/health/2018/07/20/low-level-toxins-found-blue-green-algae-blooms-st-lucie-river/805881002/
Waymer, J. (2018,
March 2). Again? Killer brown algae responsible for 2016 mass fish deaths is
blooming. Florida Today.
https://www.floridatoday.com/story/news/local/environment/lagoon/2018/03/02/again-killer-brown-algae-responsible-2016-mass-fish-deaths-blooming/381630002/
Hodges, A. (2018,
October 17). Red tide found in Indian River Lagoon. Sebastian Daily. https://www.sebastiandaily.com/inlet/red-tide-found-in-indian-river-lagoon-13237/#:~:text=Red%20Tide%20tested%20positive%20in,in%20the%20Indian%20River%20Lagoon.
Florida
Department of Health. (2019, December 20). HABs: Harmful algae blooms.
Florida Health. http://www.floridahealth.gov/environmental-health/aquatic-toxins/harmful-algae-blooms/index.html
United States
Environmental Protection Agency. (2019, August 16). Health effects from
cyanotoxins. Retrieved from https://www.epa.gov/cyanohabs/health-effects-cyanotoxins
Turner, J. (2016,
July 14). Business say they have been hurt by algae outbreak. WLRN.
https://www.wlrn.org/post/businesses-say-they-have-been-hurt-algae-outbreak
Hazen and Sawyer.
(2020). Economic value of the Indian River Lagoon in Florida. Retrieved
from
https://www.hazenandsawyer.com/work/projects/economic-value-of-the-indian-river-lagoon-in-florida/
Tetra Tech, Inc.
and Closewaters, LLC. (2020, May). Save our Indian River Lagoon project plan
update for Brevard County, Florida. Retrieved from https://www.brevardfl.gov/SaveOurLagoon/Home
Berman, D. (2020,
March 9). Commissioners to vote on updated plan to clean up Indian River Lagoon
with sales tax money. USA Today.
https://www.usatoday.com/story/news/local/environment/2020/03/09/commissioners-vote-updated-plan-clean-up-lagoon-sales-tax-money/4937033002/
Bernhard, A.
(2010). The nitrogen cycle: Processes, players, and human impacts. Nature
Education Knowledge, 3(10), 25. https://www.nature.com/scitable/knowledge/library/the-nitrogen-cycle-processes-players-and-human-15644632/
Agraz-Hernández,
C.M., del RÃo-RodrÃguez, R.E., Chan-Keb, C.A., Osti-Saenz, J., & Muñiz-Salazar,
R. (2018, March). Nutrient removal efficiency of Rhizophora mangle (L.)
seedlings exposed to experimental dumping of municipal waters. Diversity, 10(1),
16. https://doi.org/ 10.3390/d10010016
Vikrant, K., Kim,
K., Ok, Y.S., Tsang, D.C.W., Tsang, Y.F., Giri, B.S., and Singh, R.S. (2018,
March). Engineered/designer biochar for the removal of phosphate in water and
wastewater. Science of the Total Environment, 616-617, 1242-1260.
https://doi.org/10.1016/j.scitotenv.2017.10.193
United States
Environmental Protection Agency. (2018, September 13). Overview of total
maximum daily loads (TMDLs). Retrieved from https://www.epa.gov/tmdl/overview-total-maximum-daily-loads-tmdls
Manuel, J. (2014,
November). Nutrient pollution: A persistent threat to waterways. Environmental
Health Perspectives, 122(11), A304-A309. https://doi.org/10.1289/ehp.122-A304