Jane Marsh
Amid a growing global population comes a rise in industrial and agricultural activity, strains on wastewater treatment facilities, and a rising threat to water quality. As toxic effluents from household drainage systems and businesses, stormwater runoff, waste, and more discharge locally, their final dumping place in the ocean delivers unprecedented challenges.
The Importance of Water Treatment for Healthy Marine Environments
Robust wastewater treatment positively impacts seawater by eliminating pathogens, metals, chemicals, and excess nutrients from the water before it flows to estuaries and out to sea. The treated water ensures marine ecosystems maintain their fragile ecological balances and reduces harm to various species.
For instance, one study discovered that wastewater treatment plants could remove 93% of sulfide pollution — from organic matter and industrial processes — within 38 days (Quynh et al., 2023).
Sulfide can cause significantly low oxygen levels in the ocean, harming marine habitats and fish, especially mangroves, coral reefs, and seagrass estuaries. About 65% of lignin surface sediment derives from seagrass beds (Zhang et al., 2023). The lignin allows seagrass meadows to act as a carbon sink, making it significant in the fight against climate change.
Humans also benefit from healthy oceans, as they remain suitable for recreation and support wide-ranging industries, from tourism to fisheries. However, your actions matter to ensure water treatment plants work efficiently. Even staying ahead of regular home maintenance reduces strain on your local wastewater management plant — leaky plumbing could result in wasting several gallons of water each day (Ranck, 2023).
Case Study: Monroe County, Florida
The National Oceanic and Atmospheric Administration’s Water Quality Protection Program has addressed wastewater treatment and water quality at the Florida Keys National Marine Sanctuary in recent years.
The program removed tens of thousands of septic tanks, unlawful catch basins, and other small, inefficient units. By 2021, Monroe County had upgraded 94% of its dwelling units — about 41,075 — to the central sewer system (Hogue, 2021).
The Florida Keys National Marine Sanctuary also disallows sewage discharge from boats to safeguard water quality in South Florida. The program achieves this by enhancing proper waste disposal infrastructure at marinas and mooring fields – including free pump-out services — creating convenient and sustainable options for boaters to do their part.
What’s in the Water: 5 Hidden Impacts of Ocean-Bound Effluents
What happens if a treatment plant is inadequate and untreated wastewater empties into the ocean? The effects are often devastating for marine ecosystems, aquatic species, and humans alike. These five hidden impacts of water treatment failures are things to consider.
Habitat Destruction and Biodiversity Loss
Coral reefs support nearly 25% of the ocean’s species, providing food, shelter, breeding grounds, and a nursery for juveniles (Russell, 2023). The Northwest Hawaiian Island coral reefs alone are home to 7,000 marine species, including invertebrates, plants, turtles, birds, and larger marine mammals (Papahānaumokuākea Marine National Monument, n.d.).
Poorly or untreated wastewater often leads to significant habitat degradation and biodiversity loss. For example, it may choke coral reefs and seagrass meadows, leading to mass bleaching and die-off events.
In coastal wetlands — where filtration is the primary function — the oversaturation of contaminants makes mangroves more susceptible to inclement weather. The loss of these habitats has dire consequences for the entire saltwater ecosystem and marine species' survival.
Harmful Algal Blooms
Nutrient loading — especially surplus nitrogen and phosphorus from agricultural runoff — causes harmful algal blooms (HABs) or red tides. The toxins released from this blue-green algae — mainly cyanobacteria — deplete oxygen in the water, making species survival impossible in what scientists refer to as dead zones.
The largest dead zone in the United States spans 6,500 square miles across the Gulf of Mexico (EPA, 2024). This event occurs each summer when the Mississippi River Basin releases nutrient effluents.
HABs are particularly dangerous for vulnerable, threatened, and endangered species. For instance, the 2023 red tide bloom along Florida’s west coast caused 123 manatee mortalities from November 2022 to June the following year (FWC, 2023).
Microplastic Pollution
Plastic pollution is among the greatest threats to the world’s oceans, with microplastics posing the greatest challenge. Experts predict 100-250 million metric tons of plastic litter will enter aquatic environments in 2025 (Ali et al., 2021). Unfortunately, while wastewater treatment plants can remove about 90% of microplastic particles from sewage, a significant amount still ends up in waterways leading to the ocean.
Marine species often ingest microplastic when they mistake it for food. Studies have shown that these particles are endocrine-disrupting, cause developmental issues, and lead to various metabolic disorders (Marchala, 2024). Humans become impacted when eating contaminated seafood. Because microplastics don’t biodegrade easily — some take hundreds or thousands of years — they could accumulate in your body.
Microplastics also release toxic chemicals and pollutants into the marine environment, altering essential microbial functions and affecting the entire ecosystem.
Economic Losses
Imagine you book a vacation to a tropical beach. You’ll likely spend most of your time swimming in the ocean and sunbathing in the sand. However, when a red tide hits, you won’t want to be anywhere near your destination. Collectively, the loss of visitors from ocean pollution causes significant financial losses for the community.
For instance, Southwest Florida’s tourism industry lost $2.7 billion during the 2018 HAB (Alvarez et al., 2024). Researchers found that daily sales were down $868 to $3,734 when the red tide occurred. Impacted activities included saltwater fishing, beach visits, and dining out. The 2018 event also affected short-term rental bookings and daily rates.
Of course, untreated wastewater also harms global fisheries by reducing fish catches and damaging gear. This ultimately leads to higher costs for anglers, decreased revenue, and food insecurity.
Contaminated Seafood
Even if you live nowhere near the ocean, poor water treatment and low water quality may still affect you. If you love sinking your teeth into a flaky saltwater fish, you put yourself at risk of contamination. This is because seafood may swim through and consume toxic effluents that eventually pass on to you.
For example, HABs produce toxins like brevetoxin, which can contaminate shellfish and cause nausea and vomiting, diarrhea, stomach ache, dizziness, and numbness of your lips, tongue and throat (CDC, 2024).
Likewise, fish tissues can absorb up to 90% of methylmercury — from both natural sources and industrial activities — in their liver, kidneys, and brain (Brodziak-Dopierała & Fischer, 2023). It also appears in the muscle tissue, which humans then consume. Eating mercury-infected fish is extremely harmful to your nervous system.
What Can You Do to Ensure a Healthy Ocean?
Your daily water consumption and habits greatly impact ocean health. To help combat the pollution problem at sea, you should do the following:
Throw away recyclable materials correctly.
Purchase products that use minimal packaging.
Avoid single-use plastics, such as grocery bags and water bottles.
Join beach and park cleanups in your community.
Invest in low-flow fixtures to reduce your water use.
Avoid beauty products containing plastics — one study found that polystyrene microplastic accounts for 46% of water-based facial cleansers (Kukkola, 2024).
Avoid using synthetic fertilizers and pesticides in your yard, which may enter waterways as stormwater runoff.
Look for sustainable seafood with special labeling, such as certification from the Marine Stewardship Council.
Avoid pouring toxic cleaning supplies down the drain.
Use sunscreens without oxybenzone and octinoxate, which harm coral reefs.
Small changes to your water usage can make a difference in keeping marine environments clean and preventing irreversible damage within ecosystems. Of course, your efforts alone won’t fix the problem. Therefore, advocating for keeping oceans cleaner, calling for policy changes, and educating others is critical.
A Healthy Ocean Depends on Clean Water
Healthy marine ecosystems, aquatic species survival, human well-being, and the economy all depend on clean seawater. By strengthening wastewater management infrastructure and becoming more aware of what you pour into drainage systems, the world can ensure ocean vitality and a functional marine environment.
Citations
Ali, I., Ding, T., Peng, C., Naz, I., Sun, H., Li, J., & Liu, J. (2021). Micro- and nanoplastics in wastewater treatment plants: Occurrence, removal, fate, impacts and remediation technologies – A critical review. Chemical Engineering Journal, 423, 130205. https://doi.org/10.1016/j.cej.2021.130205
Alvarez, S., Brown, C.E., Garcia Diaz, M., O’Leary, H., and Solis, D. (2024). Non-linear impacts of harmful algae blooms on the coastal tourism economy. Journal of Environmental Management, 351, 119811. https://doi.org/10.1016/j.jenvman.2023.119811
Brodziak-Dopierała, B., & Fischer, A. (2023). Analysis of the Mercury Content in Fish for Human Consumption in Poland. Toxics, 11(8), 717–717. https://doi.org/10.3390/toxics11080717
CDC. (2024, June 17). Symptoms of Illnesses Caused by Saltwater Harmful Algal Blooms. Harmful Algal Bloom (HAB)-Associated Illness. U.S. Centers for Disease Control and Prevention. https://www.cdc.gov/harmful-algal-blooms/signs-symptoms/symptoms-saltwater-harmful-algal-blooms.html
EPA. (2024, January 3). The Effects: Dead Zones and Harmful Algal Blooms. U.S. Environmental Protection Agency. https://www.epa.gov/nutrientpollution/effects-dead-zones-and-harmful-algal-blooms
FWC. (2023, July 17). Manatee impacts from the 2022-2023 red tide bloom. Florida Fish and Wildlife Commission. https://myfwc.com/research/manatee/rescue-mortality-response/statistics/mortality/2023-bloom/
Hogue, E. (2021, August). The Importance of Water Quality. Sanctuaries.noaa.gov. https://sanctuaries.noaa.gov/news/aug21/water-quality-month.html
Kukkola, A., Chetwynd, A. J., Krause, S., & Lynch, I. (2024). Beyond Microbeads: Examining the Role of Cosmetics in Microplastic Pollution and Spotlighting Unanswered Questions. Journal of Hazardous Materials, 476, 135053–135053. https://doi.org/10.1016/j.jhazmat.2024.135053
Marcharla, E., Vinayagam, S., Gnanasekaran, L., Soto-Moscoso, M., Chen, W.-H., Thanigaivel, S., & Ganesan, S. (2024). Microplastics in Marine Ecosystems: A Comprehensive Review of Biological and Ecological Implications and its mitigation approach using nanotechnology for the sustainable environment. Environmental Research, 256(119181), 119181–119181. https://doi.org/10.1016/j.envres.2024.119181
Papahānaumokuākea Marine National Monument. (n.d.). Www.papahanaumokuakea.gov. https://www.papahanaumokuakea.gov/visit/
Quynh, T., Nguyen, T. Y., & Do, C. L. (2023). Treatment of Organic and Sulfate/Sulfide Contaminated Wastewater and Bioelectricity Generation by Sulfate-Reducing Bioreactor Coupling with Sulfide-Oxidizing Fuel Cell. Molecules, 28(17), 6197–6197. https://doi.org/10.3390/molecules28176197
Ranck Plumbing, Heating, AC & Excavation (2023, May 15). Your Guide To Leaky Faucets And How You Can Fix Them. Ranck Plumbing, Heating, AC & Excavation. https://www.ranckinc.com/blog/how-to-fix-leaky-faucets/
Russell, S. (2023, January 9). What Is Coral — and Why Are Coral Reefs Important? Environment Co. https://environment.co/why-are-coral-reefs-important
Zhang, M., Yu, X., Chen, Z., Wang, Q., Zuo, J., Shi, Y., & Guo, R. (2023). A Mini-Review of Seagrass Bed Pollution. Water, 15(21), 3754–3754. https://doi.org/10.3390/w15213754