Can sediment and chemicals in stormwater harm ecosystems and the reef?

Sediment and chemicals in floodwater: Sediment and chemicals contained in stormwater and flood waters can pollute the ocean and harm marine ecosystems and coral reefs in several ways. When stormwater and flood waters carry sediment and chemicals into the ocean, they can cause water quality problems, such as reduced visibility and changes in pH and nutrient levels. These changes can be harmful to marine life, including coral reefs.

Sediment and chemicals can also be harmful to coral reefs directly. When sediment is carried into the ocean by stormwater and flood waters, it can settle onto the reefs, smothering coral and reducing their ability to photosynthesize. Chemicals contained in stormwater and flood waters, such as pesticides, herbicides, and fertilizers, can also be harmful to coral reefs. These chemicals can contaminate the water and disrupt the balance of nutrients in the ecosystem, leading to the death of coral and other marine life.

Stormwater can carry other pollutants: In addition to the direct effects of sediment and chemicals on coral reefs, stormwater and flood waters can also carry other pollutants, such as oil, grease, and trash, which can have negative impacts on marine ecosystems and the animals that depend on them. Stormwater and flood waters can also alter the natural flow of water and cause erosion, which can further damage marine ecosystems and coral reefs. Overall, sediment and chemicals contained in stormwater and flood waters can have significant negative impacts on the health and vitality of coral reefs and the marine ecosystems that depend on them.

Sediment and chemicals in stormwater can harm ecosystems and the reef in Hawaii. According to the U.S. Environmental Protection Agency, polluted stormwater runoff can contain a variety of harmful chemicals, nutrients, and sediments that can damage coral reefs and other marine life (https://www.epa.gov/coral-reefs/threats-coral-reefs). Additionally, studies have found that coastal development, deforestation, agricultural runoff, and oil and chemical spills can impede coral growth and reproduction, disrupt overall ecological function, and cause disease and mortality in sensitive species (https://coralreef.noaa.gov/issues/lbsp.html).

Stormwater Runoff enters the ocean in South Maui. Photo: Vernon Kalanikau
Stormwater Runoff enters the ocean in South Maui. Photo: Vernon Kalanikau

 

Further Reading: 

West Maui watershed owner’s manual, https://repository.library.noaa.gov/view/noaa/8948

https://accession.nodc.noaa.gov/883