SewageTreatment
Sewage Treatment and the Effect on Corals
Overview
Different sources sewage -http://www.reefresilience.org/coral-reefs/stressors/local-stressors/pollution/ -groundwater - http://www.aims.gov.au/docs/research/water-quality/runoff/impact-of-runoff.html -farm runoff -fecal matter -www.sac-be.com/the_impact_of_human.shtml -golf courses www.notesfromtheroad.com/sgcr
Affect on the nutrients -http://coral.org/wordpress/wp-content/uploads/2014/09/Wear-Vega-Thurber-2015.pdf -nutrients and algae -nutrients and coral disease and bleaching -nutrients and coral growth -nutrients and microbial communities
Wastewater contains high concentrations of inorganic nutrients, such as ammonium, nitrite, nitrate and phosphate. Typically, coral reefs survive best in nutrient poor areas, so any substantial input of nutrients shifts the composition of the water. When the water contains too many nutrients, algae grow, which ruins the coral’s cover, ultimately hurting coral. Studies have shown that there is a positive correlation between the nitrogen levels in the water and amount of coral bleaching. Further experiments have shown that when nitrogen levels return to normal, these sites experience rapid recovery, implying there is causation between nitrogen levels and coral bleaching. Finally, corals can take up hormones, specifically estrogen, present in sewage waste. When corals metabolism estrogen there are negative affects on reproduction, growth rates and morphological features.
85% of wastewater going into the Caribbean is untreated, with the primary component being freshwater. Freshwater is dangerous for corals because it lowers the salinity of the water. Without the right balance, corals do not survive well. Another problem of sewage entering the waters is increasing the nutrient levels to a point that causes eutrophication. Eutrophication is when the water becomes saturated with oxygen, creating “dead zones” and collapsing the ecosystem. These dead zones contain an increased number of phytoplankton, which blocks sunlight from corals and increases algal growth, ultimately decreasing coral survivability. Lastly, when sewage or wastewater contains high levels of heavy metals, this affects coral metabolism and influences the activity of natural coral enzymes. Coral mortality is common under high concentrations of heavy metals, as well as bleaching and low fertilization success. Iron (II) in particular increases pathogen virulence to corals and increases the growth of microalgae.
Regulations - http://www.cep.unep.org/publications-and-resources/marine-and-coastal-issues-links/wastewater-sewage-and-sanitation
Monitoring of Sewage/What's being done - http://www.uvm.edu/~rlachape/dev-pacis.html http://coralreef.noaa.gov/threats/pollution/
Case Study: Sewage Treatment on St. John http://www.coris.noaa.gov/portals/pdfs/status_coralreef_usvi.pdf