Factors that influence the marine water quality
Wastewater discharge: Wastewater discharge is caused by many large and rapidly expanding coastal communities. The wastewater depletes the dissolved oxygen in the water affecting to marine organisms and natural beauty of tourism areas.
Leachate: It generated from inland waste and discharged to the sea by surface runoffs. Leachate contains high impurity consisting of organic, inorganic substance, pathogens, and other toxics, that causes marine and coastal water pollution and affects to marine organisms.
Oil and petroleum hydrocarbon: It deteriorates the quality of marine and coastal water. The leakage of oil affects the animals living at the sea surface immediately such as birds and dolphins. The oils obstruct light penetration into the sea limiting the photosynthesis of phytoplankton, algae, and aquatic plants, depletion of dissolved oxygen. High density oils, sink to the seabed, affect benthic flora and fauna. The oils, blew to the shorelines, cause contamination, dirt, and toxicity to marine organisms living in the beaches.
Agricultural activities: In some areas, agricultural wastewaters of both aquaculture and plantation, discharged into the sea, can degrade the marine and coastal water quality. Besides, chemicals and pesticides are accumulated in food webs and environment that would intoxicate the aquatic animals. Additionally, use of fertilizers results in generating agricultural wastewater with high concentrations of nutrients that causes Eutrophication, leading to algal bloom and rapid growth of aquatic plants.
Red Tides: It is caused by rapid growth of some plankton in the sea that aquatic animals and human can be beneficial or harmful which causes depletion of oxygen and biotoxin produced by plankton. Important factor that influences red tides is the increase of nutrient concentration in coastal water, caused by human activities, leading to the rapid growth of plankton.
Rapid freshwater discharge: Rapid and too much freshwater flowing into the sea would immediately reduce salinity affecting many aquatic lives, especially, the slow moving and sessile animals as well as the coastal aquaculture area such as calms, mussels, cage farming, etc.
Ocean acidification: An increase of greenhouse gases, especially Carbon Dioxide, causes the concern about the higher acidity in the ocean among scientists because of the dissolution of Carbon Dioxide resulting decrease in pH will have negative consequences on aquatic organisms, especially, calcareous organisms such as sea urchins, algae, phytoplankton, zooplankton, coral reefs, etc.