Algae blooms are caused by an oversupply of nutrients like to water bodies, causing eutrophication. In the exposed example, a reason for the high levels of phosphorus is option B. Cow pastures.
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Eutrophication is a biological process produced in water by an oversupply of nutrients or organic matter.
The source of these high nutrient levels, especially nitrogen and phosphorus, are anthropogenic activities.
This oversupply favors phytoplankton multiplication, especially cyanobacteria.
Cyanobacteria can grow in seawater, but blooms mainly occur in freshwater where the salinity level is low.
These algae species that affect freshwater bodies are microscopic, photosynthetic organisms.
Blooms of cyanobacteria reflect the sanity state of water and its abiotic characteristics. They cause severe disasters in water biota and affect human health.
This overgrowth leads to an enhance in primary productivity and reduces the pass of radiation to deeper strata. This fact affects biota in deeper zones.
Gradually sedimentation begins, caused by the death of some vegetable organisms that sink in the bottom.
These sediments suffer decomposition in the presence of oxygen.
When oxygen disappears, anaerobic bacteria act and produce fermentation.
Phytoplankton overgrowth on the surface and fermentation process in the bottom, originate toxic compounds that can damage the animals in the water body and humans that get in touch with this water.
Animals die, creating more sediments in the bottom where there are anaerobic conditions.
The lack of oxygen and light continued to increase in decomposition, and fermentation produces a bad smell and toxicity.
Concerning the sources of nutrients that might be causing these events, we can mention, among others, cow pasture.
Cow pasture increases the levels of phosphorous on the ground, which ends in water streams, and from there to ponds or lakes.
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