Biological Consequences of Water Pollution

Eutrophication

Minerals from fertilizers are leached into water bodies.

Fertilizers are high in nitrates, this results in overgrowth of aquatint plants and algae at water surfaces.

Aquatic plants below the surface die due to reduces light levels. These plants are broken down by Decomposers.

Decomposers increase in number, increased respiration of organisms. This causes oxygen to be used up. Reducing dissolved oxygen levels

Water doesn’t have enough oxygen for fish/other plants so they die.

Sewage Pollution

Water pollution occurs when sewage water is washed into waterways

Sewage causes increased growth of aerobic bacteria which feed on biological waste.

Aquatic organisms sensitive to O2 levels die, leaving organisms that survive at low Oxygen Concentrations

Aquatic ecosystem decreases in biodiversity.

Increase in pathogenic bacteria

Sewage Pollution

Sewage contains organic waste, aerobic bacteria feeds on this waste

Bacteria population increases

They use up the dissolved oxygen in water during respiration

Aquatic organisms die due to lack of oxygen

Biodiversity decreases, lack of different species

More disease causing bacteria pathogens

Difference between sewage pollution and eutrophication

Eutrophication is due to too many nutrients in water from fertilizers.

Sewage pollution is due to organic waste entering water

The reason for oxygen depletion in eutrophication is that Decomposers use this oxygen to break down dead algae and plants

The reason for oxygen depletion in sewage pollution is that bacteria respire while feeding on the sewage material.