Fertilizer, animal manure, and waste-treatment plant effluent all contain nutrients that stimulate excessive plant and algal growth in freshwater bodies. When the plants die and decompose, dissolved oxygen is depleted, causing die-offs of fish and other species living in the water.

How does pollution affect freshwater ecosystems?

When water pollution causes an algal bloom in a lake or marine environment, the proliferation of newly introduced nutrients stimulates plant and algae growth, which in turn reduces oxygen levels in the water. ... Marine ecosystems are also threatened by marine debris, which can strangle, suffocate, and starve animals.

How does pollution affect water availability?

Some rocks are permeable and allow water to flow through them. Permeable rocks can lead to less surface water. ... Pollution – some places have plenty of water, but pollution has made it unsafe to use. Untreated sewage and waste water from factories cause problems.