Which water pollutants can lead to excessive growth of water weeds​

            Water pollution also affects the ecosystem – it can cause a phenomenon called eutrophication. This can cause fish and other aquatic organisms to die. Toxic elements dissolved in water can make their way to humans through fish or other aquatic organisms.

https://byjus.com/biology/effects-of-water-pollution/

Explanation:

Excessive nutrients (nitrates) from fertilisers are flushed from the land into rivers by rainwater. Oxygen levels reach such a low point that fish and other organisms suffocate. These nutrients cause increased aquatic plant growth of algae and other plants.

Explanation:

oxygen +1 most likely

not only is it colder, it also becomes darker, less salty, and more dense.