ColdDesert77 t1_jadayu4 wrote on February 28, 2023 at 4:48 PM

Reply to comment by TheRealSmallBean in ELI5: Why is it that when fertilizers make their way into waterways, all the oxygen disappears, killing the fish? by Psychological-Dog994

Why do nitrogen and phosphorus cause algae?

TheRealSmallBean t1_jadg90q wrote on February 28, 2023 at 5:22 PM

Someone in the comments explained it really well, but plants need nitrogen and phosphorus to grow. Usually those are in limited quantities, so growth is limited by the amount available. Fertilizer is designed to provide an abundance of nitrogen and phosphorus to plants, so if those high quantities end up in the water, algae growth isn’t limited and can grow more rapidly.