The graphs show changes in the concentration of phosphate and the percentage of light penetration to the river bed in a river system over a 12-year period from 2010 to 2022.
Describe the relationship between phosphate levels and light penetration over this 12-year period.
Over this 12-year period, the population of mayfly nymphs (an aquatic insect species) in the river decreased significantly. Explain how the changes in phosphate levels could cause this decrease in the mayfly nymph population.
