High levels of certain plant nutrients in runoff can lead to rapid growth of algae (an algal bloom) in aquatic ecosystems. These algal blooms are generally followed by algal death and decomposition, which consumes large
amounts of dissolved oxygen in the water and results in oxygen levels insufficient to support aerobic respiration.
This process is known as eutrophication. The amount of algae present in a body of water can be estimated from the
amount of chlorophyll a in a sample of the water. A researcher studying eutrophication collected samples at
different times of the year in a freshwater ecosystem. The samples were analyzed for total nitrogen and chlorophyll
a concentration (Figure 1) as well as total phosphorus and chlorophyll a concentration (Figure 2).