What does the term "bloom" refer to in aquatic ecosystems?

The term "bloom" in aquatic ecosystems specifically refers to the excessive growth of phytoplankton, which can lead to the formation of surface scum. This phenomenon usually occurs when conditions are favorable, such as an increase in nutrients (often from agricultural runoff or wastewater), sunlight, and warm temperatures. During a bloom, the concentration of phytoplankton in the water can significantly increase, sometimes resulting in harmful algal blooms (HABs) that can produce toxins affecting not only aquatic life but also human health and recreational activities.

Recognizing this context is crucial since blooms can have severe ecological impacts, such as depleting oxygen levels when the phytoplankton die and decompose, thus harming fish and other aquatic organisms.