What is a likely effect on phytoplankton when large amounts of macrophytes are killed in a water body?

When large amounts of macrophytes are killed in a water body, it is likely that phytoplankton will experience an increase. This is largely due to the fact that macrophytes play a significant role in stabilizing the aquatic ecosystem by providing structure and habitat and influencing nutrient dynamics.

Macrophytes contribute to the regulation of light levels and competition for resources in the water. When they die off, there is a reduction in competition for light, nutrients, and space, allowing phytoplankton populations to flourish without the previous constraints. Moreover, the decomposition of dead macrophytes can lead to nutrient release into the water, further promoting phytoplankton growth. Thus, the overall dynamics within the aquatic ecosystem profoundly favor an increase in phytoplankton following the significant die-off of macrophytes.