Tennessee Wastewater Operator Practice Exam

When is a bloom of daphnia or rotifers most likely to occur in a pond?

1. During winter months

2. During a severe storm

3. Immediately after a bloom of green algae

4. Before an increase in water temperature

The correct answer is: Immediately after a bloom of green algae

A bloom of daphnia or rotifers is most likely to occur immediately after a bloom of green algae because these organisms are filter feeders that thrive in environments where there is an abundance of microalgae. When green algae experience rapid growth, they create a nutrient-rich environment that supports the proliferation of these zooplankton, as they feed on the algae. This relationship is part of the natural food web in aquatic ecosystems. The explosion of green algae provides an immediate food source, allowing daphnia and rotifers to increase in population quickly. Hence, their bloom typically follows closely behind that of green algae, creating a sequential pattern of organism growth in the pond's ecosystem. In contrast, the other scenarios provided do not align with the typical biological interactions and environmental conditions necessary for daphnia and rotifers to thrive. For example, during winter months, colder temperatures and reduced light conditions limit biological activity and growth. Similarly, severe storms can disrupt the pond environment, affecting the food sources and habitat for these organisms. An increase in water temperature may support growth but does not specifically correlate with the immediate blooming of daphnia or rotifers without the presence of adequate food sources.