Michigan Aquatic Pest Control Practice Exam

When large amounts of plant material decompose in warm water, oxygen stress is a significant concern because the decomposition process consumes oxygen from the water. This consumption of oxygen can lead to hypoxic or anoxic conditions, where the levels of dissolved oxygen drop significantly. Aquatic organisms, especially fish and invertebrates, rely on dissolved oxygen for respiration. If the oxygen levels fall too low, it can lead to stress or mortality among these organisms, disrupt their normal behavior, and impact the overall health and biodiversity of the aquatic ecosystem.

High nutrient availability does occur due to decomposition, as it releases nitrogen and phosphorus into the water, but this can trigger harmful algal blooms that further reduce oxygen levels when the algae die and decompose. Increased photosynthesis generally happens when conditions favor plant growth, typically due to the nutrients released, but if oxygen levels are low, heightened photosynthesis could still lead to problems instead of benefits. Pest population growth could also be influenced by nutrient levels but is not directly tied to the immediate consequences of decomposition and oxygen depletion in warm water.