1. This assessment is a modified true-false quiz. If the statement is true, simply put a “T” next to the number. If the statement is false, put an “F”, followed by correcting the underlined portion of the sentence to make it true. Example: Human-induced, or anthropogenic eutrophication is sometimes referred to as natural eutrophication. ANS: “F”; cultural or artificial eutrophication 1. An increase in eutrophication events is credited to increased carbon, and iron influx into the aquatic environment.

2. 2.Dead zones created by eutrophication are also called “hypoxic” zones due to low levels of dissolved oxygen. 3.Because certain nutrients determine levels of biological productivity, they are considered “restricting” factors. 4.A sudden increase in the growth of algae is known as an “algal bloom”. 5.The more eutrophic an aquatic area becomes, the less “turbid” it becomes.

3. 6. Hypereutrophic waters contain the least amount of nutrients, are usually clear and cool, and can support and maintain a great biodiversity of life. 7.Currently, the largest “dead zone” in the United States is adjacent to the mouth of the Colorado River, in the Bay of California. 8.An increase in eutrophication can lead to a decrease in the concentration of a toxin in the environment with an increase in trophic level, due to biomagnification. 9.Unhealthy dissolved oxygen levels are as low as 2 mg/L, as opposed to healthy levels you might find at Harriet Creek which average between 5-7 mg/L.

4. 10. As the algae begin to die, the bacterial action on their decomposing bodies acts to increase the dissolved oxygen in the water. BONUS: +10 Points Describe why dissolved oxygen levels in a eutrophic body of water might drop significantly during the nighttime hours.