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. Eutrophication can cause depleted dissolved oxygen
levels in aquatic ecosystems, which in turn can cause
corresponding “dead zones”. Another name for these
areas that contain such low levels of dissolved oxygen is
“hypoxic” zones.
3. Because certain nutrients determine levels of biological
productivity, they are considered “restricting” factors.
4. A sudden explosion in the growth of algae is known as
an “algal bud”.
5. The more eutrophic an aquatic area becomes, the more
“turbid” it becomes as well.
6. Mesotrophic 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 Missouri River, in the
Gulf of Mexico.
8. The flux of a river can also be referred to as the
nutrient “load”.
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 10-15 mg/L.
10. In analyzing the graph below, it is obvious that there is a
correlation between load and temporal and spacial extent
of the hypoxic events.
BONUS: +10 Points
Describe one reason why dissolved oxygen levels in
a eutrophic body of water might drop significantly
during the nighttime hours.
Double-Secret Bonus: +10
Using the data table above (again), why do the
scientists document the “May” flux, instead of the
“June” flux, in predicting the possible eutrophic
“dead zone”?