Lecture 14: Concepts of Eutrophication and HAB

Question 1

Is nutrient enrichment a worldwide problem?

Answer 1

Yes

Question 2

What are the 4 manifestations for eutrophication problems?

Answer 2

low oxygen, loss of SAV, toxic HABs, macroalgae

Question 3

What scientific controversies remain at play when pertaining to eutrophication?

Answer 3

N & P
anthropogenic vs. natural factors, lags, climate

Question 4

What are some uncertainties ?

Answer 4

seriousness of impact; some claim that
there are benefits (e.g. to fisheries)

Question 5

Why is it considered a high degree of management awareness?

Answer 5

It is perceived as the most serious pollution problem to estuaries in U.S.

Question 6

Are management actions effective and why?

Answer 6

It is usually well after system is considerably over-enriched. It has been ineffective at reversing impacts

Question 7

Explain this eutrophication. model. Include the drivers, primary & secondary effects and symptoms.

Answer 7

1. Increased
   N and P
   concentration
2. High algal production
   Loss of water clarity
   Epiphyte problems
   Macroalgal problems
3. Loss of SAV
   Low D.O
   Nuisance/Toxic HAB Blooms
4. Fish kills
   Loss of habitat
   Human health risks
   Loss of Tourism
   Closed fishing grounds

Question 8

List 2 effects that eutrophication’s primary Symptom of Decreased Light Penetration causes

Answer 8

Overproduction of algae leads to increased turbidity,decreased light penetration, & increased Chlorophyll A (a
byproduct of plant metabolism)

Overgrowth of macroalgae (seaweed)

Question 9

Opportunistic plant species
(diatoms →flagellates & benthic → pelagic alage) = alters
food quality
(e.g. Ches. Bay – 90% decline in oysters reduces
filtratration rate of bay from 4-5 days to 365 days) is an example of what primary symptom of eutrophication?

Answer 9

Algal Speciation Changes

Question 10

Describe primary symptom “Increased Organic Matter Decomposition”

Answer 10

due to deposition of decaying algae.

Question 11

What are the three secondary symptoms of eutrophication?

Answer 11

Loss of Submerged Aquatic Vegetation
Increased Hypoxia
Increased Occurrence of Harmful Algal
Bloom (HABs)

Question 12

Explain and give an example of secondary symptom “Loss of Submerged Aquatic Vegetation”

Answer 12

Tampa Bay Florida Larger populations increased N and Ph levels that lowered sea grass population. Best Practices has been used to reduce Point Source and NPS to retrieve sea grass populations.

Question 13

What animal can survive at 1.0 MG/L?

Answer 13

Worms

Question 14

The striped Bass needs what level of D.O?

Answer 14

5-6 mg/l

Question 15

What happens at D.O level of 0.2?

Answer 15

hydrogen sulfide builds up

Question 16

What animals are absent at 1.5 D.O?

Answer 16

Shrimps and crabs

Question 17

How many square miles is the area of hypoxia in the northern gulf of mexico?

Answer 17

20,000 square kilometers (7,722 sq. miles)

Question 18

What is the critical value that defines hypoxia?

Answer 18

The critical value that defines hypoxia is 2 mg/L, because trawlers cannot catch fish or shrimp in those areas.

Question 19

What is the spatial scale of hypoxia in the chesapeake bay?

Answer 19

0-0.2 mg/l

Question 20

What caused the fish kill in Kiawah Island?

Answer 20

Hypoxia caused by eutrophication

Question 21

What was the impact of the fish kill in Kiawah Island?

Answer 21

mpacts = Total kill was approximately 8500 lbs & included 662game fish and 200 menhaden

Question 22

What causes the HAB’s found at Lake Watertree, sc? What toxins does it produce?

Answer 22

caused by Microseira (Lyngbya) wollei which covers > 2/3 of the shore line and produces Lyngbya Toxins and Saxitoxins.

Question 23

What percent of hypoxia in the us are moderately to severely impacted by eutrophication?

Answer 23

67%

Question 24

Where was the location of pfiesteria blooms that caused major fish kills and lesions in menhaden?

Answer 24

-Neuse River, NC

Question 25

What is the flow of the DPSR model?

Answer 25

Driver(s)  Pressure  State Response Model

Question 26

What does the Overall response of the ecosystem to eutrophication Includes measurement of?

Answer 26

(1) Human Influence (OHI) index = defines causes (primarily N and Ph)
(2) Overall Eutrophic Condition (OEC) index – defines state of ecosystem in response; and (3) Determination of Future Outlook (DFO) index – defines ecosystem response to management actions using predictive models