Lecture 14: Concepts of Eutrophication and HAB Flashcards
Is nutrient enrichment a worldwide problem?
Yes
What are the 4 manifestations for eutrophication problems?
low oxygen, loss of SAV, toxic HABs, macroalgae
What scientific controversies remain at play when pertaining to eutrophication?
N & P
anthropogenic vs. natural factors, lags, climate
What are some uncertainties ?
seriousness of impact; some claim that
there are benefits (e.g. to fisheries)
Why is it considered a high degree of management awareness?
It is perceived as the most serious pollution problem to estuaries in U.S.
Are management actions effective and why?
It is usually well after system is considerably over-enriched. It has been ineffective at reversing impacts
Explain this eutrophication. model. Include the drivers, primary & secondary effects and symptoms.
- Increased
N and P
concentration - High algal production
Loss of water clarity
Epiphyte problems
Macroalgal problems - Loss of SAV
Low D.O
Nuisance/Toxic HAB Blooms - Fish kills
Loss of habitat
Human health risks
Loss of Tourism
Closed fishing grounds
List 2 effects that eutrophication’s primary Symptom of Decreased Light Penetration causes
Overproduction of algae leads to increased turbidity,decreased light penetration, & increased Chlorophyll A (a
byproduct of plant metabolism)
Overgrowth of macroalgae (seaweed)
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?
Algal Speciation Changes
Describe primary symptom “Increased Organic Matter Decomposition”
due to deposition of decaying algae.
What are the three secondary symptoms of eutrophication?
Loss of Submerged Aquatic Vegetation
Increased Hypoxia
Increased Occurrence of Harmful Algal
Bloom (HABs)
Explain and give an example of secondary symptom “Loss of Submerged Aquatic Vegetation”
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.
What animal can survive at 1.0 MG/L?
Worms
The striped Bass needs what level of D.O?
5-6 mg/l
What happens at D.O level of 0.2?
hydrogen sulfide builds up
What animals are absent at 1.5 D.O?
Shrimps and crabs
How many square miles is the area of hypoxia in the northern gulf of mexico?
20,000 square kilometers (7,722 sq. miles)
What is the critical value that defines hypoxia?
The critical value that defines hypoxia is 2 mg/L, because trawlers cannot catch fish or shrimp in those areas.
What is the spatial scale of hypoxia in the chesapeake bay?
0-0.2 mg/l
What caused the fish kill in Kiawah Island?
Hypoxia caused by eutrophication
What was the impact of the fish kill in Kiawah Island?
mpacts = Total kill was approximately 8500 lbs & included 662game fish and 200 menhaden
What causes the HAB’s found at Lake Watertree, sc? What toxins does it produce?
caused by Microseira (Lyngbya) wollei which covers > 2/3 of the shore line and produces Lyngbya Toxins and Saxitoxins.
What percent of hypoxia in the us are moderately to severely impacted by eutrophication?
67%
Where was the location of pfiesteria blooms that caused major fish kills and lesions in menhaden?
-Neuse River, NC
What is the flow of the DPSR model?
Driver(s) Pressure State Response Model
What does the Overall response of the ecosystem to eutrophication Includes measurement of?
(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
