Human Impacts on Wetlands

Question 1

Three main factors that influence wetland ecosystem health:

Answer 1

• Water level
• Nutrient status
• Natural disturbances

Question 2

WATER

Answer 2

Increased water:
Flooding, Impeding natural drainage

Decreased water:
Drainage e.g. drained for agriculture

Question 3

NUTRIENTS

Answer 3

Increased nutrients:
Eutrophication, Siltation e.g. Bogs are sensitive to atmospheric N deposition

Decreased nutrients:
Flood control, leading to reduced spring siltation

Question 4

NATURAL DISTURBANCES

Answer 4

Increased disturbance:
Burning, Reservoir construction, Off-road vehicles

Decreased disturbance:
Fire suppression, Flood control, Water level stabilization

Question 5

Why Fluctuating water levels are important (in some wetlands)?

Answer 5

1. Wading Birds:
   • Need low water periods for feeding on fish
2. Frogs:
   • Breed in temporary ponds (vernal pools)
   • Ponds must dry fish would eat tadpoles

3.Fish in floodplains:
• Annual flooding releases fish caught in vernal pools
• Water rich in nutrients
• Decayed organic matter
• Dung from grazing animals
• Explosive growth in bacteria, algae, zooplankton
• Rich fauna aquatic insects
• Vegetation grows rapidly

Question 6

Activities relating to draining?

Answer 6

• Conversion to agricultural land
• Urban and industrial development
• Coastal wetlands affected: 2/3 of the world’s population lives along coasts
• Airport construction

Question 7

Nutrient status defines the production of the wetland.

Answer 7

• All living organisms are built from CHNOPS
• Any element ↓ = ↓ growth and reproduction
• Two most important elements: N & P

• Human activity often increases nutrient levels in wetlands
- Fertilization

• More nutrients = ↑ in biomass and↓biodiversity
• Eutrophication — die-offs in aquatic plants
• Nutrient status and hydrology explain a lot about wetlands!

Question 8

Major wetlands of the world can be related to their hydrology
and nutrient status

Answer 8

See slide 34

Question 9

Eutrophication is a natural process, but is being sped up by humans!

Answer 9

Check how the process of eutrophication is!

See slide 36

Causes of eutrophication:

• Urban runoff
• Industrial discharge
• Fertilizers and Pesticides
• Erosion and sedimentation
• Nonpoint source pollution from cottages

Question 10

Disturbance removes produced biomass.

Answer 10

Disturbances are an important aspect of natural ecosystems
• Fire
• Ice scour
• Storms
• Herbivory

Disturbance has four important properties:
1. Duration
2. Intensity
• Proportion of biomass killed/removed
3. Frequency
• Floods -- 1 x a year
• Fires -- 1 x 10 years
• Hurricanes -- 1-2x in 100 years
4. Area