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Biology > *E2 Applied Ecology > Flashcards

*E2 Applied Ecology Flashcards

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1
Q

Reasons for population expansion

A

Birth rate > death rate
1. Improved agricultural technology -> increased food production
2. Use of fertilizers / pesticides -> increased food production
3. Better nutrition
4. Advances in medical technology
5. Increased awareness of public and personal hygiene

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2
Q

Impact of rapid human population growth

A
  1. Destruction of natural habitat -> decrease biodiversity -> upset ecological balance
  2. Exhaustion of natural resources
  3. Pollution to the envrionment
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3
Q

Renewable resources vs. Non-renewable resources

A

Rate of consumption vs. rate of replenishment
<: renewable
>: non-renewable

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4
Q

Fishery

A
  1. Overfishing
    - Decrease biodiversity -> upset ecological balance
    - Depletion of certain fish species
  2. Destructive fishing method (trawling)
    - Kill non-target organisms (decrease biodiversity -> upset ecological balance)
    - Destroying habitats / shelters / breeding grounds at sea bottom (eg. coral reef)
    - Stirs up sediments at sea bottom -> turbidity of water increase -> reduces light penetration -> reduces photosynthetic activities of marine plants
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5
Q

Deforestation (Advantages)

A
  • Cities bring improvement of living standards
  • More employment opportunities
  • growing crop provides food and incomes
  • timbers bring income
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6
Q

Agriculture

A
  1. Deforestation
    - Destruction of natural habitats -> decrease biodiversity -> upset ecological balance
    - Rain falls onto the soil directly without the covering of canopy + there are no root systems to hold soil together -> soil erosion -> sedimentation of soil in water + water tends to run off soil surface -> flooding / water quality becomes poor
    - Global warming
    - Rate of transpiration decreases -> overall decrease in rainfall
  2. Monoculture
    - Harvesting of crops from the land reduces the return of organic matter to the soil -> less humus is present to retain soil water -> soil texture is worsened
    - Certain minerals depleted -> infertile soil
    - Host-specific pest population increases
    - Disease spread rapidly among the crop
    - Soil erosion after harvesting
  3. Ploughing (increase aeration of soil, encourage decomposers, discourage denitrifying bacteria)
    - Soil texture of the land destroyed -> more soil cavities present for leaching
    - Loosen soil particles -> soil erosion
  4. Extensive use of fertilizers
    - Leaching of inorganic fertilizers causes algal bloom in water -> depletes dissolved oxygen in water at night -> organism die from suffocation
  5. Extensive use of pesticides
    - Kill non-target organisms (eg. pollinating agents)
    - Bioaccumulation along food chains
    - Pesticide-resistant strain
  6. Discharge of animal waste to river
    - Decomposition of organic matters by bacteria use up dissolved oxygen -> organisms die from suffocation
  7. Overgrazing (consumption rate > regeneration rate)
    - Desertification -> soil erosion
  8. Extensive use of antibiotics / growth hormone in rearing livestock
    - Microorganisms develop antibiotic resistance (some maybe pathogenic to humans)
    - Growth hormones causes health risk to humans
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7
Q

Abiotic factors that favour algal bloom

A
  • High light intensity
  • Warm temperature
  • Slow water current
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8
Q

Algal bloom

A

Advantages
- More algal species -> provide sufficient quantity of food source to aquatic life + convert more solar energy to chemical energy

Disadvantages
1. During daytime, photosynthesis rate > respiration rate -> sufficient oxygen supply to water body /At night, large population of algae stop photosynthesizing but continue to respire -> much dissolved oxygen in water body is consumed -> other aquatic lives die from suffocation
2. Decay of dead algae by decomposers consume dissolved oxygen
3. Produce toxin, killing aquatic life directly
4. Decrease light penetration -> decreases photosynthesis rate -> population of producers decreases -> population of consumers decreases
5. Clogs the gills of fish -> fish dies from suffocation

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9
Q

How increased use of pesticide leads to the rise of pesticide-resistance strain of pests?

A
  • There are genetic variations among the pests in their resistance against pesticide.
  • Those that are resistant have a higher chance of survival in the presence of pesticide.
  • They have a higher chance of production
  • The proportion of the pesticide-resistant pests increases in the subsequent generation.
  • Pesticide becomes less effective in killing the pests.
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10
Q

Bioaccumulation of toxic substances along the food chain

A
  • Pesticide is leached into the sea from farming area
  • Pesticide is absorbed by microscopic algae
  • Herbivores eat a lot of microscopic algae
  • Carnivores occupying a higher trophic level eat a lot of herbivores
  • Pesticide cannot be metabolized or excreted by the organisms readily
  • Pesticide accumulates along the food chain to a toxic level in the body of carnivores
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11
Q

Properties of toxic substances that accumulate along the food chain

A
  1. More readily soluble in fat
  2. Cannot be excreted
  3. Cannot be metabolized
  4. Stable and persistent
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12
Q

Land clearance and reclamation

A
  1. Land clearance
    - Destruction of natural habitats -> decrease in biodiversity -> upset ecological balance
    - Rain falls onto the soil directly without the covering of canopy + there are no root systems to hold soil together -> soil erosion -> sedimentation of soil in water -> flooding / water quality becomes poor
  2. Reclamation
    - Destruction of natural habitat -> decrease in biodiversity -> upset ecological balance
    - Dredging stirs up the mud of seabed -> decreases light penetration -> decrease photosynthetic activities of marine plants + clog the gills of fish
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13
Q

Major sources of air pollution

A
  1. Power stations
  2. Factories
  3. Motor vehicles
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14
Q

Air pollution

A
  1. Sulphur dioxide / nitrogen oxides (combustion of fossil fuel)
    - Irritation to eye and respiratory tract
    - Dissolve in water -> form acid rain
  2. Particulates suspended in air (incomplete combustion)
    - Impair gas exchange
    - Reduce light penetration
    - Cause shortness of breath / coughing
  3. Carbon monoxide
    - Combines more readily with haemoglobin than oxygen -> reduce oxygen carrying capacity of blood
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15
Q

Greenhouse gases

A
  1. Carbon dioxide (combustion of fossil fuels)
  2. Methane (anaerobic decomposition of organic matter by bacteria)
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16
Q

How global warming is brought about?

A
  • Atmospheric concentration of carbon dioxide has been increasing
  • When the heat radiation is reflected from the Earth surface to the atmosphere, more heat radiation is trapped by the greenhouse gases
  • This causes an increase in atmospheric temperature, resulting in global warming
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17
Q

Consequences of global warming

A
  1. Rise of sea level causes flooding
    - Global warming increases melting of icebergs and thermal expansion of sea water -> cause rise in sea level -> flooding occurs at coastal regions
  2. Loss of natural habitats
    - Melting of icebergs reduces the size of polar habitats
  3. Change of climate and impacts on crop
    - More intense rainstorms / typhoons / hurricanes -> physical destruction of crops
    - Heat waves / intensified droughts / drier summers -> impair crop growth
  4. Spread of infectious diseases
    - Growth rate of bacteria increases
    - Growth and reproductive rate of mosquitoes increases
    - More rainfall -> increases availability of aquatic habits for mosquitoes to lay eggs
18
Q

Impacts of global warming on structural changes of global ecosystems

A
  1. More unpredictable and severe weather conditions -> destroy well established ecosystems
  2. Warms up surface water of oceans -> change the annual rainfall pattern
  3. Enhance ice melting in polar regions -> rise in sea level -> flooding in coastal areas -> affects distribution of humans
19
Q

Effects of acid rain

A
  1. Lowers water pH -> killing organisms that are sensitive to acidity
  2. Increases the release of aluminium ions from soil -> increase aluminium concentration in soil -> toxic to plant roots
  3. Reduces soil fertility / dissolves soil nutrients -> facilitates their loss through leaching
20
Q

Air pollution biological indicator

A

Lichen (sensitive to sulphur dioxide)
- Types and abundance of lichens can indicate the level of air pollution
- High level of sulphur dioxide destroys chlorophyll in algae for photosynthesis -> not enough food produced for growth od algae and fungi

21
Q

Water pollution

A
  1. Domestic sewage / Agricultural sewage
    - Organic matter -> inorganic nutrients -> algal bloom
    - Decomposition of organic matter by decomposers depletes dissolved oxygen in water bodies -> organisms die from suffocation
    - Large amount of pathogens / bacteria in untreated sewage -> spread disease
    - Turbidity increases -> decreases light penetration
  2. Industrial sewage
    - Bioaccumulation of chemicals along the food chain
    - Hot water decreases oxygen solubility in water + kills heat-sensitive species
22
Q

Water pollution biological indicator

A
  1. Mayfly nymphs (only live in clean water with sufficient dissolved oxygen)
  2. Phytoplankton (multiply greatly in nutrient-enriched waters)
  3. E coli (found in human and animal faeces)
23
Q

Air pollution control

A
  1. Set tighter fuel and vehicle emission standards
  2. Offer tax reduction to encourage citizens to buy environmental-friendly petrol private cars
  3. Cooperation between governments of Hong Kong and Guangdong
24
Q

Air Quality Health Index

A
  • Useful for people who are sensitive to air pollution to take precautions when the health risk levels are high
25
Q

Solid waste treatment

A
  1. Landfills
    - Release toxic substances (methane)
    - Destruction of habitat -> decrease in biodiversity -> upset ecological balance
    - Attract pest (vectors of pathogens) -> spread diseases
  2. Incineration
    - Reduces volume of wastes quickly
    - Heat energy can be changed into electric energy
    - Air pollutants: carbon particulates / sulphur dioxide -> harmful to human health
26
Q

4Rs

A

Reduce
Reuse
Recycle (changing waste materials into useable goods)
Replace

  • Reduce use of disposable items
  • Use electronic statements
27
Q

Waste management strategy

A
  • Environmental Levy Scheme of Plastic Shopping Bags
  • EcoPark
28
Q

Sewage Treatment

A
  1. Primary Treatment
    - Large solid wastes are removed by passing through screens
    - Suspended solid wastes in sewage settle in the form of sedimentation and removed in sedimentation tank

2a. Secondary treatment
- In aeration tank, sewage is aerated to enhance activities of microorganisms -> decomposition rate of organic matter to harmless inorganic matter is fast
- Effluent is disinfected by chlorine / UV light

2b. Fermentation in anaerobic digester
- Under anaerobic condition, organic matter is decomposed by anaerobic bacteria to methane
- Methane gas produced can be used as fuel to generate power
- Residue of sludge is dried and used as fertilizers or disposed away to landfills

29
Q

Human activities that poses threats to the survival of plants and animals

A
  1. Constructions cause shrinkage of natural habitats / deterioration of water quality
  2. Illegal hunting kills or injures the animals
  3. Disturbance caused by tourism -> large number of visitors increases pressure on habitat / heavy sea traffic
  4. Increased pollution -> decline in population of food sources / drop in reproductive potential of animals -> deter the animals from resting there
30
Q

Importance of biodiversity

A
  1. Provides useful materials for human use directly
  2. Helps maintain the stability of an ecosystem
  3. Provides biological resources for scientific research
  4. Provides aesthetic and recreational service
31
Q

Measures to protect endangered species

A
  1. Legislation
  2. Ex situ conservation and captive breeding of endangered animals
    3.Gene banks
  3. Education
32
Q

Conservation of habitats

A
  • Maintain biodiversity by preserving endangered species
  • Prevent destruction of natural habitats
33
Q

Conservation areas

A
  1. Sites of Special Scientific Interest
  2. Country parks
  3. Marine parks
  4. Ramsar site
34
Q

Renewable energy sources

A

Solar energy / wind / tidal waves / hydroelectric power
- From natural phenomenon -> will not be depleted / cause less disturbance to environment
- Not feasible in HK (not cost-effective / not enough land available / tidal waves too small)

35
Q

Biofuel

A
  • Emit carbon dioxide and water only
  • Local production -> low transportation cost
  • Absorbs carbon dioxide during growth
  • Renewable
  • Planting crops requires land
  • Need water in irrigation
  • Need fertilizers / pesticides
  • Cause food shortage
  • Not all machines are bio fuel ready
36
Q

Ecological restoration of damaged land

A

Afforestation
- Trees are fast growing and capable of establishing themselves in damaged land
- Lack of biodiversity
- Plantation may be destroyed quickly due to spread of diseases and parasites
- Depletion of specific soil nutrients

Native plant species is used
- Non-native species may outcompete native species
- Native species well adapted to local environment
- Native species provide food / habitats for local animals

37
Q

Measures to conserve biodiversity of fish

A
  1. Artificial coral reef (non-toxic / long-lasting / more cavities)
    - Habitat with different biotic and abiotic factors
    - Shelters for organisms to escape from enemies
    - Sites for reproduction
    - Sites for settlements of organisms that serve as food for other species
    - Obstacle for trawling
  2. Moratorium (banning fishing activity for a period of time in a year)
    - Allow time for organisms to grow to maturity and breed -> allows recovery of population
  3. Legislation to forbid use of destructive fishing methods
    - Protect non-target organisms
  4. Restrict mesh size of fish net
    - Smaller or juvenile fish can escape from being caught -> can grow to sexual maturity -> carry put reproduction to produce offspring -> keeps a sustainable population of fish
  5. Limit fishing activities
  6. Aquaculture
    - Adequate food supply to fish
    - Better quality
    - No by-catch
    - Produce specific fishery product -> people become less dependent on fish catching
    - Provide fry which are released for recovering fish population
38
Q

Protective measures in marine park

A
  • Prohibit power-driven boats -> avoid fuel leakage
  • Provide sufficient toilet facilities
  • Provide facilities for disinfection of recreational equipment
39
Q

Proper practice in agriculture

A
  1. Organic fertilizer
    - Humus is present -> improve soil texture + hold water in soil
    - Less soluble in water -> less likely to be washed away
  2. Organic pesticides
    - Can be decomposed in nature -> will not accumulate along the food chain
  3. Natural predators (birds) -> pest control
  4. Crop rotation
    - Each crop has different nutrient requirements -> fertility of field can last longer
    - Interrupts life cycle of host-specific pests
40
Q

Graph: discharge of sewage

A

Organic matter
1. There is a sudden increase in concentration of organic matter due to entry of organic sewage
2. Organic matter then decreases due to decomposition of organic matter by decomposers / dilution effect of organic matter down the river

Decomposers
1. The population of decomposers is increasing due to the presence of organic matter in sewage, providing food for growth of decomposers and the birth rate of decomposers is greater than death rate
2. The population then decreases due to decrease in organic matter and dilution effect

Dissolved oxygen
1. A rapid decrease in concentration of dissolved oxygen due to rapid increase of organic sewage / decrease in population of algae / decomposition of large amount of organic matter in sewage depletes large amount of oxygen
2. Concentration of dissolved oxygen then increases because consumption of oxygen decreases as organic matter has been used up, less decomposers carry out decomposition / concentration of algae increases which produce oxygen by photosynthesis / oxygen continues to dissolve in the stream water due to running water

Freshwater shrimp
1. The population drops sharply due to sharp decrease in dissolved oxygen concentration
2. The population then increases due to increase in concentration of dissolved oxygen

Algae
1. Population decreases due to presence of toxic substances in sewage / toxin released by rapid growth of bacteria / increase in number of suspended particles in organic sewage, decreasing light penetration and light intensity in water, photosynthetic rate of algae decreases
2. The population then increases due to conversion of organic matter into inorganic nutrients by decomposers stimulates growth of algae
3. The population decreases again as algae are eaten by animals

Biology (38 decks)

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