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BIO234_Animal Conservation and Welfare > Habitat fragmentation and degradation > Flashcards

Habitat fragmentation and degradation Flashcards

1
Q

What is habitat degradation?

A

a reduction in the quality of habitat
- includes pollution and activities leading to desertification, erosion and sedimentation

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2
Q

What is habitat fragmentation?

A

larger continuous habitat becomes divided into smaller patches
- reduces habitat area but also changes structure of remaining habitat

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3
Q

Types of habitat degradation

A
  1. pollution
  2. desertification
  3. erosion & sedimentation
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4
Q

What is the largest environmental cause of human disease and premature death?

A

pollution

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5
Q

How many deaths does pollution cause pa?

A

9 million (16% of all deaths worldwide)

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6
Q

Types of pollutions

A
  • pesticides
  • oil spills
  • toxic metals
  • eutrophication
  • acid rain
  • pharmaceuticals
  • plastics
  • light, sounds and smell pollution
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7
Q

When were pesticides brought to the world’s attention? (pollution)

A

1962 by Racheal Carson’s book ‘Silent Spring’

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8
Q

What is DDT (pesticides - pollution)?

A

Bioaccumulation
banned across most of world

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9
Q

Why are agrochemicals harmful? and testing agrochemicals? (pesticides - pollution)

A
  • kill non-target species & remove natural predators and further increasing reliance on agrochemicals
  • undergo tests to investigate their toxicity to a standard suite of organisms - sub lethal effects (or effects on other organisms) not tested for
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10
Q

Neonicotinoids (pesticides - pollution)

A
  • widely used - controversial
  • sublethal effects on bee behaviour by impairing foraging behaviour, homing success, navigation performance and social communication - makes bees ‘drunk’
  • banned in UK and EU, but farmers can be granted exemptions
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11
Q

Effect of oil spills? (oil spills- pollution)

A
  • directly kills many species
  • clear-up processes e.g. chemicals dispersants can cause further damage
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12
Q

What are toxic metals a result of? (Toxic metals- pollution)

A
  • often result from manufacture, and directly kill many species
  • often bioaccumulate
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13
Q

What is eutrophication? (Eutrophication- pollution)

A

adding fertilisers (nitrates and phosphates) to aquatic systems

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14
Q

What does eutrophication cause? (Eutrophication- pollution)

A

algal blooms - shade bottom-dwelling plants and decomposition uses up oxygen

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15
Q

‘Dead zones’ in coastal habitats (Eutrophication- pollution)

A
  • 245,000 km2 of ‘dead zone’ in >400 coastal habitats around the world
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16
Q

Long-term effect of eutrophication on ecosystems (Eutrophication- pollution)

A

can be difficult for ecosystems to recover, even if pollution is removed

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17
Q

How is acid rain produced and its effects? (Acid rain- pollution)

A
  • Nitrogen and sulphur released into ai form nitric and sulphuric acids, lower pH of rainwater
  • can kill plants & animals
  • can travel hundreds of miles, effecting ‘pristine’ ecosystems
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18
Q

Pattern of acid rain in the world (Eutrophication- pollution)

A
  • reducing in Europe and North America
  • increasing in East and South Asia
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19
Q

Examples of pharmaceuticals (Pharmaceuticals - pollution)

A

e.g. medicines, cosmetics, disinfectants, detergents

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20
Q

Effects of pharmaceuticals (Pharmaceuticals - pollution)

A
  • emerging pollutant source - little is known about consequences
  • antimicrobial resistance can be caused by antibiotic misuse (e.g. antibiotic resistant TB)
  • hormones e.g. from contraceptive pills can impact on aquatic animal reproduction (e.g. shrunken gonads)
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21
Q

Plastics as a pollutant (Plastics - pollution)

A
  • fast-growing form of environmental pollution
  • problematic in marine ecosystems - get washed in from land
  • more than 5 trillion pieces of plastic weighing > 250,000 tons are afloat in the world’s oceans
  • can be mistaken for food, and break down releasing toxins
  • microplastics are another emerging pollutant
22
Q

Effects of light, sound and smell pollution? (light, sound and smell - pollution)

A
  • affect behaviour
23
Q

Effect of light pollution (light, sound and smell - pollution)

A
  • light pollution - impacts circadian rhythms and disrupts normal feeding and breeding behaviour
  • e.g. street lighting leads to 47% decline in moth caterpillar abundance in hedgerows and 33% decline in grass margins
  • disrupts nocturnal feeding behaviour and likely disrupts egg-laying behaviour
24
Q

Effect of sound pollution (light, sound and smell - pollution)

A
  • impacts vocal communication, orientation and foraging
  • e.g. blue whale forging is disrupted by boat traffic
  • increasing evidence from marine and terrestrial species
25
Q

Effect of smell pollution (light, sound and smell - pollution)

A
  • little investigation but pollution can most likely disrupt natural scent communication (reproduction, social behaviour)
26
Q

Examples, cause, and effect of desertification (Habitat degradation)

A
  • poor soil and water management -> further drying of already dry areas
  • pre-history, the Sahara was grassland
  • rates of desertification are increasing
  • e.g. The Mesopotamian Marshes, Iraq were drained by Saddam Hussein - now in the process of restoration
  • most cases are not on purpose e.g. Aral Sea -> was 4th largest inland lake; irrigation upstream for cotton production drained it in 30 years; led to ecosystem collapse and human tragedy; restoration has started but has a long way to go
27
Q

What are the current rates of soil erosion, in relation to previous levels? (Erosion & sedimentation - Habitat degradation)

A
  • current rates of soil erosion are 11-38 times faster than previous levels
28
Q

What causes erosion and sedimentation? (Erosion & sedimentation - Habitat degradation)

A

due to deforestation, overgrazing, and unsustainable agricultural methods

29
Q

Cause of erosion & sedimentation (Erosion & sedimentation - Habitat degradation)

A
  • causes degradation of agricultural land, and deposition of soil chokes up natural landscapes
30
Q

Solutions for habitat degradation

A

solutions lie in environmental regulation at local, national and international levels

31
Q

what is habitat fragmentation and what is it associated with?

A

divides larger habitat into smaller pieces
associated with habitat loss, but leads to specific biological consequences

32
Q

Types of variation in patch and what it leads to (Habitat degradation - Biological consequences)

A

variation in patch:
- size
- shape (amount of edge)
- number
- isolation
leads to variation in species responses

33
Q

Effect of habitat fragmentation (Habitat degradation - Biological consequences)

A

mostly negative but can be beneficial for some species in some situations

34
Q

What is the relationship between habitat fragmentation and habitat loss? (Habitat degradation - Biological consequences)

A

aspects of habitat fragmentation do not correlate linearly with habitat loss

  • mean patch size - negative correlation
  • number of patches - bell-like curve
  • total edge habitat - bell-like curve
  • mean nearest neighbour distance - steep decline, then slower decline over time
35
Q

Species richness equation

A

S=CA^Z
S=species richness
A=habitat area
C=constant that depends on the unit of measured used
exponent of Z is scaling factor that dictates how species richness changes with area

36
Q

What are extinction thresholds? (Habitat degradation - Biological consequences)

A

Species have extinction thresholds - minimum habitat size that are required for them to persist

37
Q

What are allele effects? (Habitat degradation - Biological consequences)

A

small populations are disproportionately likely to go extinct. Need to find mates, dilution effects from predators etc.
Behavioural aspects can have a big effect on these

38
Q

What are edge effects? (Habitat degradation - Biological consequences)

A

Smaller patches have proportionately more edge, as do more elongated patches
- e.g. a Haddad et al. (2015) found that 70% of world’s remaining forest is within 1 km of forest edge, and nearly 20% is within 100 m of an edge

39
Q

Edge habitats (Habitat degradation - Biological consequences)

A
  • less resilient (more changeable conditions)
  • vulnerable to invasive species
  • behaviour of specific species involved is key to determining which will thrive and which will decline
  • dominated by generalists that adapt well to anthropogenic landscapes
  • predation often high (e.g. by corvids and domestic cats)
40
Q

Human-wild life conflict (Habitat degradation - Biological consequences)

A
  • related to habitat loss, increased edges, anthropogenic food sources
  • understanding traits of animals and humans that are of greater risk is important
  • In Asian elephants, human mortality occurs mostly while chasing wild elephants using firecrackers. Lone male elephants are more likely to attack people
  • behavioural solutions can be important e.g. using beehive fences to deter elephants
41
Q

Patch isolation (Habitat degradation - Biological consequences)

A
  • increases with fragmentation
  • behaviour is important here
42
Q

What does the ability to disperse between patches depend on? (Habitat degradation - Biological consequences)

A
  • distance between patches
  • hostility of the environment
43
Q

What does increased connectivity between patches affect? (Habitat degradation - Biological consequences)

A

reduces probability of reaching extinction threshold
can reduce genetic diversity and increase risk of local extinction

44
Q

Solutions for patch isolation (Habitat degradation - Biological consequences)

A
  • different solutions may be required for species with different characteristics
  • some solutions may be better for a wider range of species
45
Q

Island Biogeography Theory - MacArthur & Wilson (1963)
What is the expected species diversity of ‘island’ related to? (applications for landscape-scale conservation)

A
  1. The distance of the island from the mainland
  2. Island size
  3. The number of species on the mainland that are not already on the island
46
Q

What is the Island Biogeography Theory? (applications for landscape-scale conservation)

A
  • larger ‘Islands’ = higher species richness (lower extinction)
  • larger reserves should be better than smaller ones
  • but single large reserve always better than two smaller ones?
  • not necessarily e.g. are they preserving common or scarce habitats? Are they preserving different habitat types or species?
47
Q

Effect of species richness on ‘Islands’ close to ‘mainland’? (applications for landscape-scale conservation)

A
  • ‘Islands’ close to ‘mainland’ are likely to have a greater species richness due to increased dispersal
48
Q

What is best in the Island Biogeography Theory? (applications for landscape-scale conservation)

A
  • Having a network or reserves with dispersal corridors is best
  • Create a metapopulation
49
Q

Metapopulation models (applications for landscape-scale conservation)

A
  • ‘Islands’ varying in size and quality
  • Dispersal can occur between them
  • Source populations have expanding populations and supply dispersers
  • sink populations have contracting populations
  • can create mathematical models of real landscapes to design effective reserve networks
50
Q

Applications for landscape-scale conservation

A
  • identify source and sink populations
  • identify areas in need of habitat restoration
  • create corridors or stepping stones to aid dispersal
  • decide on size and shape of nature reserves: larger, more circular, but need to be appropriate for landscape and incorporate target habitats

BIO234_Animal Conservation and Welfare (17 decks)

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