Human Impact🤦🏻♂️ Flashcards
(39 cards)
Why are species becoming endangered?
•Loss of habitat
-habitat can become too small or too widely dispersed to support a species
•Invasive species
-some species exploit their new ecosystem
->outcompete native species
->predation of natives
•Overexploitation
-exploiting resources
-overfishing
-poaching
•Pathogens/disease
-spread of domesticated animals
-native population may have little resistance
•Pollution
-pesticides/fertilisers/greenhouse gases/thermal/light/noise
-reduce survival rates of local animal populations
What are upwelling zones?
•A combo of winds and currents causes water close to the sea bed to rise
-upwelling carries nutrients into higher water where there is sufficient light to support photosynthesis
Where are fish populations most abundant?
•Where phytoplankton productivity is highest
•Phytoplankton productivity is directly related to mineral nutrients in the surface waters
-Generally, oceans have a low conc of nutrients at surface so low pop of phytoplankton and fish
What are demersal fish?
Bottom-feeding fish
What are pelagic fish?
Surface-feeding fish
Stock size equation
Sn (stock size now)
= Sn (stock size last year)
- 1
+ G (biomass added by growth of fish already in stock)
+ R (biomass added by recruitment)
- M (biomass lost by mortality/harvesting)
Impact of overfishing
•Causes fall in number
•Young, smaller fish become increasingly common
•Catching large numbers of small fish before they spawn can reduce the ability of the population to reproduce
-may lead to fall in local populations
What are sustainable yields (in fishing)?
- Fish must not be caught faster that the fish stocks can replenish themselves
- Varies with size of population and its growth rate
What is maxim sustainable yield (MSY)?
The largest amount of a naturally renewable resource that can be regularly harvested without causing a decline in stock
What regulations can prevent overfishing?
•Quotas
-less endangered fish are removed from the ocean-> allows recovery
•Minimum mesh sizes
-should be large enough to allow immature fish to pass through-> can survive to breed
•Closed seasons
-times when fishing is not allowed
•Exclusion zones
-areas where fishing is banned completely
Benefits of fish farming
•Can reduce pressure on wild stocks of fish, while still meeting human demands
Negatives of fish farming?
•Can encourage spread of pathogens/parasites (due to high density) which could spread to wild fish
-antibiotics & pesticides are used->can harm marine invertebrates
•Waste produced by fish can cause increased nitrate concentration
-leads to eutrophication
•Less genetic variation due to selective breeding
•Less biodiversity due to escaped farm fish
-reduces gene pool
-invasive species & hybrid sterile fish out-compete wild fish
Causes of deforestation
- Firewood
- Make room for infrastructure
- Pulp and paper
- Timber for construction
- Acid rain
- Replacement of native trees with fast-growing species
What is the effect of deforestation on biodiversity?
Reduce biodiversity of species
-some can have potential medical benefits
What are the effects of deforestation on nutrient cycles?
- Forest burning releases huge quantities of CO2 directly and quickly into the atmosphere
- Burning trees significantly reduces nitrogen held in ecosystem
- Tree roots hold soil particles together
- Tree canopy reduces rain eroding soil
- Nutrients are lost through leaching
Examples of sustainable development
- Managed timber production
- Land designated as set asides
- Agroforestry
- Ecotourism
- Coppicing
- Selective cutting
- Plantations
- Education
- Local incomes
What are the aims of biological conservation?
- Maintain quality of natural environments and their biological resources
- Actively managing biotic and abiotic components to ensure the survival of the maximum number of species and genetic diversity
- Maintain biodiversity, ensure survival of endangered species and conserve existing gene pools
What is sustainable development?
- Development that can continue indefinitely
- Based on exploiting renewable resources, while minimising environmental damage, maintaining the overall integrity of the ecosystem and conserving species
What is in situ conversation?
•Conservation of species in their natural habitats, e.g.
- mowing
- grazing
- burning
- coppicing
- control of water level
- wildlife corridors
- selective cutting
- sustainable replanting
- pollarding
How can burning conserve species?
It can halt succession to keep particular communities in an environment
What is coppicing/pollarding?
- Coppicing - pruning shrubs to ground level
- Pollarding - similar but higher up
- Allows regeneration
What is ex situ conservation?
•Preservation of components of biodiversity outside their natural habitats, e.g.
- breeding programmes
- sperm/seed banks
- reintroduction
- restricting trade of endangered species
- controlling pollution
- international cooperation and treaties
Why is conservation of genetic diversity important?
- Conservation of species ensures the conservation of existing gene pools
- Ethical reasons
- Prevent loss of potentially useful genes to man and the species
What happens if breeding numbers become too small?
•Less chance of finding a mate
•Less genetic diversity/smaller gene pool
-inbreeding
-alleles are less likely to help species survive environmental changes
