Ecosystems At Risk Flashcards
Describe the vulnerability and resilience of ecosystems by natural and human factors.
Ecosystems are constantly in a dynamic equilibrium (balanced change). Vulnerability and resilience vary between ecosystems.
Factors affecting vulnerability:
- location: what nutrients and energy it has available; the more specialised to a particular environment the more vulnerable it is; any human populations nearby
- extent: how much does it overlap with other ecosystems, one may affect the other; large or small land, many or few species; endemic
- biodiversity: genetic, species and ecosystem
- linkages between organisms in the food web
Resilience generally depends on how diverse an ecosystem is. Elasticity refers to an ecosystem’s rate of recovery after stress; its malleability is distance between it’s final recovery and pre-stress level. The greater malleability, the less resilient.
Natural stress:
- drought
- fire
- flood
- landslide
- disease
- cyclone
- climatic change
- ecological succession (one species taking over as environment changes in their favor)
- immigration
Human stress (may be intentional or inadvertant):
- introduction of foreign species
- habitat destruction e.g. deforestation, farming, fire, mining
- water and air pollution
- urbanisation
- conservation measures
Describe the functioning of ecosystems, including their nature, spatial patterns and interactions.
An ecosystem is an identifiable system of interdependent relationships between living organisms and their biophysical environment. It is highly dynamic - i.e. ever-changing and adapting. Biomes or terrestrial ecosystems are land-based; water-based are called aquatic ecosystems.
E.g. Polar, tundra, coniferous forest, temperate grassland, Mediterranean, desert, tropical forest, mountain.
The boundary of an ecosystem is very much a blurred line. The zone of transition between two ecosystems is called an ecotone which contains organisms common to both ecosystems.
The ecosphere is the collection of all living and dead things and their interactions between each other and their environment. i.e. it encompasses every ecosystem on earth. Ecology is the study of relationships between five levels of organisation: organisms, populations, communities, ecosystems and the ecosphere.
The productivity of an ecosystem depends on how much energy and nutrients are available to it. It’s level of productivity can generally be measured via how much biomass it produces (mass of new living matter produced per square metre of area), or how much energy organisms contain per unit of time.
In a food chain (or foodweb), nutrients are constantly recycled through. This cannot be done for energy. Organisms at the same level of the food chain are said to be part of the same trophic level.
There are four trophic levels:
- first trophic level: producers
- second trophic level: herbivores (primary consumers)
- third trophic level: omnivores (secondary consumers)
- fourth trophic level: carnivores (tertiary consumers)
Then there’s decomposers which runs through the entire foodchain.
About 90% of energy is lost per level.
Besides energy, there other cycles within an ecosystem: carbon, phosphorous, nitrogen, water and oxygen.
Factors that affect the functioning of an ecosystem:
- hydrosphere: how much water?
- biosphere: autotrophs and heterotrophs; energy and nutrients
- lithosphere: climatic factors e.g. hot, cold; orographic rainfall
- atmosphere: temperature and rainfall
Bioaccumulation increases up the trophic levels and can prove fatal e.g. toxic, non-biodegradable materials such as DDT
Explain the importance of ecosystem management and protection.
Reasons for management and protection:
- maintenance of genetic diversity
Promotes resilience for ecosystems and preservation of different species
- utility value (both current and potential)
Uses for human survival e.g. medicine technology, natural resources to build or fuel - intrinsic value
Right to exist is irrelevant of utility value. - heritage value
“Natural features consisting of physical and biological formations or groups of such formations, which are of outstanding universal value from the aesthetic or scientific point of view.” World Heritage Council
The Australian Heritage Commission: “those places, being components of the natural environment of Australia or the cultural environment of Australia, that have aesthetic, historic, scientific or social significance or other special value for future generations, as well as for the present community.”
- need to allow natural change to proceed
- large enough area to keep ecosystems intact and allow evolutionary processes
- have boundaries that reflect environmental and not political needs
- account for the interests of local people
- well-managed and effectively resourced
- surrounded by a buffer zone
Evaluate traditional and contemporary management strategies
- preservation
- conservation
- utilitarianism
- exploitation
The Great Barrier Reef was one case study for this topic. Describe its nature and spatial distribution, natural stresses, human impacts, and traditional and contemporary management of it.
SPATIAL DISTRIBUTION
- approx. 2300 km
- strip of reef closely following the shape of the coast of Queensland at continental shelf
- NW/SE orientation
- from Papua New Guinea’s Fly River in the north (8 degrees S) to Fraser Island (24 degrees S)
- 348 000 km square
- below sea level
- majority offshore (barrier) reef; fairly continuous
NATURE
- covers about 1% of the world’s ocean yet it is home to over 10% of the world’s ocean species
- largest reef in the world
- symbiotic relationship with coral polyps (respires, nutrients, protection, Co2) and zooxanthallae algae (photosynthetic, O2, sugars/food, colour)
- cycling of nutrients is fast and limited; too much energy means too much algae
- each coral has a specific algae and vice versa
SPECIES
- 1500/13000 world’s fish species
- 6/7 world’s turtle species
- 200 bird species
- 500 species of seaweed
- 600 echinoderm species (sea cucumbers and urchins, etc)
- 125 shark and ray species
- 360 hard coral species
NATURAL STRESSES
- cyclones
- ocean currents such as El Nino and El Nina
- climate change
- continental drift
HUMAN IMPACTS
- tourism
- climate change - ocean acidification
- oil spills and ship traffic
- coral harvesting
- scientific research
- mining
- sewerage and waste disposal from human populations
- overfishing
- land clearing
TRADITIONAL AND CONTEMPORARY MANAGEMENT
- 1982 World Heritage Listed
- Great Barrier Reef Marine Park Authority
Zoning
- Great Barrier Reef Marine Park Zoning Plan, 2004
- 19 zones e.g. general use, habitat protection, marine national park, preservation, conservation park, scientific research, buffer
Special Management Areas
- Restricted access without written permission e.g. Maclennan Cay Reef, Raine Island Reef
- Public Appreciation e.g. Restricts spearfishing and commercial aquarium fish collecting, aquaculture
- Seasonal Closure (offshore ribbon reefs); reefs located at the edge of the continental shelf; fishing and detached dories are prohibited 1 Jan to 31 Aug yearly
- Species Conservation (Dugong Protection Areas) e.g. Princess Charlotte Bay where fishers need a permit; use of set mesh nets restricted in some other areas
Specific Site Management
- e.g. Raine Island, Moulter Cay and MacLennon Cay site widely known for marine turtles and island nesting areas for seabirds
- under Marine National Park zone
- requires a permit to access
- designated as National park (scientific)
- remote natural area meaning largely unaltered by human works
- Indigenous land use to traditional owners such as the Wuthathi People of Cale York
