habitats Flashcards
What are the ecological features of tropical coral reefs? (3)
1) Coral nutrition
2) Reef building corals: Many species of coral secrete a limestone base which is continually added to, building up into a reef.
3) Abiotic conditions: Tropical coral reefs are only found where there are very specific abiotic conditions, which makes them vulnerable to environmental change.
What abiotic conditions are critical to coral survival and why? (5)
1) Light: The symbiotic algae within the coral polyps require bright sunlight. In the tropics.
2) Temperature: Temperature must be warm and constant, in the range of 25-29C
3) Immersion: Polyps must be covered in water almost all of the time to prevent them drying out. They can’t live in deep water because not enough light would reach them for algal photosynthesis.
4) Turbidity: Seawater must have very low turbidity as turbid water reduces light penetration so photosynthesis would be reduced. Suspended solids carries by the water could also settle on the reef, sticking to the cilia and blocking entrance to the stomach.
5) Salinity: If the salinity of the water changed outside the narrow range of the corls, the cells would be killed by osmosis with water flowing into or out of the cells.
What are the importances of tropical coral reefs and explain? (5)
1) Fisheries: Coral reefs support many species that are exploited for food, including fish, crustaceans such as lobsters and molluscs such as coral.
2) Medicinal discoveries: Many species on coral reefs don’t have spines, teeth or a hard shell to protect themselves. Instead, they may produce toxic chemicals which may be useful as medicines when used in carefully controlled amounts.
3) Climate Control: growing coral reefs are an important carbon sink, helping to resist climate change.
4) Erosion protection: Coral reefs absorb the energy of waves that would otherwise have eroded or washed away nearby islands.
5) Tourism: Coastal areas and islands with coral reefs are popular tourist populations for ecotourism activities such as scuba diving and snorkeling, as well as relaxation in pleasant surroundings.
What are the threats to tropical coral reefs? (7)
1) Physical damage: Hard objects can kill polyps as they are pushed against the hard limestone beneath the living cells. Litter such as bottles, lost fishing gear, boat anchors and careless drivers can all damage reefs
2) Sedimentation: Turbid waters carried by rivers or sediments disturbed by coral developments can cover and kill corals.
3) Pollution: Pollutants such as oil spills can cover coral reefs which is toxic to corals. Nutrients such as nitrates and phosphates from agricultural runoff can stimulate the growth of algae which covers the corals.
4) Introduced Species: introduced from ballast water discharged from ships, escaped fish from fish farms and accidental and international releases from aquaria.
5) Fishing: If there is an excessive catch-rate, fish populations will decrease and affect other inter-dependent species. Over-fishing of the Giant Triton allowed Crown of Thorns starfish populations to rise which are harmful to coral reefs
What are the conservation efforts for tropical coral reefs (5)?
1) Marine protected areas: fixed mooring bays to reduce use of anchors, divers/swimmers told not to touch the corals, controlling of fishing, sustainable development of ecotourism.
2) Control of fishing: Fishing for some species that have been over-exploited may be banned so their populations can recover. Control methods include: length of fishing seasons restricted, No take zones where fishing is banned, restrictions of damaging fishing equipment.
3) Control of tourism: Recreational activities may be restricted to minimise the damage the damage that may be caused (eg banning of spear fishing and turtle nesting beaches may be protected to reduce disturbance).
What are the ecological features of deep water coral reefs:
Coral polyps that form deep water coral reefs do not have the symbiotic algae that are found in tropical coral reefs so they have much less food energy available and grow much more slowly than shallow-water tropical coral reefs. The slow rate of deep water growth means that reefs recover much more slowly from damage than tropical coral reefs in shallow water.
What are the importances of deep water coral reefs?
They support a large biomass of fish but these are often slow-growing species with a low reproductive rate so it is easy to over-exploit the populations.
What are the threats to deep water coral reefs (3)?
1) Deep water trawling has over-exploited fish populations, killed a lot of by-catch species, and damaged the deep water coral reefs that support the fish. The slow rate of coral reef growth means that it may take hundreds of years for the damage to be repaired.
2) The expansion of oil and gas exploration in deep water is a future threat,
3) Increased releases of carbon dioxide are gradually causing the acidification of oceans. This may threaten the survival of deep water corals.
Describe how named methods of conservation protect
Antarctica. [5 marks]
- limited numbers of tourists ashore/ areas visited/ boats to prevent
disturbance to wildlife / erosion - shoe covers/ sterilisation/ protective clothing/ no dogs to reduce
introduction of disease/ non-native species - visitors with guides only to restrict disturbance/ raise awareness
- removal of waste to prevent contamination/ pollution
- no mining/ resource exploitation to prevent habitat destruction/
pollution - no military use/ weapons testing to prevent damage to biotic and
abiotic environment - restrictions on fishing/ monitoring of fish populations to reduce overexploitation/ food chain impacts
- named methods to control greenhouse gas concentrations to
reduce global climate change/ named impact - control of ODS/CFCs to reduce Antarctic ozone depletion/ reduce
UV impacts to phytoplankton/ wildlife - freedom of scientific inv
- Antarctic Treaty (1959)/ Madrid Protocol (1998/1991)
What are the conditions in the Antarctic treaty?
1) Antarctica should only be used for peaceful means
2) Antarctica can be used for scientific research but all research has the right to be shared and cooperated on
3) All stations and operations can be inspected at any time
4) Antarctica is not any country’s territory
5) Nuclear activity is banned
What are the criticisms of the Antarctic treaty?
1) Not mandatory meaning countries can choose not to sign it
2) Inspections do not occur often
3) All decisions must be unanimous
