4.3, 4.4: Water, Food Production Systems and Society
Continental shelf: extension of continents under the seas and oceans (creates shallow water)
→ has 50% of oceanic productivity but 15% of its area
→ light reaches shallow seas so producers can be photosynthesize
→ countries can claim, exploit, and harvest it
Zooplankton: single-celled animals that eat phytoplankton and their waste
Fishery: when fish are harvested in a certain way
→ 90% oceans and 10% freshwater
→ 70% of the world’s fisheries are exploited
Aquaculture: farming aquatic organisms (coastal and inland) involving interventions in the rearing process to enhance production
→ Impacts of fish harms: loss of habitat, pollution, spread of diseases, escaped species may survive to interbreed with wild fish, escaped species may autocomplete native species
Maximum Sustainable yield (MSY):
→ SY: increase in natural capital (natural income that can be exploited each year without depleting original stock)
→ MSY: highest amount that can be taken without permanently deleting the stock
Pollutants can be: anthropogenic or natural, point or nonpoint source, organic or inorganic, direct or indirect
Organic:
→ pollutant: sewage, animal waste, pesticide
→ example: human waste, insecurities
→ effects: eutrophication, loss of biodiversity
Inorganic:
→ pollutant: nitrates and phosphates radioactive material, heavy toxic material
→ example: industry, nuclear power stations, fertilisers
→ effects: eutrophication, bioaccumulation, biomagnification
Both:
→ pollutant: solid domestic waste, debris, suspended solids
→ example: silt form construction, household garage
→ effects: damage controls, plastics
Freshwater pollution: agricultural runoff, sewage, solid domestic waste
Marine pollution: rivers, human pollution, pipelines
Measuring water pollution:
BOD: amount of dissolved oxygen required to breakdown organic material in a given volume of water
Indicator species: plants and animals that show something about the environment by their presence, absence, abundance
Biotic index: indirectly measures pollution by assessing the impact on species within the community according the their tolerance, diversity, and relative abundance
Eutrophication: when lakes and coastal waters receive inputs of nutrients (nitrates and phosphates) that result in an excess growth of plants and phytoplankton
The eutrophication process:
→ Fertiliser enters rivers/lakes
→ High level of phosphates, algae grows faster
→ More algae, more food for zooplankton or small animals that feed on them. A lack of zooplankton animals means that these are less to eat algae
→ Algae die and are decomposed by aerobic bacteria
→ Not enough oxygen is present therefore everything dies and the food chain collapses
→ oxygen levels fall lower, dead organic material sediments on the lake or the river bed and turbidity increases
→ All life is gone and sediment settles to leave a clear blue lake. This process in which bodies of water become enriched with nutrients and minerals
Biochemical oxygen demand: amount of DO required to break down organic material in a given volume of water
→ biological monitoring and indicator species can be used to determine levels of pollution
→ strengths: stationally, sensitive and representative
→ weaknesses: identification
Continental shelf: extension of continents under the seas and oceans (creates shallow water)
→ has 50% of oceanic productivity but 15% of its area
→ light reaches shallow seas so producers can be photosynthesize
→ countries can claim, exploit, and harvest it
Zooplankton: single-celled animals that eat phytoplankton and their waste
Fishery: when fish are harvested in a certain way
→ 90% oceans and 10% freshwater
→ 70% of the world’s fisheries are exploited
Aquaculture: farming aquatic organisms (coastal and inland) involving interventions in the rearing process to enhance production
→ Impacts of fish harms: loss of habitat, pollution, spread of diseases, escaped species may survive to interbreed with wild fish, escaped species may autocomplete native species
Maximum Sustainable yield (MSY):
→ SY: increase in natural capital (natural income that can be exploited each year without depleting original stock)
→ MSY: highest amount that can be taken without permanently deleting the stock
Pollutants can be: anthropogenic or natural, point or nonpoint source, organic or inorganic, direct or indirect
Organic:
→ pollutant: sewage, animal waste, pesticide
→ example: human waste, insecurities
→ effects: eutrophication, loss of biodiversity
Inorganic:
→ pollutant: nitrates and phosphates radioactive material, heavy toxic material
→ example: industry, nuclear power stations, fertilisers
→ effects: eutrophication, bioaccumulation, biomagnification
Both:
→ pollutant: solid domestic waste, debris, suspended solids
→ example: silt form construction, household garage
→ effects: damage controls, plastics
Freshwater pollution: agricultural runoff, sewage, solid domestic waste
Marine pollution: rivers, human pollution, pipelines
Measuring water pollution:
BOD: amount of dissolved oxygen required to breakdown organic material in a given volume of water
Indicator species: plants and animals that show something about the environment by their presence, absence, abundance
Biotic index: indirectly measures pollution by assessing the impact on species within the community according the their tolerance, diversity, and relative abundance
Eutrophication: when lakes and coastal waters receive inputs of nutrients (nitrates and phosphates) that result in an excess growth of plants and phytoplankton
The eutrophication process:
→ Fertiliser enters rivers/lakes
→ High level of phosphates, algae grows faster
→ More algae, more food for zooplankton or small animals that feed on them. A lack of zooplankton animals means that these are less to eat algae
→ Algae die and are decomposed by aerobic bacteria
→ Not enough oxygen is present therefore everything dies and the food chain collapses
→ oxygen levels fall lower, dead organic material sediments on the lake or the river bed and turbidity increases
→ All life is gone and sediment settles to leave a clear blue lake. This process in which bodies of water become enriched with nutrients and minerals
Biochemical oxygen demand: amount of DO required to break down organic material in a given volume of water
→ biological monitoring and indicator species can be used to determine levels of pollution
→ strengths: stationally, sensitive and representative
→ weaknesses: identification
