Unit 4 Flashcards

Question

Aquaculture. Then Open vs Semi-closed aquaculture systems

Answer 1

Aquaculture is the farming of aquatic organisms 2012, aquaculture contributed 66.6 million tonnes of fish and shellfish and 23.8 million tonnes of aquatic algae produced globally. Aquaculture not only provides a vital protein source in many regions but provides a livelihood for millions of people. The FAO estimate that in 2012, over 18.8 million people were working within the aquaculture sector. Open: Most popular. Farming organisms within natural aquatic ecosystem Examples: fish cages, clam beds, oyster rafts Semi-closed: More control. Abstraction of water to tanks or ponds on land. More expensive Impacts: Loss of habitat (by land clearance) Increase in organic sediments (waste like fish feces and medicines) Increase in nutrients --> algal blooms --> damage fish grills and can be toxic. Spread of disease in dense cages Predators can get entangled and caught in nets

Answer 2

Inland and coastal pollution: - Domestic sewage: Source of pathogens like bacteria and viruses. - Industrial discharge: Can include organic matter or toxic metals - Agricultural run-off - Urban run-off: Organic waste - Land development: Buildings may involve forest clearance which increases soil erosion. - Acid mine drainage: Rainwater percolates through either disused or active mines. Marine based sources: Outfall pipes (discharge material at dea) Materials dumped at sea Shipping activities (derrame de petroleo de Repsol)

Answer 3

Organic pollution Sewage effluent, farm runoff and food waste Inorganic plant nutrients If dropped in water, eutrophication happens (enrichment of waters with plants and nutrients, it becomes overly rich in plant nutrient and doesn’t allow for sunlight to reach the bottom of the lake or river.) Toxic metals (toxic by interfering with essential cellular processes) Synthetic compunds (like DDT they bioaccumulate) Suspended soils (supress plant life by preventing light penetration) Hot water (lower concentrations of oxygen result in increased stress level by organisms) Oil (death of organisms. fur loses ability to repel water) pathogens (health hazards) Invasive species light and noise pollution

Answer 4

pH: indicate the acidity or alkalinity of the water. Extreme pH levels can harm aquatic life. Temperature: Water temperature affects the amount of dissolved oxygen, and changes can stress organisms. Warmer water holds less oxygen than cooler water. Suspended Solids: These are small particles in the water that can affect sunlight penetration, photosynthesis, and block feeding and respiratory systems of aquatic organisms. They can be measured by weighing collected residues or using instruments like turbidity meters or secchi disks. Dissolved Oxygen (DO2): DO2 levels are essential for aerobic respiration in aquatic organisms. Low or no oxygen levels can lead to species loss, and oxygen levels can be affected by temperature and organic matter. Biochemical Oxygen Demand (BOD): BOD measures the oxygen used to break down organic material in water. High BOD indicates pollution, as it reflects the amount of organic material that can be oxidized. Metals: High concentrations of metals, whether from natural geology or human activities, can have adverse effects on the ecosystem and human health. Common examples include arsenic and mercury. Biological monitoring: Individual indicator species Representative due to it being stationary Biotic Index: Biotic indices are used to assess water quality based on the presence and abundance of specific aquatic organisms. High biodiversity indicates good water quality, while reduced species diversity may suggest pollution. Some species are sensitive to pollution (indicator species), while others are more tolerant.

Answer 5

Preliminary treatment: Screens to remove large objects that may damage equipment. Primary treatment: Piped sewage allowed to settle within tanks in which solids are removed. Secondary treatment: Biological process in which micro-organisms use unsettled organic waste as food source. Tertiary treatment: Nitrate removal (ammonium ions oxidised) and desinfection to kill pathogens.

Answer 6

reducing human activities that produce pollutants (for example, alternatives to current fertilizers and detergents) reducing release of pollution into the environment (for example, treatment of wastewater to remove nitrates and phosphates) removing pollutants from the environment and restoring ecosystems (for example, removal of mud from eutrophic lakes and reintroduction of plant and fish species). Minimize the amount of nutrients being released into the system by: limiting production/use of detergents containing phosphates alternative methods of enhancing crop growth create buffer zones between agricultural land and water sources regulating and reducing at point of emission prevent animal waste from leaching into groundwater and rivers/streams Treat the polluted area by: pumping air into the water source divert or treat sewage properly dredge (dig up) contaminated sediments physically remove algae blooms reintroduce plant and fish species pumping mud from eutrophic lakes

Answer 7

A major problem with the use of fertilisers occurs when they're washed off the land by rainwater into rivers and lakes. The resulting increase of nitrate or phosphate in the water encourages algae growth, which forms a bloom over the water surface. This prevents sunlight reaching other water plants, which then die. Bacteria break down the dead plants and use up the oxygen in the water so the lake may be left completely lifeless The main effects caused by eutrophication can be summarized as follows: Species diversity decreases and the dominant biota changes Plant and animal biomass increase Turbidity increases Rate of sedimentation increases, shortening the lifespan of the lake Anoxic conditions may develop Because of the high concentration of organisms in a eutrophic system, there is often a lot of competition for resources and predator pressure. This high degree of competition and the sometimes-high chemical or physical stress make high the struggle for survival in eutrophic systems. As a result the diversity of organisms is lower

Answer 8

Changing human activities Possible measures to reduce nitrate loss (based on the northern hemisphere) include the following. Avoid using nitrogen fertilizers between mid-September and mid-February when soils are wet and fertilizer is most likely to be washed through the soil. Do not apply nitrogen just before heavy rain is forecast (assuming that forecasts are accurate). Use less nitrogen if the previous year was dry because less will have been less lost. This is difficult to assess precisely. Do not plough up grass as this releases nitrogen. Use steep slopes for permanent pasture grass or woodland; use flat land above slopes for arable crops. This minimizes the greater risk of wash from steep land. Incorporate straw – straw decay uses nitrogen, with up to 13 per cent less nitrogen lost – it also locks up phosphorus. Direct drilling and minimal cultivation reduces nitrogen loss by up to a half. Less disturbance means less conversion of nitrogen to nitrate but straw has to be burnt. Regulating and reducing the nutrient source Public campaigns in Australia have encouraged people to: use zero- or low-phosphorus detergents wash only full loads in washing machines wash vehicles on porous surfaces away from drains or gutters reduce use of fertilizers on lawns and gardens compost garden and food waste collect and bury pet faeces. Clean-up strategies Once nutrients are in an ecosystem, it is much harder and more expensive to remove them than it would have been to tackle the eutrophication at source. The main clean-up methods available are: precipitation (e.g. treatment with a solution of aluminium or ferrous salt to precipitate phosphates) removal of nutrient-enriched sediments, for example by mud pumping removal of biomass (e.g. harvesting of common reed) and using it for thatching or fuel.

Unit 4 Flashcards

(32 cards)