Negative Human Impacts on biodiversity

1. Negative Human Impacts on biodiversity Habitat change Invasive species Pollution Pesticide Overexploitation Climate change

2. Habitat change • Habitat loss • Definition: Loss of natural ecosystems • Human activity: conversion into farmland, urban sprawl, transportation routes • Fragmentation • Definition: Dividing up of a region into smaller parcels or fragments • Edges of an ecosystem are more susceptible to damage by outside influences • Fragmentation increases the perimeter

3. Factors that improve sustainability of habitat fragments

4. Factors that improve sustainability of habitat fragments

5. Global impact of habitat change • On a global scale, habitat loss and fragmentation are second to climate change as the most serious threat to sustainability of natural terrestrial ecosystems • In the Amazon, the world’s largest remaining rainforest is being cleared and burned to create pasture for cattle sold to foreign markets • Reducing demand for agricultural products produced in tropical regions can reduce rainforest habitat loss

7. Aquatic ecosystem: Loss of wetland

8. Aquatic ecosystem: Loss of wetland

9. Invasive Species • Exotic species: non-native species • Usually exotic specie fail in a new environment because it has been removed from its tolerance limits for all abiotic factors • Invasive species: exotic species that grow rapidly, spread and have a negative effect on the environment • Examples: carp, earwig, starling (bird)

10. Why exotic species become invasive • Growth of exotic species is unchecked due to: • lack of population controls in the new environment that were present in the old environment (e.g. predators, disease) • native species does not compete well with the exotic species

11. Impact of Invasive species • Ecological: compete with native species, leading to their population decline; alter nutrient cycles • Economic: lower crop yields; disease and pests may destroy livestock/crops • Health: disease-causing organisms; pesticide use • Tourism: choked waterways rendering them impassable to boats; negative impacts on recreation

12. Control Methods on Invasive species • Chemical: pesticides • Mechanical: physical barriers or removal • Plants: Cut down, burned, removed by hand • Animals: Hunted, trapped • Biological: using intentionally introduced organisms • Invasive plant: purple loosestrife • Biological control: 3 species on insects that feed on it without feeding on native plants

13. Pollution • Toxic materials that are release into the environment • Examples: • Purposeful pollutants: pesticide, fertilizer • By-products: car exhaust, product packaging

14. Acid Precipitation • Sulfur dioxide and nitrogen oxides produced in industrial processes and burning fossil fuels combine with water vapour to form acids

15. Why is the Canadian Shield more susceptible to the effects of acid rain? • Certain minerals (e.g. limestone) can neutralize acid • Limestone is often found near lakes • The Canadian Shield is made of granite

16. Effects of acid precipitation • Lowers the pH of water and soil • Acid leaching, nutrients in soil depleted • Speeds up corrosion of metals • Dissolves materials on building structures • Ironically, acid lakes are desirable for recreation. Why? • Few organisms live in them • So they appear clear and clean

17. Solution to acid precipitation • Wrong way: “Solution to pollution is dilution” • Concentration of pollutants is decreased by mixing them with large volumes of air or water • Although effects were less severe it spread over a greater area

18. Oil Spill • Oil is toxic, slow to break down, difficult to clean • Sea birds ingest it when cleaning themselves • Bird feather and seal fur lose their ability to insulate when covered with oil

19. Methods to clean oil spills • Skim/vacuum • Bioremediation: microorganisms that are capable of feeding on oil • Burn: oil lit on fire to prevent it from sinking or washing up on shore, but it pollutes the air • Dispersal agent: break up oil into small droplets using detergents allowing it to be washed out to sea and dispersed

20. Pests • Pests: organisms that people consider harmful or inconvenient • Agricultural pests: organisms that compete with or damage crop species • Examples: weeds, insect, mice • No pests exist in nature

21. Pesticide • Chemicals designed to kill pests • Herbicides: kill plants • Insecticide • fungicide

22. Characteristics of Pesticides • Persistence: how long the pesticide remains active in the environment • Is long or short persistence better?

23. Characteristics of Pesticides • Targeted: ability to kill only the intended pests • Broad-spectrum pesticides: effective against a wide range of species • E.g. DDT toxic to most insects • Narrow-spectrum pesticides: effective against a limited number of species • E.g. Bt (Bacillus thuringiensis), derived from bacteria, toxic only to caterpillars, beetle larvae and fly larvae • Is broad or narrow spectrum better?

24. Case study: DDT • Island of Borneo, 1995 • Malaria problem • DDT spray to control mosquitoes • DDT also killed wasps • Caterpillar  wasps • Caterpillars ravaged thatched homes • DDT also killed roaches • Roach  Lizards  cat (death!!!) • Rat population increased • Rats carry fleas which carry the plague

25. Bioaccumulation & Bioamplification • Some pesticides are not broken down or eliminated • Thus you can have an accumulation of pesticides in… • an individual organisms • in a food chain as one organism eats another

26. Bioaccumulation • An increase in the concentration of a chemical in an organism over time, compared to the chemical's concentration in the environment. • Compounds accumulate in living things any time they are taken up and stored faster than they are broken down (metabolized) or excreted. • A normal and essential process for the growth and nurturing of organisms. • All animals bioaccumulate vital nutrients (e.g. vitamins A, D and K, trace minerals and essential amino acids)

27. Uptake • Entrance of a chemical into an organism • Uptake methods: • breathing • swallowing • absorption through the skin

28. Factors that affect bioaccumulation • Concentration in the environment • Duration of exposure • Uptake rate • concentration of the chemical in the environment compared to an organism’s cells • tend to move from areas of high concentration to areas of low concentration (diffusion) • Lifetime of organism • Anatomy of organism • Solubility of pesticide (water soluble is more easily excreted than fat soluble)

29. large, fat, long-lived individuals with low rates of metabolism or excretion of a chemical will bioaccumulate more than small, thin, short-lived organisms. • Thus, an old lake trout may bioaccumulate much more than a young bluegill in the same lake.

30. Bioamplification / Biomagnification • A process that results in the accumulation of a chemical in an organism at higher levels than are found in its food. • It occurs when a chemical becomes more and more concentrated as it moves up through a food chain. • An animal at the top of the food chain, through its regular diet, may accumulate a much greater concentration of chemical than was present in organisms lower in the food chain.

32. Algae  water flea  minnow trout  eagle/human

33. For fish and other aquatic animals, bioaccumulation occurs after uptake through the gills or skin. • Storage: means the deposit of a chemical in body tissue or in an organ.

34. Example of bioamplification • Soil nutrients  earthworms  robins • DDT bioamplification • In soil: 10 parts per million (ppm) • In earthworms: 141 ppm • In robins: 444 ppm

35. Consequences of Bioamplification • death • abnormal behavior • decreased ability to reproduce • decreased resistance to disease

36. Resistance • Pests can develop resistance against pesticide • Individuals that survive (are resistant) will pas on their resistance to their offspring

37. Sustainable techniques of controlling pests • Biological control • Crop rotation • Altered timing: plant and harvest to avoid peak pest populations • Baiting pests: pheromones can confuse mating insects

38. Integrated pest management (IPM) • Takes advantage of all types of management methods • Goal is to maximize efficiency, keep costs low, reduce harm to environment

39. Overexploitation • Definition • Require consumption and resource management

40. Forestry Practices • Clear-cutting: removal of all or most of the trees in a given area • Takes large blocks or strips • Shelterwood cutting: mature trees harvested in series of two or more cuts • Long narrow parallel strips • Selective cutting: periodic harvesting of selected trees • Performed on private woodlots • Where there is high values for individual trees or where appearance of forest is highly value

41. Comparing forest management practices

42. Comparing forest management practices

43. Forestry Management • Fire suppression - good or bad?

44. Wildlife Management • Managed hunts to control populations • First Nations and Inuit people harvested wildlife in a sustainable way

45. Stewardship • Taking responsibility for managing and protecting the environment • Past: arrival of European settlers were more interested in resource as a source of revenue

46. Types of artificial ecosystem • Agroecosystem: Farms • Urban ecosystem: cities, roads

47. Comparing natural vs artificial

48. Comparing natural vs artificial