ECOLOGY

1. ECOLOGY Done by: Glenn Tan (26) 2P4

2. What is Ecology? • Ecology is the study of interactions among organisms, and their surroundings. • Scientists who study ecology are called ecologists.

3. Ecosystem • An ecological system formed by the interaction of living organisms and their non-living environment. • A community and its physical or abiotic environment together make up an ecosystem. • Grassland, desert, river, forest etc.

4. Community • A cluster comprising many different populations and interacting in a given habitat.

5. Population • A group of organisms of the same species living in a specific area.

6. Habitat • The place the organism lives in.

7. Abiotic environment • Also known as physical environment • Abiotic environments are the non-living environmental factors in the ecosystem. • They affect the lives and distribution of organisms.

8. Abiotic environment

9. Abiotic environment

10. Abiotic environment

11. Biotic environment • Biotic environment consists of all living organisms in the ecosystem • It can by classified into three main groups: • Producers • Consumers • Decomposers • There is a feeding relationship between the living organisms to form a food chain.

12. Food Chain • A food chain is a series of organisms through which energy and nutrients are transferred. Each level in a food chain is knows as a trophic level. • The first trophic level in a food chain is always a producer. A producer is any organism which is able to manufacture its own food.

13. Food Chain • A consumer is any organism that feeds on another organism. This can be further classified as: • Primary Consumers are herbivores that feed on green plants • Secondary Consumers are carnivores that feed on primary consumers. They are the predators and the primary consumers arte the prey. • Tertiary Consumers will feed on the secondary consumers. • Omnivores consume both plants and animals, thus they may occupy more than one trophic level.

14. Food Chain • Decomposer is an organism that breaks down dead animals and plants into simple substances. Examples of decomposers are bacteria and fungi. • Many food chains may be linked together to form a food web.

15. Food Web • A food web is a series of interrelated food chains that gives an accurate feeding relationship in an ecosystem. This is because an organism usually feeds on more than one type of organism.

16. Ecological pyramids • Food chains can be expressed quantitively as pyramids of numbers, biomass or energy. Pyramid of numbers • Each level represents the number of organism at each trophic level.

17. Ecological pyramids Pyramid of numbers • Each level represents the number of organism at each trophic level. • There is usually a decrease in the number of organism as we go up each successive trophic level. This is because there is less energy available for organisms at higher trophic levels.

18. Ecological pyramids • Sometimes a pyramid of numbers can be inverted, in the case of one significantly large organism supporting many other organisms.

19. Ecological pyramids Pyramid of biomass • Biomass is the total mass of organisms in a population • A pyramid of biomass is constructed based on the dry mass of organisms in each trophic level within a given unit of environmental area or at a particular time • The shape of a pyramid of biomass usually follows that of the pyramid of numbers. In the case of an inverted pyramid of numbers, the shape of pyramid of biomass can vary. This is because the amount of living matter at higher trophic levels has to be supported by a relatively larger amount of living matter at a lower trophic level.

20. Ecological pyramids Pyramid of biomass • This is because the herbivore populations can only thrive if there is sufficient vegetation available to feed on. Similarly, the number of carnivores can only increase if the herbivore population is large enough to support them.

21. Ecological pyramids Pyramid of energy • As food is transferred from a lower trophic level to a higher one, energy is lost through as heat, respiration, excretion, egestion and undigested matter • Since total amount of energy decreases along the food chain, the pyramid of energy is broad based and tapers to the top. • Energy is lost from one trophic level to the next; hence food chains are kept short so that the final consumer can still obtain a significant amount of energy.

22. The Carbon Cycle • The carbon cycle involves the conversion of inorganic carbon dioxide to organic carbon that is replenished back to the surroundings as carbon dioxide • Carbon is the main constituent of all organic molecules and it is essential for life, hence its presence in the atmosphere has to be relatively constant.

23. The Carbon Cycle

24. Effects of human activity on the ecosystem • Humans have devastating effects on the environment through our activities.

25. Deforestation • Forests are cleared to make way for areas for cultivation of crops, industrialization and urbanization. • Habitats are destroyed and many species of animals become endangered. This is because they lose shelter and food their natural habitat confers and thus gradually die out. • Without protection from the forest canopy, soil becomes exposed to the elements of weather and eventually gets washed away by heavy rain, resulting in soil erosion.

26. Deforestation • Eroded soil washed down to rivers and streams may block the flow of water, causing widespread flooding and damage. • Without the trees, less carbon dioxide is removed from the atmosphere and, at the same time, more is added. This adds to Global Warming. • When sunlight falls directly onto soil, water will evaporate rapidly and soil hardens. New plant life cannot grow on this soil and organisms, which depend directly or indirectly on these plants for food also die off, leaving back a piece of barren land. This phenomenon is called desertification.

27. Undesirable Fishing Practices • Over-fishing is a situation where the populations of fish stocks are reduced below the accepted level by fishing activities • Bottom trawls are large nets which are used to catch the fish commercially. They are one of the most destructive methods because they directly threaten the biodiversity by catching a variety of unmarketable species.

28. Undesirable Fishing Practices • Cyanide fishing is another destructive method used to collect reef fish, which causes damage to the surrounding coral reefs. This method is inexpensive and effective for collecting reef fishes in many places around the world. The fishermen swim to coral reef areas and places the concentrated cyanide into crevices where reef fish hide. The cyanide stuns the fish temporarily, making them unable to move so that they can be captured. The live reef fish are brought back to the ship and are put in seawater for transportation.

29. Undesirable Fishing Practices • Blast fishing uses dynamite or other homemade explosives to kill or stun reef fish. This method gives rise to several detrimental results which include diminished ability of corals to regrow and the extinction of coral species.

30. Sewage • Sewage is the used water carrying waste substances from homes and industries that flows to a wastewater treatment plant. It should not be directly discharged into rivers because it can cause an epidemic. • Untreated sewage contains a host of bacteria that deplete oxygen content in water when they multiply rapidly. • Depletion of oxygen in water causes the death of aquatic organisms.

31. Eutrophication • The excessive use of fertilisers to produce more crops result in the eutrophication of water bodies. • The fertilisers contain minerals such as nitrates and phosphates, which are not absorbed by the crops are washed away into water bodies. • Nitrates and phosphates promotes rapid growth for algae and water plants which causes a thick layer to form at the surface, preventing submerged plants to die off due to lack of sunlight.

32. Eutrophication • The decomposition of submerged plants by aerobic bacteria further lowers the oxygen content in the water, resulting in the death of marine life.

33. Insecticides • Insecticides are non-biodegradable substances and may get washed into water bodies. • They are insoluble in water, so once digested by organisms, they will not be excreted but stored as fat. • Insecticides accumulated in the bodies of organisms are passed along food chains in increasing concentration. • The consumers at the end of the food chain will consume and accumulate high levels of insecticides that can pose serious toxic effects on their body. This is called bioaccumulation.

34. Conservation • To prevent serious consequences, we have to consciously take steps to conserve and protect our environment • Conservation maintains the biodiversity of living organisms because biodiversity contributes valuable resources such as food, timber, fuels or medicines.

35. Environmental biotechnology • Environmental biotechnology is the technologies based on biological systems to reduce or utilise waste to protect our natural environment from pollution. • Sewage treatment makes use of environmental biotechnology to reduce water pollution. It involves the use of microorganisms as decomposers.

36. Sewage treatment • Sewage treatment is the process of removing unwanted and harmful substances from wastewater so that it can be safely discharged into the sea.

37. Conservation of forests • Reforestation is the planting of forests to replace trees that have been cut down. • Introduce laws to enforce the practice of selective logging so that only old and matured trees are cut down. After the trees have been removed, replanting of the trees should be carried out immediately.

38. Conservation of fishing grounds • Enforcement of laws needs to be increased to ban destructive fishing practices. Make people aware of the detrimental effects of destructive fishing practices and educate them on alternative fishing methods, for example, using nets with suitable hole size to avoid catching young fish • Allows enforcement officers to patrol the area for illegal fishing practices

39. Conservation of fishing grounds • Destructive fishing practices lead to damaged fish habitat and less fish, which makes fishery unsustainable. Coral reefs can be protected with a system of a new Marine Protected Areas (MPAs) and better management of current MPAs. • Governments of different countries need to cooperate closely to regulate the import and export of fish that are caught sustainably.

40. THANK YOU VERY MUCH!