Unit 4 The Sustainability of Ecosystems Page | 190 Slide 1___________________________________ Sustainability of Ecosystems __________________________________ __________________________________ _ _ __________________________________ __________________________________ _ _ __________________________________ __________________________________ _ _ Slide 2___________________________________ ancient Greek word for home. Ecology and Ecosystems Textbook pages 284 onward • Ecology – [Definition] • Ecosystem – [Definition] 2. An Ecosystem is all the interacting parts of a biological community and it’s physical environment. This includes the relationships between populations of various organisms. (biotic and abiotic 1. Ecology is the study of the interactions among living things and their nonliving environment. The prefix “eco” is from the Ecosystems may… • vary in size - from a log ecosystem to a forest or ocean • be terrestrial (on land) or aquatic (in water) factors in the environment. Page | 191 Ecotone - [Definition] Ecotones are biologically diverse! The area that connect two or more ecosystems is called an ecotone. For example, the marshland between a pond and a forest is an ecotone. In our study of ecology, we want to make the distinction between organism, species, population and community • Organism – an individual plant, animal or single celled life form • Species – a group of similar living organisms capable of breeding and producing offspring. • Population – All of the members of the same species in an ecosystem or habitat • Community – The collection of all the populations of species in the ecosystem. From Species to Community video on YouTube: “Ecosystem Dynamics”: https://www.youtube.com/watch?v=57FGF hsHtFQ Niche and Habitat • Niche - Niche refers to the role that a species plays within its ecosystem. In balanced eco systems, each species occupies its own niche. The niche is like the organism’s profession. ▪ Each organism in an ecosystem tends to have a different niche. This helps reduce competition between species for the same resources and territory. ▪ Example: Owl and hawk feed on the same organism but they occupy distinctly different niches. How is that so? ▪ Check out the diagram. Notice how each warbler has its own niche. Page | 192 Slide 7___________________________________ •Habitat –refers to the place where an organism lives. This means that the habitat of a species is different than its niche, it is one part of its niche. The organism’s habitat is its address - where it lives. Slide 8___________________________________ “What is a Niche? ” Check out YouTube: https://www.youtube.com/watch?v=6-aGxYTUPu0 Extra Video: “Populations, Habitats and Niches https://www.youtube.com/watch?v=fupYSpg64dM Slide 9___________________________________ Abiotic and Biotic Components of Ecosystems Textbook pages 286 onward • Abiotic factors - [Definition] Abiotic factors include: 1. Temperature: Environmental temperature affects biological processes and the ability of organisms to regulate temperature. Few organisms have active metabolisms at temperatures below 0oC or above 45oC. The temperature of an area will affect the type of organisms found in an ecosystem. 2. Amount of sunlight: Sunlight is the ultimate source of energy for all photosynthetic organisms, which in turn provide the resources for other living things. Light also affects the development and behaviour of many organisms. Page | 193 Slide 10___________________________________ 3. Strength and direction of wind: Some areas of Newfoundland are particularly windy, and this affects not only the type of plants that grow, but how they grow. It also affects the type of organisms found in an area, and can affect how they behave. Slide 11___________________________________ __________________________________ 4. Soil (inorganic and organic soil nutrients): Inorganic soil nutrients include minerals such as phosphates, nitrates, potassium, magnesium and a host of other minerals derived from rocks. Organic nutrients include organic compounds in humus which promote the growth of bacteria, fungi, and a host of other organisms beneficial to the soil. The physical structure, water holding potential, pH, and nutrient level of soil limit the distribution of plants and in turn, the animals that inhabit a terrestrial region. _ __________________________________ _ __________________________________ Planting corn in this province is a challenge! Given the last two abiotic factors, why do you think this is so? _ __________________________________ _ __________________________________ __________________________________ _ _ Slide 12___________________________________ _ 5. Space: All organisms require enough space or territory to insure adequate resources to food, water, shelter, and mates. 6. Oxygen: Most living organisms require oxygen for cellular respiration, which is a process that releases energy from food. 7. Water: Water (humidity) is necessary for all life. The ability to find water, to maintain water balance, and to conserve water, help determine the habitat range for each species. __________________________________ _ __________________________________ _ __________________________________ _ __________________________________ __________________________________ _ _ __________________________________ Page | 194 Slide 13___________________________________ Biotic Factors __________________________________ • Biotic factors – [Definition] Biotic factors include: 1. Predator-prey relationships. This important biotic factor helps to limit the size of populations within an ecosystem. A predator is an animal that kills and eats another animal for food. The prey is the hunted animal. An example is the lion and the zebra. When a lion kills a zebra for food, the lion helps to prevent the overpopulation of the zebra. If the number of zebra declines too much, the lion will starve. There needs to be a balance between the number of predator and prey in any sustainable ecosystem. _ __________________________________ _ __________________________________ _ __________________________________ _ _ __________________________________ __________________________________ _ Slide 14___________________________________ _ 2. Disease is the result of infection by fungi, bacteria, virus, and other pathogens. Disease is an important biotic factor because disease tends to reduce the number of organisms within the community. __________________________________ _ __________________________________ 3. Competition involves the struggle for survival which occurs between two organisms. Competition tends to limit the size of the population keeping it in balance with the available resources. Populations commonly compete for living space and / or food within an ecosystem. _ __________________________________ _ __________________________________ __________________________________ _ _ __________________________________ Slide 15___________________________________ __________________________________ Two types of competition: 1. Interspecific Competition – [Definition] _ __________________________________ 2. Intraspecific competition - [Definition] _ __________________________________ _ __________________________________ __________________________________ _ _ __________________________________ _ Page | 195 Slide 16___________________________________ _ 4. Symbiosis - [Definition] Here an osprey is nesting in a tree. What type of symbiosis is this? Read on… __________________________________ _ __________________________________ _ __________________________________ _ __________________________________ __________________________________ _ _ __________________________________ Slide 17___________________________________ _ Types of Symbiosis: 1. Parasitism – [Definition] ▪ Ex: Tapeworm __________________________________ _ 2. Commensalism – [Definition] ▪ Ex: Tree and nesting bird. 3. Mutualism – [Definition] ▪ Ex: Clownfish and anemone. (Earlier YouTube video: https://www.youtube.com/watch?v=fupYSpg64dM) __________________________________ _ __________________________________ _ __________________________________ __________________________________ _ _ __________________________________ Slide 18___________________________________ _ Food Chains and Food Webs In an ecosystem, certain organisms provide energy for other organisms. These relationships are shown with food chains and food webs. __________________________________ _ Food chains • Show a step-by-step sequence of which organism consumes another in an ecosystem • Each level in the food chain is called a trophic level. __________________________________ • Producers are found in the first trophic level, then consumers in all levels afterward. _ __________________________________ _ __________________________________ __________________________________ _ _ __________________________________ Page | 196 Slide 19___________________________________ __________________________________ • Producers (a.k.a. autotrophs) are organisms that can make their own food. These are located in the first trophic level. Producers are organisms which use photosynthesis or another form of chemical synthesis to make food. Ex: plants, algae and some types of bacteria • Consumers (a.k.a. heterotrophs) are organisms that cannot make their own food, and thus obtain nutrients from consuming other organisms. There are several groups of heterotrophs: herbivores, carnivores, omnivores and decomposers. _ __________________________________ _ __________________________________ _ __________________________________ _ __________________________________ __________________________________ _ _ Slide 20___________________________________ _ Primary consumers are organisms that feed on the producers, located in the second trophic level. (These are herbivores: they eat only plants) Secondary consumers are located in the third trophic level and feed on the organism in the second trophic level (These are carnivores – eat only meat, or omnivores – eat plant and meat) Tertiary consumer is the “top carnivore”, found at the fourth tropic level. This is an organism that relies on the secondary consumers as its principal source of energy. __________________________________ _ __________________________________ _ __________________________________ _ __________________________________ __________________________________ _ _ __________________________________ Slide 21___________________________________ __________________________________ Check out YouTube: “The Food Chain” https://www.youtube.com/watch?v=0ZOvqYypOuo _ __________________________________ _ __________________________________ _ __________________________________ __________________________________ _ _ __________________________________ _ Page | 197 Slide 22 ___________________________________ _ Scavengers and Decomposers Some food chains include organisms considered to be scavengers or decomposers: • Scavengers consume decaying organic material, such as meat or rotting plant material. • Decomposers (a.k.a Saprobes) are organisms or microorganisms that complete the final breakdown of organic matter; an organism that feeds on detritus (waste from plants and animals, including their dead remains) in the process releasing nutrients to the soil and water, where they can be used (again) by other organisms. How do scavengers and decomposers allow the “circle of life” in an ecosystem to continue? __________________________________ _ __________________________________ _ __________________________________ _ __________________________________ __________________________________ _ _ __________________________________ Slide 23___________________________________ a food web. Which organisms in the above food web would be Food Webs • To show all the feeding relationships in an ecosystem we can use competing? __________________________________ __________________________________ _ _ __________________________________ __________________________________ _ _ __________________________________ __________________________________ _ _ Slide 24___________________________________ _ Sustainable Ecosystems Depend Upon Diverse Food Webs __________________________________ • For an ecosystem to be sustainable there must be a balance between food production, food consumption, and decomposition. _ • This means that a stable ecosystem must have: • a source of energy (usually sunlight for photosynthesis) • producers to capture the sunlight and make food __________________________________ • consumers to eat the food • decomposers to recycle the nutrients back to the producers. • Resilience is the ability of an ecosystem to remain functional and stable in the presence to disturbances of its parts. A more diverse food web is directly related to a more resilient ecosystem. Why do you think this is the case? _ __________________________________ _ __________________________________ __________________________________ _ _ __________________________________ Page | 198 Slide 25___________________________________ Check out YouTube: “The Food Web” _ https://www.youtube.com/watch?v=MGODmyXkkPU __________________________________ _ __________________________________ _ __________________________________ _ __________________________________ _ __________________________________ _ __________________________________ Slide 26___________________________________ _ The Pyramid of Energy (This is an optional topic.) The “10 Percent Rule” mentioned in the earlier video leads to the idea of the pyramid of energy as we go up the trophic levels in a food chain or food web. The pyramid of energy is a measurement or indication of the energy present at each trophic level. Energy is measured in Joules, “J”. __________________________________ _ __________________________________ _ __________________________________ _ __________________________________ __________________________________ _ _ __________________________________ Slide 27___________________________________ • In general, 10% of all the energy in a lower trophic level gets passed on to the next higher level. This generalization suggests that 90% of the energy taken in by an organism at any trophic level is lost by the life processes of that organism as well as lost as heat. Hence the “10 Percent Rule”. • As a result of this pyramid of energy, the amount of life that can be sustained at each level, going to the top, decreases. This is why there are so few if any fourth order consumers in an ecosystem. _ __________________________________ _ __________________________________ _ __________________________________ _ __________________________________ _ __________________________________ _ __________________________________ Page | 199 Slide 28___________________________________ _ Pesticide Use and Food Chains Textbook page 310 Pests are living organisms that man believes are undesirable, and are not wanted around us. Examples include: - unwanted dandelions in lawns; - rodents or insects that eat fruits, vegetables or other crops; - micro-organisms that cause disease in forest, fish, or crop resources. Pesticides are chemicals designed to kill pests __________________________________ _ __________________________________ _ __________________________________ _ __________________________________ __________________________________ _ _ __________________________________ Slide 29___________________________________ _ Early Pesticide Use Early pesticides included the use of toxic inorganic metallic compounds such as lead salts, arsenic, or mercury. These substances were generally effective against the intended pest, but also created some environmental problems because they also killed other beneficial organisms, and polluted water and soil resources used by man. Most early pesticides were non-biodegradable (meaning that they were not broken down within the ecosystem). As a result, these early pesticides began to accumulate in the environment, contaminating water and soil resources. __________________________________ _ __________________________________ _ __________________________________ _ __________________________________ __________________________________ _ _ __________________________________ Slide 30___________________________________ _ “Modern” Pesticides By the twentieth century, chemists began to develop organic pesticides that were designed to be less toxic to man and more specific toward the intended pests. Although this was initially believed to be a step in the right direction, man soon discovered that the organic pesticides also caused unexpected environmental effects. Some of these pesticides were fat soluble. This characteristic lead to a problem known as bioaccumulation. __________________________________ _ __________________________________ _ Enter DDT… __________________________________ _ __________________________________ __________________________________ _ _ __________________________________ Page | 200 Slide 31___________________________________ _ A Pesticide “Legend”: DDT DDT is a chlorine-containing organic pesticide, developed in the earlier part of the 20th century. DDT was one of the first chemicals in widespread use as a pesticide. Following World War II, it was promoted as a wonder-chemical, the simple solution to pest problems large and small. __________________________________ _ __________________________________ _ __________________________________ _ __________________________________ __________________________________ _ _ __________________________________ Slide 32 ___________________________________ _ Organic pesticides that contain chlorine, such as DDT, are soluble in fat but not in water As a result, they cannot be released in urine or sweat, and bioaccumulate in the fatty tissues of animals Small amounts of chemicals enter the food chain at the lowest levels… … but the problems gets worse and worse as the toxin moves up the trophic levels of the food chain. At each stage of the food chain, the concentration of toxins gets higher; so the higher the trophic level, the greater the amount of toxins This process is referred to as bioamplification or biomagnification. __________________________________ _ __________________________________ _ __________________________________ _ __________________________________ __________________________________ _ _ __________________________________ Slide 33 ___________________________________ _ __________________________________ _ __________________________________ _ __________________________________ _ __________________________________ _ __________________________________ _ __________________________________ Page | 201 Slide 34 ___________________________________ _ One example of this problem is illustrated by the damage done to predatory birds as a result of bioaccumulation of DDT. __________________________________ _ __________________________________ _ As a result of this problem, DDT has been banned from use in North America since the 1970s. __________________________________ _ __________________________________ __________________________________ _ _ __________________________________ Slide 35___________________________________ _ Mercury and Methylmercury Bioaccumulation See: https://www.youtube.com/watch?v=1vwjZseY-9w __________________________________ _ __________________________________ _ __________________________________ _ __________________________________ __________________________________ _ _ __________________________________ Page | 202