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How Ecosystems Work

How Ecosystems Work. Chapter 5. Lake Victoria’s Ecological Imbalance. World’s second largest freshwater lake 400 species of cichlids, important food source Nile Perch introduced in 1960s 1985, most catch was perch, ate cichlids

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How Ecosystems Work

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  1. How Ecosystems Work Chapter 5

  2. Lake Victoria’s Ecological Imbalance • World’s second largest freshwater lake • 400 species of cichlids, important food source • Nile Perch introduced in 1960s • 1985, most catch was perch, ate cichlids • Today, more than 50% of cichlids and other native fish are extinct • Algae eating cichlids disappeared, algal explosion, no Oxygen in bottom of lake dead zone • If the rest of cichlids disappear, perch won’t have anything to eat, and fisher will collapse • http://www.youtube.com/watch?v=VK9v3ioiYBU

  3. What is Ecology? • Learning Objectives: • Define ecology • Distinguish among the following ecological levels: population, community, ecosystem, landscape, and biosphere

  4. What is Ecology? • The study of the interactions among organisms and between organisms and their abiotic environment • Environment: • Biotic (living) - all organisms • Abiotic (non-living) - physical factors: space, temperature, sunlight, soil, precipitation, etc. • Focus can be local or global • Broadest field of Biology • Linked to all parts of biology, and to geology, chemistry, physics

  5. What is Ecology? • Levels of Interest: • Population: a group of organisms of the same species that live in the same place at the same time, e.g., population of marsh grass, walruses • Communities: a natural association that consists of all the populations of different species that live and interact together within an area at the same time, e.g., Alpine meadow, tidal pool • Ecologists would study how species interact with each other, including feeding relationships

  6. What is Ecology?

  7. What is Ecology? • Ecosystem: includes all the biological interactions of a community AND the interactions of organisms with their abiotic environment • Very complex interactions between energy flow and nutrient cycling • Ecologists would study how energy, nutrients, or water level affects the organisms living in a desert • Landscape: studies ecological processes over large areas and several interacting ecosystems

  8. What is Ecology?

  9. What is Ecology? • Biosphere: the layer of Earth that contains all living organisms • Ecologists study the global interrelationships among water, land, atmosphere, and organisms • Includes organisms, communities, ecosystems, landscapes, etc. depend on the Earth’s other layers: • Atmosphere: layer of air • Hydrosphere: supply of water • Lithosphere: soil and rock of Earth’s crust

  10. Global Climate Change • What is the definition of ecology? • What is the difference between an ecosystem and a landscape? Between a community and an ecosystem?

  11. The Flow of Energy Through Ecosystems • Learning Objectives • Define energy and state the first and second laws of thermodynamics • Distinguish among producers, consumers, and decomposers • Summarize how energy flows through an ecosystem

  12. The Flow of Energy Through Ecosystems • Energy: the ability to do work • Potential energy: stored • Kinetic Energy: energy of motion Potential energy Kinetic energy

  13. The Flow of Energy Through Ecosystems • Thermodynamics: study of energy and its transformations • First Law of Thermodynamics • Energy cannot be created not destroyed • Can change from one form to another • Photosynthesis/cellular respiration • Heat - not usable for biological work • Total energy of organisms and surroundings is constant

  14. The Flow of Energy Through Ecosystems • The Second Law of Thermodynamics • The amount of usable energy in the universe decreases over time • As energy is converted form one form to another, some of it is degraded into ‘heat’ • Heat: less usable form of energy, disperses into environment, less organized than usable energy • Entropy: a measure of disorder or randomness • Energy conversions are is not 100% efficient

  15. The Flow of Energy Through Ecosystems • Producers, Consumers and Decomposers • Producers: manufacture large organic molecules from simple inorganic molecules • Consumers: consume other organisms as a source of energy and bodybuilding materials • Primary Consumers/Herbivores: eat producers • Secondary Consumers/Carnivores: eat primary consumers • Tertiary Consumers/Carnivores: eat secondary consumers • Omnivores: eat everything • Detritivores/Detritus feeders: eat detritus (animal carcasses, leaf litter, feces) • Decomposers: break down dead organisms and waste products • Release simple inorganic molecules that can be re-used by producers

  16. The Flow of Energy Through Ecosystems

  17. The Flow of Energy Through Ecosystems • The Path of Energy Flow in Ecosystems • Energy Flow • The passage of energy in a one-way direction through an ecosystem, as part of a food chain • Food Chain • A diagram showing linear feeding relationships • grassrabbitsnakeeagle • Trophic level: each link in a food chain • First trophic level: producers • Second: primary consumers • Third: secondary consumers, etc. • Decomposers are at every step • Food Web • A complex of interconnected food webs in an ecosystem

  18. The Flow of Energy Through Ecosystems

  19. The Flow of Energy Through Ecosystems

  20. The Flow of Energy Through Ecosystems • Energy Flow • Linear movement of energy along food chain or food web • From one organism to the next • When ‘food’ energy is converted into ‘work’ energy, some is degraded into heat • Second Law of thermodynamics • The longer the food chain, the less energy is available for higher trophic levels • Limited numbers of trophic levels

  21. Global Climate Change • What is the first law of thermodynamics? What is the second? • Why is a balanced ecosystem unlikely to contain only producers and consumers? Only consumers and decomposers? Explain your answer. • How does energy mover through a food web?

  22. The Cycling of Matter in Ecosystems • Learning Objectives: • Diagram and explain the carbon, hydrologic, nitrogen, sulfur, and phosphorous cycles

  23. The Cycling of Matter in Ecosystems • Biogeochemical Cycles • Matter: the material of which organisms are composed • Biogeochemical: involves biological, geological, and chemical processes • Humans have GREAT influence • Cycling vs. Flow: • Matter cycles through ecosystem • From abiotic environment to organisms to environment • Energy flows through the ecosystem • From producers to consumers to decomposers, to heat

  24. The Cycling of Matter in Ecosystems • The Carbon Cycle • The global movement of carbon between the abiotic environment (atmosphere, ocean) and organisms • Atmosphere/oceanphotosynthesiscellular respiration/combustion/decompositionatmosphere/ocean • Carbon is an essential component of organisms’ molecules • Also essential component of abiotic environment

  25. The Cycling of Matter in Ecosystems

  26. The Cycling of Matter in Ecosystems • The Hydrologic Cycle • Water circulates from the ocean to the atmosphere to the land, and back to the ocean • Provides renewable supply of purified water • Balance of water on land, oceans, and atmosphere • Evaporation • Transpiration • Precipitation • Runoff from watersheds • Percolation

  27. The Cycling of Matter in Ecosystems

  28. The Cycling of Matter in Ecosystems • The Nitrogen Cycle • Nitrogen is an essential component of proteins and nucleic acids • Atmosphere is 78% Nitrogen gas • Steps: • Nitrogen fixation: N gas into ammonia, by bacteria physical, and human activities • Nitrification: ammonia to nitrate, bacteria • Assimilation: plants absorb nitrate/ammonia • Ammonification: organisms produce N-containing waste • Denitrification: nitrate is converted back into N gas

  29. The Cycling of Matter in Ecosystems

  30. The Cycling of Matter in Ecosystems

  31. The Cycling of Matter in Ecosystems

  32. The Cycling of Matter in Ecosystems • The Phosphorous Cycle • Cycles from land into living organisms and back • No atmospheric component • Erosion of rocks releases phosphorous into soil • Plants absorb it and use it for nucleic acids and ATP, pass it on to consumers • Decomposers release phosphorous into water • Can be lost at bottom of ocean fro millions of years • Aquatic cycle is also interesting

  33. The Cycling of Matter in Ecosystems

  34. Biomagnification

  35. Global Climate Change • What are the differences and similarities between the five biogeochemical cycles, particularly in the roles organisms play in them?

  36. Ecological Niches • Learning Objectives: • Describe the factors that contribute to an organism’s ecological niche • Explain the concept of resource partitioning

  37. Ecological Niches • Niche: • The totality of an organism’s adaptations, its use of resources, and the lifestyle to which it is fitted • Describes the place and function of an organism within the ecosystem • Takes into account all aspects of an organism’s existence • The “way of life of an organism” • Habitat: • Part of an organism’s niche, the place where the organism lives

  38. Ecological Niches • Fundamental Niche: • The potential, idealized niche of an organism • It’s probably broader than it is in nature • Realized Niche: • The niche an organism actually has and the resources it actually uses • Competition and other factors usually make the realized niche narrower than the fundamental niche

  39. Ecological Niches

  40. Ecological Niches • Resource Partitioning • The reduction in competition for environmental resources among coexisting species, by reducing similarities in their niches • When two species are very similar, their niches may overlap • Ecologists think that species cannot occupy the same niche in a community • Species with similar niches divide up resources in such a way that they reduce competition among themselves

  41. What a Scientist Sees

  42. Global Climate Change • What are three aspects of an organism’s ecological niche? • What is resource partitioning?

  43. Interactions Among Organisms • Learning Objectives: • Distinguish among mutualism, commensalism, and parasitism • Define predation and describe predator-prey relationships • Define competition and distinguish between intraspecific and interspecific competition • Discuss an example of keystone species

  44. Interactions Among Organisms • Organisms are not independent from others • Symbiosis • Predation • Competition • Keystone Species - a special case

  45. Interactions Among Organisms • Symbiosis • An intimate relationship or association between members of two or more species • One species lives in or on another species • Relationship may be beneficial, neutral or harmful • Result of coevolution • Interdependent evolution of two interacting species • E.g., plants and pollinators

  46. Interactions Among Organisms

  47. EnviroDiscovery • Bee Colonies Under Threat • Coevolutionary relationships are very specific • If one species is affected suffers, so is the other • Colony Collapse Disorder (CCD) • Since 2006, 30–90% of bees in colonies in US have died • Pesticides, pathogens, parasites, viruses • Bees are necessary for pollination of many important crops and wild species

  48. EnviroDiscovery

  49. Interactions Among Organisms • Symbiosis • Three types: • Mutualism • An association where both organisms benefit • Bull Horn Acacia and acacia ants • Commensalism • One species benefits, the other doesn’t benefit or is harmed • Tropical trees and epiphytes • Parasitism • One species benefits, the other is harmed • Parasite-Host relationship • Internal and external types of parasites

  50. Environmental InSight

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