Dynamics of Ecosystems

Overview * Sustainability * Cycling of the Elements * Bioaccumulation of toxins in the food chain * Population dynamics * Species Biodiversity * Human actions and effects

What is an ecosystem?  Define: is a community of living things (biotic) interacting with non living things (abiotic) in the environment  Biotic: all the living things (plants, animals, bacteria etc.)  Abiotic: all the non-living things (air, water, rocks, weather etc.)  Bill Nye : Ecosystems

 All living things require some form of energy to survive Life forms use energy to create the materials (building blocks) and food that they need If the energy source runs outs  can’t make/get the food it needs  life form dies

 Virtually all life on Earth gets its energy from the light energy of the sun The sun burns Hydrogen in a process called fusion Some life forms on Earth can use this energy directly to make food (ie. Plants) Photosynthesis Some life forms on Earth can use this energy indirectly by eating other organisms (ie. Animals) – Cellular Respiration

Trophic Levels  The relationships between the organisms that harness the suns energy is analyzed when studying trophic levels  A trophic level represents a specific level of a food chain a series of organisms that show predator – prey relationships  We will look at 4 distinct levels

Producers (1 st level)  ‘bottom’ of the food chain  can use energy from the sun directly  they can make the food they need

Consumers (2nd-4th levels)  get energy from what it eats  Fall into 1 of 3 levels: 1. Primary consumers - eat plants  Ex. Herbivores 2. Secondary consumers - eat small animals  Ex. Small carnivores 3. Tertiary/Quarternary consumers - eat larger animals, ‘top’ of the food chain  Ex. Large carnivores

‘Kinds’ of Consumers  Herbivore: an organism that eats only plants  Ex.Caterpillars  Carnivore: an organism that eats only animals  Ex.A robin  Omnivore: an organism that eats both plants and animals  Ex.Human Beings

 Detritivore: an organism that eats the bodies of smaller dead animals, dead plant matter and animal dung  Ex.Earthworms  Decomposer: an organism that consumes any remaining dead plant and animal matter  Ex.Fungi (Mushrooms)  EX. Bacteria ‘Kinds’ of Consumers (cont.)

FOODCHAIN

How do Carbon, Oxygen and Nitrogen get recycled through the ecosystems? 