Warm-up: April 8 th

1. Warm-up: April 8th • What is homeostasis? • What happened to the population numbers when equilibrium was met? • Which tropic level is always the largest?

2. A series of predictable changes that occurs in a community over time Occurs through slow changes after a sudden natural disaster (forest fire, volcano, glacier retreat) or from human activity (clearing of a forest) Ecological Succession

3. Primary Succession • Occurs on surfaces where no soil exists (after a volcanic eruption or after a glacier retreats) • First species to populate this area is called a pioneerspecies – usually lichens. • Why are lichens usually pioneer species?

4. Secondary Succession • Occurs after a disturbance that destroys a community without destroying the soil (wildfire, disease, clearing of a forest)

5. Succession in a Marine Ecosystem • Also known as a “whale fall” • Occurs in 3 stages

6. Marine Succession • Stage 1 • Begins when a large whale dies and sinks to the ocean floor • Attracts scavengers and decomposers (hagfish, sharks, crabs, shrimp), which eat the soft tissue

7. Marine Succession • Stage 2 • After 1 year, most of the soft tissue has been eaten • Decomposition of the body enriches the sediment with nutrients, which attracts fish, crabs, and many marine snails and worms

8. Marine Succession • Stage 3 • Begins only when the skeleton remains • Bacteria decompose the oils inside the bones • The bacteria support a community of mussels, marine snails, marine worms, crabs, and clams