Transcript Ecological Succession - Mrs. Murchison's 8th Grade Science

Warm-up: April
1. What is
homeostasis?
2. What happened
to the population
numbers when
equilibrium was
met?
3. Which tropic level
is always the
largest?
th
8
Ecological Succession
• 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)
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 pioneer
species – usually lichens.
– Why are lichens usually pioneer species?
Secondary Succession
• Occurs after a disturbance that destroys a
community without destroying the soil
(wildfire, disease, clearing of a forest)
Succession in a Marine Ecosystem
• Also known as a “whale fall”
• Occurs in 3 stages
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
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
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