1. Succession, Shoaling, and Biodiversity
Based on the interrelationships among organisms, what makes some organisms more successful than others at surviving?

2. What is a Shoal?
Large numbers of fish of the SAME species and approximately the SAME size.
Referred to as a ‘school’ when the group of fish is swimming together in a coordinated way.

3. Benefits of Shoaling Hydrodynamic efficiency
Groups of fish save energy when swimming together
Individuals obtain reduction in drag by following in “slip-stream” of neighbors

4. Benefits of Shoaling Predator avoidance:
a) Confusion effect: It is difficult for predators to pick out individual prey from groups
b) Many eyes effect as size of group increases, the task of scanning for predators can be spread out

5. Benefits of Shoaling
Foraging Advantages : Time taken to find food is decreased
Reproductive Advantages: Provides increased access to potential mates

6. Examples of shoalers Skipjack tuna and sardines
When threatened, sardines form massive “bait balls” of hundreds or thousands!
Skipjack tuna forms shoals of up to 50,000!

7. Types of shoalers Fish can be obligate or facultative shoalers:
Obligate – spends all their time shoaling or schooling and may become agitated when separated from the group (examples: tuna, herring, anchovy)
Facultative – shoal only some of the time, perhaps only for reproductive purposes
(examples: Atlantic cod)

8. What is Succession?
The gradual process of change that occurs in community structure over a period of time
Example

9. Succession
As plant communities change the animal communities change.

10. Succession at Hydrothermal Vents
One of the first animal species to inhabit the area around a hydrothermal vent is the tube worm Tevnia.
Tevnia is replaced by the larger and faster growing tube worm Riftia.
Riftia tubeworms can grow up to two meters long. This adult tubeworm that has been removed from its white tube.

11. Riftia
Tevnia
Tevnia are usually white, but this clump of worms is stained brown from iron in the vent fluids. The largest worm in this clump (with more white color) is a different species - a Riftia tubeworm.

13. Biodiversity Takes into account: Examples:
# of different species present
Range of habitats and ecosystems
Examples:
CORAL REEFS
High biodiversity w/ many species present
SANDY SHORE
Low biodiversity w/ few species present

14. Quadrat
A square used in ecology and geography to isolate a sample, usually about 1m2 or 0.25m2
Used to investigate the diversity of organisms in a suitable habitat (example: rocky shore or sandy shore)

15. Extreme & Unstable Environments
Tend to have LOW biodiversity!
Example 1: Sand on a reef slope (unstable)
Easily dries out
Easily eroded by wind and water currents
Animals here have to living in sediments in order to survive (Infauna)
Worms, clams, sand fleas, crabs, etc.
Example 2: Hydrothermal vents (extreme)
Extremely high pressure
High temperature
Few organisms adapted to these conditions
Lack of sunlight
Bacteria, tube worms, crabs, fish, mussels, clams

16. Stable & Favorable Environments
Tend to have HIGH biodiversity!
Example: Coral Reefs
Balance between predators and prey (sharks feed on sick & dying; keeps a strong healthy population of small reef fishes)
Algae = primary producers (zooanthellae inside coral polyps & algae growing on the reef)
Organisms found here:
Sharks, groupers, snappers,
worms, butterfly fish, urchins,
sea stars, algae, corals, anemones,
turtles, sponges, etc.

17. Specialized Niche Generalized Niche
Exploit a wider range of food sources
Live in wider range of habitats
Ex: Tuna
Migratory
Feed on many different species of fish
Narrow range of food requirements
Live in specific habitat
Example: Butterfly fish
Territorial
Live closely w/corals and anenomes

18. Why do habitats with high biodiversity tend to contain narrow ecological niches?
Each species has its OWN niche within the ecosystem
High biodiversity means that many different species live within one ecosystem.
What would happen if the niches overlapped?
INTERSPECIFIC COMPETITION and one species will die out!
Narrow niches reduce overlap and therefore reduce competition