Biogeography Of The Pacific Islands

Question 1

How many Island Origins are there?

Answer 1

Three: Crust/lithosphere movement (raising and lowering of sea floor), Volcanism, Relics of continents
Qualities of island based on origin

Question 2

Island Origin: Crust/lithosphere movement

Answer 2

1. Plates can go one under another and rub against each other pushing it up
2. Trench where plate dives down and creates ravine under water

Question 3

Island Origin: Volcanism

Answer 3

1. Trench rubbing against asthenorphere pushing magma up
2. Hot spots also relate to volcanos

Question 4

Island Origin: Relics of continents

Answer 4

1. Pieces of old continents and have old rocks
2. Animals and plants stowaways and are unique to that island

Question 5

Crust Movement: Makatea Islands

Answer 5

1. Upraised sea floor (Bodies of dead planktons compressed)
2. Made of compressed calcium carbonate (limestone made from corals)
3. Porous little surface water (landed on one very sad because flat, hard placed to live) (plants that can grow on it very limited because harsh) (If rains water goes right through)
4. Examples: Niue Island (Cutout where waves crash and erode rock; Trace upwave of island through cutouts; Can’t farm so can’t survive/thrive on it; Hardest to live on)

Question 6

Volcanism: Island Arcs (Two Processes)

Answer 6

1. Plate margin volcanics (volcanism along edge of plates) (Plates dive under each other) (In a line of them (linear arrangement))
2. Hot spot volcanics (volcanism within a plate) (Hawaiian archipelago) (Plate slide over hotspot)

Question 7

Example of Plate Margin Volcanism

Answer 7

Tonga
1. 2 years ago new one and created tsunami and cut off tonga because cut cable (internet) connecting Tonga and Fiji (Seabed shooting to surface; active underwater volcano)
2. 2015 new one (wanted to see what plants get there first)
3. 2022 bigger eruption and created tsunami mentioned before (heard all the way to US and Japan) (Enough of a deposit to start island)

Question 8

Example of Hot Spot Volcanism

Answer 8

Hawaii
1. Most active part of island on Hawaii island
2. New volcano off shore of big island will erupt one day; Rivers of lava; Newest; Aleutian oldest and underwater mostly

Question 9

Example of Continental Relics

Answer 9

New Caledonia
1. South America, Antarctic, Australia connected in past
2. Part of Australia in past
3. Lowland rugged landscape
4. Lots of tiny mountains
5. Animals related to Australia and landscape

Question 10

Island Transformations: What are the three main causes

Answer 10

1. Erosion
2. Sinking
3. Coral reef formation
   (Dependent on temperature and weather)

Question 11

Island Transformation: Erosion

Answer 11

1. Weathering
2. Eventually all islands eroded away and sink
3. Ball’s Pyramid, the remains of a volcano (Inner core of volcano; rest eroded away)

Question 12

Island Transformation: Sinking

Answer 12

1. Volcanic islands have this issue because magma mainly basalt and is heavy and eventually will sink
2. Sink as they age
3. Leave atoll with a deep lagoon (hole of volcano)

Question 13

Island Transformation: Coral Reef Formation

Answer 13

1. Forms on outer edge of islands and grow to reach sunshine
2. Forms the atoll (Volcano sink and coral grows around it) (Colder climate prohibit coral growth (Near South America with winds from Antarctica))

Question 14

What is Coral?

Answer 14

1. Phylum Coelenterata
2. In aquarium, coral fussy so hard to raise with fish
3. Stinging tentacles and a mouth
4. Live in colonies, produce a skeleton of calcium carbonate
5. Coral cells contain zooxanthellae algae
6. Algae use the coral cell’s waste as a chemical ingredient in the process of photosynthesis
7. Different species created different colony patterns and algae create different colors
8. Larva is sent away from main base to grow in other places and spread
9. Coral reefs with white sand, sand produced by fish who eat coral (poop out the sand) (Eating the coral selenanada)
10. Different wavelengths of light can go through laters of ocean so corals at bottom of ocean “eat” the red light at bottom and other “eat” the other lights closer to surface
11. If lose coral reeds due to climate change, not good because lose a lot of other organisms in ocean (Fish)

Question 15

Kinds of Islands: High Islands

Answer 15

1. Young, tall peaks (Hasn’t eroded a lot)
2. Erosion down flanks
3. Coral reef forms around edge (Coral sands)
4. Will eventually sink (Will become atoll) (Take long time for big islands)
5. Examples: Mo’orea, Society Islands; Rarotonga, Cook Islands; Bora Bora, Society Islands (Passages in coral reefs to get to lagoon)

Question 16

Kinds of Islands: Atolls

Answer 16

1. Subsided high islands
2. Reef “ring” remains (Crescent reed because rest of ring sunk)
3. Lagoon with shallow water (Wait for high tide to get over reef to get to lagoon)
4. Island center will eventually sink
5. Climate change kills coral, stop growing, atoll will sink eventually
6. Examples: Aitutaki, Cook Islands; Taiaro, Tuamotu Group; Tikehau, Society Islands (Just reef mainly with few super tiny islands)

Question 17

Winds and Currents

Answer 17

1. Tradewinds (Turning of our planet causes winds to move in certain way) (Pacific called tradewinds)
2. North/South Pacific gyre
3. Currents go and meet at equator
4. El Niño reversals