ENVR101 Pacific Islands Environment and Environmental Change Summary
Lake Opening and Eel Migration
- Tomatohapuku lake opening involved digging away the gravel barrier bar to allow eels to migrate out to Tonga.
- Thousands of eels migrate to the sea during this event.
Pacific Islands Overview
- Focus on Samoa, Vanuatu, and the geology of island formation.
- Island transect includes Papua New Guinea and Rapa Nui for scale.
Human Settlement Patterns
- Papua New Guinea settled 40,000+ years ago, similar to Australia.
- Settlement of Vanuatu, Fiji, Western Samoa, and Tonga began around 3,500 years ago.
- East Polynesia, including Aotearoa and Hawaii, settled later.
La Pita Complex
- Associated with ceramic potware, cooking, and ceremonial traditions.
- Pottery designs first recorded in New Caledonia.
Voyaging Technology
- Double Latine sail Wakahuru used for ocean voyaging, based on Micronesian traditions.
- A Tickerpin-led expedition in 2010 marked the first ocean voyage of that scale since the 1870s.
Factors Influencing Settlement
- Voyaging technology, climatic patterns, resources, and environmental changes influenced settlement.
Island Ecology
- Forest diversity declines with remoteness from continental land masses.
- Aotearoa retains high biodiversity due to its continental land mass (Zealandia).
Cultural and Linguistic Diversity
- Cultural and linguistic diversity also declines with remoteness.
- Papua New Guinea has 1,000+ languages, while Rapa Nui has a single language.
Disease Burden
- Malaria may have impacted settlement patterns in islands west of Fiji and Tonga.
Geological Complexity
- Continental geology is more diverse with volcanic and tectonic activity.
- Remote islands have simpler geology formed by volcanic and limestone processes.
Precipitation Patterns
- High rainfall zones (over 4 meters annually) in continental islands.
- Atoll environments are arid, receiving less than 500mm of rainfall per year.
Cyclones
- Cyclones significantly influence annual rainfall, causing extreme rainfall events.
Ecosystem Engineers
- Prehuman ecosystems were driven by different species in different regions.
- Papua New Guinea: tree kangaroos and couscous.
- Vanuatu, New Caledonia, and Fiji: tortoises (before extinction).
East Polynesian Ecosystems
- Lack large birds or tortoises; seabirds and invertebrates were dominant.
- Some invertebrates, like weevils, exhibit high diversity.
Taro Cultivation
- Taro (Colocasia esculenta) was a main staple crop in Pacific Island societies.
- Infrastructure includes dry stone walls and terraces.
- Rapa Nui used rock-mounted stone-lined turtle gardens due to drier conditions.
- Volcanic eruptions and island formation, using the Tonga eruption of Hunga Tonga-Hunga Ha'apai as an example.
- Vegetation can re-establish rapidly on new volcanic islands.
Island Evolution
- Seamounts form from fissures in the ocean crust, leading to lava flows or explosive events.
- Shield volcanoes can create large islands like Tahiti.
- Atolls form as volcanoes subside, with coral reefs growing around them.
Sea Level Change
- Sea level rise impacts island communities, compounded by subsidence.
- Isostatic rebound affects sea levels differently across The Pacific.
Hydro Isostasy
- Earth's mantle shifts due to the transfer of water mass from poles to oceans.
- Past sea levels were higher; coastlines adjusted to these changes.
- People construct islands (e.g., Llangalanga Lagoon in the Solomon Islands) to counter subsidence and for defense.
- This also reduces malarial load because of reduced mosquito populations.
Nauru
- Uplifted limestone island with phosphate-rich guano deposits.
- Extensively mined for fertilizer, impacting agricultural systems globally, including in New Zealand.
- Important history with Micronesian language, refugee detention center, fertilizer factories.