Transcript Anak Krakatau

Krakatau
Cataclysm and Rebirth
The Eruption
• On August 27, 1883 the Krakatau volcano blew
up destroying Krakatau.
• This was the beginning of a natural biological
experiment that was followed beginning in
1884.
Rakata Island (Remains of Krakatau)
Anak Krakatau – Child of Krakatau (emerged in 1930)
Basic Facts
• Krakatau’s eruption was the equivalent to 100 to
150 million tons of TNT.
• It could be heard 4,600 kilometers away (2,900
miles away – it was heard in Perth, Australia).
• There were over 30,000 confirmed dead but
estimates reach well in excess of 100,000 (whole
human settlements were washed away).
• The tsunami reached 40 meters high.
Basic Facts
• The eruption lifted 18 cubic kilometers of rock
and earth into the air.
– Its residual of sulfuric-acid aerosol and dust
entered the atmosphere and spread around the
world – creating brilliant red sunsets for several
years after the blast.
– Rakata survived the blast as a sterile island. As
E.O. Wilson put it “. . . the spinning reel of
biological history halted, then reversed, like a
motion picture run backward, . . .”
The story of life after the eruption
• The first search for life was by a French
expedition in May of 1884.
– The expedition’s naturalist wrote:
“notwithstanding all my researches, I was not
able to observe any symptom of animal life. I
only discovered one microscopic spider – only
one; this strange pioneer of the renovation was
busy spinning its we.”
– How did the spider get there?
Aeolian Plankton
• Aeolian plankton means “plankton carried by
the wind.”
– Aeolian plankton species are those dispersed by
the wind.
– Examples: bacteria, fungus spores, small seeds,
insects, spiders, and other small creatures
continuously fall from the sky after being carried
away (sometimes into the stratosphere).
– Can be significant over a period of weeks and
months.
The story of life after the eruption
• In the 1980s, an Australian team visited both
Rakata and Anak Krakatau (volcano that
emerged in 1930).
– The part of Anak Krakatau they visited was nearly
sterile from eruptions (resembling Krakatau in
1893).
– They set traps (plastic containers filled with
seawater) to collect seeds and organisms.
– They alone caught 72 species of wind borne
arthropods (spiders, moths, beetles, barklice, etc.)
The story of Rakata’s Life (rebuilding
an ecosystem)
• Other arrivals were those creatures that could
swim – like the semi aquatic monitor lizard.
– Was recorded in 1899 eating crabs and other
creatures along Rakata’s shoreline.
Another swimmer from either Java or
Sumatra was the reticulated python.
The story of Rakata’s Life (rebuilding
an ecosystem)
• The birds more than likely crossed over by
powered flight; however, only a small
percentage of species from Java and Sumatra
were represented.
– Scientists have discovered that many forest
species refuse to cross water gaps, even when
islands are in full view.
• A few species of bats made the crossing along
with larger flying insects like butterflies and
dragonflies also arrived.
The story of Rakata’s Life (rebuilding
an ecosystem)
• Rafting is less common but still important.
– Some species were carried to Rakata via downed
trees and mats of vegetation blown across the
saltwater gap by the winds (or carried by
currents).
• Amphibians (frogs and toads) and reptiles, along with
small mammals (rodents), microorganisms and other
insects seem to have made the crossing this way.
• Most animals are miniature arks carrying parasites and
many other microorganisms in the soil clinging to their
bodies.
The story of Rakata’s Life (rebuilding
an ecosystem)
– Pseudoscorpions, tiny replicas of true scorpions, use their
lobster-like claws to seize the hairs of dragonflies and
other winged creatures – then ride them for long
distances.
The story of Rakata’s Life (rebuilding
an ecosystem)
• Some of the new arrivals found niches in the
reborn Rakata – others went extinct unable to
handle the difficult conditions.
• Plant species that arrived only grew up in
mosaics as only the plants able to survive in
the nutrient poor pumice fields were able to
take hold.
– They spread and retreated across the island.
– Some species returned almost immediately.
The story of Rakata’s Life (rebuilding
an ecosystem)
• In 1884, the French found only a few tufts of
grass.
• In 1886, 15 species of grasses and shrubs were
recorded.
• In 1897, 49 species of grasses and shrubs were
found.
• In 1928, the number had grown to nearly 300
grasses, shrubs, and trees.
The story of Rakata’s Life (rebuilding
an ecosystem)
The story of Rakata’s Life (rebuilding
an ecosystem)
• In 1919, a Dutch botanist found forest patches
surrounded by nearly continuous grassland.
• Ten years later, the same Dutch botanist found
an island well on its way to being reforested –
the grasses were being choked out.
• Today, Rakata appears to be completely
covered by a typical Asian rainforest, though
outward appearances are deceiving.
The story of Rakata’s Life (rebuilding
an ecosystem)
• The process of colonization is hardly complete
as the species of primary, mature rainforest
have not made it from Java and Sumatra.
– Another hundred years or many more may be
required to get a forest fully comparable to the
primary forests of the Indonesian archipelego.
• The problem is those forests are rapidly disappearing.