Transcript File

Title: Natural History of the
Galapagos Islands
Nothing gets lost,
nothing is created,
everything transforms.
-Lavoisier
Map of the Islands
Las Islas Encantadas=
The Enchanted Islands Resources
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Pierre Constant Marine Life of the
Galapagos
– Good maps and drawings = p12
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Julian Fitter Wildlife of the Galapagos
– page 7 = Conservation Plea
– page 8 = Introduction
• 2 major conservation issues:
– Introduction of invasive species
– Population increase
DOMINANT GALAPAGOS THEMES:
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ISOLATION
STRONG CURRENTS
INACCESSIBILITY
ARID CONDITIONS
SANCTUARY
EXPLOITATION
BIODIVERSITY
EVOLUTION
CONSERVATION
Biodiversity
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Galapagos organisms are very
susceptible to competition from
introduced species from S. America,
etc
CDRS on Santa Cruz in Puerto Ayora
focused on conservation
– In early years, eradication of goats from
Sante Fe (by 1975 all were gone),
Espanola and Pinta and rats from Pinzon
was a priority
– Successful captive breeding program of
tortoises and now land iguanas
– goats are biggest problem, other
mammals are pigs, dogs, cattle,
donkeys, horses, cats, rats and mice
– invertebrates are fire ants, blackfly,
wasps
– plants include quinine tree, guayava,
elephant grass
– expensive to eradicate--need human
and financial resources
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As population grows (5% annually),
islanders must help protect islands and
provide answers for conservation
General Setting of the Islands
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Stretch over a 320 km (174 mile) axis
from east to west
600 miles west from coast of
Ecuador
Made of 19 islands and 42 + islets or
surfacing rocks
Islands are purely oceanic
Archipelago is entirely volcanic
Geology of the Islands
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Islands are situated on the
confluence of three of the earth’s
tectonic plates
– Pacific, Cocos and Nazca
• The three plates are pushed apart by
convection currents caused by heat deep
inside the earth
• The Galapagos drifts southeasterly at the
rate of about 4-6 cm a year
• Hot Spot!
Tectonic Plates
Hot Spot Theory
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Hot spot has a fixed position
A hot spot is related to a weakness of the
oceanic crust which leads to fissures on the
ocean floor
Under the Nazca plate, the hot magma is
always in motion due to convection currents
The hot spot creates a magmatic plume when
the hot magma contacts the cold ocean water
to build a platform
Platform grows and grows….into a cone
Hot Spot Theory continued
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A volcanic cone is created which in a few
years reaches the surface of the ocean
This new island joins the others on the slowmoving “conveyer belt”
Once drifted away from the hot spot, an
island experiences little or no more volcanic
activity and the now dormant volcano is
eroded away by wind and sea
More hot spot…or is it “mantle
plume”
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Islands originated through hot spot
activity no earlier than 3-5 million years
ago
Hot spot also responsible for forming
Hawaiian islands
Galapagos Plumology
Age of the Galapagos
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Oldest islands in east and youngest to
west
– Espanola is oldest
– Fernandina is youngest (hence volcano in
2009)
Climate
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Galapagos are desert islands
Are considered subtropical
Located on equator but don’t have
equatorial climate therefore have
micro-climates
Climate is largely determined by
ocean currents
2 seasons
– warm, wet season from Jan to June
– cool, dry season from July to Dec
known as garua (mist)
Oceanic Currents
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In cool season, the cold Humboldt (aka
Peruvian) current flowing from the
southeast keeps the islands cooler than
you would expect on the equator and the
mist garua condenses in the air
In warm season, annual rains for first 3
months, SE winds and Humboldt vanish.
Warm waters come from Panama and
Columbia
Upwelling from currents allows for
nutrients to be pumped to surface for
plants to grow and the food chain to
survive
Distribution of Currents
(also on page 212 Fitter)
El Nino-La Nina Phenomenon
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Some years, warm water coming from north
increases around around Christmas time
In 1982-1983, a big Nino brought nine
months of rain, increased humidity,
suffocating heat, increased sea temp.
therefore increase in animal mortality
Another in 1997-1998
Nina is counter event with cold period…good
for marine life
Facts about El Nino
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As many as 50% of sea lions and
marine iguanas dies
Increased rainfall promotes plant growth
and rising sea levels cause loss of
beaches resulting in major habitat
change
Human History of the Galapagos
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1535 = Bishop of Panama, Tomas de
Berlanga’s ship was swept off course;
he described giant tortoises and
iguanas
1570 = Abraham Ortelius, Flemish,
draws the first map of the Insulae de los
Galopegos (Islands of the Tortoises)
1600-1720 = Buccaneers use islands as
bases for raids on Spanish ports; eat
turtles, use wood
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1790 = Alessandro Malaspina, Sicilian,
leads first scientific mission to islands;
records are lost
1793 = James Colnett, English,
explores whaling on islands; Post
office barrel established in Floreana
1795-1895 = Heavy exploitation
endangers species; whales
population destroyed, tortoises eaten
1813 = David Porter, U.S., destroys
British whaling fleet
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1819 = Major eruption of Fernandina
volcano
1830-1832 = Ecuador becomes an
independent republic and annexes the
islands; establishes a penal colony on
Floreana
1835 = Darwin visits the islands (only
there 5 weeks of his 5 year
voyage..visited San Cristobal, Floreana,
Isabela, James Islands)
1836-1940 = attempts at colonization
1850-1860 = Britain and US attempt to
lease or purchase islands with no success
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1928 to mid 1930’s = Floreana Island
was inhabited by Ritters, Wittmers
and Baroness of Vienna and Paris=
murder mystery= Galapagos Affair
1934= Ecuador enacts the first
protective legislation for the islands
1957 = Choose site for CDRS
1959 = Ecuador declares all islands
except already colonized are a national
park; the Charles Darwin Foundation is
formed
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1968 = Conservation programs
begin; Fernandina erupts and its
calderan collapses
1969 = Organized tourism begins
1982-1983 = El Nino events cause
changes in population of organisms
1985 = Fire set by humans burns more
than 200 sq km of S. Isabela Island
1986 = Ecuador govt establishes
Marine Reserve
1997-1998 = Another El Nino
MORE NATURAL HISTORY…
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FOUND IN REFERENCE SECTION OF
YOUR COURSE READER:
– “A Traveler’s Guide to the Galapagos
Islands” by Barry Boyce
– Good information for Introduction Section of your
Paper = pages 7-37….mark this with sticky note