Transcript Deep Vents - COSEE West

Deep Vents
• LP 10 AdVENTurous Findings on the Deep
Sea Floor
• Mystery of the Megaplume from
Submarine Ring of Fire
• LP 22 Who Promised You a Rose Garden
• LP 18 Let’s Make a Tubeworm!
Packet
• Hydrothermal Vent Challenge
• The Volcano Factory – both from the 2004
Submarine Ring of Fire
Schematic cartoon of a venting system on a submarine arc volcano. These systems are driven by magma bodies that range in
temperature depending on composition. Dashed lines represent permeable crust into which seawater penetrates to form a
hydrothermal circulation cell with ascending fluids discharging at ~100°-350°C depending on depth. Yellow bubbles and saw-tooth
arrows represent exsolved magmatic fluid. Some chemicals within volcanic vent fluid may precipitate near the sea floor interface as
hydrothermal mineralization. The remaining (most) chemicals will buoyantly rise to form “black smoker” plumes. Hydrothermal
plumes are sensed as temperature anomalies or optically detected as light scattered off particles and detected chemically as gas and
metal concentration anomalies.
Make Your Own Deep Vent
• Superheated water emerges from the
vents along a ridge.
• Minerals that dissolved in the water while it
was in the fractured crust precipitate out
as the water cools from contact with cold
deep sea water.
• The chemicals form chimneys around
vents. The chemistry varies with the crust
chemistry.
Back
Mystery of the Megaplume
• Juan de Fuca Ridge data from 1986
• Tow-Yos – vertical, up and down
movement of a CTD (conductivity,
temperature and depth) meter as ship
moves
• Used to locate vents along a spreading
center or ridge
The crew of the Thompson launching ABE over the side of the ship for another
night of data collection. ABE is outfitted with a host of scientific sensors to log
temperature, conductivity, magnetics, and multibeam bathymetry.
Red and orange dots show where the most chemically reactive water from vent
sources were detected along ABE tracklines, shown in black.
Mystery of the Megaplume
• Use a permanent Sharpie marker
• Plot the depth on the y axis (3 units/100m) and
the location along a 20+ mile transect on the x
axis (2 units/mile).
• Each data point is written as the temperature
anomaly at the location and depth. Do all the
2000 and 1200 m first. Connect with dotted line
and then put intermediate numbers on the line.
• Connect the areas of common temperature
anomaly.
• Color in the areas of common
temperature using dark red for the
highest temperature differences, going
down the visible spectrum with colors
as the areas are cooler.
• Compare your work with these data.
A cross-section of a hydrothermal plume over Magic Mountain, which is at the
shallowest point of the Southern Explorer Ridge. The plume was mapped using
the CTD. Red NTU values indicate a high amount of particulates in the water
column, which are a signature of hydrothermal plumes. The black lines are the
CTD tow yo track as it is being towed up and down through the water column.
The bathymetric profile was derived from the recently-collected EM300 data.
Who Promised you a Rose
Garden?
Deep vent systems are extremely
geologically active, dynamic systems
What changes are observed over time? In
1979 the Rose Garden had extensive
fields of the tubeworm Riftia, mussels
were abundant and clams were absent.
Compare the 1985 map of the Rose Garden
with the 1979 observations.
Back
Rosebud
• The Rose Garden was found to be dead in
subsequent visits, but recently the
beginning of a new community was
located and named Rosebud.
Let’s Make a Tubeworm
• Deep vent tube worms are unique organisms –
vestimentiferans.
• They have endosymbiotic bacteria in an organ
called the trophosome which oxidize hydrogen
sulfide. The energy from this process is used to
synthesize carbon compounds from CO2 and
water – chemosynthesis.
• Use the illustration on the back cover of your
curriculum book as a model for what your deep
vent tubeworm is going to look like.
Ocean Explorer Web Site
http://oceanexplorer.noaa.gov
Ocean Explorer Web Site
http://oceanexplorer.noaa.gov
Vents and Seeps
• Using real data to model the way that
ocean scientists ask and answer
questions.
• Start with cold methane seeps which have
the more challenging activities.
• Progress to deep vents and end with the
most fun and least intellectually
challenging activity.
Cold Seeps
• LP 19 This Old Tubeworm
• LP 17 Biochemical Detectives
• How Diverse is That? From Windows on
the Deep
• Packet
• What’s the Big Deal? A student literature
research project
Common Feature: Chemosynthesis
Some organisms use methane as an energy and
carbon source and some use hydrogen sulfide
as an energy source with carbon dioxide as a
carbon source.
Methane hydrate is a clathrate – a lattice of one
compound (water) inside which a second
compound (methane) is contained. There are no
covalent bonds. Stable due to pressure and
temperature. Methane may be released rapidly
when conditions change.
Methane Hydrate
• USGS estimates two times as much carbon as is
stored in known reserves of coal, oil and natural
gas.
• Methane is a greenhouse gas; Large release
could result in a quick climate change.
• Release could trigger a landslide, causing a
tsunami.
• Unusual communities of organisms utilize the
energy sources; new species, including bacteria.
Cold Methane Seeps
• Located on continental shelf where
methane seeps out of the sediments and
hydrogen sulfide is also common.
• Have worms related to those of deep
vents with chemosynthetic bacteria as well
as clams and mussels with other
chemosynthetic bacteria.
• Realitively stable through time.
Ocean Explorer Web Site
http://oceanexplorer.noaa.gov
Ocean Explorer Web Site
http://oceanexplorer.noaa.gov
Back
This Old Tubeworm page 146
• Plot the growth rate data on graph paper
for Lamellibranchia.
• Then use the worksheet to figure out how
long it takes to grow 10 cm for each part of
their life cycle.
• Add the years up to estimate how old a 2
meter worm would be.
Biochemical Detectives pg 128
• Not all seep organisms have the same kind of
bacteria nor do they get their energy from the
same source.
• Carbon source varies – sea water and methane
for chemosynthetic bacteria and atmosphere for
detritus from photic zone or land
Bivalves – mussels and clams tested for 13C – a
stable isotope of carbon
13 C expressed as o/oo when compared
with a standard
Carbon from sea water is 0 o/oo
Carbon from photosynthetically dervied
material is 18-20 o/oo
Carbon from methane is 40 o/oo or higher
Carbon from sulfide metabolism is 30-40
o/oo
Note error on page 130 higher not lower
• Use the data sheet on page 132 and plot
clams and mussels as a histogram on
graph paper.
• What groupings do you find? How does
each grouping obtain its food?
How Diverse is That?
•
•
•
From Windows on the Deep
Data rich but complicated
We are going to use the data but in a
less complicated form:
1. Count the number of species for site A and B,
seep and non-seep areas and record your
findings.
2. Use the form provided to make a bar graph,
comparing seep and non-seep numbers of
individuals in each species. Use two colors on
one graph as lines side by side. Do site A.
Questions
• Which has more kinds of organisms –
seep or non-seep at Site A? Site B?
• Which supports more numbers of
organisms – seep or non-seep for Site A?
Site B?
• Are there species that only occur at
seeps?
• What might account for the Site B seep
numbers?