Post on 20-Dec-2015
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 SiteOcean Explorer Web Site
http://oceanexplorer.noaa.govhttp://oceanexplorer.noaa.gov
Ocean Explorer Web SiteOcean Explorer Web Site
http://oceanexplorer.noaa.govhttp://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 SiteOcean Explorer Web Site
http://oceanexplorer.noaa.govhttp://oceanexplorer.noaa.gov
Ocean Explorer Web SiteOcean Explorer Web Site
http://oceanexplorer.noaa.govhttp://oceanexplorer.noaa.gov
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?