Part 1: Introduction
How do you find chemosynthetic organisms ("chemos")
on the seafloor?
They have picked a good spot to hide because light does
not penetrate far beneath the ocean's surface and the environment in which
they live is one in which humans can go only with great difficulty. |
Note:
Read Cruise Background first
for basic information about chemosynthetic organisms and hydrocarbon seeps. |
|
You could get a submarine and cruise around the seafloor,
but it's dark at the bottom of the ocean and even the brightest lights won't
let you see more than a few tens of meters. It's a lot like trying to find
your car in the middle of the biggest parking lot you can imagine with no
lights except for a small flashlight. You might find it if you are lucky.
Indeed, many of the chemo sites that we know about were
found by accident during trawling (dragging the bottom with nets), or coring
for sediments, or mapping oil platform sites. What is more, we know a lot
about a few sites that have been visited time and time again, but we can't
answer the very important basic question of whether chemos are "ants"
or "elephants" (i.e., are they all over the place or are there
just a few). |
Chemo Clue #1: Look for oil on the surface
One strategy to find chemos is to look for seep signatures
instead.
You could look for places where seeping oil floats to the
sea surface to form slicks (Fig. 1). Beneath these slicks there are certainly
"gushers." But we have to be a little more clever than that because
ocean currents move the slicks laterally away from the seep vents and it
also looks like chemos don't like gushers anyway. Evidently there is too
much oil emanating from high-flow seeps and this makes the environment toxic.
Chemos seem to like medium flow seeps, especially where gas hydrates are
present. |
Fig. 1a. Seeping oil floats to the surface to form slicks.
Fig. 1b. Locations of sea surface slicks in the northern Gulf of Mexico
determined using space photography. |
