Today we are in the North part of Endeavour segment of Juan De Fuca and we have Steve
here.
And so, what is a hydrothermal vent?
Well a hydrothermal vent is basically a place where hot water comes into the bottom of the
seafloor.
We're at a spreading centre so we're making seafloor in this part of the ocean so the
seafloor comes out, spreads out towards the coast and towards the middle of the ocean
and at that area we're very close to the magma, the hot molten lava that's in the Earth.
And since water percolates down into the substrate and down towards this hot magma it gets superheated
to really hot temperatures, up to about 375 degrees.
So very hot.
It doesn't turn into gas there because we have very high pressures and that keeps it
in liquid form.
So this hot water then rises back up and where it's rising up it builds these structures,
these chimney-like structures, because the hot water is so hot that it strips a bunch
of stuff out of the rock so the minerals that are in the rocks, the things that make up
the rocks, come into this liquid form and as it comes out the surface of the seafloor
it hits this very cold, two degree water, and all these things, these minerals, basically
precipitate out to cause this black smokey kind of substance that we'll see in some of
the pictures.
And basically it also forms the rock again because it came from rock and now it's building
new rock.
And that's what these chimney structures are made of.
A lot of it is iron based but there's a lot of other minerals in there as well.
I saw the black smoke from the cameras, it was amazing, like there's something living
down in the ocean I guess.
There's many different types, the ones that we have are rater large tall smokers, they're
one of the more spectacular ones in this region.
But there's also more diffuse venting where the water's not 300 to 400 degrees but lower
temperatures and they also develop structures around them but not as spectacular as the
ones we see here.
So what is the effect, the impact, of these structures , black smoke, and hydrothermal
vents on ecology and the inhabiting organisms here?
Well basically hot water is a form of energy so that's one reason we have more life forms
here but we also really disrupt the chemical structure of the water column here.
We're bringing a lot of chemistry into it.
There are bacteria that lives off this chemistry and they actually, different types of animals
utilize the bacteria.
Some in their guts and stuff like that to actually gain energy from them that way and
basically we build up an ecology around them.
Actually to give an idea, how big is this area?
Well the Endeavour Ridge is part of the Juan De Fuca Ridge, a larger piece, of a very large
piece that's about 90 000 kilometres long circling the whole oceans and we have a small
piece called Juan De Fuca Ridge which is set off by some transform faults and ours, the
section we're looking at is one of six sections or segments of the Juan De Fuca Ridge, it's
the Northern most one and it's about 10 kilometres long and maybe a kilometre wide and just because
the Earth's crust is now coming out in this area it's pushing out sideways, we have two
little mounds and we've got a valley in between.
The valley's about a kilometre wide and 10 kilometres long and it provides an area where
all these life forms can actually sort of stay out of the way of deep ocean currents,
and actually congregate.
So it's about 10 kilometres long, one kilometre wide, maybe two or three hundred kilometres
high on the sides.
10 kilometres very long, it's a big piece actually and currently there are four moorings
installed on each corner of the area, so two up in the Northeast and Northwest and just
yesterday Southeast and Southwest moorings installed.
So there's a kind of circulation and the measurement instruments are installed so what's the purpose
of this study and measurements?
What kind of instruments do you have in the mooring?
Well basically the purpose of those moorings is that now we have a valley, and in that
valley are these five hydrothermal venting areas and we have a very diverse group of
life living here so we're trying to understand how they stay here and what brings them here.
We have that notion that we talked about before about the chemosynthesising bacteria which
provides a food but there's also these other secondary kind of processes that help keep
the creatures there and one of them is the fact that we're actually putting in about
1600 megawatts of energy into the bottom waters here which is about the size of a medium sized
nuclear power plant, so quite a bit of energy coming in from the seafloor and that drives
the circulation.
So it's quite similar to what we see in coastal areas where you have a valley.
If anybody is a windsurfer they know that in maybe the Columbia River Gorge or Nitinat
Lake in British Columbia, during the day around noon time the wind picks up because the ground
heats up from the sun ad you get this beautiful wind blowing into it.
Well an analogy to that, we have this warm energy coming in as a form of hot water rising
up through the middle of this valley that we have, which is the Endeavour segment and
it drives this flow in on either side, cold water flow.
So if you're a not very mobile creature like larva of some of these creatures that live
down there you're kept in this area because you have this trapping flow that we have and
if you stay below the top of the ridges then you won't get blown away by the deep ocean
currents so what we're using is these moorings to study the strengths of the currents that
are coming in and the temperature and salinity of the water so we know what the water masses
are that are coming together here and trapping these little fellows that don't have much
swimming power.
As you'll see in some of the videos they sort of move along quite slowly.
So any kind of current will override their own swimming power.
So this is the 18th day of the NEPTUNE Canada Wiring the Abyss 2012.
And where are we going next tomorrow?
Good question but I have some information that tells us that we're going to the main
Endeavour Field which is the first discovered field of the whole region, it's the biggest
field, it's the most energy input and we have a number of instruments there.
We have temperature sensors, we've got a imaging sonar that images the plumes that are coming
out of the hydrothermal vents and we have a couple vents that we populate with these
instruments.
There's Hulk, there's Grotto and it's going to be a good fun day to look at some very
interesting pictures.
That's so exciting!
So Dr. Steve Mihaly was with us, thank you for the wonderful interview Steve.
Well it's very nice to have this interview, thank you.
Thanks.