[meteorite-list] Habital Planet Discovery Announcement

From: Darren Garrison <cynapse_at_meteoritecentral.com>
Date: Thu, 30 Sep 2010 16:43:11 -0400
Message-ID: <11s9a65i823t487mi3t0o50ar3lbskrpsc_at_4ax.com>

On Wed, 29 Sep 2010 21:27:42 -0500, you wrote:

> Because it would have 3 times the water but only two
>times the surface, the average ocean depth would be about
>4500 meters! The pressure at the depths of these oceans
>would be about 9000 atmospheres. The highest mountains
>possible would be about 4000 meters (calculating from the
>median diameter), so if you were the greatest mountain
>climber on this Super Earth, standing on the top of Super
>Earth's highest mountain, you would still have 500 meters
>of water above you!

Which has serious implications to the types of life that would be
possible/likely. On Earth, the elements needed by the primary producers in the
ocean (phytoplankton) are mostly supplied from erosion of the land-- either
supplied through run-off into the ocean or through wind-blown sand and dust. No
land means no elements delivered to the top layers of the ocean means that the
phytoplankton equivalent would be limited to only the equilibrium-state elements
dissolved into the sea water which means orders of magnitude lower biomass
production as compared to a world with continents and erosion. Think of
agricultural nitrate and phosphate run-offs causing algal blooms. Think of
experiments seeding the ocean surface with iron leading to as much as 85x
increase in growth of diatoms. Very low production of phytoplankton means very
low production of zooplankton, means very small production of the critters that
eat the plankton, means very low production of the critters that eat the
critters that eat the plankton...

The most likely ecosystems on a waterworld would be hydrothermal vent
communities with primary producers being chemoautotrophs, the way they are on
the abyssal plains of Earth. You could imagine life-forms that would "bulk up"
on building blocks down at the hydrothermal vents and then migrate to the
surface waters, but _why would they_? It would be a stretch to imagine
selective pressures that would lead to that.

If you are currently packing for a trip to Gliese 581g, you better make room for
Alvin.

http://en.wikipedia.org/wiki/Eutrophication

http://www.palomar.edu/oceanography/iron.htm
Received on Thu 30 Sep 2010 04:43:11 PM PDT