Reading 10/22

The one after the midterm

Water temp range for deep-sea

-1 - 4 C

True of False: Oxygen content is rarely limiting in deep-sea

true

How fast are deep ocean basin currents in general?

<5 cm per sec

How fast are deep boundary currents?

25 cm/sec

What is dominant between 1000 - 2000m but scarce below 2500 m?

sponges

At what point do starfish dissapear?

7000m

What makes up 80% of biomass in deeper areas?

Elpidia longicirrata (sea cucumber)

sea cucumber

holothurian

Where do holothurians dominate

below 4000 m

What percentage of species present below 2000m in the Atlantic are also found in the pacifc or indian oceans

20%

Active suspension feeders (sponges and tunicates)

use their own energy to pump water through a filtering structure

Passive sispension feeders (crinoids, some polychaetes, cnidaria)

rely on water currents to convey food

benthic boundary layer

friction of water over the seafloor creates physical mixing of the bottom water

How does species diversity change with depth?

increase with depth from 200 - 2000m then declines rapidly

Diversity of many smaller organisms ( ) with depth

increases

Biomass and density of deep sea

low

What percentage of food produced in euphotic zone is transferred to the abyssal seafloor?

1-5%

Potential food sources

dead phytoplankton, zooplankton, fish, and mammals; fecal pellets and crustacean molts; macrophyte detritus; animal migrations

chitinoclastic bactera

live in guts of many species and digest molted exoskeletons