MAST 427 EXAM 2 QUESTIONS AND
ANSWERS GRADED A+ 2025/2026
Benthic Physical Environment - ANS - Very flat and relatively uniform
- Vertical relief often exaggerated in graphics
- Abyssal: 2000-6000m
-
Pelagic Zone Terms (from shallowest to deepest) - ANS - Epipelagic
- Mesopelagic
- Bathypelagic
- Abyssopelagic
- Hadalpelagic
General Characteristics of the Deep Seafloor - ANS - Most of the seafloor, most of the planet
- Accounts 60% of the ocean area
- Stable but "extreme"
--- temperature
--- pressure
--- productivity
--- consistent for at least 8,000 years
1 @COPYRIGHT 2026 ALLRIGHTS RESERVED.
, Environmental Factors in the Benthos - ANS - Low flows, tidal to abyssal circulation (mostly
depositional, some exceptions)
- Immense pressure (1 atm or every 10 m depth; 100s-1000s atm ambient pressure)
- No light
- 2.4 degrees C below 1000 m
- Very saline
- Abundant oxygen
100 m^2 - ANS Amount of deep sea quantitatively sample
Food Sources in the Benthos - ANS Rain of detritus (fecal pellets, marine snow, crustacean
molts, dead/ dying phytoplankton/ zooplankton, dead fish, dead whales)
Organic Content of Benthic Sediment - ANS - Inner continental shelf: 2-5%
- Open ocean: 0.5 - 1.5%
- Abyssal bottom: < 0.25%
Martin Curve - ANS Particulate organic carbon fluxes decrease exponentially with depth
- F = F(sub 100) * (z/100)^(-b)
--- F(sub 100) = POC flux at 100 m
--- z = trap depth
--- b = unitless parameter
- 1% or less OM in the euphotic zone reaches deep sediments
2 @COPYRIGHT 2026 ALLRIGHTS RESERVED.
ANSWERS GRADED A+ 2025/2026
Benthic Physical Environment - ANS - Very flat and relatively uniform
- Vertical relief often exaggerated in graphics
- Abyssal: 2000-6000m
-
Pelagic Zone Terms (from shallowest to deepest) - ANS - Epipelagic
- Mesopelagic
- Bathypelagic
- Abyssopelagic
- Hadalpelagic
General Characteristics of the Deep Seafloor - ANS - Most of the seafloor, most of the planet
- Accounts 60% of the ocean area
- Stable but "extreme"
--- temperature
--- pressure
--- productivity
--- consistent for at least 8,000 years
1 @COPYRIGHT 2026 ALLRIGHTS RESERVED.
, Environmental Factors in the Benthos - ANS - Low flows, tidal to abyssal circulation (mostly
depositional, some exceptions)
- Immense pressure (1 atm or every 10 m depth; 100s-1000s atm ambient pressure)
- No light
- 2.4 degrees C below 1000 m
- Very saline
- Abundant oxygen
100 m^2 - ANS Amount of deep sea quantitatively sample
Food Sources in the Benthos - ANS Rain of detritus (fecal pellets, marine snow, crustacean
molts, dead/ dying phytoplankton/ zooplankton, dead fish, dead whales)
Organic Content of Benthic Sediment - ANS - Inner continental shelf: 2-5%
- Open ocean: 0.5 - 1.5%
- Abyssal bottom: < 0.25%
Martin Curve - ANS Particulate organic carbon fluxes decrease exponentially with depth
- F = F(sub 100) * (z/100)^(-b)
--- F(sub 100) = POC flux at 100 m
--- z = trap depth
--- b = unitless parameter
- 1% or less OM in the euphotic zone reaches deep sediments
2 @COPYRIGHT 2026 ALLRIGHTS RESERVED.
