Deep Ecosystems Flashcards
Oceans Biological Carbon Pump Diagram
Refer to notes to draw out all 5 steps
why is biological pump important
Sink atmospheric carbon
Important for connecting nutrient cycles and productivity
Bring food source to deep ocean
Would atmospheric CO2 concentrations be different if the biological carbon pump didn’t exist
Yes there would be more CO2
How does the biological carbon pump effect climate
It reduces atmospheric CO2, less heating and more cooling of earth
How might climate change effect the biological carbon pump
OA: this may affect remineralization
Temperature: warmer water holds less gas, less ice and more stratified waters
Explain the thermohaline circulation that drives the worlds oceans
This is driven by density
Begins in the warm shallow waters of the Pacific to Indian to Atlantic
Cools in the North Atlantic sinks and flows south to join the deep cold waters of Antarctica
Flows back to Indian and Pacific ocean and warms and rises
Very slow, around 1000 years from N Pacific to N Atlantic (2000 year-round trip)
Where on the figure of NADW is oxygen highest and lowest?
Highest near the surface
Lowest at moderate depths with long time since surface and deep basins
What processes explain oxygen trends with depth and latitude?
Time, respiration and ventilation (gas exchange with surface)
What controls respiration rate?
Particle sinking rates (density)
Organic matter degradation rate (mineral protection)
Amount of O2
Highest between 100-300m
Respiration, Renewal and Oxygen concentration at depths comparisons
Shallow (100-300m):
Respiration - highest
Renewal - Fastest
Oxygen - High
Mid-Depth:
Respiration - Not too low
Renewal - Slow
Oxygen - Low
Shallow (>3000m):
Respiration - lowest
Renewal - slowest
Oxygen - medium
Highest and lowest nutrient concentrations on the NADW
Lowest at surface of north
Increase with depth and as you head south
What processes explain the nutrient concentration trends
Time, Remineralization and productivity
What are calcareous sediments made from and what makes them
calcium carbonate
Coccolithophores, zooplankton (foraminifera) and pteropods
How is solubility of calcareous skeletons affected with depth
rate of dissolution increases with depth
Higher pressure
Lower temperature
Higher CO2 (acidic)
Begins dissolving at ~500m in Pacific and 1500m in Atlantic
Lysocline
depth at which transition to carbonate undersaturated begins
Carbonate compensation depth (CCD)
all calcium carbonate dissolved
Where do you find calcareous sediment
Usually on elevated sea floor: flanks of mid-ocean ridges and seamounts
Patchy preservation: Carbonate can be buried before it is able to dissolve
Siliceous sediment
silica skeletons
Diatoms & Radiolarians
Does not dissolve as readily, but the ocean is still undersaturated
Organic layers preserve the skeleton
Deposits on sea floor mirror surface production of organisms
Inputs to the deep-sea
Phytoplankton: most consumed or lost to degradation
Zooplankton: most consumed or degraded before sea floor
Large animals: sink rapidly, some consumed at intermediate depths, available to benthic scavengers
Fish dumping: large portion of catch, increase benthic food supply
Faecal matter: sink rapidly to reach sea floor, mostly indigestible material, colonized by bacteria
Crustacean moults: low nutritional value, more benthic input, bacteria colonize
Macrophyte detritus: feed detritivores and bacteria
Vertical Migrations: downward transfer of organic material
