Module 4: Microbial Ecosystems (Oceanic and Soil Environs.) Flashcards
What percentage of Earth is covered by water?
70%
What percentage of oceanic biomass is microbes?
> 98% of oceanic biomass consists of microbes (viruses, bacteria, archaea, eukarya)
What is the salt concentration of ocean waters?
35g of salt / L of water
= 3.5% salt!
What is the composition of oceanic water salt?
~2/3 of the oceanic salt is composed of Na+ and Cl- ions
The rest consists of small amounts of the following ions:
1) Mg2+
2) Ca2+
3) K+
4) SO4-
5) HCO3-
Ocean water is _______ for the most part which means that _______ can occur
Ocean water is largely OXIC which means that aerobic respiration can occur
What is a common characteristic of oceanic waters?
Oligotrophic conditions
–> Low concentration of Nitrogne, Phosphorus, and Iron
Oceanic water is low in…
this makes it characterized as….
Concentration of:
1) Nitrogen (N)
2) Phosphorus (P)
3) Iron (Fe)
OLIGOTROPHIC
Oligotrophs
Organisms that utilize nutrients at very low concentrations
What has been found to decrease the oxygen content of ocean waters?
(generally)
An increase in nutrient concentration!
–> Causes greater growth of heterotrophs == greater aerobic respiration == greater O2 consumption!
What are the divisions of the ocean (and their depths)?
1) Surface Zone (0-200m)
2) Dark Mid-Water Zone (200-4,000m)
3) Deep Sea Zone (>4,000m)
What are the characterizing features of the ocean zones?
1) Surface zone = Light can penetrate!
2) Dark Mid-Water Zone = Constant temp of around 2-3C (No light)
3) Deep Sea Zone = Very high pressure
What is the typical ocean seafloor depth?
How does this compare to the deepest know spot (what is this)?
Typical Seafloor Depth = 3,500m
Deepest Spot = Mariana Trench @ 11,000m
How are microorganisms distributed throughout the ocean?
NOT uniformly!
–> As depth increases, microbial abundance decreases
BUT: As depth increases, the PROPORTION of archaea increases!!!
For most of the ocean’s volume, there is a greater # of ________ compared to ___________
Greater # of ARCHAEAL cells than BACTERIAL cells
The surface zone of the ocean is home to:
Photosynthetic microbes, mainly PHYTOPLANKTON
(And some zooplankton)
Phytoplankton
Photosynthetic microorganisms (aquatic)
What is example of phytoplankton?
Cyanobacteria such as:
–> Prochlorococcus
–> Synecoccus
What is the significance of phytoplankton?
Responsible for oxygenating the ocean waters AND support all other life in the oceans! (Original “source” of energy)
What are the main primary producers within oceans?
Phytoplankton
Main primary producers in oceans vs soil:
Oceans = Photosynthetic microbes
Soil = Plants
Zooplankton
Non-photosynthetic consumer microorganisms
–> Feed on primary producer phytoplanktons!
In the dark mid-water zone, ___________ is not possible BUT __________ exist here
Photosynthesis is not possible (no light)
BUT zooplankton live here!
Where do zooplankton get food from in zones below the surface zone?
From organic materials released from viral lysis of phytoplankton that drift down into lower zones
Viral Lysis of Phytoplankton
(What gets released?)
Bacteriophages and other viruses that target phytoplankton invade these photosynthetic cells, reproduce like crazy inside them, and lyse the photosynthetic cells
–> Results in the release of organic materials such as frags. of:
1) PM
2) DNA
3) Protein
4) and Nutrients
The materials released from lysis feed zooplankton in all zones of the oceans
Lysis mainly occurs in the dark mid-water zone!!!!