Water Environments Flashcards
How much of the earth is water? Fresh water?
- 8%
0. 4%
How much of the primary production on earth is aquatic?
50%
Where is the nutrient rich part of the ocean?
Costal
Why are there salty lakes in prairies?
- Net water deficit in summer
- H2O comes in and carries salts in- evaporates and leaves salts behind
Why are there water stressors in Canada?
Lakes not good location, decreased rain, increased population
What are 3 zones of lakes?
- Littoral Zone-Photic; near shore; primary production high at sediments
- Pelagic Zone- photic; open water
- Profundal Zone- Aphotic; Water and sediment below oxygen = consumed
What’s the pelagic zones 3 regions?
- Epilimnion
- Thermocline
- Hypolimnion
What are oxygen concentrations in aquatic systems are dependent on?
The amount of organic matter present and the physical mixing of the system
Whats stratification in summer? What happens in the fall?
- Based on heat exchange
- Temp barrier preventing cold deep water from mixing with top hot water
- In the fall cooling of the top where it’s the same temp as bottom uses mixing of lake= no stratification
Why is water at 4 degrees most dense?
It floats
What happens to the lakes temperature in the winter?
- Ice forms- can’t diffuse O2
- Traps O2 under ice
- Temp decreases which slows aerobic respiration which decreases O2 usage
- Will become anoxic
What are the different light zones of a lake?
Photo zone: 0-200 m allows light penetration and photosynthesis
Aphotic zone: No light, ∴ heterotrophic activity
Turbid waters:
Light penetration < 1m
What does ability of light penetrating O2 depend on?
Depth and particles
Why are there only the colour blue in deep ocean water?
Because only blue wavelengths can penetrate that deep
Coastal and Ocean Waters, compared to most freshwater environments, the open ocean environment is?
• Saline
• Low in nutrients, especially with respect to nitrogen,
phosphorus, and iron
• Cooler
What are major factors in earths C balance?
Microbial activities in oceans
Where is there more microbes in the ocean?
Shore because of higher nutrients
What are the 5 zones of an ocean?
- Photic zone
- Benthic zone
- Pelagic Zone
- Aphotic zone
- Nertic zone
- Intertidal zone
3 areas of the pelagic zone in the ocean
- Mesopelagic
- Bathypelagic
- Abyssopelagic
What tropies are lakes, wetlands and oceans?
lakes are oligotrophic (nutrient poor), wetlands eutrophic (well nourished), oceans both depending on location
What are upwelling zones?
- Bring cold, nutrient rich water up from depth
- Mixing of oceans
What does red represent in the picture on page 15 lecture 5?
Chlorophyll levels
What is phytoplankton? Bacterioplankton?
- Phytoplankton-eukaryotic (algae) and prokaryotic (cyanobacteria)- harmful toxins
- Bacterioplankton- bacteria that don’t have to be attached to anything
What are 4 plankton habitats?
- phytoplankton
- bacterioplankton
- viruses
- zooplankton (incl. protozoan)
Why is sampling the pelagic zone easier than soils?
- more homogeneous
- less site-to-site variation
- can use pumps and lines
- known volumes and depths can be sampled
- less destructive
Why is sampling bacteria in water hard?
- processing difficult due to low numbers of MOs
* generally use filtration- hard to catch on filter
What does primary production depend on? How much is done in oceans? Where does it happen?
- Nutrients
- 50%
- nutrients (N and P), Temp, turbidity (light), Fe
- happens mainly in areas of upwelling, and coastal areas
What is most of the primary productivity in the open oceans is due to? How much O2 is it responsible for? Describe the organism
- photosynthesis by prochlorophytes
- 20-50% O2
- Non motile
- Most plentiful org on earth
What biomass does Protochlorocuccus account for? How much net primary production?
- > 40% biomass of marine phototrophs
- 50%
What do harmful algal blooms occur from? Result?
- Phytoplankton toxins
- often occur in upwelling and high nutrient areas
- kill marine life and are harmful to us
How much of the C fixed by primary producers is released back into water? Used by what?
- More than half
- Bacterioplankton
Whats the microbial loop? Slide 38 Lecture 5
- Phytoplankton releases C to DOM (excrete and lysis) and zooplankton graze on them
- Bacterioplankton uptake DOM and are lysed DOM; also release (mineralization) CO2 which phytoplankton uptake
- Zooplankton excrete DOM and grase on bactivorous zooplankton and phytoplankton
- Bacteria production (utilization of DOM) available to the secondary production
Whats POM and DOM?
- POM – particulate organic matter – large macromolecules that make up structural components of cells
- DOM – dissolved organic matter – smaller soluble material that passes through a 0.7um filter
How much small planktonic heterotrophic prokaryotes are in pelagic marine waters?
abundant (10^5–10^6 cells/ml)
How much microbes in surf water vs deep?
Surface waters contain ~106 cells/ml; cell numbers drop to 10^3–10^5/ml below 1,000 m in depth
Whats the most abundant marine bacteria? Why?
- Pelagibacter ubique
- Streamlined genome reduces the amount of energy required for cell replication
- Saves energy by using the A and T (≈70.3% of all base pairs) because they contain less N
What are the most abundant microbes in the ocean with the most genetic diversity? How much? What does it influence?
- Viruses
- 10^30 viruses in the ocean
- influence the composition of marine communities and are a major force behind biogeochemical cycles
- Selection
- Major source of mortality and disease in marine orgs
What takes up the most biomass or abundance in an ocean?
Biomass- Prokaryotes
Abundance- Virueses
Whats a viral shunt? Benefit?
-Moves material from heterotrophs and photoautotrophs into POM and DOM
-chemical composition of the POM and DOM are not the same as the orgs the
material came from
-Makes POM and DOM accessible to orgs
What are benthic habitats? Characteristics?
• transition zone between water and mineral subsurface • diffuse and noncompacted mixtures of OrganicMatter, mineral
material, and water
• nutrient rich – MO activity and diversity is v. high
-Similar to soil except water on top
How much slower does O2 diffuse in water than air? Why is it easily depleted by heterotrophs?
10^4
By anaerobic organisms
How to sample benthic zone?
Cores- Keep samples intact
- Can study over time
- Good way
What does that amount of mercury depend on?
amount of gram negative sulfate-reducing bacteria (SRB)
Whats Desulfovibrio
- gram negative sulfate-reducing bacteria (SRB)
- commonly found in aquatic environments with high levels of OM
- growth may be limited in aerobic environs, they can survive in presence of O2 (aerotolerant)
How is inorganic Hg methylated to MeHg? What does the amount of MeHg depend on? What is MeHg?
- By Sulphate reducing bacteria
- Depends in part on the activity of the SRB, as well as Hg available
- MeHg is a neurotoxin that gets into fish
- SRB mediated MeHg production is NB b/c this is the main source of MeHg in aquatic systems
What are biofilms? What do they do?
• Surface association of MOs attached by an extracellular polymer matrix
•Assemblages of bacterial cells adhered to a surface and
enclosed in an adhesive matrix excreted by the cells
•The matrix is typically a mixture of polysaccharides
•Biofilms trap nutrients for microbial growth and help prevent detachment of cells in flowing systems
Why are surfaces important microbial habitats?
- Nutrients adsorb to surfaces
* Microbial cells can attach to surfaces
Why do bacteria form biofilms?
- Self-defense
- Biofilms resist physical forces that sweep away unattached cells, phagocytosis by immune system cells, and penetration of toxins (e.g., antibiotics)
- Allows cells to remain in a favorable niche
- Allows bacterial cells to live in close association with one another
How much antimicrobial does it take to get rid of biofilms?
~1000 times more antibiotic dose to eliminate bacteria attached to a surface in a biofilm compared to normal free-living bacteria
How to sample biofilms?
- difficult to sample b/c associations btwn MOs and substrate can be strong
- can scrape, very invasive
- artificial substrates are useful
- microelectrodes are often used
What type of bacteria are abundant in biofilms?
Extremophiles
Whats a microbial mat? Built by what bacteria?
- interfacial aquatic habitat – multi-layered sheet of micro- organisms, mainly bacteria and archaea.
-Very thick biofilms - phototrophic at some point
- can exist on land
- usually held together by
slimy substances secreted by MOs
-phototrophic and/or chemolithotrophic bacteria
How long have cyanobacteria mats been in ecosystems?
3.5 billion years
What are stromatolites?
- built up of layers of lime-secreting cyanobacteria and trapped sediment
- Very old
- 6-10 cm thick
- Slow growing
- Oldest fossils
Whats at West Chaplin Lake
A microbial mat
