Lecture 5: Aquatic Flashcards
Which of the following is most likely to be true?
A. Water near the mouth of a river is always oligotrophic.
B. Water near the mouth of a river is always eutrophic.
C. Algal blooms are more common near the mouth of rivers.
D. Both A & C
E. BothB & C
A. Water near the mouth of a river is always oligotrophic.
B. Water near the mouth of a river is always eutrophic.
C. Algal blooms are more common near the mouth of rivers.
D. Both A & C
E. BothB & C
_____ of Earth’s surface is water.
70%
What are the studies of freshwater and marine habitats called?
- Freshwater: limnology
- Marine: oceanography
Lentic refers to _____.
Lotic refers to _____.
- Lentric= lakes/ponds (still water)
- Lotic = rivers (running water)
Define neuston.
Surface layer film of microbes that forms under still conditions
What are the three nutrient classifications in freshwater habitats?
oligotrophic (low nutrient load) –> mesotrophic –> eutrophic (high nutrient load)
Define biochemical oxygen demand.
The amount of oxygen consumed by bacteria and other microorganisms while they decompose organic matter under aerobic conditions at a specified temperature
What does lacustrine mean?
Associated with lakes
Why are allocthanous terrestrial animals common in riverine environements?
- Runoff
- Dissolved organic matter (DOM)
Describe the upper, middle, and lower portions of a river.
- Upper
- Fast flow, rocky bottom
- Oxygenated, cold water
- Shaded in forest (low 1º production) - Middle
- Warmer, slower water (higher 1º production) - Lower (estuary)
- Slow flow –> silt/mud deposition
- Influence of salt water
- High 1º production
Stratification of freshwater systems is driven mainly by:
A. Rainfall events
B. Decreasing temperature in the late fall and winter
C. Increasing temperature in the late spring and summer
D. Both A & C
E. All of the above
A. Rainfall events
B. Decreasing temperature in the late fall and winter
C. Increasing temperature in the late spring and summer
D. Both A & C
E. All of the above
What are estuaries?
Intersection between riverine and marine habitats
- Strong salinity gradient
- Highly variable
Why are estuaries highly variable (i.e. what influences them)?
- Marine influence from tides
- Riverine influence from storm run-off
Describe the different pelagic environments.
- Open ocean: very low nutrients
- Near shore: higher nutrients (from terrestrial and depth)
- Surface (epipelagic): high light, warm temps
- Deep (bathypelagic, hadal): cold and dark
What is marine snow?
Continuous shower of organic detritus greater than 0.5 mm in size
Aquatic bacteria are mainly Gram-_____ and _____.
- negative
- motile
Info on SAR11?
Now cultured in high-throughput dilute medium
- Pelagibacter
Define guild.
A group of species that exploit the same resources, or that exploit different resources in related ways.
Which of the following about oceanic habitats is true?
A. Aside from phototrophs, Crenarchaeota are the most abundant group of surface microbes.
B. Particles are very important for keeping nutrients near the surface.
C. Sulfate reduction is the major anaerobic metabolism in ocean sediments.
D. Open ocean habitats have more nutrients than coastal habitats.
A. Aside from phototrophs, Crenarchaeota are the most abundant group of surface microbes.
B. Particles are very important for keeping nutrients near the surface.
C. Sulfate reduction is the major anaerobic metabolism in ocean sediments.
D. Open ocean habitats have more nutrients than coastal habitats.
Describe the surface layer conditions that support photoautotrophy?
- ~50% of global CO2 fixation
- Plenty of light and CO2 for photosynthesis
- Light attenuation with depth
- Below that is the profundal zone (lakes) or bathyal zone (ocean)
Explain algal blooms (what causes them, buoyancy mechanisms, toxin production, high BOD).
- Seasonal changes in nutrients lead to high density growth of algae (high nutrients)
- Cyanobacteria have gas vesicles
- Red tides (dinoflagellates) and microcystins (cyanobacteria)
- High BOD: death of a large amount of algal biomass leads to increases respiration –> depletes oxygen and leads to fish-kills
Define eutrophication.
The influx of nutrients which causes phytoplankton numbers to rise rapidly (called a “bloom”)
Whta problems can blooms cause? What is the result of this?
- Reducing the amount of light available to organisms attached to the bottom
- Dead zones
Describe the cell walls of diatoms.
- Shell of silica called a frustule (2 glass silica shells)
Many pennate diatoms have a raphe, which is used for _____.
secreting mucilage, which is also used for diatom mobility
When did diatoms first appear in the fossil record?
Cretaceous
Describe the cell walls of dinoflagellates.
Cellulose cross-linked plates as “armor”
- Some are naked
What is bioluminescence?
Chemiluminescence that takes place inside a living organism
What are protozoa shells made of?
Calcium carbonate
Pseudopods extend through pores in the shell where they are used to _____.
capture minute food particles such as phytoplankton
Describe the cell walls of radiolarians.
Shell of silica
What is the marine microbial loop?
Trophic pathway in marine microbial food web that returns carbon to higher trophic organisms
Which of the following is a logical outcome of the microbial loop?
A. Greater efficiency in carbon/nutrient cycling mean that large predators have more food.
B. Greater efficiency in carbon/nutrient cycling mean that large predators have less food.
C. Because they are so large, sharks are unaffected by the microbial loop.
D. None of the above
A. Greater efficiency in carbon/nutrient cycling mean that large predators have more food.
B. Greater efficiency in carbon/nutrient cycling mean that large predators have less food.
C. Because they are so large, sharks are unaffected by the microbial loop.
D. None of the above
