Microbial Ecology Flashcards
When do lakes stratify?
During summer months from increased solar radiation, with weak summer wind unable to mix the dense cold water beneath.
When does wind mixing occur?
Fall turnover
Why does spring and summer support algal blooms?
As deep-layer nutrients are brought up from the mixing period in the winter and early spring.
Algal importance in ecosystems?
Photosynthetic primary producers, consumed by protozoa, crustaceans, consumed by consumers.
Oligotrophs
The ability for micro-organisms to grow when oxygen levels are low, being slow growing.
Eutrophic
Enrichment of nutrients increasing plant/algal growht in coastal winter and estuaries.
When do eutrophs exist?
Not in winter due to low nutrient concentrations
Microbial Loop
Models aquatic ecosystems comprising bacteria, dinoflagellates, ciliates and other zooplankton.
Phagotrophic
This is feeding by engulfing good cell or particles and ingesting it in phagocytic vacuoles.
How is organic matter assimilated?
By bacteria
What are the domainant primary producers in marine envrionments?
Planktonic algae.
Redfield Ratio
Describes C ; N ; P ratio nearly constant at 106 ; 16 ; 1.
What sunlight do lakes recieve?
Shortwave solar and reflected longwave.
What is downward lake movement mediated by?
Mechanical energy
How is stratfication ecologically important?
When stratified, the metalimnion prevents water-column mixing, thus isolating hypolimnion from atmospheric gas exchange
When might the hypolimnion recieve light for photosynthesis?
Clearer lakes allow deeper penetration
When does stratifcaition occur summer?
Temperate lakes
How might deep water temperature increase?
Humic substance oxygenation produces heat, and sediment heat release.
Effects on Diurnal variations?
Solar radiation increases with cloudless days incerasing stratification
Types of lake based on stratification?
Dimictic
Monomictic
Oligomictic
Polymictic
Amictic
Meromictic
Dimictic
Typical of temperate climates where stratification occurs twice a year.
Monomictic
Experience turnover only once a year, thic can be cold or warm.
When do monomicitc lakes occur?
Cold below 4C or subtropics never below 4C
Oligomictic
Do not stratify every year, found say in low humid and high wind equatorial regions, with little seasonal changes
