Limnology Flashcards
What factors impact oxygen concentration in water?
Temperature
(higher T = lower DO)
Atmospheric Pressure
(lower P = lower DO)
Salinity
(higher S = lower DO)
Metabolic demand
(higher MD = lower DO)
(CCAC, 2005; ENSC 3106 Notes)
How are dissolved oxygen and temperature in water related?
How does this relate to organisms within the water?
The solubility of oxygen in water is negatively correlated with water temperature.
When temperature increases, biological oxygen demand increases so on top of there being less oxygen available due to a lack of solubility, the oxygen that is available is used up more quickly.
(Marshall et al, 2021)
Biogeochemical
The transfer of chemical elements and simple substances between living systems and the environment.
(Mac Dictionary)
Stratification
The layering of water in oceans and lakes due to differences in water temperatures and density with depth.
Determines the movement of nutrient and oxygen.
(BIOL 2600 Notes)
Eutrophication
Increased algal production in lake as a result of too much primary production because of too much P (i.e., cyanobacteria blooms).
(ENSC 3106 Notes)
Why is dissolved oxygen important?
In many cases it is the single most important variable in understanding aquatic ecosystems.
It is essential to the metabolism of all aquatic organisms.
Low DO alters the growth and distribution of animals and the solubility of nutrients and metals.
(ENSC 3106; Wetzel, 1975)
Hypoxic
Oxygen defificiency.
According to Marshall et al, 2021 this is when [DO] is less than 5 and more than 2 mg/L (btw 2-5ppm).
According to my ENSC 3106 Notes it’s when DO levels in water are between ~2-3 ppm.
Anoxic
The complete absence of oxygen.
According to Marshall et al, 2021 this is when [DO] is less than 2 mg/L (btw 2 ppm).
According to my ENSC 3106 Notes it’s when DO levels in water are 0 ppm.
What are the main sources of DO in water?
Turbulence from wind creating an exchange with the atmosphere.
Photosynthesis by algae and plants.
(ENSC 3106 Notes)
How does [DO] relate to time of day?
[DO] has a diel cycle i.e., in changes based on a 24 hour cycle.
It is higher during the day when photosynthesis is taking place and lower at night when photosynthesis is not happening.
(ENSC 3106 Notes)
How is [DO] and [P] related?
Higher [P] lowers [DO].
Also, lower [DO] reduces the redox potential in the water making sediments more soluble releasing P.
This is a positive feedback loop and it’s almost impossible to fix.
(ENSC 3106 Notes)
Why is organic carbon in aquatic ecosystems important?
It supports zooplankton and bacteria (important to food web).
High concentrations of it can reduce photosynthesis (and therefore [DO]) since it’s coloured and can block light.
(ENSC 3106 Notes)
Where does organic carbon come from? What is it made of?
Made mostly of humic substances which are produced by the biodegradation of dead organic matter (e.g., plants, algae, bacteria).
Can also be brought via groundwater and surface water.
(ENSC 3106 Notes)
Macrophyte and Types
Large aquatic plants growing in littoral and riparian zones.
Can be emergent, submerged, or floating.
(ENSC 3106 Notes)
Turbidity
Restriction of the transmission of light through water due to scattering and absorption caused by suspended sediments.
(Allan & Castillo, 2009)
