Fundamentals of the aquatic systems Flashcards
What are some properties of water?
1) High freezing and boiling= Due to ability to form hydrogen bonds, and ice is less dense than water as hydrogen bonds are most closely associated at 4 degrees celsius
2) Universal Solvent
3) Transport and reaction system
4) Ice can form barrier between air and water
What is the difference between turnover rate for freshwater and salt water?
Fresh water: Divided and small= High turnover as it is faster for renewal
Salt water= low
What is the difference in accumulation of salt for freshwater and salt water?
Freshwater= Low, liquid outflow so little accumulation of salts
Salt water= High evaporation and concentration of salt
What is the species diversity in freshwater compared to salt water?
Freshwater= Low, due to shorter time scale and more disruptions as there is discontinuity
Salt water= High, due to longer time scale and less disruption
What is an example for the importance of continuity?
Example: Two lakes in Malawi
Lake Chilwra= Shallow, dries out. Limited biota
Lake Malawi= Deep, doesn’t dry out and have great diversity
What do organisms living in freshwater need in order to disperse and colonise? (not sure..)
1) Lifecycle stage resistant to desiccation (dry)
2) Can spread through wind dispersal
3) But most need to stay in water as land is inhospitable habitat
Rivers and lakes are short-lived
Glacial periods shape geomorphology and therefore dispersal/ colonisation
What is the freshwater made up of?
1) Water reaching land already complex as it picks up particles
2) Atmospheric gases and acidity: CO2 dissolves in water to form carbonic acid= Determines the acidity of rainwater
Also: SO2 dissolves in water= Strongly reduces pH
3) Geology: Buffering capacity affected by underlying geology e.g. Igneous rock= Low buffering capacity, tight whereas sedimentary rock= jumbled particles, often porous= High buffering capacity
4) Inorganic materals: Calcium= Needed for exoskeleton of molluscs, Also have: Mg, Na, K and P
Sulphur is from rain
Phosphorus usually limiting for plant growth
What does eutrophication affect?
Increases primary productivity due to increased levels of nutrients
What is the difference between oligotrophy and eutrophy properties?
Oligotrophy: Low nutrients= Low primary productivity
Eutrophic: High nutrients
Altitude:
Oligotrophy: Upland
Eutrophy: Lowland
Underlying rocks:
Oligotrophy: Igneous rocks
Eutrophy: Sedimentary rocks
Catchment
Oligotrophy: Upper parts of catchment
Eutrophy: Increases downstream
As lakes ‘get older’, they become more eutrophic
What are some human activities which increase nutrients in freshwater?
1) Agriculture: Vegetation clearance= Less loss of P and N from natural vegetation, Slurry from livestock and fertiliser loss= Nitrate concentrations increase
2) Settlement: Human sewage from waste water can run off into the rivers, High organic matter leading to high Biochemical Oxygen Demand= Severe deoxygenation
Can also have increases in phosphate levels from domestic detergents
3) Industry= Lots of chemicals. heavy metal pollution. Can also have trace organic pollutants such as hormones which can make fishes change sex or become infertile
What happens to the oxygen in freshwater?
Less available than in air, solubility inversely related to temperature
Causes biggest problems for large tropical aquatic animals= Have to swim near the surface
What is the difference between lotic and lentic water and their properties?
Lotic= Flowing water, such as rivers and streams Lentic= Still water such as lakes and ponds
1) Current:
Lotic: Unidirectional
Lentic: Variable but slow
2) Size
Lotic: Variable
Lentic: Variable but can be deeper/wider
3) Circulation
Lotic: Well mixed, isothermal
Lentic: Deep lakes show thermal stratification in summer= Stagnation
4) Suspended material
Lotic: Currents are eroding, leading to high amounts of suspended material
Lentic: Low, although seasonally variable. Higher if shallow and exposed body of water
