Water Quality - Aquatic Ecosystems Flashcards
What four things contribute to the subjective definition of water quality?
Wholesomeness
Appearance
Odour
Abundance of life
What 3 thing make up the objective definition of water quality?
Physical parameter (temperature, turbidity) Chemical parameters (salinity, pH, hardness) Biological parameters (species richness and composition, abundance, health)
Characteristics of a river
Characterised by a unidirectional flow of water
Conditions determined by surrounding catchment and upstream inputs
Current primary determinant of community structure
Ensure most species are benthic
In which river system would pollution a siting organisms live?
Swift flowing with eroding substrata
Which river system would a naturally tolerant organism of organic pollution live?
Slow moving, silted region
What is the benthic zone?
The ecological region at the lowest level of a body of water
Key points about benthic organisms
Diversity of microhabitats on river bed and margins determines species diversity
Sediment type and water chemistry are key influences on river species
Benthic organisms entering water current drift downstream
Downstream drift can be active or passive
What types of pollution are there?
Natural processes
- chemical reactions between water and rocks
- sedimentation by flowing water
- percolation (movement) of surface water into groundwater
- residence time of reservoirs
- weathering of rocks (crustal)
Human related
- point source pollution
- non point source pollution
Name ten sources of water quality deterioration
Agriculture Sewage Urban storm water Industrial discharges Acidification Forestry Mining and quarrying Contaminated land Fish farming General development
Sources of point source pollution?
Contaminant discharge (eg pipe)
- easy to spot and quantify
- immediate evaluation of impacts
Factories and wastewater treatment plants
Former or abandoned mines
Landfills
Underground tanks and above ground storage tanks
What kinds of pollution can underground storage tanks cause?
Groundwater contamination and soil pollution
What are the sources of non point source pollution?
Broad or dispersed contaminant discharge Agricultural practises or processes Gardens and golf courses Waste disposal Construction Surface water runoff Dredging
Why and to what are gardens parks and golf courses a non point source of pollution?
Risk to surface and ground water
Excessive use of manure, fertilisers and pesticides
Insufficient cleaning and disposal of animal refuse
How is construction a non point source of pollution?
Erosion - sedimentation into local streams
- improper site management
- inadequate storing of materials
What is dredging and why is is harmful to water quality?
Dredging is an excavation activity or operation usually carried out at least partly underwater with the purpose of gathering up water sediments and disposing of them at a different location
- can be ingested by aquatic organisms
- water temperature can be changed due to increased suspended sediments
What is organic pollution?
Oldest and most widespread form of water pollution
One of the main causes of pollution in Scottish waters
Sources include - sewage, agricultural waste, food processing waste, waste from manufacturing of natural textiles and paper, aquaculture waste
Why does an increase in aerobic microbes have a negative effect on a water system?
Dissolved oxygen is used up and can not be replaced by photosynthesis or aeration and so the area of water becomes a dead zone
What effects does organic pollution have on the biota?
Organic pollution changes the physical and chemical environment
- dissolved oxygen levels decrease
- suspended solids and silt increase
- toxic waste products of decomposition increase (ammonia, acetic acid)
Organisms which cannot tolerate these changed conditions disappear
What are the 4 zones in organic pollution effects?
Polysaprobic zone
Alpha-mesosaprobic zone
Beta-mesosaprobic zone
Oligoaprobic zone
What is the polysaprobic zone and what organisms exist there?
Very low oxygen
High levels of solids and silts
High ammonia
Contains sewer fungus, Protozoa, tubificids
What is the alpha-mesosaprobic zone and what organisms exist there?
Low-mid oxygen
High nitrates
High phosphates
Contains chironomids, cladophora, asselius, algae
What is the beta-mesosaprobic zone and what organisms exist there?
Mid-slightly reduced oxygen
Contains Chironomids, cladophora, asselius,algae, some clean water fauna
What is the oligoaprobic zone and what organisms exist there?
Normal oxygen levels
No evidence of pollution
Contains clean water fauna
Name some pollution tolerant species
Chironomidae Tubificidae Platyhelminthes (free living flatworms) Asellus (water louse) Leeches
Name some pollution sensitive species
Mayfly nymph
Stone fly nymph
Cased caddis fly larvae
Freshwater pearl muscle
Why use biological criteria for water quality?
Detects intermittent pollution
Chemical sampling often based on spot samples but variables such as BOD, O2 and NH3 can vary rapidly in time and space
Cannot test for all chemicals
Some chemicals toxic below existing analytical detection limits
Bioaccumulation may concentrate toxins
Essentially interested in quality of water to sustain life
What are the properties of an ideal indicator species?
Readily identified Easily sampled Cosmopolitan distribution Abundant autecological data Economic importance Readily accumulate pollutants Easily cultured in laboratory Low variability
What type of aquatic systems exist?
Marine (oceanography)
Freshwater (limnology)- streams, lakes, riffles, pools, substrate
Brackish water - wetlands
