L5 - Assessing water quality Flashcards
What is organic pollution?
Material derived from organisms (carbon based, and full of nutrients)
What are the 2 major sources of organic pollution?
- Livestock farm waste
- Human sewage (both treated and untreated)
How does organic pollution harm macroinvertebrates?
- Suspended solids (clog gills)
- Nutrients (increase microbial activity → using up all oxygen)
How is microinvertebrates sensitivity to pollution determined?
Determined by their mode of oxygen acquisition
What are the 2 modes of oxygen acquisition within microinvertebrates?
Spiracles – less subject to clogging (all land insects, some aquatic larvae)
Gills - more subject to clogging (most macroinvertebrates)
What are the negative effects of macroinvertebrates with gills?
Organic pollution leads to:
- Clogged gills
- Less oxygen in the water
Organisms are more sensitive if gills are:
- located externally
- not protected
What is a result of the negative effects of gills in macroinvertebrates?
Some can overcompensate (increase amount of water flowing over gills) in low O2 to get more water reaching their gills, but this takes LOTS of energy
What are the effects of treated sewage in terms of oxygen levels?
Nutrients (C, N, & P) increase microbial activity…
→ which increases biological oxygen demand (BOD)…
→ which lowers oxygen saturation
Water quality recovers with distance downstream from discharge site
What are the effects of treated sewage input on river biota?
Suspended solids (POM):
Clog gills
Reduce light penetration (= algae)
Presence of bacteria and “sewage fungus”
How is water quality assessed through macroinvertebrates?
Presence/absence of different species can be used to assess water quality
What are the 4 orders/suborders of insect larvae that are sensitive to pollution (in clean water) (and their common name)?
- Plecoptera (stoneflies)
- Emphemeroptera (mayflies)
- odonata/zygoptera (damselflies)
- odonata/anisoptera (dragonflies)
Identify the clear water insect larvae based off their order-level morphology:
1. does it have antennae?
2. does it have big external abdominal gills?
3. does it have caudal filaments (tail spikes), if so how many?
4. does it have bulbous eyes?
- yes = stonefly
- yes = mayfly
- 0 = dragonfly, 2 = stonefly, 3 = mayfly or damselfly
- yes = damselfly or dragonfly
What are the characteristics of stoneflies (plecoptera)?
Laval timespan = 1-4 years (molt~30 times)
Food source = CPOM, detritus, periphyton (Mostly shredders, some scrapers, a few predators)
Anatomy = Tufts of external gills on abdomen, neck, & thorax
Sensitivity = Gills subject to clogging
Can overcompensate at low O2
What are the characteristics of mayflies (ephemeroptera)?
Laval timespan = 1-2 years (molt 12-35 times)
Food source = Detritus, periphyton (collectors & scrapers)
Anatomy = Large external gills on abdomen
Sensitivity = Gills very subject to clogging
The most sensitive to pollution
What are the characteristics of damselflies and dragonflies (odonata)?
Laval timespan = 2-3 years (molt 8-18 times)
Food source = Other macroinvertebrates (including mosquitoes), some even eat frogs or fish! (predators)
DRAGONFLIES
Anatomy = Internal rectal gills
Sensitivity = Can overcompensate at low O2
DAMSILFLIES
Anatomy = 3 external feathery gills (tail) also used for swimming
Sensitivity = Gills subject to clogging
More sensitive than dragonflies
What macroinvertebrates are less sensitive to pollution (mid pollution)?
A mix of insect larvae, crustaceans, and molluscs
e.g. freshwater shrimp
What are the characteristics of caddis flied (trichopetra)?
Laval timespan = 1 year (molt 5-7 times)
Food source = Detritus, periphyton (scrapers)
Some build nets out of silk (periphyton)
Anatomy = Soft-bodied after first 3 segments
Build cases out of different materials
Gills on abdomen
Sensitivity = Gills, cases, & feeding nets subject to clogging
Wide variety of sensitivity to pollution
What macroinvertebrates are relatively tolerant to pollution (moderate pollution)?
Slightly different mix of insect larvae, crustaceans, and molluscs – now with worms!
e.g. leeches and asellus
What are the characteristics of alderflies (megaloptera)?
Laval timespan = 2 years (molt 10 times)
Food source = Macroinvertebrates (predators)
Anatomy = Protected abdominal gills (encased in spines), also used for swimming
Sensitivity = Quite tolerant
What macroinvertebrates are tolerant to pollution (severe pollution)?
Worms and insects that kinda look like worms
e.g. Oligochaeta
What are the characteristics of true flies (diptera)?
Larval timespan = 1-2 years (molt 12-35 times)
Food source = FPOM, detritus (collectors)
Anatomy = Lack thoracic legs
Functional spiracles
Sensitivity = Very tolerant to pollution
What are the 3 family types of Diptera (true flies)?
- Crane flies (Tipulidae)
- Black flies (Simuliidae)
- Non-biting midges (Chironomidae)
What is the standardised assessment of river water quality (BMWP)?
Collect 3 minute kick sample
Record presence or absence of families (not numbers)
Assign a score (0 – 12.5) to each macroinvertebrate family
> Pollution sensitive families = high score
> Pollution tolerant families = low score
*sensitive families have a high score (high scores have good water quality)
What is the biological monitoring working party (BMWP)?
Standardised assessment of river water quality?
