L5 - Assessing water quality

Question 1

What is organic pollution?

Answer 1

Material derived from organisms (carbon based, and full of nutrients)

Question 2

What are the 2 major sources of organic pollution?

Answer 2

1. Livestock farm waste
2. Human sewage (both treated and untreated)

Question 3

How does organic pollution harm macroinvertebrates?

Answer 3

1. Suspended solids (clog gills)
2. Nutrients (increase microbial activity → using up all oxygen)

Question 4

How is microinvertebrates sensitivity to pollution determined?

Answer 4

Determined by their mode of oxygen acquisition

Question 5

What are the 2 modes of oxygen acquisition within microinvertebrates?

Answer 5

Spiracles – less subject to clogging (all land insects, some aquatic larvae)

Gills - more subject to clogging (most macroinvertebrates)

Question 6

What are the negative effects of macroinvertebrates with gills?

Answer 6

Organic pollution leads to:
- Clogged gills
- Less oxygen in the water
Organisms are more sensitive if gills are:
- located externally
- not protected

Question 7

What is a result of the negative effects of gills in macroinvertebrates?

Answer 7

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

Question 8

What are the effects of treated sewage in terms of oxygen levels?

Answer 8

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

Question 9

What are the effects of treated sewage input on river biota?

Answer 9

Suspended solids (POM):
Clog gills
Reduce light penetration (= algae)
Presence of bacteria and “sewage fungus”

Question 10

How is water quality assessed through macroinvertebrates?

Answer 10

Presence/absence of different species can be used to assess water quality

Question 11

What are the 4 orders/suborders of insect larvae that are sensitive to pollution (in clean water) (and their common name)?

Answer 11

1. Plecoptera (stoneflies)
2. Emphemeroptera (mayflies)
3. odonata/zygoptera (damselflies)
4. odonata/anisoptera (dragonflies)

Question 12

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?

Answer 12

1. yes = stonefly
2. yes = mayfly
3. 0 = dragonfly, 2 = stonefly, 3 = mayfly or damselfly
4. yes = damselfly or dragonfly

Question 13

What are the characteristics of stoneflies (plecoptera)?

Answer 13

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

Question 14

What are the characteristics of mayflies (ephemeroptera)?

Answer 14

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

Question 15

What are the characteristics of damselflies and dragonflies (odonata)?

Answer 15

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

Question 16

What macroinvertebrates are less sensitive to pollution (mid pollution)?

Answer 16

A mix of insect larvae, crustaceans, and molluscs
e.g. freshwater shrimp

Question 17

What are the characteristics of caddis flied (trichopetra)?

Answer 17

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

Question 18

What macroinvertebrates are relatively tolerant to pollution (moderate pollution)?

Answer 18

Slightly different mix of insect larvae, crustaceans, and molluscs – now with worms!
e.g. leeches and asellus

Question 19

What are the characteristics of alderflies (megaloptera)?

Answer 19

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

Question 20

What macroinvertebrates are tolerant to pollution (severe pollution)?

Answer 20

Worms and insects that kinda look like worms
e.g. Oligochaeta

Question 21

What are the characteristics of true flies (diptera)?

Answer 21

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

Question 22

What are the 3 family types of Diptera (true flies)?

Answer 22

1. Crane flies (Tipulidae)
2. Black flies (Simuliidae)
3. Non-biting midges (Chironomidae)

Question 23

What is the standardised assessment of river water quality (BMWP)?

Answer 23

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)

Question 24

What is the biological monitoring working party (BMWP)?

Answer 24

Standardised assessment of river water quality?

Question 25

How do you work out BMWP?

Answer 25

Site score (BMWP) = sum of scores of individual families present
(++=)

Question 26

How do you calculate ASPT (average score per taxon)?

Answer 26

Average score per taxon (ASPT) = BMWP/Number of indicative families

Question 27

What is RIVPACS - river invertebrate prediction and classification system?

Answer 27

A database of expected macroinvertebrate communities in ‘pristine’ rivers

Question 28

What are the 12 environmental attributes that are used to assign a reference river by RIVPACS?

Answer 28

distance from source (km)
altitude (m)
mean substratum (phi units)
discharge category (out of 9)
mean water width (m)
mean water depth (cm)
latitude (°N)
longitude (°W/°E)
alkalinity (mg CaCO3 L-1)
slope (m km-1)
mean air temperature (°C)
air temperature range (°C)

Question 29

What do RIVPACS make lists of/have data on?

Answer 29

→ the expected macroinvertebrate taxa if healthy
→ the actual taxa observed in the river

Question 30

What are the pros of ecological monitoring for macroinvertebrates?

Answer 30

ORGANISM: ubiquitous, large number of species, sedentary nature, long life cycles

TECHNIQUE: cheap and easy, taxonomy well sorted, many methods of data analysis, responses of common species to organic pollution are known

Question 31

What are the cons of ecological monitoring for macroinvertebrates?

Answer 31

ORGANISM: they don’t respond to all impacts, seasonal variability complicates comparability, drift into areas

TECHNIQUE: quantitative sampling difficult, some groups taxonomically difficult