Invert ID and Sampling

Question 1

Why are benthics so useful for bio monitoring? (3)

Answer 1

Long after conditions within a river have normalized, the aquatic biota will still show the impact (e.g. from an episodic pollution event)

Common inhabitants of lakes and steams

Important for moving energy through the food web

Question 2

What is a benthic macroinvertebrate? (3)

Answer 2

Bottom-dwelling
No backbone
Can be captured by net mesh sizes between 200-500um

Question 3

What are the 4 benthic feeding groups?

Answer 3

Shredders - feed on OM
Collectors-gatherers - feed on scraps from shredders
Scrapers - feed on algae
Predators - feed on others

Question 4

How do you know that a stream might be impacted by its diversity of macroinvertebrates? (2)

Answer 4

In healthy streams, all feeding groups should be present

Therefore, we can use ratio and number of macroinvertebrates do assess ecological status of the biotic community and water quality

Question 5

Why are macroinvertebrates useful biological indicators? (5)

Answer 5

They are sessile and so they reflect local conditions

They respond rapidly to changes in their environment

They are generally abundant and can be collected anywhere

They are diverse and respond to a wide range of stressors

They are a key part of the food web

Question 6

What metrics might we use to monitor benthic macroinvertebrate communities? (4)

Answer 6

Richness
Diversity
Tolerance
Functional feeding groups

Question 7

What is the CABIN protocol? (3)

Answer 7

Stands for Canadian Aquatic Biomonitoring Network

Provides a standardized sampling protocol and a recommended approach for assessing aquatic ecosystem condition

Established by Environment Canada to develop a network of reference sites that can be used in Reference Condition Approach (RCA) biomonitoring studies

Question 8

What is the Reference Condition Approach (RCA)? (2)

Answer 8

Indicators from potentially impaired sites are compared to those from a group of regional “reference” sites that have had minimal human impact

Based on these comparisons, the status of potentially impaired sites is determined (e.g. stressed, severely stressed etc.)

Question 9

What is the Reference Conditions Approach (RCA) process? (6)

Answer 9

A database of minimally disturbed regional reference sites is established, representing a range of physical, chemical, and biological characteristics

These sites are classified into homogenous groups that define the “reference condition” across the range of natural variability in the study area

The RCA assumes that the group of reference sites represents a range of normal or unimpaired conditions

A model is then developed to predict the biological assemblage for the study site from a set of environmental variables measured at the reference sites

Test sites are then assigned to each reference group based on the predictive model and deviations from the test site with the reference site show the degree to which the sites are different

This then determines the classification on a gradient of perturbation relative to the reference site

Question 10

What is the EPT Index? (6)

Answer 10

An index that uses three Orders of aquatic insects that are easily sorted and identified as indicators of water quality

Works on the premise that high-quality streams have the greatest species richness and that as pollutants increase, biodiversity declines

Works because benthic organisms exhibit varying levels of tolerance to pollution

Orders used are: Ephemeroptera, Plecoptera, and Trichoptera

If all 3 are strongly present, it indicates clean water

If they are absent and there is a strong presence of Diptera and Chironomids, this indicates poor water quality

Question 11

Ephemeroptera (4)

Answer 11

Mayflies

Diversity decrease in response to most types of human influence

Many mayflies graze on algae so are particularly sensitive to chemical pollution

In streams that have high agricultural influence, mayflies may be abundant - however, lower numbers of stoneflies and caddisflies will indicate enrichment

Question 12

Ephemeroptera identification (4)

Answer 12

Long tails, usually 3 but sometimes 2

No obvious antennae

Plate-like, feathery fills along abdomen

Primarily shredders

Question 13

Plecoptera (4)

Answer 13

Stoneflies

First to disappear from stream as human disturbance increases

Many stoneflies are predators that hide in rocks so as sediment is deposited, they lack habitat

Most stoneflies need cool temperatures and high oxygen to complete their life cycles

Question 14

Plecoptera identification (5)

Answer 14

2 long antennae

2 tails

Single or branched filament gills on thorax and along legs

2 small hooks at end of each leg

Primarily carnivorous

Question 15

Trichoptera (2)

Answer 15

Caddisflies

Found in a diversity of habitat types but will steadily disappear as humans eliminate the variety and complexity of in-stream habitat

Question 16

Trichoptera identification (5)

Answer 16

Caddisflies have such small antennae that you can hardly see them

Legs located close to head/mouth

Some build houses out of stream bed materials

Generally shredders and collectors

Kind of looks like a shrimp

Question 17

Other aquatic critters (5)

Answer 17

Dragonfly nymphs - have wing pads and unhinged jaw

Damselfly nymphs - have leaf-like gills

Diptera - true flies and midges

Coleoptera - good indicator of water quality

Gastropoda - snails (two types - lunged and gilled) gilled snails are sensitive to pollution and lunged snails are not ( can tell them apart as lunged snails have opening on left side)

Question 18

When is invertebrate sampling usually conducted and why? (5)

Answer 18

Late summer or fall because:

Most benthics are in their aquatic life stage

Life cycles have progressed enough to ID

Flow conditions are usually low (sampling is safer)

Low water levels mean substrate belie wetted stream channel is stable (not ephemeral)

Question 19

What are the measurements and samples taken for the CABIN protocol? (7)

Answer 19

Primary site data (basin name, coordinates, stream order etc.)

Site description (drawings, land use etc.)

Reach characteristics (habitat types, canopy cover etc.)

Water chemistry (physical and chemical water quality parameters)

Benthic macroinvert survey

Substrate characteristics (embeddedness, substrate size)

Channel measurements (width, depth, velocity)

Question 20

How do you select a reach for invert sampling? (5)

Answer 20

Select a reach that is representative of the area in terms of aquatic habitat and stream side vegetation

Reach us defined as 6X the bankfull width

Should represent a complete pool-riffle sequence and contain the desired aquatic habitat

The benthic sample, substrate, channel measurements, and water samples are collected within the erosional zone of the reach (only the riffle area)

Other observations such as riparian vegetation, canopy cover, macrophyte cover, slope etc. are evaluated for the entire reach

Question 21

How do you establish a reach? (4)

Answer 21

Estimate bankfull width visually (do not enter the stream!)

Multiply bankfull width by 6 to calculate sample reach size

Ensure that all crew members are aware of the reach area

Make sure to have a site description and take photographs so that future visits can sample the same location

Question 22

How do you take your benthic invertebrate samples? (7)

Answer 22

Define the kick area and path in the erosional zone of the sampling reach before entering the stream

At the downstream side of the kick area, place the kick net downstream of the sampler, flat side of the triangle resting on the substrate of the stream

Walk backwards in an upstream zigzag direction, dragging the net along the bottom

Kick the substrate to disturb it to a depth of 5 to 10 cm

Zigzag from bank to bank for a period of 3 minutes

If need to get around obstruction, stop timer and restart afterwards

Sample any stream habitats adjacent to the stream to take into account unique fauna

Question 23

How do you transfer your samples? (5)

Answer 23

Splash the side of the net n the river to transfer all material to the collection cup

Remove collection cup attached and empty contents into wide mouth plastic sample jar (holding it over pail in case of spill)

Wash any material remaining in the cup/net into the sample jar using a squeeze bottle and forceps to remove and clingers

Transfer any sample from pail (if using) to sample jar

Store samples in preservative until taxonomic identification

Question 24

What taxonomic group do you identify macroinverts to?

Answer 24

Generally family or the lowest practical level, which varies depending on the expertise of the observer

Question 25

What is the stream keepers protocol for sampling invertebrates? (2)

Answer 25

Using a Surber Sampler

Intended for use in shallow 30cm deep or less flowing waters

Question 26

What are the steps to the Surber Sampler protocol? (7)

Answer 26

Choose a wetted width location where substrate is fairly uniform

Provide a description of general habitat (e.g. run, riffle, pool etc.) And position the sampler securely at a random location on the stream bottom parallel to water flow with the net portion downstream

Carefully turn over and lightly rub all rocks and stones that lie within the frame to dislodge organisms

In order to maintain compatibility between stations, a limit of 5 minutes per station is set

Stir remaining gravel with your hands to a depth of 5 to 10 cm

Move sampler upstream to a new randomly selected patch of stream bottom and repeat steps until 5 patches of stream bottom have been sampled (total area sampled depends on size of sampler)

Return to shore and carefully invert the net into a shallow pan containing stream water