Invert ID and Sampling Flashcards
Why are benthics so useful for bio monitoring? (3)
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
What is a benthic macroinvertebrate? (3)
Bottom-dwelling
No backbone
Can be captured by net mesh sizes between 200-500um
What are the 4 benthic feeding groups?
Shredders - feed on OM
Collectors-gatherers - feed on scraps from shredders
Scrapers - feed on algae
Predators - feed on others
How do you know that a stream might be impacted by its diversity of macroinvertebrates? (2)
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
Why are macroinvertebrates useful biological indicators? (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
What metrics might we use to monitor benthic macroinvertebrate communities? (4)
Richness
Diversity
Tolerance
Functional feeding groups
What is the CABIN protocol? (3)
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
What is the Reference Condition Approach (RCA)? (2)
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.)
What is the Reference Conditions Approach (RCA) process? (6)
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
What is the EPT Index? (6)
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
Ephemeroptera (4)
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
Ephemeroptera identification (4)
Long tails, usually 3 but sometimes 2
No obvious antennae
Plate-like, feathery fills along abdomen
Primarily shredders
Plecoptera (4)
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
Plecoptera identification (5)
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
Trichoptera (2)
Caddisflies
Found in a diversity of habitat types but will steadily disappear as humans eliminate the variety and complexity of in-stream habitat
Trichoptera identification (5)
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
Other aquatic critters (5)
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)
When is invertebrate sampling usually conducted and why? (5)
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)
What are the measurements and samples taken for the CABIN protocol? (7)
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)
How do you select a reach for invert sampling? (5)
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
How do you establish a reach? (4)
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
How do you take your benthic invertebrate samples? (7)
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
How do you transfer your samples? (5)
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
What taxonomic group do you identify macroinverts to?
Generally family or the lowest practical level, which varies depending on the expertise of the observer
What is the stream keepers protocol for sampling invertebrates? (2)
Using a Surber Sampler
Intended for use in shallow 30cm deep or less flowing waters
What are the steps to the Surber Sampler protocol? (7)
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
