|
The picture to the right shows the surber sampler worked into the stream bed, in this case rocks and gravel. The rocks are scrubbed in the screen so that up-steam sediments and invertebrates are carried into the screen. Clean pebbles and rocks that wash into the screen in the screen and remove the larger rocks. In quiet waters draw the sampler through bottom sediment. If the sediment is muddy, wash the screen multiple times to clear away most of the fine sediments, leaving the macro-invertebrates and other objects behind.
|
|
Making and Using a Surber Sampler
A surber sampler collects macro invertebrates from shallow riffles and/or runs. Flowing water carries the invertebrates into the collecting net as the benthos is disturbed. Obviously, samplers of different sizes can accommodate different conditions (e.g. larger samplers can be used in deeper areas, smaller samplers sometimes work better in shallow streams with low velocity). The sampler may also be used for qualitative sampling by dragging the sampler across a pond bottom.
How to make your own surber samplers:
This will require sewing, measurements, rod bending, drilling, hacksawing and welding
A surber sampler collects macro invertebrates from shallow riffles and/or runs. Flowing water carries the invertebrates into the collecting net as the benthos is disturbed. Obviously, samplers of different sizes can accommodate different conditions (e.g. larger samplers can be used in deeper areas, smaller samplers sometimes work better in shallow streams with low velocity). The sampler may also be used for qualitative sampling by dragging the sampler across a pond bottom.
How to make your own surber samplers:
This will require sewing, measurements, rod bending, drilling, hacksawing and welding
|
Materials
32 by 82 cm silkscreen mesh with a 500 micron openings 2 inch bias tape x 100 cm and 1 inch wide bias tape ¼ inch by 100 cm coated steel rod 5/16 redirod connector Construction steps Bend the rod into a rectangle 33 cm wide and 15 cm deep, joining at the mid point along the top side. Cut the rod so the two top edge pieces match. Drill a ¼ inch hole through the mid point of the redirod connector. The two ends of the rectangle pass through these holes and weld them in place. Cut the silk screen into a strip 32 cm wide by 56 cm long then cut two side panels 16 x 21 cm. Sew the two side panels onto the longer strip, forming a box 15 cm x 33cm x 20 cm with an open top. Cover the seams with 1 inch bias tape and sew in place. Sew an edge of the 2 inch bias tape around the open end of the box. Fold the bias tape around the ¼ rod frame and sew back onto the screen. This will require sliding the screen along the rod as you get to the corners. Hand sew the final section to close the screen. Weld the 5/16 bolt on to the end of the 40 cm rebar to create a removable handle. This can be twisted into the redirod connector and disconnected late. You can make a longer handle for deeper sampling. |
|
How to use a surber sampler
- Choose the Sampling Locations: An appropriate riffle must be chosen in the reach. (Shallow runs can be chosen if riffles are not present or cannot be sampled.) Stream depth must be equal to or lower than the height of the surber sampler but the stream must also be deep enough that water can flow into the sampler. Stream velocity must be adequate for water to pull dislodged organisms into the net. The actual location in the riffle must be chosen at random. A Random number table can be used to pick coordinates in the riffle for the exact sampling location. If the location chosen does not meet the standards required for sampling, another site must be chosen. It is more important that the sampling procedure be done appropriately and consistently across all samples.
- Set the Surber Sampler: The base of the sampler (all the way around) (Figure 1) must be firmly against or embedded into the substrate. If space exists below the bottom of the frame, particularly along the back or the sides, organisms dislodged from the benthos may not be captured and diversity and/or abundance may be underestimated.
- Initial Benthic Disturbance: When the sampler is firmly on the bottom, one or two individuals (depending on sampler size) will disturb the streambed in the area inside the samplers frame (Fig.1). Each large rock must be individually cleaned of all invertebrates. This can be done by hand or with a kitchen scrub brush. It is important to make sure that dislodged individuals either flow into the net or are cleaned directly into the net. Often, it is best to clean the rocks while holding them in the net of the sampler. Each large rock should be visually inspected to make sure that all organisms are removed.
- Final Benthic Disturbance: After large rocks on the streambed surface are cleaned and removed, the remaining finer substrates should be disturbed by hand or with some sort of tool The benthos is disturbed to a set depth (usually a few inches) depending on the characteristics of the benthos. The overall depth that the streambed is disturbed will vary depending on the site conditions. The sampling depth should remain constant across all sites and throughout the project. Armored streams require greater sampling depths. However, benthic invertebrates will not be carried into the sampling net from deep holes. When working in urban streams, be careful about disturbing the substrate by hand because sharp objects may exist in the substrate.
