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180º panorama of Salmon Creek - December 2006 |
This page contains images of macroinvertebrates collected from Salmon Creek, near Hockinson, WA (December 2005). The full set of macroinvertebrate images collected at this location are available on the following page: Salmon Creek Macros 2004-05 The dialog below comes from an email correspondence between Michael Clapp (MC) , CAM Jr. High science teacher, and Jeff Adams (JA), Director of Aquatic Programs for The Xerces Society and author of the CD-ROM, The Stream Bugs as Biomonitors: Guide to Pacific Northwest Macroinvertebrate Monitoring and Identification. Jeff has encouraged our efforts to collect, photograph, and identify aquatic macroinvertebrates as part of our water quality testing activities. We're grateful that Jeff is willing to share his expertise with us, and for his permission to publish that information on this webpage. Instructions: For a larger view of the specimens below, click on an image. The enlarged image will appear on your screen in a new window. Close this new window when you are through viewing it. Further information on the identification and ecology of aquatic macroinvertebrates can be found from the materials mentioned on our Resources page. |
MC: The small snails were interesting. They are different from the one's collected at the East Fork in that they are smaller (didn't find any large ones) and have an undulating shell. From looking at your CD, it appears that they are Juga? JA: I've always called these immature Juga, but have never had them confirmed. When you look at the pointy end of larger Juga, the first whorl or two will have some ridges even if the rest of the shell is smooth. The annual meeting of the Taxonomic Workgroup will be having a snail specialist this year, so hopefully, I'll be able to confirm this. The New Zealand Mud Snail is about the same size as these guys and can have the ridges like this, so if you see something like this show up by the many many thousands, it would be good to pickle some specimens and send them to the Center for Lakes and Reservoirs at Portland State University. |
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JA: The first riffle beelte larvae is probably Zaitzevia as is the adult.The other larvae are probably Optioservus. You may be starting to recognize the general differences in body shape by now - skinnier and rounder vs. broader and more angular. These are the two most common genera in the habitats you're sampling, but I'll always say "probably" because there are several others that look just like them. I've always liked riffle beetles.They can be frustrating to identify, but having both adults and larvae in the same place really sets them apart from other aquatic macros. |
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JA: The flatheaded mayflies throw me a bit because I think I'm realizing you can't see the gills very well on these. I'm guessing they are Rhithrogena, on which the front and back pairs of gills overlap to form a suction cup of gills. You might try getting a picture of one of these from underneath or on its back sometime. The shape and pattern looks right as does the common-ness. |
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MC: The only other thing that's really new here (for me, anyway) are the American grannom (humpless) caddisflies. These are the first one's I've collected and photographed. I have seen one once before, and it had the square case. Unfortunately, the specimen was discarded before I had a chance to save it for posterity. JA: Good stuff! These are the genus Micrasema. The square-cased relatives are Brachycentrus and get much larger. In fact, this is probably the species Micrasema dimicki because it has a straight case. It's also more tolerant than other species in the genus. Micrasema has another cousin called Amiocentrus that looks very similar and is found regularly with the more sensitive species of Micrasema. Amiocentrus is more orangey than brown, and the plates on top of the middle segment of the thorax have only a pair of hairs in the middle of the front edge (- the edge has hairs all along it in Micrasema). |
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JA: I'm sure you probably realized this, but the two different sizes of midge pupa tell you you've got at least two species. Great fish food! | ||||
Once again, we'd like to thank Jeff Adams, Director of Aquatic Programs for The Xerces Society, for taking the time to look at and comment on the macroinertebrate images above. As author of the CD-ROM, The Stream Bugs as Biomonitors: Guide to Pacific Northwest Macroinvertebrate Monitoring and Identification, he has considerable knowledge in identifying aquatic macroinvertebrates and experience in using "stream bugs" as bio-indicators of water quality. If you'd like to hear more from Jeff about macroinvertebrates, check out a scaled down Internet version of The Stream Bugs as Biomonitors... CD-ROM at The Xerces Society website. Better yet, order a copy for yourself. (PC compatible only; many images won't show on a Macintosh) |
The following links have not yet been updated follow a change in servers: |
Webpage created by M. Clapp
Modified: 2/10/06; 5/5/13