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| A close up of one species from damselfly family. Diamond-shaped jaw is the point we should find to identify its species. It is observable only via microscope. |
For the study, the prefecture published a reference book, downloadable free from here. Unfortunately, the publication date was March 2020 when COVID-19 started to halt all human activities on the planet. It did not become much news at that time. Almost 3 years have passed since then, and many have realized it’s a damned good book for practical works at bench. Ministry of Environment also published a reference book, also downloadable from here. But I think Ministerial version is a bit cumbersome to use with microscope. On the other hand, Prefecture’s reference book is concentrated on the creatures probably found in rivers of Kanagawa. I don’t know if such region-specific documentation is useful in the other parts of the planet or, for that matter in another prefectures of Japan. With these caveats, if you’re interested in nature reference books of aquatic lives of Japanese fresh water, please check them. It’s free!
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| The reference book |
The way to identify the specimens stored in a jar is
1. By naked eyes, sort out the specimens in several large categories, starting from a question if their body has apparent sections. If not, next check if it has shell or not. Up to this stage, we identified 3 categories, right? Next, with tweezers gather each category in 3 different petri dishes filled with 80% ethanol.
2. Set a petri dish under stereo microscope. For the dish of creatures with sections, check if it has legs with sections. If one does not have segmented legs, but has a large head, probably it is a larva for Crambidae family with environmental score 7. If the head is not so large, it would be in a family of Diptera. We proceed to check which species of Diptera it is. On the other hand, if the bug has segmented legs, then check the number of legs … 6, 8, or more? Next, (ctd) … We simply follow Yes/No questions with arrows in the reference until it stops to one particular species that is/is not assigned the score to measure the quality of water where they lived.
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| The first stage page for identification. |
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| The third stage page for Diptera. |
3. We do the above repeatedly until all the specimens in a jar are identified and recorded their existence. Some bugs can be identified in level 2 stage. We plug in the score numbers for an excel sheet. The number of individuals does not matter. So, as in a below photo, even if we find lots of freshwater shrimps, we simply record “We’ve identified freshwater shrimp.”
4. For conclusion, the scores each specimen earned are summed up, then divided by the number of species that has >0 score found in that particular spot. Say, for one place where the specimen was created, if the total score was 45 and 7 species were identified, the score of water quality of that place is 45/7 = 6.43. The higher the score, the better the water quality. Full score is 10, and extremely polluted stream has score 0. Such value of each species is determined by the academic community and the Ministry of Environment who modified English Biological Monitoring Working Party according to the characteristics of Japanese biosphere.
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| The body of this water spider really glittered gold. I was charmed … |
I found the approach for calculation is easy to use for citizen volunteers like me without college degree for biological studies. The real effort goes to the identification stage using the microscope and the reference book. In today’s post, I’m showing you the photos from microscopic study for specimens found in the water near Higashi-Oshima Camping Ground of Sagamihara City 東大島キャンプ場 (; my post on November 11, 2022). There were lots of lots of freshwater shrimps (Atyidae). Shrimps are easy to identify. Atyidae earns 0, zero, zilch, nada. At least in Kanagawa Prefecture, critical species for endemic shrimp-like creatures in our rivers are the families for Pontogeneia rostrata, Anisogammaridae and Gammaridea. All of them earn score 8, i.e. for very clean water. The rest of the shrimps and shrimp-like things are foreign invaders brought to our water by recreational anglers and tropical fish lovers who used them as bites/feed, then casually threw them away in nearby river as “surplus garbage.” Such introduced species scores zero and do not contribute higher numbers of water quality. It seems to me the scientists for Environmental Research Center are fed up with finding lots of shrimps (and American crawfishes of course; pls see my post on November 11 and 18, 2022) in the midstream and downstream of Sagami 相模川 and Sakawa Rivers 酒匂川. In addition to zero value for water quality measurement, they imply the local ecosystem is highly affected by invasive foreign species. Whether their effect is positive or not would be a different matter, yeah. Lots of shrimps could be good for endemic fishes for their lunch. But …
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| This house has two-way construction. Inside is made of sand and silk. It is then enclosed by the bits of reeds. The bug inside must have been very diligent. |
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| The specimen pulled out from the nest. It was about 5mm long. |
I have to do the same microscopic study for the other specimens I collected last year by the end of this month. Staying in a wide-open space from the top of the mountain is irresistible. Studying tiny creatures with microscope is fascinating. The nature of forest is all tantalizing from big to small.
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| The jar and a stereo microscope |
If you find environmental issues in waters of Kanagawa Prefecture, please make a contact with Kanagawa Environmental Research Center 神奈川県環境科学センター
1-3-39 Shinomiya, Hiratsuka City, 254-0014
〒254-0014平塚市四之宮1-3-39
Phone: 0463-24-3311
FAX: 0463-24-3300
k-center@k-erc.pref.kanagawa.jp
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