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Trial at Shinkawa
Shinkawa river
Shinkawa river is a small river, about 3 km long, and flows through Tsuchiura city into Kasumigaura lake of Ibaragi prefecture. I live in Tsuchiura city, close to Shinkawa river, which is polluted, abundant of blue-green algae throwing off fowl odor. Fishes and insects were hardly be seen. Ecology almost collapsed in and around the river.
Trial overview
- Period: July 22 through October 28, 2002 (100 days)
- Pour, every day, 20 litters of "T.S Minetase" into the river at a point of 2 km up from the river mouth.
- Monitor and record changes of ecology system of the river.
Results
It was confirmed that "T.S Minetase" activated ecology system of the river and helped improve polluted water.
- Soon after I started to pour "T.S Minetase" into the river, small fishes were seen to swim up from the lake.
- Dragonflies and other insects also were seen to come back.
- As days go on, recovery of ecology became more and more visible.
- Foul odor of the river lessened. Transparency of the water improved. Phytoplankton became active and quality of water improved.
Right upper picture was taken on October 27, one day before termination of the trial period. Color of the water and smelling of the environment was quite different from 100 days ago. Number of fishermen alongside the river also increased.
Summary
Following is a summary of 100 days observation record. Ecology system has recovered its health, which in turn, helped the river regain self-purification capacity.
Fishes swimming up from the lake
- Soon after start of trial period, I started to see small fishes coming up. Small fishes were seen at down stream spot of the river. Then, number increased and moved up to middle stream. Finally I observed the fishes at a point upper than pouring spot (Aug. 16). Size of the fish was 5-6 cm in the beginning, then it grew up to 7 cm, 10 cm, 15 cm (Aug. 20), reached 23-30 cm (Oct. 16).
- Silver carp started to show up around the river mouth (Aug.3). Then, moved to 7-800 meters up stream (Aug. 8). It was confirmed the number increased and habitat range expanded (Sep. 1).
- Observed dead Ayu (fish) flowing down from the upper stream (Aug. 6).
- Observed dead Ayu for several days. Probably, Ayu swam up from the lake and died at the stream upper than pouring point (of "T.S Minetase").
- As ecology system recovered, carnivorous fish such as black bass and bluegill started to swim up (Aug. 28). Then, number increased (Sep. 17), and habitat range expanded (Sep. 22).
- Observed carp swimming up to upper stream from an early stage of the trial (Aug. 4).
- Captured seaweed shrimp for the first time (Sep. 14). Seaweed shrimp serve as prey for many other fishes, it is considered to indicate a further activation of ecology system.
- Other fishes were green turtle (July 22), goro fish (Aug. 8), yamabe (Zacco platypus) (Aug. 25), freshwater needlefish (Sep. 13), snakehead (Sep. 17).
Activation of other ecology system
- Dragonflies （July 27, July 29, Aug. 2, Aug. 3, Aug. 15, Aug. 22, Aug. 23, Aug. 25)
- Oniyanma (anotogaster sieboldii) （Aug. 9, Aug. 10, Aug. 11, Sep. 10, Sep. 18, Oct. 14)
- People in this area said they had never seen oniyanma in past 10 years.
- Observed a number of tadpoles, many different species (Aug. 6).
- Several kinds of water birds were found habitat (Aug. 27).
Improvement of river water
- Transparency of the river water changes day by day affected by weather or construction at the upper stream. However, difference became visible between up and down stream from a pouring point (July 27, Sep. 12). In down stream, river bed became visible sometimes. As the water became transparent fishes became nervous and tend to dive deeply (Sep. 27).
- In usual summer, blue-green algae grow proliferously and then become corrupt. This year blue-green algae was not observed (Aug. 1, Aug. 13).
- Phytoplankton became active and quality of water improved. (July 24, Aug. 4, Aug. 14, Aug.15)
- Heard fishermen's conversation that fishes are abundant this year than usual. (Aug. 3, Oct. 12, Oct. 19)
Pictures
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