The Institute of Environmental Sciences evaluates the comprehensive water environment, including the water quality of rivers in the city's waters, and shows the transition of biota to increase the interest of citizens in rivers and the sea. For the purpose, we have been investigating creatures that inhabit rivers and seas in the city almost every three years since 1973.
In river area, we performed the 14th investigation in 2014, 2015.
Over the past 40 years, some creatures have returned to the river in Yokohama, even though they have disappeared once like Ayu due to improvements in water quality due to the spread of sewerage and improvement in the river environment by installing fishways. While the types of fish, shrimp, and crabs coming and going through rivers and the sea are increasing, the number of alien species is also increasing, and it is necessary to pay attention to future trends.
The survey points are 41 6 water systems (2015 results) of rivers flowing through the city.
- Tsurumi River water system (12 points)
- Katabira River water system (four points)
- Okagawa River System (7 points)
- Miyagawa water system (two points)
- Samurai River Water System (3 points)
- Sakaigawa water system (13 points: including 1 outside the city)
We investigate fish, benthic animals, aquatic plants, attached algae, and water quality, and evaluate the water quality of rivers from creatures.
In recent years, we have been conducting surveys at each point in summer and winter.
Examples of river organisms
Rivers and sea creatures in Yokohama (No. 14 and Rivers) (Results of 2014 and 2015 Survey, issued in March 2016)
Accumulation and disclosure of biological data
This map introduces the points of the river creature survey conducted by Yokohama City.
You can see photos of 41 water systems such as Tsurumi River, Katabira River, etc. You can see photos of 41 water systems and water quality evaluation results based on biological indicators.
To the river creature survey point map
Return to Yokohama's Biodiversity page