Biodiversity in Yokohama

Yokohama City is a large city with a population of more than 3.7 million (as of December 1, 2018), but there are many forests and farmlands that are cohesive in places close to citizens, mainly in the suburbs. It is characterized by a variety of natural environments due to the sea, rivers, and undulating terrain. However, the green coverage of the city area is on a downward trend, and as of 2009, it is less than 30%.
The following points are the background and issues of the biodiversity crisis in Yokohama City.

• Loss, fragmentation, and deterioration of habitats and habitats due to land use modifications associated with development
• Degraded habitat and growth environment of living creatures due to inadequate management
• Lack of comprehensive accumulation of biological survey data
• Changes in lifestyles and consciousness due to improvements in the convenience of life
• Lack of initiatives that consider biodiversity

As the importance of biodiversity is attracting worldwide attention, it is necessary to share these backgrounds and issues with citizens in the metropolis of Yokohama and connect rich Yokohama-like biodiversity to future generations.

"Invasive creatures (naturalized species)" refers to creatures that were not originally in the area but came from other areas through human activities. There are many creatures that originally lived and did not grow in Yokohama, such as those brought in as pets and became wild, and those that were attached to ships.
Some naturalized species is subject to pest control as damage or potential damage to ecosystems, human life and body, agriculture, forestry and fisheries, but it is difficult and requires a great deal of effort to eradicate naturalized species, which has once spread outdoors.
In order to connect Yokohama-like biodiversity to future generations, the principle of naturalized species is "do not enter," "do not throw it away," and "do not spread it."

We investigate fish, benthic animals, aquatic plants, attached algae, etc. for the six water systems of rivers flowing through the city, and evaluate the water environment of rivers from creatures.
The survey has been conducted almost every three years since 1973, and the 15th survey was conducted in FY2018 and FY2019.

We conduct surveys on fish, coastal animals, seaweeds, plankton, etc. at the estuaries, coasts, and inner bays in the city, and evaluate the water environment of the sea from creatures.
The 14th survey was conducted in FY2016.

In order to utilize the conservation in the headwater area and its surrounding areas, we conducted a basic survey on water environment in the headwater area from fiscal 2004 to fiscal 2008.
In addition, we carried out biota investigation in four ponds in the city and one educational paddy field in 2010.

Since fiscal 2013, the Institute for Environmental Science has been conducting surveys of living creatures throughout Yokohama, with the aim of raising citizens' interest in nature and living things in the region and acquiring basic data that contributes to the biodiversity conservation.

In Yokohama City, departments other than the Institute for Environmental Science are also conducting surveys on biological habitats. We accumulate the status of these surveys and information on biological habitats, and disclose (partly) data.

The results of the biopharmace survey are published in the survey results report and the summary version of the survey results, but a booklet has been created to make it easier to use and use in the environment in Yokohama.

・Click here for the booklet

We evaluate the aquatic environment by setting indicator organisms based on accumulated data from research institutes on aquatic organisms.

• Research reports on water area biological indicators
• Report on Revision of River Biological Indicators