Biodiversity in Yokohama

Yokohama City is a large city with a population of more than 3.7 million (as of December 1, 2018), but it has a cohesive forest and farmland in places close to citizens, mainly in suburban areas. It is characterized by the fact that a diverse natural environment remains due to the sea, rivers, and rugged terrain. However, the green coverage in the city area is on a downward trend, and has fallen below 30% as of 2009.
The background and challenges of the biodiversity crisis in Yokohama are the following points.

• Loss, divisions, and deterioration of habitats and habitats due to changes in land use due to land use due to development
• Degraded the habitat and growth environment of living creatures due to poor proper management
• Lack of comprehensive accumulation of biological research data
• Changes in lifestyle and awareness by improving the convenience of life
• Lack of biodiversity-oriented initiatives

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

"Exotic organisms (invasive species)" are creatures that have come in from other areas due to human activities, even though they were not originally in the area. There are many creatures that originally inhabit and did not grow in Yokohama, such as those brought in as pets and become wild, and those that have been attached to ships.
Some alien species are subject to control as they may or may damage the ecosystem, human life and body, agriculture, forestry and fisheries, but once they have spread to the outdoors. It is difficult to eradicate alien species and requires a great deal of effort.
In order to connect Yokohama's biodiversity to future generations, the main principle is to "do not enter", "don't throw away", and "do not spread" alien species.

We investigate fish, benthic animals, aquatic plants, adhering algae, etc. in 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 fifteenth survey was conducted in fiscal 2018 and 2019.

We conduct surveys on fish, coastal animals, seaweeds and seaweeds, plankton, etc. at the mouth of the city, coast, and inner bay of the city, and evaluate the water environment of the sea from creatures.
The 14th survey was conducted in FY2016 and FY29.

From 2004 to 2008, we conducted a basic survey on water environments at the headwaters of major rivers in Yokohama and its surrounding areas for the restoration of conservation and environmental activities.
In addition, we carried out biota survey in four ponds in the city and one educational paddy field in 2010.

Since 2013, the Institute of Environmental Sciences has been conducting surveys of elementary school students throughout Yokohama City since 2013 with the aim of raising citizens' interest in local nature and living things and acquiring basic data that contributes to the conservation Biodiversity.

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

The results of the biota 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 the environment in Yokohama.

・Click here for more information.

Indicator organisms are set based on data accumulated by research institutes on aquatic organisms, and evaluates the aquatic environment.

• Research Report on Waters Indicators
• Report on Revision of River Biological Indicators