Red tide

Red tide is a phenomenon in which seawater discolors due to abnormal growth of plankton. When the ocean is polluted and nutrients such as phosphorus and nitrogen increase in seawater, plankton increases abnormally due to temperature and other effects.
Seawater may turn reddish brown or orange due to the growth of plankton, and sometimes turn blue-green. This kind of plankton is called red tide plankton.

Tokyo Bay contains a lot of nitrogen and phosphorus, which are nutrients of plankton. When the temperature of seawater rises from spring to autumn, phytoplankton in seawater and animalplankton that preyes on it grow.
An abnormally large breeding of certain planktons causes seawater to become muddy and red tide.

• Because phytoplankton performs photosynthesis, there is a lot of oxygen.
• The outbreak period is concentrated in June, with abnormal breeding of algae when the water temperature exceeds around 20 ° C.
• A major factor is the increase in water temperature to the appropriate temperature after rainfall.

• Oxygen is consumed by the decomposition of organic matter, and an oxygen water mass is formed.
• There are many creatures that can live without oxygen.

Here are some of the red tide plankton found at Yokohama Port.

Spiral algae are single cell and have two whip hairs. You can move this whip hair to swim around.
Depending on the type, there are various characteristics, such as armor plate (yoroiban), which is covered with hard shells, and those that are connected to each other to form a cluster.
Some species are harmful to fish and shellfish and humans, but no recent cases have been found at Yokohama Port.

Algae have brown chlorophylls and perform photosynthesis. Also, since they don't have whip hair, they rarely move around.
It can occur in large quantities from spring to summer, but few are toxic to seafood and humans.
Various types of algae are also confirmed in Yokohama Port throughout the year.