Red tide

The red tide is a phenomenon in which seawater is discolored due to abnormal growth of plankton. When the ocean is polluted and nutrients such as phosphorus and nitrogen are increased in seawater, plankton increases abnormally due to temperature and other effects.
Seawater may discolor reddish brown or orange, and sometimes blue-green due to the growth of plankton. Such plankton is called red tide plankton.

Tokyo Bay contains a lot of nitrogen and phosphorus, which are the nutrients of plankton. From spring to autumn, when the temperature of seawater rises, phytoplankton in seawater and phytoplankton that prey on it grow.
Abnormally large breeding of certain planktons, the seawater becomes turbid and red tide is generated.

• Because phytoplankton performs photosynthesis, it has a lot of oxygen.
• The outbreak time is concentrated in June, and abnormal breeding of algae when the water temperature exceeds around 20 ° C, abnormal breeding
• The main factor is the rise of water temperature to the optimal temperature after rainfall.

• Oxygen is consumed by the decomposition of organic matter, resulting in an oxygen water mass.
• Many creatures that can live without oxygen are seen.

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

Spiral algae are monocellular and have two whip hairs. You can swim around by moving this whip hair.
Depending on the type, there are various features, such as those covered with a hard shell called armor board, and those that connect cells to form a group.
There are some species that are harmful to seafood and humans, but examples found in Yokohama Port have not been found in recent years.

Silicon algae has brown chlorophyll and perform photosynthesis. Also, since it does not have whip hair, it rarely moves around by itself.
It can occur in large numbers from spring to summer, but few are toxic to seafood and humans.
Various types of algae are also found in Yokohama Port throughout the year.