The Sea Off Liaoning Province Suddenly Turns Dark... Why?

Changed to a Soy Sauce-Like Color in Seawater
A Phenomenon Caused by Seaweed Decay Due to Climate Change

A phenomenon where seawater turned black occurred on a beach in Bohai Bay, Liaoning Province, China. It is presumed to have been caused by the large-scale decay of seaweed.

According to Chinese media Shangyou (上游) Newspaper on the 1st, the seawater at a beach in Yingkou City, Liaoning Province recently turned pitch black.

A local resident who visited the beach said, "It looks like soy sauce was poured into the seawater. This is the first time I've seen such a sight," and posted a related video. The video shows people enjoying swimming in the blackened sea. Vacationers played in the water riding tubes in the black sea, and black waves rolled onto the white sandy beach.

Sea water turned black due to seaweed decay [Image source=Chinese SNS Weibo·Yonhap News]

Another resident said that the blackened sea caused the color of a child's clothes to change. The video posted by the resident shows the child's white clothes turning dark brown after being dipped in the seawater.

The Yingkou city authorities estimated that the cause of this phenomenon is related to the decay of seaweed. The authorities explained that a type of seaweed called "Gasi parae" has recently exploded in number, and as this seaweed decays underwater, the seawater color changed. Gasi parae is a green algae belonging to the Ulvaceae family, growing like grass in tidal flats where freshwater and seawater mix.

The authorities explained the reason for the rapid increase in seaweed as "recent temperature rises, heavy rainfall, and increased oxygen content have created an environment favorable for seaweed growth.".

A child who came out after entering the seawater. [Image source=Chinese SNS Weibo·Yonhap News]

An official from Yingkou City said, "September is the season when parae disappears," but added, "The relevant department is monitoring and researching the situation, but currently there is no fundamental solution."

Why is it hard to see blue seas? Because of 'climate change'

Meanwhile, a recent study highlighting that climate change is turning the color of the sea green has attracted attention. Researchers from the UK National Oceanography Centre (NOC) and the Massachusetts Institute of Technology (MIT) in the US published a study in the international journal Nature last July, reporting that 56% of the world's oceans have changed color over the past 20 years.

The researchers tracked how much green or blue light was reflected from the ocean surface worldwide from 2002 to 2022 using satellite data. As a result, color changes were detected in more than 56% of the world's oceans, an area larger than all the land on Earth combined. Particularly, the color changes in tropical seas near the equator, which are heavily affected by climate change, were more pronounced.

The researchers stated that the sea turning green is due to climate change affecting the microbial ecosystems in the ocean. Stephanie Dutkiewicz, a senior researcher at MIT's Center for Environmental Science and a co-author of the study, said, "All changes cause imbalances in the natural composition of ecosystems," and warned, "Such imbalances will worsen over time if the ocean continues to warm."

This content was produced with the assistance of AI translation services.