According to AFP, the US National Oceanic and Atmospheric Administration (NOAA) said that the surface water temperature along the California coast is currently about 3-4 degrees Celsius higher than the average.
NOAA oceanographic researcher Andrew Leising said that this sea heat wave has lasted for about 6 months and shows no signs of ending.
Mr. Leising expressed concern that this phenomenon occurred right when El Nino returned.
The El Nino phenomenon is forecast to be in the strongest group ever recorded, even exceeding the 2015-2016 period - the time California suffered the most severe sea heat in history.
When seawater temperatures rise, schools of fish near the water surface will decline sharply, leading to thousands of seabirds dying from lack of food. Many dead sea lions and whales also drift to the coast of California.
Similar signs are gradually reappearing. In just the past few months, dozens of pelicans and cormorant have been found dead near San Diego city (California, USA).
Not stopping there, rising seawater temperatures also promote the phenomenon of toxic algae blooming. These algae produce domoic acid - a toxin accumulated in anchovies and sardines, which is the main food source for sea lions. When eating poisoned fish, sea lions can suffer neurological damage, get sick and die.
In Monterey Bay, south of San Francisco, the outbreak of toxic algae is believed to be the cause of 2 humpback whales drifting ashore in early June.
Mr. Elliott Hazen, professor concurrent of Ecology and Evolutionary Biology at the University of California, Santa Cruz, said that the phenomenon of whale deaths due to algae poisoning has not occurred in the past decade.
These are predators at the top of the food chain. The fact that they are also affected shows that the concentration of domoic acid in the ecosystem has been very high," Mr. Hazen said.
Not only marine mammals, large white sharks are also changing their behavior due to rising sea temperatures. On a whaling vessel off the coast of California, tourists encountered a white shark floating on the water surface - an image that rarely appears in this area.
This action raised concerns about safety at the beaches. Last week, a resident in Malibu recorded a white shark swimming just a few meters away from a group of children while they were completely unaware of its presence.
The appearance of sharks near the shore has caused local authorities to ban tourists from going to the sea at Huntington beach 3 times this spring.
Scientists warn that if sea heat waves continue to repeat with high frequency, the ocean ecosystem will gradually lose its ability to recover. At that time, not only marine animals will be affected, but many fish species serving human food needs are also at risk of serious decline.
