The high temperatures might be left over from the warm-water "blob" off California in 2014.

California State Parks scientists are running tests this week to determine what caused about 1,500 fish to die in Malibu Lagoon last week, but officials suspect higher-than-normal water temperatures may have played a role.

Extreme heat events wreak havoc on marine ecosystems and will only get worse in coming decades.

Marine heatwaves are growing longer, stronger and more frequent thanks to climate change.