TOKYO, Aug. 4 (UPI) -- A heat wave has caused mass deaths of clams and crabs in Tokyo Bay, ecological researchers say.
Scientists from Toho University say they believe the die-off of up to 80 percent of baby-neck clams was due to lack of oxygen when the extended heat wave accelerated the decomposition of marine algae, The Yomiuri Shimbun reported.
A Toho graduate student noticed the phenomenon July 28, prompting an urgent study.
Large amounts of edible green algae called sea lettuce grow every year on tidal flats in the bay.
Researchers think the algae dissolved abruptly as the heat wave warmed waters in the bay, resulting in less oxygen in the water and making it deadly for certain species of clams and crabs.
Weather records show the average temperature in the Tokyo area this year has been 5 degrees Fahrenheit higher than normal, The Yomiuri Shimbun reported.