To give some perspective its worth remembering that 85Db will damage human hearing over a period and 120 dB may do so immediately.

-Decibels are also exponential. A 10 Db increase is a ten-fold increase. It might not have been "adequately studied" but it's really not hard to predict what a repeated 240 Db would do to any creature with hearing in the ocean:

"The blasts are no doubt keenly heard by cetaceans..."

-Not for long.