Ocean noise is a whale of a stressor

Post-9/11 quiet calmed marine mammals

Stress hormones in North Atlantic right whales fell during a lull in shipping activity following the September 11, 2001 attacks on the World Trade Center and Pentagon. The finding suggests that ship noise may do more than annoy the marine mammals. 

Large ships like the one shown here emit low-frequency sounds that may stress out right whales living near busy commercial shipping lanes.