Editorial: Before-After Control-Impact (BACI) Studies in the Ocean

BACI is not a perfect methodology, as site choice and sampling rate need to be determined strategically (Smokorowki and Randall, 2017), but baseline studies before expected large-scale impacts lend themselves to the “before” or “control” portions of BACI experiments. [...]learning how to best implement BACI methodologies from other ecological fields and applying them to the ocean could provide a common language for understanding human impacts. The articles show that sound was significantly reduced during the early months of the pandemic (1) at a cold-water coral reef under a passenger ferry route between Norway and Sweden (De Clippele and Risch), (2) in a high-traffic area for cruise ships in Glacier Bay National Park in Alaska (Gabriele et al.), (3) in a sperm whale habitat in the Bahamas (Dunn et al.), (4) at two sites in the Baltic Sea (Basan et al.), (5) in the Monterey Bay National Marine Sanctuary (Ryan et al.), and (6) in the Halifax Harbor of Nova Scotia (Breeze et al.). Fernandez-Betelu et al. found that far-field impulsive sounds from pile driving do not force coastal bottlenose dolphins to vacate their habitat, but do affect their behavior, whereas Benhemma-Le Gall et al. determined that harbor porpoises were displaced during pile-driving activities and from associated construction vessel activity for offshore wind farms. [...]Stack et al. used a “before-after” scale of hours in a tropical environment in Australia, to show potentially detrimental behavioral changes in humpback whales due to ecotourism activities.