Deep water 20069/25/2023 ![]() Today, use of a 4K camera at full zoom can effectively be like looking through a deep-sea underwater microscope. Since that time, our understanding of the deep ocean and its ecosystems has changed enormously, enabled by technological advances that have allowed us to map the seabed at high resolution, generate startlingly detailed images in photographs and video, record animal sounds, document their mass migrations, even detect gas bubbles acoustically, and “sniff” the chemistry of seawater remotely. Sampling of deep-sea sediments in the 1950s and 1960s revealed these small inhabitants to be surprisingly diverse (Sanders and Hessler, 1969). The first hundred years of deep-sea exploration, conducted with sampling gear lowered from the ocean surface, painted a picture of a fairly homogeneous, mud-covered seafloor, understood to be cold, dark, environmentally stable, food-poor, and inhabited by small life forms. Despite the monster stories, the concept of the deep ocean as an azoic, lifeless desert dominated public perception until the 1860–1880s, when major expeditions ( Lightning, Porcupine, Challenger) undertaking serious sampling of the deep sea provided consistent, incontrovertible evidence of an abundance of life in deep water (Koslow, 2007). These monsters inspired fear, mystery, and some wonderful literature, such as Jules Verne’s 1870 classic 20,000 Leagues Under the Sea ( Figure 1b). This realm, largely out of sight and poorly explored, remains one of planet Earth’s final frontiers.Įarly imaginings of the ocean were as a home to sea monsters, like the kraken, a giant cephalopod in Norse mythology ( Figure 1a). Because of their great depth, deep-ocean waters (below 200 m) represent over 95% of the volume on Earth that is habitable for animal life as we know it. The ocean covers 71% of our planet, but few people realize that most of the ocean consists of deep water, with an average depth of 3,800 m (nearly 2.4 miles). Levin, the twentieth annual lecturer, spoke on April 24, 2019, at the National Academy of Sciences. The Roger Revelle Commemorative Lecture Series was created by the Ocean Studies Board of the National Academies in honor of Roger Revelle to highlight the important links between ocean sciences and public policy.
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