SF Fig. 9.4. (A) Scuba divers are attached to a central buoy by ropes.
Image courtesy of Larry Madin, National Oceanic and Atmospheric Administration (NOAA)
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Practices of Science: Blue Water Diving
NGSS Science and Engineering Practices
NGSS Crosscutting Concepts
NGSS Disciplinary Core Ideas
Table of Contents
SF Fig. 9.4. (B) One diver coordinates the rope-pulley system called a “trapeze”.
Image courtesy of National Oceanic and Atmospheric Administration (NOAA)
Blue water diving is a branch of technical diving that takes place in the middle of the ocean. Diving in this environment, in the middle of the ocean away from coastlines, reefs, and artificial structures, allows scientists to study zooplankton that are rarely seen elsewhere (SF Fig. 9.4). Blue water diving is the best way to learn about mid-water organisms in their natural environment. Many of the organisms that live in the epipelagic zone are difficult to collect and study because they are small and gelatinous (soft-bodied) organisms, such as jellyfish and ctenophores (“comb jellies”). Collection with nets from a boat can harm their soft bodies. Because these epipelagic organisms live in the open ocean, it is difficult to collect from a boat without damaging the animal or to study their behavior in the confines of an aquarium (SF Fig. 9.5).
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SF Fig. 9.5. (A) Ctenophores, a phylum of comb jellies
Image copyright and source
Image courtesy of Arctic Exploration 2002, Kevin Raskoff, U.S. National Oceanic and Atmospheric Administration (NOAA)
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SF Fig. 9.5. (B) Portuguese man o’ war (Physalia physalis)
Image copyright and source
Image courtesy of Islands in the Sea 2002, U.S. Department of Commerce, National Oceanic and Atmospheric Administration (NOAA)
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SF Fig. 9.5. (C) Salps, planktonic tunicates
Image copyright and source
Image courtesy of Hartmut Olstowski, adapted from Wikimedia Commons
With no points of reference it is important for blue water divers to avoid disorientation and to be aware of their horizontal and vertical position so they do not make unsafe ascents or descents while collecting organisms. Blue water divers work in teams. A long drop line is attached to a float connected to the boat. Four divers connect to the drop line with 10 m lines. The point of connection is called a trapeze. One of the divers, designated the safety diver, helps move the trapeze up and down while the remaining divers swim out to a maximum distance of 10 m to look for zooplankton. Underwater communication between all divers is important to keep lines from getting tangled and to respond to any risky situations that may arise, such as curious sharks! The boat driver also has to keep an eye on the drop line and be aware of strong winds and currents that could suddenly move the boat and drag the divers below the surface.
