Why scuba dive at all? Advancement of science is the answer for the 18 research divers aboard the White Holly. Far from the recreational diving pursuits of relaxation, enjoyment of the underwater scenery and paying for it, this is our job and we're getting paid to do it.
Scientific diving programs, such as at Scripps Institution of Oceanography and the Smithsonian Institution, serve a dual function: research suppot, and diving safety/risk management. Scientists who need to dive for their research enter the program, which covers diving and medical training and operational procedures. Scuba is but a tool that assists us in collecting our data in support of our research objectives. We don't employ divers per se, but recruit top-level scientists based on their research interests and credentials. It's more efficient to make a diver out of a scientist than a scientist out of a diver.
Scripps and Smithsonian have collaborated for many years on interdisciplinary projects. Now we find ourselves on the Line Islands expedition. Relieving Christian McDonald (Scripps Diving Officer) as Diving Supervisor for the final leg of the cruise to Kingman and Washington, our team had about 30 minutes after landing on Palmyra to discuss diving issues before the plane departed on its return flight to Honolulu.
Scientific diving is reasonably safe, as evidenced by decompression sickness incident statistics recorded by the American Academy of Underwater Sciences. Our DCS rate is an order of magnitude less than that of recreational diving and another order less than that of commercial diving. The nature of the calculated risk is well understood and mitigated by the scientific diving community, but DCS is a probabilistic event and can occur at any time. We plan for such an event by carrying emergency oxgen kits, which we are all trained to use in conjunction with CPR, and by diving fairly conservative depth/time profiles. This is of particular importance at remote sites such as Kingman where a medevac to a hyperbaric chamber facility could potentially take days.
The daily diving operations take place in teams: benthic, fishes, microbes, and photodocumentation. All research divers have their specific function on each dive and bottom time is efficiently used. This is where our scientific diver training pays off. No time is wasted with buoyancy control problems, uncertainty about data collections or wasted breaths. As a matter of fact, most dive times to finish a sampling station average well over an hour, which translates into excellent air consumption rates. It is also a sign that the divers are at ease and focused on the research task.
As a 25-year veteran scientific diving instructor, marine biologist and lecturer, the two most commonly asked questions by the public are "how deep can you dive?" and "will a shark eat you?" Dive computers have replaced the U.S. Navy dive tables as the preferred means of monitoring decompression status. Each diver on the ship wears at least one. The algorithm in the computer calculates required stops or remaining bottom time based on a depth (pressure) and time input. The deeper you dive, the shorter the available no-decompression bottom time and the amount of work that can be accomplished. At a remote site such as Kingman the maximum depths are typically limited for safety reasons. As for the sharks eating divers, we're not part of their regular diet. From previous dispatches you will know that the dominant shark species here is the gray reef shark, a top-level predator. Most of these individuals are less than 4 feet long and we have managed to co-exist under water.
A watchful eye will identify a shark that is agitated or perceives the diver as an intruder on its territory. Sound advice is to not bleed profusely, stay with your dive buddy and keep the animal in sight, and remain calm while you exit the immediate area. Aggressive signs include rapid, erratic swimming, biting the water, an arched back, and displaying lowered pectoral fins. The attack itself is blindingly fast and consists of an initial single strike. We're not quite sure if a 3' long PVC pipe would suffice to ward off the incoming bullet. The gray reef shark appears to take an increased interest in activity at the water's surface, and actively hunts at night. Since no one is overly interested in night diving with a school of sharks, we remove ourselves from that potential conflict.
The diving done for the day and the gear secured on deck, we're back at logging data, cataloging specimens and analyzing samples from Kingman during our 18-hour steam to Fanning.
Safe diving in support of science increases our knowledge of the underwater world!
Director, Smithsonian Scientific Diving Program
Scripps Line Islands Expedition 05