Strange and beautiful fishes from the ocean’s deep and lesser-known twilight zone reefs are hitching a ride to the surface thanks to the newly invented SubCAS (or Submersible Chamber for Ascending Specimens). This ingenious pressurized chamber, engineered by the scientists-turned-inventors at the California Academy of Sciences and the Monterey Bay Aquarium, stretches two feet long and is used by scientific divers to collect and safely surface charismatic reef residents for further study and public display. The device was described today in Frontiers in Marine Science.
“The ability to physically dive to twilight zone depths using closed-circuit rebreathers means we can closely explore these environments without relying on large submarines or remotely operated vehicles, so we needed a similarly agile way to collect important fishes and bring them back alive,” says lead author Bart Shepherd, Senior Director of the Academy’s Steinhart Aquarium and Hope for Reefs co-leader. “Before the SubCAS, hand-collecting and surfacing live fishes involved the invasive process of needling a hole in their gas-filled swim bladders to prevent over-expansion. The chamber now allows us to eliminate this step and surface precious species in a non-invasive way for closely monitored care, research, and public display.”
Into the twilight zone
Shepherd is part of a deep-diving research team that explores the twilight zone, a mysterious coral habitat stretching across a narrow band of ocean 200 — 500 feet beneath the surface. At this depth, sunlight is scarce between the light-filled shallows and the deep dark sea. As part of its Hope for Reefs initiative, the Academy team is exploring this unknown frontier with the help of high-tech equipment like closed-circuit rebreathers, which require extensive training and allow scientists to extend their research time underwater. Most fishes in the twilight zone have never before been seen by humans — many are also new to science. The long journey to bring new species to the surface is a delicate, carefully orchestrated process for both divers and their aquatic finds.
“A rapid ascent can rupture a fish’s swim bladder,” says co-author Dr. Luiz Rocha, the Academy’s Curator of Fishes and Hope for Reefs co-leader. “Using an adjustable pressure control valve, we ensure that the pressure inside the chamber is similar to the depth where the fishes were collected. Over the course of two to three days, we bring them to the surrounding surface pressure in a highly controlled manner.”
Co-author Matt Wandell, an aquatic biologist at the Monterey Bay Aquarium who designed and built the chamber during his former work at the Academy, knows that twilight zone dives present physiological challenges for divers as well as animals.
“In designing the SubCAS, we knew ease of operation was critical so as not to distract divers from keeping pace with critical decompression stops or monitoring their life support equipment,” says Wandell. “Every second counts.”
Read more from the original article @ ScienceDaily