Deep-Sea Dive off Guam Reveals Astonishing New Marine Life

The ocean's 'twilight zone,' a region lurking more than 300 feet below the surface near Guam, remains one of the planet's most mysterious ecosystems. Sunlight barely penetrates this depth, creating an environment that's challenging and costly to explore.

Recently, a team of scientific divers from the California Academy of Sciences embarked on a series of extremely deep dives to retrieve monitoring equipment. These devices, anchored to Guam's deep reefs, have been diligently gathering data on marine life and water temperatures for over eight years.

The divers encountered a remarkable array of marine creatures. Delicate corals, shimmering worms, spiky sea slugs, and hairy crabs were among the organisms observed. Data from the retrieved monitors also offers insight into ocean temperature variations, possibly indicating that even these deep waters are susceptible to the effects of climate change.

The depths of the upper twilight zone present significant challenges for divers. Conventional scuba gear is inadequate at such depths. Instead, these experts employed specialized equipment to breathe a unique blend of helium and air.

At these depths, the pressure causes gases to dissolve into the body. A slow ascent, with pauses at regular intervals, is crucial to prevent decompression sickness, a dangerous condition caused by gas bubbles forming in the bloodstream. According to Luiz Rocha, a diver and ichthyology curator, even a brief 10-minute stay at 500 feet necessitates a six-hour return to the surface. This severely limits the amount of time they can spend working.

Despite these challenges, Rocha and his team successfully recovered 13 monitoring devices during eight dives in November. These structures, resembling small underwater hotels, are composed of PVC plates where marine organisms can settle and grow.

The retrieved monitors, encrusted with colorful marine growth, were transported to the University of Guam Marine Laboratory. There, scientists painstakingly sorted through the collected material, identifying, photographing, and preserving each specimen. Remaining material was sent for DNA analysis.

After two weeks of analysis, the scientists identified 2,000 specimens, including 100 species not previously documented in the region. Twenty of these could be entirely new species. Discoveries included a possible new cardinalfish species, an orange-clawed crab not seen before in Guam, and a vibrantly colored sea slug.

Rocha highlighted the discovery of a hermit crab utilizing clam-like shells as its home, a departure from the gastropod shells typically used by other hermit crab species.

Beyond the excitement of new discoveries, the scientists expressed concern about the future of these deep reefs. Rocha noted that over half the species inhabiting these reefs remain unidentified, yet they are already vulnerable to human impact, including fishing, pollution, and climate change.

Research indicates that plastic pollution, largely from the fishing industry, increases with depth, reaching its peak in the upper twilight zone. Rocha lamented that despite being the first humans to observe these reefs, they consistently encounter human-produced waste.

Additionally, temperature data hints that warming trends observed in other ocean regions may also be affecting these deep waters, challenging the assumption that they offer a refuge from climate change.

The Guam expedition marks the beginning of a two-year project to collect 76 monitors from deep reefs across the Pacific. Scientists hope that this effort will yield a clearer picture of life in the twilight zone and inform strategies to protect this fragile ecosystem.