By Liz Boatman
In December 2010, Vertebrate Zoology research zoologist Carole Baldwin received what she thought was a prank phone call. But it turned out that the man on the other end of the phone, Adriaan "Dutch" Schrier, wasn't pranking Carole at all. Dutch, the owner of the Sea Aquarium in Curaçao as well as a submersible (the Curasub) capable of taking four passengers to depths of 1000 feet, really was inviting Carole and the Smithsonian Institution to visit his exotic and beautiful establishment to try out the submersible for research purposes.
Sensing that this offer might be once-in-a-lifetime, Carole moved quickly to organize a visit. "He convinced me! That same month a colleague and I went down, and [Dutch] put us in the sub, and I couldn't have been more impressed," recalls Carole. Even so, she had her reservations, simply because "these people had never worked with scientists so we didn't know if [the relationship] would be workable."
Carole funded the Smithsonian’s first research trip with a grant from the Bill and Melinda Gates Foundation through the Consortium for Understanding and Sustaining a Biodiverse Planet. The effort is now officially known as the Deep Reef Observation Project (DROP), and accordingly, there are two primary objectives of DROP. One is to gain a better understanding of biodiversity, and the other is long-term reef monitoring.
Scientific discoveries in the "deep" reef
What attracts most scientists to the field of marine biology, of course, is the biodiversity. DROP has already discovered over 30 new species of invertebrates and small fishes [Baldwin & Robertson 2014], leading to multiple journal publications and more on the way. In one case, the team has recovered several individuals of a tiny, new species of brittle sea star from the surfaces of discarded glass bottles and tires found between 900 and 1000 feet, leaving the team wondering about the natural habitat of these little guys.
With so many discoveries already, it might surprise you to learn that, in many ways, DROP has just begun. Until recently, the submersible was deployed directly from the aquarium dock. This kept the cost of operation low, at approximately $5,300 for 6 hours of underwater work versus $19,000 for a typical day's work when launched from a ship. "For space exploration that's a drop in the bucket, but for marine biology that's a lot of money you don't typically get," explains Carole.
But, while promoting cost-conscious research, launching from the dock has limited the area that the team can cover. To remedy this problem, Dutch recently purchased and overhauled an old National Oceanic and Atmospheric Administration (NOAA) vessel, the R/V Chapman. Pending funds to support the cost of a cruise, the DROP team can now launch the submersible from anywhere in the Caribbean. If they can sail to it, they can study it! (As long as the Curasub remains above a depth of 1000 feet, that is...)
Depth limitation promotes discovery, and collaboration
Most submersibles can dive to depths of tens of thousands of feet. But Dutch’s Curasub submersible, designed by Vancouver-based Nuytco, is restricted to shallower depths. Fortunately, the team has discovered an unexpected benefit of working at depths of 1000 feet or less. As it turns out, "deep" reefs (reefs at depths greater than 150 feet) have largely been overlooked in the past, which means there are exciting discoveries—new species, new findings in biodiversity, new insight into genetic connectivity among shallow and deep reefs—everywhere the team looks. "For decades scientists have been trapped in the shallower scuba zone or zooming past these reefs en route to deeper depths...a whole world of biodiversity has been missed," says Carole.
To better understand deep reefs, the DROP team has grown substantially over the years, because every new researcher brings an important new perspective. The growth in the DROP collaboration is exciting to Carole. "For the most part, we all do our own thing," she says. What Carole means is that researchers from different disciplines tend not to mingle. She continues, stating that the exciting degree of collaboration among the participants of DROP grew out of an ambitious thought—"let's not just focus on one taxon, but let's see if we can characterize the ecosystem."
Teaming up with Invertebrate Zoology researchers Nancy Knowlton and Chris Meyer, the team took advantage of the submersible to deploy and retrieve units known as autonomous reef monitoring structures (ARMS), also used by NOAA. At present, DROP has 36 ARMS deployed along three depth transects, from shallow to deep waters. Off Curaçao, where settlement rates are low, the units are left for two years, allowing reef organisms to grow on their surfaces. When recovered, the surfaces are cleaned and the organisms removed are genetically sequenced for species identification. Not only has this project required the development of new high-throughput processing techniques for samples containing DNA from multiple organisms, but the work is also shedding light on the depths at which reef species live.
The arms of the submersible are also used to deploy temperature gauges along similar depth transects, ranging from 50-800 feet. These gauges record variations in water temperature year-round, to the resolution of one minute. Water temperature micro-analysis is important for understanding the organisms that live in the reef and provides long-term data concerning temperature changes at different ocean depths.
Four years later, this collaboration has expanded to include nearly forty Smithsonian Institution researchers and staff, from the departments of Vertebrate Zoology, Invertebrate Zoology, and Botany, the Smithsonian Marine Station at Ft. Pierce, and the Smithsonian Tropical Research Institute. The collaboration also provides opportunities for graduate students and postdoctoral scholars to engage in NMNH field work. And back in the lab, specimens recovered from DROP provide high school students the opportunity to learn about cutting-edge marine biology research and DNA processing techniques through the Smithsonian's Youth Engagement through Science (YES!) program.
In the future, no doubt we'll be hearing many more exciting stories from Carole and the DROP team. In the mean time, Dutch has applied for funding from the government of Curaçao to build a state-of-the-art research lab at the aquarium, which would greatly benefit the scientists as they process specimens between dives. And with the ability to launch the submersible from the R/V Chapman, the team will have access to entirely new regions of the deep reef.