The following is a blogpost about an expedition sponsored by the Smithsonian's Global Genome Initiative.
There’s more to reefs than fishes and coral, far more. In fact, it is estimated fishes and coral make up less than 1% of all reef-associated animal species. The other 99% of reef diversity – what is known as the cryptobiota – live within the reef matrix and play a critical role in reef functioning.
Not to be confused with yetis, bigfoot, or the Loch Ness Monster, crytopbiota are generally small, often tiny, and largely understudied. They contain members from across almost all branches of the tree of life. This hidden component lies among the nooks and crannies, and is what I aim to document as a research zoologist here at NMNH.
One way to get at these cryptic communities is through the use of Autonomous Reef Monitoring Structures (ARMS). ARMS are constructed as standard units, consisting of a stack of 9 PVC plates that mimic the complexity of the reef. Like pre-fabricated homes, these units are deployed for a period of time, recovered and analyzed to see who has moved in. Because they are standardized, ARMS can be compared around the world and over time to measure patterns and changes in marine biodiversity.
Recently, the Global Genome Initiative (GGI) provided funding for ARMS to be deployed at three sites in the Islas Murciélagos, in Sector Marino of the Area de Conservacion Guanacaste (ACG), off the Pacific Coast of northwestern Costa Rica. These are the first installations of ARMS in the tropical Eastern Pacific. GGI is a collaborative endeavor to collect the Earth’s genomic biodiversity, preserve it in the world’s biorepositories, and make it available to researchers everywhere. This project enables us to work strategically towards that goal by focusing on the collection, processing, and preservation of genomic material from poorly known – yet extremely diverse – communities.
After a year, we will collect the deployed ARMS and bring them back to the lab to sample them for biodiversity. The ARMS plates are disassembled plate-by-plate and photographed for spatial analyses. Motile specimens are sorted through different sized sieves; those larger than 2 mm are further sorted into taxonomic groups, which are then processed as standard voucher-based specimens and DNA barcoded. Similarly, representative vouchers are sampled from sessile specimens to build a comparable reference library of species.
Once vouchers are taken, the plates are scraped clean and the resulting material is homogenized in a blender and preserved for DNA analyses. These sessile communities, and smaller motile fractions (< 2 mm), are analyzed all together using an advanced “next-generation sequencing" method called metabarcoding to get diversity profiles from each fraction. A portion of the samples is processed right away, while others are stored in the NMNH's Biorepository for future genomic research.
One of the ARMS sites is near the local research station in the Bay of Isla San Jose, so it can be easily monitored as it accumulates species and can be shown easily to visitors and students at the station.
During the ARMS recoveries, along with our Costa Rican colleagues, we will be training "parataxonomists" who are local individuals interested in biodiversity studies, but have little taxonomic expertise in many of the marine groups. We use the ARMS and resulting specimens for first-hand taxonomic training about the cryptobiotic community . We are teaching the parataxonomists how to deploy and recover ARMS, so they can address their own questions in the future.
By Chris Meyer, Research Zoologist in the NMNH's Department of Invertebrate Zoology (edited by GGI Staff).