Assessing cryptic reef diversity of colonizing marine invertebrates using Autonomous Reef Monitoring Structures (ARMS) deployed at coral reef sites in Timor-Leste from 2012 to 2014

The data described here, including photographs, genetic sequences, and specimen information, were collected by the NOAA Coral Reef Ecosystem Program (CREP) from Autonomous Reef Monitoring Structures, or ARMS, moored for two years at fixed climate survey sites located on hard bottom shallow water (< 15 m) habitats in Timor-Leste. Climate sites were established in Timor-Leste in October 2012 to establish ecological baselines for climate change by measuring multiple features of the coral reef environment (in addition to the data described herein) over time.

Three ARMS units were typically deployed by SCUBA divers at each survey site. Each ARMS unit, constructed in-house by CREP, consisted of 23 cm x 23 cm gray, type 1 PVC plates stacked in alternating series of 4 open and 4 obstructed layers and attached to a base plate of 35 cm x 45 cm, which was affixed to the reef. Upon recovery, each ARMS unit was encapsulated, brought to the surface, and disassembled and processed. Disassembled plates were photographed to document recruited sessile organisms, scraped clean and preserved in 95% ethanol for DNA processing. Recruited motile organisms were sieved into 3 size fractions: 2 mm, 500 µm, and 100 µm. The 500 µm and 100 µm fractions were bulked and also preserved in 95% ethanol for DNA processing. The 2 mm fraction was sorted into morphospecies, photographed, and identified to the lowest taxonomic identification possible. The plate photographs, sequences generated from the DNA metabarcoding of the scrapings and the 500- and 100-µm fractions, specimen photographs, and specimen identifications are included in the ARMS dataset. The data can be accessed online via the NOAA National Centers for Environmental Information (NCEI) Ocean Archive.

ARMS are used by CREP to assess and monitor cryptic reef diversity across the Pacific. Developed in collaboration with the Census of Marine Life (CoML) Census of Coral Reef Ecosystems (CReefs), ARMS are designed to mimic the structural complexity of a reef and attract/collect colonizing marine invertebrates. The key innovation of the ARMS method is that biodiversity is sampled over precisely the same surface area in the exact same manner. Thus, the use of ARMS is a systematic, consistent, and comparable method for monitoring the marine cryptobiota community over time.