COS 86-3 - Metabarcoding a tropical lagoon: Diversity patterns across habitats, taxa, and body sizes

Thursday, August 15, 2019: 2:10 PM
L011/012, Kentucky International Convention Center
Bryan N. Nguyen1,2,3, Andrew H. Altieri4,5, Nancy Knowlton6, Gustav Paulay7, Robert M. Lasley7, François Michonneau7,8, Giovanna C. Kupiec3, James L. O'Donnell9, W. Owen McMillan10, Keith A. Crandall1 and Matthieu Leray11, (1)Computational Biology Institute, George Washington University, Washington, DC, (2)National Museum of Natural History, Smithsonian Institution, Washington, DC, (3)Department of Biological Sciences, George Washington University, Washington, DC, (4)Department of Environmental Engineering Sciences, University of Florida, Gainesville, FL, (5)Environmental Engineering Sciences, University of Florida, Gainesville, FL, (6)Department of Invertebrate Zoology, Smithsonian Institution, Washington, DC, (7)Florida Museum of Natural History, University of Florida, Gainesville, FL, (8)Whitney Lab for Marine Bioscience, University of Florida, Saint Augustine, FL, (9)School of Marine and Environmental Affairs, University of Washington, Seattle, WA, (10)Smithsonian Tropical Research Institute, Panama, (11)Smithsonian Tropical Research Institute, Panama City, Panama
Background/Question/Methods

The majority of ecological knowledge in tropical marine systems comes from studies of conspicuous macroorganisms, such as corals and fishes, and often ignores smaller, more cryptic species where most biodiversity resides. Filling in this blindspot is critical to a better understanding of how scaling patterns differ across habitats, body sizes and marine taxa. We combined spatially-structured sampling (with plots ranging from ~50 m to >20 km apart) of four key tropical coastal marine ecosystems—coral reef, mangrove forests, seagrass beds and sediments—with extensive barcoding and metabarcoding to examine the spatial scaling patterns of biodiversity within the Caribbean marine lagoon of Bocas del Toro, Panama. Animals inhabiting plots of each habitat were separated and metabarcoded in three fractions representing sessile/encrusting organisms, motile organisms under 2 mm, and motile organisms under 500 µm.

Results/Conclusions

Contrary to belief that smaller organisms have fundamentally different scaling patterns, we found that both of our motile organism size fractions exhibited fairly similar patterns of spatial turnover. The highest diversity was found in sediment samples, with the regional diversity of mangrove root epibionts and coral reefs being lower and relatively similar. A considerable fraction of sequences from metabarcoding could not be assigned even to phylum, with the greatest proportion of unidentified sequences originating from sediment samples. DNA metabarcoding is critical for a more complete picture of marine biodiversity, but there is still a great need for improving the taxonomic coverage of genetic databases, such as GenBank, using high-quality, taxonomist-verified entries, especially for understudied cryptic taxa such as interstitial meiofauna.