"You are(n’t) what you eat: DNA profiling of microbial communities" by Scott Santos (Pres 25: 5ISAE)
This presentation was a part of the 5th International Symposium on Anchialine Ecosystems (5ISAE), held in Kailua-Kona November 3-5, 2022.
Presentation 25: "You are(n’t) what you eat: DNA profiling of environmental microbial communities relative to the gut of Halocaridina rubra Holthuis, 1963 (Decapoda: Atyidae) from the Hawaiian anchialine ecosystem."
Session 7: Hawai‘i - Biological Sciences
Presentation Authors: Scott R. Santos (1), Pamela M. Brannock (2), Reyn M. Yoshioka (3), Rebecca C. Vaught (4); Kaile‘a Carlson (5), Collin Edwards (6), Allison Tracy (7), Cornelia W. Twining (8), Yun Zheng Yun Zheng (9), Alan Wilson (10); Nelson G. Hairston Jr. (11), Justin C. Havird (12)
Affiliations: (1) Dept. of Biological Sciences, State University of New York at Buffalo, Buffalo, NY, USA; (2) Dept. of Biology, Rollins College, Orlando, FL, USA; (3) Oregon Institute of Marine Biology, University of Oregon, Charleston, OR, USA; (4) Van Heron Labs, Huntsville, AL, USA; (5) Kaloko-Honokōhau National Historical Park, National Park Service, Kailua-Kona, HI, USA; (6) Dept. of Biology, Tufts University, Medford, MA, USA & School of Biological Sciences, Washington State University, Vancouver, WA, USA; (7) Smithsonian Environmental Research Center, Edgewater, MD, USA; (8) Dept. of Fish Ecology and Evolution, Eawag, Kastanienbaum, Switzerland; (9) Dept. of Civil and Environmental Engineering, Cornell University, Ithaca, NY, USA; (10) School of Fisheries, Aquaculture, and Aquatic Sciences, Auburn University, Auburn, AL, USA; (11) Dept. of Ecology and Evolutionary Biology, Cornell University, Ithaca, NY, USA; (12) Dept. of Integrative Biology, The University of Texas at Austin
Presentation Abstract: Microbes are key players in the biogeochemical transformation of nutrients and trace elements, primary productivity, and the carbon cycle of many ecosystems. Furthermore, macro-organisms such as plants and animals rely on microbes for essential aspects of their biology, in turn shaping environmental microbial communities or macro-organisms’ microbiomes in the process. However, detailed studies of animal-microbe interactions are limited from the anchialine ecosystem, characterized as landlocked coastal ponds, pools, and caves whose salinities and depths vary with the tides due to simultaneous subterranean connections to the underlying groundwater aquifer and sea. To address this, we utilized laboratory microcosm experiments as proxy anchialine microbial communities to demonstrate that ecologically relevant levels of grazing by the endemic Hawaiian anchialine shrimp Halocaridina rubra Holthuis, 1963 (Decapoda:Atyidae) alters epilithon biomass. In the field, H. rubra grazes on diverse benthic microbial communities, including green algal mats and orange cyanobacterial-bacterial crusts. DNA profiling of ribosomal RNA hypervariable regions (i.e., Bacteria-specific V6 and Eukarya-biased V9) from these two distinctive substrate types relative to shrimp guts also suggest grazing altered environmental microbial community composition, either through physical interactions and/or selective consumption. Fecal pellets from H. rubra phenotypically resembled either the green algal mats or orange cyanobacterial-bacterial crusts they were consuming, with DNA profiling finding in all cases that fecal-associated microbial communities are most like the substrate type being grazed by shrimp. Notably, our analyses revealed H. rubra harbors a resident gut microbiome, distinct from any environmental microbial community, that is relatively simple and stable in composition across space (i.e., habitats with different microbial communities) and time (i.e., wild-caught individuals vs. those captive for greater than 2 years). Thus, while shrimp grazing plays a significant role in shaping environmental microbial communities of the Hawaiian anchialine ecosystem, these same communities apparently have little influence on the gut microbiome of H. rubra.