Anchialine environments are coastal land-locked bodies of brackish water exhibiting tidal fluctuations due to their simultaneous subterranean connections to the ocean and groundwater aquifers. Home to often regionally endemic organisms, this ecosystem type is increasingly becoming endangered due to anthropogenic pressures. This is especially true in the Hawaiian Islands, which has the only natural anchialine environments in the US but where >90% have already been lost or degraded. Thus, the opportunity to document the biodiversity contained within Hawaii's anchialine ecosystem is rapidly dwindling. While microbes are essential to the function of this ecosystem, they have so far been poorly characterized. To rectify this, this project will utilize high-throughput DNA sequencing and environmental data to identify factors influencing Hawaii's anchialine microbial community composition across space and time as well as quantify how perturbation alters community structure and function. Furthermore, a Hawaiian Anchialine Microbial (HAM) repository will be established to maintain access to these microbial communities given their potential for containing taxa of basic research and/or applied scientific value.
Overall, this project will broaden the basic biological knowledge for one of Hawaii's least studied and potentially most endangered ecosystems. Additionally, undergraduates and a graduate student from underrepresented groups will be trained and mentored over the work's duration. Federal and State of Hawaii governmental agencies have also identified information to be developed by the proposed work as having significant value in the future implementation of anchialine environment management strategies in the Hawaiian Islands. Lastly, Hawaiian anchialine environments and their biota will be utilized as a tool for educating K-12 students, teachers, and the general public in Hawaii and Alabama on a range of scientific topics
Anchialine environments are land-locked bodies of coastal brackish water exhibiting tidal fluctuations due to their simultaneous subterranean connections to the ocean and groundwater aquifer. Home to often regionally endemic organisms, this ecosystem is increasingly becoming endangered by anthropogenic pressures. This is especially true in the Hawaiian Islands, which has the only natural anchialine environments in the US but where >90% have already been lost or degraded. Thus, the opportunity to document the biodiversity contained within Hawaii’s anchialine ecosystem is rapidly dwindling. While microbes are essential to the function of the anchialine ecosystem, their identities have so far been poorly characterized in Hawaii or elsewhere. This project utilized high-throughput DNA sequencing along with environmental data to identify factors influencing microbial community composition of Hawaii’s anchialine ecosystem across space and time as well as quantify how perturbation alters community structure and function. Surveys of 20 distinct anchialine habitats from the islands of Oahu, Maui and Hawaii, representing the broad combinations of geological and physical parameters characteristic of this ecosystem in the islands, documented ~1,000-1,600 operational taxonomic units (OTUs) of Bacteria, Archaea and micro-Eukarya. Importantly, these OTUs exhibited non-random distributions; while many were common among habitats, an equal number were restricted to particular habitat types (i.e., the rare orange cyanobacterial-bacterial crusts unique to Hawaii’s anchialine ecosystem; Image 1) or single habitats. In this latter situation, habitats in close proximity were often found to significantly differ in microbial community compositions due to the presence of "private" (i.e., confined to a single location) OTUs. This brings up important implications when it comes to conservation of anchialine habitats in Hawaii and highlights the need to consider the uniqueness of microbial communities among habitats when implementing management plans for any ecosystem. Microbial community composition also varied over the course of the year in Hawaii’s anchialine ecosystem. Specifically, certain OTUs were found to vary in their relative abundances and statistical analyses suggested rainfall levels are apparent drivers of these patterns. Further support for this conclusion came from the fact that many of these OTUs correspond to taxa that have been previously sampled from freshwater environments and are at their highest prevalence during the rainy season, when anchialine habitats typically experience the largest influxes of water from the underground aquifer. Along with this, little to no change was observed in microbial community composition following removal of invasive fishes from anchialine habitats, likely due to the relatively recent nature of the removal. During the course of the project, a Hawaiian Anchialine Microbial (HAM) repository encompassing >300 samples was established with Ocean Genome Legacy to maintain access to these microbial communities given their potential for containing taxa of basic research and/or applied scientific value. Broader Impacts related to project included implementation of educational activities and outreach components that utilized the Hawaiian anchialine ecosystem and its biota as a tool for educating GK-12 students, teachers, and the general public in Hawaii and Alabama on biological topics such as the importance of microbes in aquatic environments, conservation biology, ecology, and evolution. These include talks at venues such as the Kilauea Visitor Center in Hawai'i Volcanoes National Park (Image 2), contributing to a poster on Hawaii’s anchialine ecosystem made freely available through the Conservation Council of Hawaii to State of Hawaii GK-12 teachers, the video piece "Disappearing Red Shrimp" in Science Nation (the science video series from NSF), and presentations and classroom module development with eight (8) public high school teachers around Auburn, AL through the Alabama Science in Motion (ASIM) program. The project also trained four (4) undergraduate students (three females, one being a NSF Research Experience for Undergraduates participant), with two (2) having traveled to Hawaii for field collections (Image 3). Three (3) graduate students (one minority female) also participated in, or were supported by, the project. Other products from the project to date include: two (2) websites and two (2) software tools, 28 presentations at regional or national conferences by undergraduate and graduate students, six (6) invited talks by the PI at national or international institutions, and seven (7) manuscripts in peer-reviewed scientific journals (4 published, 1 in press, 2 in review). Of these, three (3) manuscripts included undergraduate students as first or co-authors, with one (1) being a featured 2013 cover article in the international journal Hydrobiologia (Image 4). Additional manuscripts from peer-review are in preparation and will be forthcoming in the near future. All products acknowledged Federal support to the project via the National Science Foundation.
