Building consensus around the assessment and interpretation of Symbiodiniaceae diversity.

Within microeukaryotes, genetic variation and functional variation sometimes accumulate more quickly than morphological differences. To understand the evolutionary history and ecology of such lineages, it is key to examine diversity at multiple levels of organization. In the dinoflagellate family Symbiodiniaceae, which can form endosymbioses with cnidarians (e.g., corals, octocorals, sea anemones, jellyfish), other marine invertebrates (e.g., sponges, molluscs, flatworms), and protists (e.g., foraminifera), molecular data have been used extensively over the past three decades to describe phenotypes and to make evolutionary and ecological inferences. Despite advances in Symbiodiniaceae genomics, a lack of consensus among researchers with respect to interpreting genetic data has slowed progress in the field and acted as a barrier to reconciling observations. Here, we identify key challenges regarding the assessment and interpretation of Symbiodiniaceae genetic diversity across three levels: species, populations, and communities. We summarize areas of agreement and highlight techniques and approaches that are broadly accepted. In areas where debate remains, we identify unresolved issues and discuss technologies and approaches that can help to fill knowledge gaps related to genetic and phenotypic diversity. We also discuss ways to stimulate progress, in particular by fostering a more inclusive and collaborative research community. We hope that this perspective will inspire and accelerate coral reef science by serving as a resource to those designing experiments, publishing research, and applying for funding related to Symbiodiniaceae and their symbiotic partnerships.

Stimulated microbial reductive dechlorination following surfactant treatment at the Bachman Road site.

A pilot-scale demonstration of surfactant-enhanced aquifer remediation (SEAR) was conducted in July 2000 at the Bachman Road site located in Oscoda, MI. The Bachman aquifer is a shallow, relatively homogeneous, unconfined aquifer formation composed primarily of sandy glacial outwash with relatively low organic carbon content (0.02 wt %). A 6 wt % aqueous solution of Tween 80 (a nonionic, food-grade surfactant) was flushed through a localized dense nonaqueous phase liquid (DNAPL) source zone to recover approximately 19 L of tetrachloroethene (PCE). Post-treatment monitoring revealed PCE concentrations were reduced by up to 2 orders of magnitude within the source zone, and there was no evidence of concentration rebound after more than 450 d. Concentrations of PCE dechlorination products (trichloroethene, cis-1,2-dichloroethene) 450 d after SEAR operations ceased were more than 2 orders of magnitude greater than pretreatment values, suggesting stimulation of native dechlorination activity. Post-treatment monitoring detected increased concentrations of volatile fatty acids generated from the fermentation of residual-level Tween 80 surfactant. These field data suggest that Tween 80 not only induced and maintained anaerobiosis but also provided reducing equivalents to reductively dechlorinating populations present in the oligotrophic Bachman aquifer. Experience from this site supports application of staged treatment strategies that couple SEAR and microbial reductive dechlorination to enhance mass removal and reduce contaminant mass flux emanating from treated source zones.