Tracking coastal diatom carbon metabolic mechanisms and microbial networks with time-series -omics data

Diatoms are spring bloom formers and dominant contributors to coastal carbon cycling. In Cape Cod Bay, spring diatom blooms are common, but with high variability. For over 20 years, the Massachusetts Water Resources Authority and Provincetown Center for Coastal Studies have collected water samples for physico-chemical monitoring and plankton counts from a series of Cape Cod Bay sites, and we collected metatranscriptomic samples in 3 spring seasons. We captured spring blooms of Guinardia and Proboscia and a modest spring bloom of Thalassiosira in the metatranscriptomes. We also captured mid-summer growth of diatoms Dactyliosolen and Leptocylindrus. This diversity of abundant diatom taxa in different seasons, temperatures, and nutrient contexts enabled us to test our hypothesis that different diatom taxa would result in different dominant expressed carbon-related genes. We contextualized our metatranscriptomes with 18S and 16S rRNA gene data, evaluated genetic distance between diatoms observed in adjacent years, and constructed networks of environmental associations between phytoplankton and bacteria. We applied a k-mer clustering approach to the metatranscriptomic assemblies to annotate diatom sequences more precisely and identified carbon metabolism genes specific to diatoms, especially photorespiration and carbon concentrating mechanisms. We correlated expression of carbon pathway genes that produce less labile intermediates to bacterial abundance. Our results highlight how -omics approaches can illuminate aspects of diatom metabolism and their community context.

Presentation Preference: Oral

Primary Presenter: Arianna Krinos, Brown University (akrinos@vt.edu)

Authors:

Arianna Krinos, Brown University  (akrinos@whoi.edu)

Amy Costa, Center for Coastal Studies  (acosta@coastalstudies.org)

Sara Shapiro, Woods Hole Oceanographic Institution  (sara.shapiro@whoi.edu)

Harriet Alexander, Woods Hole Oceanographic Institution  (halexander@whoi.edu)

Mara Freilich, Brown University  (mara_freilich@brown.edu)

Margaret Mars Brisbin, University of South Florida  (mmarsbrisbin@usf.edu)