Sampling After the Storm: Combining Phytoplankton Imagery, Genomics and Physical Data to Assess Community Structure After a Hurricane

Hurricane Harvey made landfall in Texas in 2017 and released a large amount of precipitation over the greater Houston area. Much of this precipitation made its way to the Gulf of Mexico and created a large freshwater plume along the coast of Texas that provided a unique opportunity to sample a coastal ocean environment in the wake of a large disturbance event. A series of samples were collected for metatranscriptomics/metabarcoding and phytoplankton abundance, captured with an Imaging FlowCytobot (IFCB), all of which permit a more detailed, species level analysis. By combining these data with physical and chemical properties, we investigated the response of the coastal plankton community to the hurricane. Sampling began approximately ~2 weeks after the storm and ended ~2 months after the storm. In the middle of this time period, two cruises were conducted, a week apart and sampled from Galveston Bay to south of Corpus Christi Bay. Abundance estimates from IFCB data and metabarcoding comparing the two cruises were similar for 4 of 6 stations with increases/decreases in abundance mirrored between the two datasets with stations S16 and GI exhibiting opposite responses for diatoms. The metabarcoding and metatranscriptomic data were also similar for 5 of the 6 stations with S16 again showing a different response. An offshore intrusion of high salinity water was observed at S16 and may have served to disrupt the community in this region. Metatranscriptomic data indicated the diatoms Chaetoceros, Thalassiosira, and Skeletonema were initially stressed as evidenced by increased expression of HSP70 and peroxidase genes sampled ~2 weeks after the storm. High expression of chitin synthase genes was observed for Thalassiosira and Skeletonema two weeks after the storm. Silicon transporter genes exhibited increased expression ~2 weeks after the storm for Chaetoceros while Thalassiosira had high expression ~1 month after the storm. In the dinoflagellates, peroxidase and HSP70 gene expression for Karenia increased over time with the highest expression observed during the second cruise, coinciding with dinoflagellate dominance in the community. While the community as a whole was impacted by the large input of freshwater into the system, expression profiles taken two months after the storm showed the plankton community had recovered.