Hurricane Harvey was the strongest hurricane to hit the Texas coast in decades and the resulting tidal surges, flooding and terrestrial runoff had severe impacts on the coastal ocean. This RAPID project focused on the response of the phytoplankton community along the Texas coast during the recovery period following Hurricane Harvey. In the aftermath of the hurricane, a freshwater plume from Galveston Bay, along with nutrients and potential toxins, extended down the Texas coast. Determining the impact of these drastic changes on the coastal phytoplankton community is important because phytoplankton are the first step in the food chain of this important fishing region. Two research cruises were conducted starting from Galveston Island extending south to Port Aransas, TX in the month following the hurricane. Timing of the cruises (Sept 23-26/ Sept 29-Oct1), a week apart, allowed examination of the state of the phytoplankton community and the shift in phytoplankton abundance, taxonomic diversity, and gene expression in response to the altered physical and chemical properties. The cruise results were put into context by comparing with ongoing phytoplankton time series data from two sites on the Texas coast, Port Aransas (since Sept 2007) and Surfside Beach (since May 2017). Additional samples collected at the Surfside time series site provided taxonomic and gene expression data for the phytoplankton community as the coastal environment recovered. Prevailing conditions along the Texas coast restricted the freshwater plume to the immediate coast. Observed salinities during the first cruise were considerably fresher than the average for this period, particularly the upcoast stations nearer Galveston Bay. By the second cruise leg, the freshwater had move farther downcoast, so at most stations, salinity decreased slightly, the surface mixed layer deepened and salinity at the southernmost station (S01) decreased from ~33 to ~26 (Fig. 1). To identify changes in the phytoplankton community as the freshwater moved down the coast, we used a novel imaging system, the Imaging FlowCytobot (IFCB), which records pictures of all the microorganisms in a known volume of water. Dramatic shifts in community composition were noted between the two cruises that took place just 1 week apart. From these images, we found that the community shifted from a typically diatom-dominated system to one in which dinoflagellates were the dominant group among the phytoplankton. Results from high throughput sequence metabarcoding supported the increased relative abundance of dinoflagellates (Fig. 2). This is one of the first studies to compare data on phytoplankton abundance from the IFCB with taxonomic diversity estimates from metabarcoding. Surprisingly, up to 40 potential harmful algal bloom species were identified from the barcoding analysis. To assess the physiological responses of the phytoplankton community, a metatranscriptomics approach was taken. This provided an indication of the metabolic strategies employed and functional relationships within the plankton community in response to changes in the environment. The advantage of a metatranscriptomic approach is that the entire molecular response to the environment is captured. So, while the response of phytoplankton to increased nutrient inputs from floodwater runoff is targeted, the responses to other environmental stresses (toxics, hypoxia, acidification) can also be captured. The series of metatranscriptomic data from the cruises and additional Surfside samples 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. 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 appeared to have recovered. The combination of these multiple approaches permitted examination of the response of the coastal plankton community at a detail (genus or species-level) not possible otherwise. Immediate and continuous sampling is the only way to fully capture the effects of environmental disturbances and to identify when conditions return to "normal". This project has provided training and professional development opportunities for four undergraduate students, two graduate students, and a postdoctoral researcher. Results have been disseminated at local workshops, international and national conferences, including the August 2018 Hurricane Harvey Research Symposium in Port Aransas, TX and the 2019 Aquatic Sciences Meeting in Puerto Rico. Data are presented in manuscripts to be submitted for publication and publicly available databases. The IFCB image data are available on the dashboard at http://toast.tamu.edu/HRR_cruise. Cruise hydrographic data are deposited in the Biological and Chemical Oceanography Data Management Office as ?HRR Cruise bottle data?: https://www.bco-dmo.org/dataset/784290. Metatranscriptome and barcoding data have been submitted to the National Center for Biotechnology Information (NCBI) in BioProject PRJNA592369: https://dataview.ncbi.nlm.nih.gov/object/PRJNA592369). Last Modified: 01/30/2020 Submitted by: Lisa Campbell
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