Phytoplankton are the main source of primary production supporting food webs in marine ecosystems and play an essential role in biogeochemical cycling. The Texas Observatory for Algal Succession Time series (TOAST) was established in 2007 at Port Aransas, TX and has provided nearly continuous high temporal resolution (hourly) data on the dynamics of phytoplankton community composition and structure on the Texas coast using the Imaging FlowCytobot (IFCB). The IFCB uses a combination of flow cytometric and video technology to capture high resolution (1 µm) images of the phytoplankton (Olson & Sosik 2007 see Workplan, below).</p><p>Previously, TOAST provided evidence that hurricanes in the Gulf of Mexico (GOM) produce an immediate and major impact in the phytoplankton community (Angles et al. 2015). The study revealed that passage of tropical cyclones initially caused blooms of diatoms, which subsequently where replaced by blooms of dinoflagellates. This change in the community structure was hypothesized to be related to the ability of dinoflagellates, compared to diatoms, to assimilate the organic compounds supplied by the high river discharge that resulted from the rainfall.</p><p>Hurricane Harvey is the strongest hurricane to hit the GOM in decades therefore, the impact of this hurricane on the phytoplankton community may be unprecedented in terms of response and duration. It is imperative that a rapid response to this event is accomplished to elucidate the phytoplankton community response. Unfortunately, the hurricane damaged the TOAST site however, in May of 2017 we added a second IFCB to the network at Surfside Beach, just 60 km southwest of Houston, TX. Thus, the Surfside IFCB will play an important role in this RAPID response project.</p><p>Preliminary data from the Surfside Beach IFCB are revealing blooms of dinoflagellates one week after Hurricane Harvey’s passage. (The TOAST site did not survive the hurricane aftermath, but efforts are underway to find an alternative site and restore TOAST). Our response cruise from Galveston to Buoy B (Fig. 1) on 9/8/2017 obtained an initial look at the phytoplankton community structure from IFCB operation. In addition, RNA samples for subsequent metatranscriptome analysis have been preserved to assess the initial state of the phytoplankton community response.</p><p>This RAPID project is requested to fund additional sampling of the Texas coastal phytoplankton community during the recovery period from Hurricane Harvey. The proposed program will allow us to determine the impact of environmental changes caused by the hurricane on the physiological responses of the phytoplankton. Based on previous work, special focus will be on metabolic responses to nutrient limitation, specifically nitrogen, and potential ocean acidification. The project will address two hypotheses:</p><p>1. Community structure will be a flagellate-dominated system as long as the high river discharge continues. Community structure will shift to a diatom-dominated system when environmental conditions return to normal.</p><p>2. Nitrogen will be the main driver of shifts in community metabolic responses.
