Hurricane Harvey brought record-setting rain to the Houston-Galveston Bay region between August 26 – 29, 2017. In its aftermath, the environmental community sought answers to questions about Harvey’s impacts on the region, but the impacts cut across disciplines and data were scarce or difficult to find. The Houston Advanced Research Center (HARC) compiled over 15 datasets on water quality, water flow, rainfall, superfund sites, air quality, wetlands, development, Harvey-related damages, power demand and outages into a Harvey Impacts storymap Harveyimpacts.HARCresearch.org. This publicly available, interactive visualization tool is designed to facilitate research, discussion, and action related to the resiliency of the Houston-Galveston region. As of October 1, 2017 HARC's Harvey Impacts storymap site has been visited over 5,000 times and over 280 datasets have been downloaded.

In September 2017, Hurricane Harvey brought over 50 inches of rain to the Gulf of Mexico (GOM) coast, adding a total volume of 33 trillion gallons of freshwater to the region. This massive freshwater input was expected to result in changes in the biogeochemical composition of the northwestern GOM. Given changes in salinity and nutrient availability we expected to also observe changes in the phytoplankton community. This study investigates the effects of the Hurricane Harvey floodwater plume on nutrient concentrations and phytoplankton composition. To do this, data were compared from four cruises in the northwestern GOM that sampled dissolved nutrient availability and size-specific groups of phytoplankton (as chlorophyll-a) along an onshore-offshore gradient from Galveston Bay, TX. These include samples collected prior to Hurricane Harvey on the Gulf of Mexico Ecosystems and Carbon Cruise (GOMECC-3) in late July 2017 and three cruises after the storm in October 2017 (RAPID-1), January 2018 (RAPID- 2), and March 2018 (RAPID-3). The three RAPID cruises were designed to understand both the initial effects and recovery of the system. Preliminary results suggest that nearshore and continental shelf stations showed differences in inorganic nitrogen concentrations six weeks after Hurricane Harvey. Additionally, nearshore phytoplankton communities showed an order of magnitude decrease in combined pico- and nanophytoplankton biomass (<20 µm) and a threefold increase in microphytoplankton (>20 µm) during that same period. By January 2018 (approx. 4 months post-hurricane), we observed pico- and nanophytoplankton biomass return to pre-hurricane concentrations, while microphytoplankton remained consistent. In contrast, phytoplankton communities on the continental shelf showed a sixfold increase in combined pico- and nanophytoplankton biomass in surface waters six weeks after Hurricane Harvey, which remained high into January 2018. These preliminary results suggest that phytoplankton community composition differed pre- and post-Hurricane Harvey, and that these differences varied along an onshore-offshore gradient.

As a foundation species in aquatic food webs, phytoplankton in estuaries react rapidly to environmental disturbances due to their quick growth rates. Changes in phytoplankton community composition were used as a proxy to gauge the major long- and short-term impacts on the biogeochemical processes of the Mission-Aransas Estuary after Hurricane Harvey, a category 4 hurricane, struck the coast of Texas in August 2017. Phytoplankton community was determined by size using size fractionation filtration and flow cytometry, and by using accessory pigments determined by high performance liquid chromatography (HPLC). Three days after the hurricane, salinity decreased by 36% at Copano Bay West (CW), the site closest to the Aransas River mouth, and by 47% at the Ship Channel (SC), the site closest to the Gulf of Mexico. The salinity did not return to pre-Hurricane levels by the time of sampling, 7 months after the Hurricane. The phytoplankton community at CW maintained a constant percent composition from June before the hurricane until October after the hurricane, with a high proportion of cyanobacteria. There was no obvious chlorophyll a peak at CW or SC following the storm. Phytoplankton community composition at SC showed common seasonal trends in the fall after the hurricane, with an increase in cyanobacteria and a decrease in diatoms. One notable exception is that dinoflagellates made up a large proportion of the percent composition of phytoplankton on September 13 after the hurricane, but decreased by the next sampling point on September 28, which might have been caused by the seasonal temperature drop. Percent composition of plankton by size six months after Hurricane Harvey showed common seasonal trends as well, indicating the phytoplankton community was not affected in the long-term by the sharp drop in salinity brought on by the hurricane.

Estuaries are highly productive ecosystems and phytoplankton serve a key role in supporting secondary productivity. In conjunction with routine water quality monitoring in Pensacola Bay (FL), we collected monthly plankton samples from surface and bottom waters of the Escambia Bay sub-estuary from Apr. 2014 to May 2016. This region of the bay is often strongly stratified yet is shallow enough to be euphotic to the bottom. Thus, we examined the potential for stratification to create unique niches, resulting in distinctive phytoplankton communities. We used two principal methods to examine the phytoplankton composition: 1) direct enumeration of pico-cyanobacteria via epifluorescence microscopy, and 2) enumeration of larger phytoplankton (>10-20 µm) via FlowCam® and subsequent image analysis. Like earlier studies (e.g. Murrell and Lores 2004, Murrell and Caffrey 2005), we observed very high abundances of pico-cyanobacteria (peak abundances >3 X 10^9 L-1) during summer months. For larger phytoplankton, flow Cam analysis has yielded an image library of phytoplankton images. The abundance and biovolume of major taxonomic groups will be summarized for surface and bottom waters over a seasonal cycle and placed in context with the prevailing physical environment.