Project: RAPID: Collaborative Research: Impact of freshwater runoff from Hurricane Harvey on coral reef benthic organisms and associated microbial communities

NSF Award Abstract:
Coral reefs are ecologically and economically important ecosystems, and are threatened by a variety of global (climate change) and local (overfishing, pollution) stressors. Anthropogenic climate change is increasing the frequency and severity of storms, which can physically damage reef structures and reduce reef health through changes in seawater quality. In August of 2017, Hurricane Harvey caused widespread flooding in southeast Texas when it released more than 50 trillion liters of rain, which then accumulated along the Texas Shelf. This runoff is expected to impact nearby coral reefs in the Flower Garden Banks National Marine Sanctuary (FGBNMS, northwest Gulf of Mexico) via eddies and jets that transport coastal waters offshore. Findings from this project will allow managers to quickly predict whether extreme storm events are likely to induce reef mortality and ecosystem decline due to freshwater accumulation, by tracking of low salinity water masses coupled with microbial community characterization and metrics of coral health. These data are critical to managing coastal ecosystems, including the high coral cover reefs in the FGBNMS, and will help stakeholders (e.g., diving and fishing communities) plan for and minimize disruption to their livelihoods following these storms. Results will be communicated broadly across scientific arenas, in graduate and undergraduate education and training programs, and to the general public through outreach. The investigators have seven 7 square meter 2-D Reef Replicas from 2014 depicting representative FGBNMS reef bottoms, and will construct additional 2-D Reef Replicas from both banks following the arrival of Harvey runoff, allowing the public to directly experience and quantify the effects of Hurricane Harvey on local reefs using quadrats and identification guides. This project will also synergize with NSF REU programs at Boston University and Texas A&M University, providing transformative research experiences for undergraduates. One post-doctoral scholar, four graduate students, a technician and more than 5 undergraduates will be involved in all aspects of the research. All datasets will be made freely available to the public, and will serve as an important set of baselines for future lines of inquiry into the processes by which hurricanes and other extreme storms impact reef health.

Hurricanes and other extreme storm events can decimate coral reefs through wave-driven physical damage. Freshwater runoff from extreme storms is also potentially detrimental to reefs but has received comparatively less attention. This research will provide unprecedented resolution on how hurricanes and other extreme storm events may trigger cascading interactions among water chemistry, declines in metazoan health and shifts in their associated microbial communities, ultimately resulting in coral reef decline. The freshwater runoff initiated by Hurricane Harvey is likely to impact reefs within the FGBNMS, one of the few remaining coral-dominated reefs in the greater Caribbean. The effects of Harvey runoff will be compared to a previously documented storm-driven runoff event that was associated with invertebrate mortality on the same reef system. Sampling seawater chemistry, microbial communities (water column and benthic), and host gene expression and proteomics before, immediately after, and six months after Harvey runoff enters the FGBNMS will allow us to identify commonalities among large-scale freshwater runoff events and track the response of benthic invertebrate health, microbial community diversity, and the trajectory of reef community recovery or decline. The investigators will determine if changes in water chemistry induce pelagic microbial shifts, if microbial communities typically associated with corals and sponges are altered, and whether feedbacks occur between these potential drivers of benthic invertebrate mortality.