More Like this

1. On a Reef Far, Far Away: Anthropogenic Impacts Following Extreme Storms Affect Sponge Health and Bacterial Communities

   https://doi.org/10.3389/fmars.2021.608036  

   Shore, Amanda; Sims, Jordan A.; Grimes, Michael; Howe-Kerr, Lauren I.; Grupstra, Carsten G.; Doyle, Shawn M.; Stadler, Lauren; Sylvan, Jason B.; Shamberger, Kathryn E.; Davies, Sarah W.; et al (April 2021, Frontiers in Marine Science)

   null (Ed.)

   Terrestrial runoff can negatively impact marine ecosystems through stressors including excess nutrients, freshwater, sediments, and contaminants. Severe storms, which are increasing with global climate change, generate massive inputs of runoff over short timescales (hours to days); such runoff impacted offshore reefs in the northwest Gulf of Mexico (NW GoM) following severe storms in 2016 and 2017. Several weeks after coastal flooding from these events, NW GoM reef corals, sponges, and other benthic invertebrates ∼185 km offshore experienced mortality (2016 only) and/or sub-lethal stress (both years). To assess the impact of storm-derived runoff on reef filter feeders, we characterized the bacterial communities of two sponges, Agelas clathrodes and Xestospongia muta , from offshore reefs during periods of sub-lethal stress and no stress over a three-year period (2016—2018). Sponge-associated and seawater-associated bacterial communities were altered during both flood years. Additionally, we found evidence of wastewater contamination (based on 16S rRNA gene libraries and quantitative PCR) in offshore sponge samples, but not in seawater samples, following these flood years. Signs of wastewater contamination were absent during the no-flood year. We show that flood events from severe storms have the capacity to reach offshore reef ecosystems and impact resident benthic organisms. Such impacts are most readily detected if baseline data on organismal physiology and associated microbiome composition are available. This highlights the need for molecular and microbial time series of benthic organisms in near- and offshore reef ecosystems, and the continued mitigation of stormwater runoff and climate change impacts. 

   more » « less
2. Gene Expression of Endangered Coral (Orbicella spp.) in Flower Garden Banks National Marine Sanctuary After Hurricane Harvey

   https://doi.org/doi.org/10.3389/fmars.2019.00672  

   Wright, Rachel M.; Correa, Adrienne M.; Quigley, Lucinda A.; Santiago-Vázquez, Lory Z.; Shamberger, Kathryn E.; Davies, Sarah W. (November 2019, Frontiers in marine science)

   About 190 km south of the Texas–Louisiana border, the East and West Flower Garden Banks (FGB) have maintained > 50% coral cover with infrequent and minor incidents of disease or bleaching since monitoring began in the 1970s. However, a mortality event, affecting 5.6 ha (2.6% of the area) of the East FGB, occurred in late July 2016 and coincided with storm-generated freshwater runoff extending offshore and over the reef system. To capture the immediate effects of storm-driven freshwater runoff on coral and symbiont physiology, we leveraged the heavy rainfall associated with Hurricane Harvey in late August 2017 by sampling FGB corals at two time points: September 2017, when surface water salinity was reduced (∼34 ppt); and 1 month later when salinity had returned to typical levels (∼36 ppt in October 2017). Tissue samples (N = 47) collected midday were immediately preserved for gene expression profiling from two congeneric coral species (Orbicella faveolata and Orbicella franksi) from the East and West FGB to determine the physiological consequences of storm-derived runoff. In the coral, differences between host species and sampling time points accounted for the majority of differentially expressed genes. Gene ontology enrichment for genes differentially expressed immediately after Hurricane Harvey indicated increases in cellular oxidative stress responses. Although tissue loss was not observed on FGB reefs following Hurricane Harvey, our results suggest that poor water quality following this storm caused FGB corals to experience sub-lethal stress. We also found dramatic expression differences across sampling time points in the coral’s algal symbiont, Breviolum minutum. Some of these differentially expressed genes may be involved in the symbionts’ response to changing environments, including a group of differentially expressed post-transcriptional RNA modification genes. In this study, we cannot disentangle the effects of reduced salinity from the collection time point, so these expression patterns could also be related to seasonality. These findings highlight the urgent need for continued monitoring of these reef systems to establish a baseline for gene expression of healthy corals in the FGB system across seasons, as well as the need for integrated solutions to manage stormwater runoff in the Gulf of Mexico. 

   more » « less
3. Increased dominance of heat-tolerant symbionts creates resilient coral reefs in near-term ocean warming

   https://doi.org/10.1073/pnas.2202388120  

   Palacio-Castro, Ana M.; Smith, Tyler B.; Brandtneris, Viktor; Snyder, Grace A.; van Hooidonk, Ruben; Maté, Juan L.; Manzello, Derek; Glynn, Peter W.; Fong, Peggy; Baker, Andrew C. (February 2023, Proceedings of the National Academy of Sciences)

   Climate change is radically altering coral reef ecosystems, mainly through increasingly frequent and severe bleaching events. Yet, some reefs have exhibited higher thermal tolerance after bleaching severely the first time. To understand changes in thermal tolerance in the eastern tropical Pacific (ETP), we compiled four decades of temperature, coral cover, coral bleaching, and mortality data, including three mass bleaching events during the 1982 to 1983, 1997 to 1998 and 2015 to 2016 El Niño heatwaves. Higher heat resistance in later bleaching events was detected in the dominant framework-building genus, Pocillopora, while other coral taxa exhibited similar susceptibility across events. Genetic analyses of Pocillopora spp . colonies and their algal symbionts (2014 to 2016) revealed that one of two Pocillopora lineages present in the region ( Pocillopora “ type 1”) increased its association with thermotolerant algal symbionts ( Durusdinium glynnii ) during the 2015 to 2016 heat stress event. This lineage experienced lower bleaching and mortality compared with Pocillopora “type 3”, which did not acquire D. glynnii . Under projected thermal stress, ETP reefs may be able to preserve high coral cover through the 2060s or later, mainly composed of Pocillopora colonies that associate with D. glynnii . However, although the low-diversity, high-cover reefs of the ETP could illustrate a potential functional state for some future reefs, this state may only be temporary unless global greenhouse gas emissions and resultant global warming are curtailed. 

   more » « less
4. Severe and widespread coral reef damage during the 2014-2017 Global Coral Bleaching Event

   https://doi.org/10.1038/s41467-025-67506-w  

   Eakin, C Mark; Heron, Scott F; Connolly, Sean R; Devotta, Denise A; Liu, Gang; Geiger, Erick F; De_La_Cour, Jacqueline L; Gomez, Andrea M; Skirving, William J; Baird, Andrew H; et al (December 2026, Nature Communications)

   Abstract Ocean warming is increasing the frequency, extent, and severity of tropical-coral bleaching and mortality. During 2014–2017, marine heatwaves caused the Third Global Coral Bleaching Event. We analyze data from 15,066 reef surveys globally during 2014–2017. Across all surveyed reefs, 80% and 35% experienced moderate or greater (affecting >10% of corals) bleaching and mortality, respectively. We assess the global extent of coral bleaching and mortality by applying bleaching response curves calibrated from surveyed reefs to predict bleaching globally, based on comprehensive remote-sensing of heat stress. These models predict that 51% and 15% of the world’s coral reefs suffered moderate or greater bleaching and mortality, respectively, during one or multiple years, surpassing damage from any prior global coral bleaching event. Our findings demonstrate that the impacts of ocean warming on coral reefs are accelerating, with the near certainty that ongoing warming will cause large-scale, possibly irreversible, degradation of these essential ecosystems. With heat stress levels during this event surpassing those observed previously, the National Oceanic and Atmospheric Administration developed more extreme Bleaching Alert levels that are now being used during the ongoing Fourth Global Coral Bleaching Event. 

   more » « less
5. Mesoscale Circulation and Coral Community Disturbance at Isolated Reefs

   https://doi.org/10.1002/gcb4.70005  

   Carpenter, Gaby E; Farmer, Benjamin H; Craft, Hannah E; Apprill, Amy; Brandt, Marilyn E; Correa, Adrienne_M S; Mydlarz, Laura D; Holstein, Daniel M (January 2026, Global Change Biology Communications)

   ABSTRACT Marine disturbance events are often influenced by the environment, making it difficult to parse abiotic and biotic drivers. This is particularly true of disease infection and spread in coral reef environments, where pathogens are challenging to isolate and transmission may occur through the movement of water masses. Here we assess mesoscale conditions related to coral community disturbance from 2001 to 2023 on isolated reefs, using the Flower Garden Banks (FGB) as a case study. During the study period, relative to other western Atlantic reefs, this high latitude coral reef system experienced relatively few disturbance events (2 disease events, 1 hypoxia event, and 6 thermal stress events) and lower coral mortality, allowing it to maintain remarkably high coral cover. We explore mesoscale oceanographic features during the study period, predominantly the northwest extension of the Loop Current (LC), to understand its connection to disturbance events at FGB. LC position was linked to disease and hypoxia events, but not consistently to thermal stress events. Low LC extension, as seen in 2016, may have facilitated the transport of freshwater river output across the GoM resulting in a hypoxia event at FGB. To examine the influence of circulation and upstream connectivity to disease at FGB, we used a biophysical Lagrangian particle tracking model to backtrack virtual disease agents from FGB over 23 years of hydrodynamic forcing. Our results highlight a link between observed coral disease incidence at FGB, seasonality, and a 30‐day connectivity window to reefs of the Mesoamerican Reef. Operational biophysical and oceanographic models can provide a valuable tool for reef disturbance prediction and monitoring. These models are likely to become increasingly relevant as climate change alters the behavior of ocean circulation, with implications for reef connectivity, disease dispersal, freshwater inputs, and the management of these and other isolated coral reefs. 

   more » « less