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Valerie J. Paul

Publications and source records attributed to Valerie J. Paul.

7 recordsLinked to original sources
USGS2023

Investigating microbial size classes associated with the transmission of stony coral tissue loss disease (SCTLD)

Effective treatment and prevention of any disease necessitates knowledge of the causative agent, yet the causative agents of most coral diseases remain unknown, in part due to the difficulty of distinguishing the pathogenic microbe(s) among the complex microbial backdrop of coral hosts. Stony coral tissue loss disease (SCTLD) is a particularly destructive disease of unknown etiology, capable of transmitting through the water column and killing entire colonies within a matter of weeks. Here we used a previously described method to (i) isolate diseased and apparently healthy coral colonies within individual mesocosms containing filtered seawater with low microbial background levels; (ii) incubate for several days to enrich the water with coral-shed microbes; (iii) use tangential-flow filtration to concentrate the microbial community in the mesocosm water; and then (iv) filter the resulting concentrate through a sequential series of different pore-sized filters. To investigate the size class of microorganism(s) associated with SCTLD transmission, we used 0.8 µm pore size filters to capture microeukaryotes and expelled zooxanthellae, 0.22 µm pore size filters to capture bacteria and large viruses, and 0.025 µm pore size filters to capture smaller viruses. In an attempt to further refine which size fraction(s) contained the transmissible element of SCTLD, we then applied these filters to healthy “receiver” coral fragments and monitored them for the onset of SCTLD signs over three separate experimental runs. However, several factors outside of our control confounded the transmission results, rendering them inconclusive. As the bulk of prior studies of SCTLD in coral tissues have primarily investigated the associated bacterial community, we chose to characterize the prokaryotic community associated with all mesocosm 0.22 µm pore size filters using Illumina sequencing of the V4 region of the 16S rRNA gene. We identified overlaps with prior SCTLD studies, including the presence of numerous previously identified SCTLD bioindicators within our mesocosms. The identification in our mesocosms of specific bacterial amplicon sequence variants that also appear across prior studies spanning different collection years, geographic regions, source material, and coral species, suggests that bacteria may play some role in the disease.

PeerJ↗
USGS2023

Rapid prototyping for quantifying belief weights of competing hypotheses about emergent diseases

Emerging diseases can have devastating consequences for wildlife and require a rapid response. A critical first step towards developing appropriate management is identifying the etiology of the disease, which can be difficult to determine, particularly early in emergence. Gathering and synthesizing existing information about potential disease causes, by leveraging expert knowledge or relevant existing studies, provides a principled approach to quickly inform decision-making and management efforts. Additionally, updating the current state of knowledge as more information becomes available over time can reduce scientific uncertainty and lead to substantial improvement in the decision-making process and the application of management actions that incorporate and adapt to newly acquired scientific understanding. Here we present a rapid prototyping method for quantifying belief weights for competing hypotheses about the etiology of disease using a combination of formal expert elicitation and Bayesian hierarchical modeling. We illustrate the application of this approach for investigating the etiology of stony coral tissue loss disease (SCTLD) and discuss the opportunities and challenges of this approach for addressing emergent diseases. Lastly, we detail how our work may apply to other pressing management or conservation problems that require quick responses. We found the rapid prototyping methods to be an efficient and rapid means to narrow down the number of potential hypotheses, synthesize current understanding, and help prioritize future studies and experiments. This approach is rapid by providing a snapshot assessment of the current state of knowledge. It can also be updated periodically (e.g., annually) to assess changes in belief weights over time as scientific understanding increases. Synthesis and applications: The rapid prototyping approaches demonstrated here can be used to combine knowledge from multiple experts and/or studies to help with fast decision-making needed for urgent conservation issues including emerging diseases and other management problems that require rapid responses. These approaches can also be used to adjust belief weights over time as studies and expert knowledge accumulate and can be a helpful tool for adapting management decisions.

Journal of Environmental Management↗
USGS2022

Biofilms as potential reservoirs of stony coral tissue loss disease

Since 2014, corals throughout Florida’s Coral Reef have been plagued by an epizootic of unknown etiology, colloquially termed stony coral tissue loss disease (SCTLD). Although in Florida the movement of this waterborne coral disease has been consistent with natural transport via water currents, outbreaks in the Caribbean have been more sporadic, with infections occurring in locations inconsistent with spread via natural means. Often Caribbean outbreaks have been clustered near ports, potentially implicating ships as mediators of SCTLD into new regions. Biofilms attached to ship hulls, ballast tank walls, or other surfaces could represent a possible vector for the disease. We investigated whether bacteria shed by healthy and SCTLD-diseased corals would form distinct biofilms, and whether a SCTLD signal would be detectable within biofilm bacterial communities. Stainless steel plates serving as proxies for ship hulls, ballast tank walls, and other colonizable surfaces were incubated for three days in filtered seawater mesocosms containing healthy or SCTLD-infected corals. Resulting biofilm bacterial communities were characterized through sequencing of the V4 region of the 16S rRNA gene. We determined that bacteria shed by healthy and diseased corals formed significantly different biofilms consisting of highly diverse taxa. Comparison with 16S data from previous SCTLD investigations spanning different coral species, collection locations, years, and source material revealed the presence of numerous genetically identical sequences within the biofilm bacterial communities formed during exposure to SCTLD-infected corals, including several previously identified as possible SCTLD bioindicators. These results suggest ship-associated biofilms may have the potential to be vectors for the transmission of SCTLD into new regions.

Frontiers in Marine Science↗
USGS2022

Combining tangential flow filtration and size fractionation of mesocosm water as a method for the investigation of waterborne coral diseases

The causative agents of most coral diseases today remain unknown, complicating disease response and restoration efforts. Pathogen identifications can be hampered by complex microbial communities naturally associated with corals and seawater, which create complicating “background noise” that can potentially obscure a pathogen’s signal. Here, we outline an approach to investigate waterborne coral diseases that use a combination of coral mesocosms, tangential flow filtration, and size fractionation to reduce the impact of this background microbial diversity, compensate for unknown infectious dose, and further narrow the suspect pool of potential pathogens. As proof of concept, we use this method to compare the bacterial communities shed into six Montastraea cavernosa coral mesocosms and demonstrate this method effectively detects differences between diseased and healthy coral colonies. We found several amplicon sequence variants (ASVs) in the diseased mesocosms that represented 100% matches with ASVs identified in prior studies of diseased coral tissue, further illustrating the effectiveness of our approach. Our described method is an effective alternative to using coral tissue or mucus to investigate waterborne coral diseases of unknown etiology and can help more quickly narrow the pool of possible pathogens to better aid in disease response efforts. Additionally, this versatile method can be easily adapted to characterize either the entire microbial community associated with a coral or target-specific microbial groups, making it a beneficial approach regardless of whether a causative agent is suspected or is completely unknown.

Florida↗
USGS2011

Chemically-mediated interactions between macroalgae Dictyota spp. and multiple life-history stages of the coral Porites astreoides

Competition between corals and macroalgae is often assumed to occur on reefs, especially those that have undergone shifts from coral to algal dominance; however, data examining these competitive interactions, especially during the early life-history stages of corals, are scarce. We conducted a series of field and outdoor seawater-table experiments to test the hypothesis that allelopathy (chemical inhibition) mediates interactions between 2 common brown macroalgae, Dictyota pulchella and D. pinnatifida , and the coral Porites astreoides at different life-history stages of the coral. D. pinnatifida significantly reduced larval survival and larval recruitment. The extracts of both D. pinnatifida and D. pulchella significantly reduced larval survival, and the extract of D. pulchella also negatively influenced larval recruitment. There was no measurable effect of the crude extracts from Dictyota spp. on the photophysiology of adult corals. Our results provide evidence that these Dictyota species chemically compete with P. astreoides by negatively affecting larval settlement and recruitment as well as the survival of larvae and new recruits. Macroalgae may perpetuate their dominance on degraded reefs by chemically inhibiting the process of coral recruitment.

Marine Ecology Progress Series↗