Dustin Kemp | The University of Georgia (original) (raw)
Papers by Dustin Kemp
PLOS ONE, 2015
Coral surface mucus layer (SML) microbiota are critical components of the coral holobiont and pla... more Coral surface mucus layer (SML) microbiota are critical components of the coral holobiont and play important roles in nutrient cycling and defense against pathogens. We sequenced 16S rRNA amplicons to examine the structure of the SML microbiome within and between colonies of the threatened Caribbean reef-building coral Acropora palmata in the Florida Keys. Samples were taken from three spatially distinct colony regions-uppermost (high irradiance), underside (low irradiance), and the colony base-representing microhabitats that vary in irradiance and water flow. Phylogenetic diversity (PD) values of coral SML bacteria communities were greater than surrounding seawater and lower than adjacent sediment. Bacterial diversity and community composition was consistent among the three microhabitats. Cyanobacteria, Bacteroidetes, Alphaproteobacteria, and Proteobacteria, respectively were the most abundant phyla represented in the samples. This is the first time spatial variability of the surface mucus layer of A. palmata has been studied. Homogeneity in the microbiome of A. palmata contrasts with SML heterogeneity found in other Caribbean corals. These findings suggest that, during non-stressful conditions, host regulation of SML microbiota may override diverse physiochemical influences induced by the topographical complexity of A. palmata. Documenting the spatial distribution of SML microbes is essential to understanding the functional roles these microorganisms play in coral health and adaptability to environmental perturbations.
PLOS ONE, 2015
Coral surface mucus layer (SML) microbiota are critical components of the coral holobiont and pla... more Coral surface mucus layer (SML) microbiota are critical components of the coral holobiont and play important roles in nutrient cycling and defense against pathogens. We sequenced 16S rRNA amplicons to examine the structure of the SML microbiome within and between colonies of the threatened Caribbean reef-building coral Acropora palmata in the Florida Keys. Samples were taken from three spatially distinct colony regions-uppermost (high irradiance), underside (low irradiance), and the colony base-representing microhabitats that vary in irradiance and water flow. Phylogenetic diversity (PD) values of coral SML bacteria communities were greater than surrounding seawater and lower than adjacent sediment. Bacterial diversity and community composition was consistent among the three microhabitats. Cyanobacteria, Bacteroidetes, Alphaproteobacteria, and Proteobacteria, respectively were the most abundant phyla represented in the samples. This is the first time spatial variability of the surface mucus layer of A. palmata has been studied. Homogeneity in the microbiome of A. palmata contrasts with SML heterogeneity found in other Caribbean corals. These findings suggest that, during non-stressful conditions, host regulation of SML microbiota may override diverse physiochemical influences induced by the topographical complexity of A. palmata. Documenting the spatial distribution of SML microbes is essential to understanding the functional roles these microorganisms play in coral health and adaptability to environmental perturbations.
Applied and environmental microbiology, Jan 24, 2015
White pox disease (WPD) affects the threatened elkhorn coral, Acropora palmata. Owing in part to ... more White pox disease (WPD) affects the threatened elkhorn coral, Acropora palmata. Owing in part to the lack of a rapid and simple diagnostic test, there have been few systematic assessments of the prevalence of acroporid serratiosis (caused specifically by Serratia marcescens) versus general WPD signs. Six reefs in the Florida Keys were surveyed between 2011 and 2013 to determine disease status of A. palmata and prevalence of S. marcescens. WPD was noted at 4 of the 6 reefs, with WPD lesions found on 8% - 40% of the surveyed colonies. No disease-associated mortality was observed. S. marcescens was detected in 26.9% (7/26) of WPD lesions and in mucus from apparently healthy colonies, both during and outside of disease events (9%; 18/201). S. marcescens was detected with greater frequency in A. palmata than in the overlying water column, regardless of disease status (P = 0.0177 ). S. marcescens could not be cultured from A. palmata but was isolated from healthy colonies of other coral s...
Applied and environmental microbiology, Jan 24, 2015
White pox disease (WPD) affects the threatened elkhorn coral, Acropora palmata. Owing in part to ... more White pox disease (WPD) affects the threatened elkhorn coral, Acropora palmata. Owing in part to the lack of a rapid and simple diagnostic test, there have been few systematic assessments of the prevalence of acroporid serratiosis (caused specifically by Serratia marcescens) versus general WPD signs. Six reefs in the Florida Keys were surveyed between 2011 and 2013 to determine disease status of A. palmata and prevalence of S. marcescens. WPD was noted at 4 of the 6 reefs, with WPD lesions found on 8% - 40% of the surveyed colonies. No disease-associated mortality was observed. S. marcescens was detected in 26.9% (7/26) of WPD lesions and in mucus from apparently healthy colonies, both during and outside of disease events (9%; 18/201). S. marcescens was detected with greater frequency in A. palmata than in the overlying water column, regardless of disease status (P = 0.0177 ). S. marcescens could not be cultured from A. palmata but was isolated from healthy colonies of other coral s...
Coral reefs of the Florida Keys typically experience seasonal temperatures of 20–31 °C. Deviation... more Coral reefs of the Florida Keys typically experience seasonal temperatures of 20–31 °C. Deviation outside of this range causes physiological impairment, potentially leading to colony death. In January and February 2010, two closely spaced cold fronts caused record-breaking cold temperatures producing sudden and severe seawater temperature declines in the Florida Keys. Inshore coral reefs (e.g., Admiral Reef) experienced lower sustained temperatures (i.e., <12 °C) than those further offshore (e.g., Little Grecian Reef, minimum temperature = 17.2 °C). During February and March 2010, we surveyed Admiral Reef and observed a mass die-off of reef-building corals, whereas 12 km away Little Grecian Reef did not exhibit coral mortality. Following this event, the physiological effects of low temperature stress on three common reef-building corals (Montastraea faveolata, Porites astreoides, Siderastrea siderea) were experimentally investigated over a range of temperatures that replicated the inshore cold-water anomaly (i.e., from 20 °C to 16 °C to 12 °C and back to 20 °C). Throughout the temperature modulation, coral respiration as well as endosymbiont gross photosynthesis and maximum PSII photosynthetic efficiency were measured. In addition to these physiological measurements, Symbiodinium genetic identity, cell densities and chlorophyll a content were quantified at the beginning and conclusion of the experiment. Although all corals were significantly affected at 12 °C, species-specific physiological responses were found indicating different coral and/or zooxanthellaSymbiodiniume cold tolerances. Montastraea faveolata and P. astreoides appeared to be most negatively impacted upon return to 20 °C, with significant reductions in gross photosynthesis and dark respiration. Under comparable temperature conditions, S. siderea recovered to pre-treatment rates of dark respiration and gross photosynthesis. Visual surveys of inshore reefs corroborated these results, with S. siderea being minimally affected by the cold-water anomaly whereas M. faveolata and P. astreoides experienced approximately nearly 100% mortality. This study highlights the importance of understanding genetically distinct coral-Symbiodinium symbioses and emphasizes potential physiological tolerance, recovery and consequences to an environmental perturbation. These data document a less studied environmental stressor that inshore Florida Key coral reefs are subjected to and highlight the importance of understanding how local weather and long-term global change will affect coral-Symbiodinium symbioses and coral reef communities.
Coral Reefs, 2010
Denaturing gradient gel electrophoresis (DGGE) is commonly utilized to identify and quantify micr... more Denaturing gradient gel electrophoresis (DGGE) is commonly utilized to identify and quantify microbial diversity, but the conditions required for different electrophoretic systems to yield equivalent results and optimal resolution have not been assessed. Herein, the influence of different DGGE system configuration parameters on microbial diversity estimates was tested using Symbiodinium, a group of marine eukaryotic microbes that are important constituents of coral reef ecosystems. To accomplish this, bacterial clone libraries were constructed and sequenced from cultured isolates of Symbiodinium for the ribosomal DNA internal transcribed spacer 2 (ITS2) region. From these, 15 clones were subjected to PCR with a GC clamped primer set for DGGE analyses. Migration behaviors of the resulting amplicons were analyzed using a range of conditions, including variation in the composition of the denaturing gradient, electrophoresis time, and applied voltage. All tests were conducted in parallel on two commercial DGGE systems, a C.B.S. Scientific DGGE-2001, and the Bio-Rad DCode system. In this context, identical nucleotide fragments exhibited differing migration behaviors depending on the model of apparatus utilized, with fragments denaturing at a lower gradient concentration and applied voltage on the Bio-Rad DCode system than on the C.B.S. Scientific DGGE-2001 system. Although equivalent PCR–DGGE profiles could be achieved with both brands of DGGE system, the composition of the denaturing gradient and application of electrophoresis time × voltage must be appropriately optimized to achieve congruent results across platforms.
Journal of Phycology, 2008
Coral Reefs, 2006
Coral bleaching, in which corals become visibly pale and typically lose their endosymbiotic zooxa... more Coral bleaching, in which corals become visibly pale and typically lose their endosymbiotic zooxanthellae (Symbiodinium spp.), increasingly threatens coral reefs worldwide. While the proximal environmental triggers of bleaching are reasonably well understood, considerably less is known concerning physiological and ecological factors that might exacerbate coral bleaching or delay recovery. We report a bleaching event in Belize during September 2004 in which Montastraea spp. corals that had been previously grazed by corallivorous parrotfishes showed a persistent reduction in symbiont density compared to intact colonies. Additionally, grazed corals exhibited greater diversity in the genetic composition of their symbiont communities, changing from uniform ITS2 type C7 Symbiodinium prior to bleaching to mixed assemblages of Symbiodinium types post-bleaching. These results suggest that chronic predation may exacerbate the influence of environmental stressors and, by altering the coral-zooxanthellae symbiosis, such abiotic-biotic interactions may contribute to spatial variation in bleaching processes.
Limnology and Oceanography, 2014
Journal of Phycology, 2008
PLOS ONE, 2015
Coral surface mucus layer (SML) microbiota are critical components of the coral holobiont and pla... more Coral surface mucus layer (SML) microbiota are critical components of the coral holobiont and play important roles in nutrient cycling and defense against pathogens. We sequenced 16S rRNA amplicons to examine the structure of the SML microbiome within and between colonies of the threatened Caribbean reef-building coral Acropora palmata in the Florida Keys. Samples were taken from three spatially distinct colony regions-uppermost (high irradiance), underside (low irradiance), and the colony base-representing microhabitats that vary in irradiance and water flow. Phylogenetic diversity (PD) values of coral SML bacteria communities were greater than surrounding seawater and lower than adjacent sediment. Bacterial diversity and community composition was consistent among the three microhabitats. Cyanobacteria, Bacteroidetes, Alphaproteobacteria, and Proteobacteria, respectively were the most abundant phyla represented in the samples. This is the first time spatial variability of the surface mucus layer of A. palmata has been studied. Homogeneity in the microbiome of A. palmata contrasts with SML heterogeneity found in other Caribbean corals. These findings suggest that, during non-stressful conditions, host regulation of SML microbiota may override diverse physiochemical influences induced by the topographical complexity of A. palmata. Documenting the spatial distribution of SML microbes is essential to understanding the functional roles these microorganisms play in coral health and adaptability to environmental perturbations.
PLOS ONE, 2015
Coral surface mucus layer (SML) microbiota are critical components of the coral holobiont and pla... more Coral surface mucus layer (SML) microbiota are critical components of the coral holobiont and play important roles in nutrient cycling and defense against pathogens. We sequenced 16S rRNA amplicons to examine the structure of the SML microbiome within and between colonies of the threatened Caribbean reef-building coral Acropora palmata in the Florida Keys. Samples were taken from three spatially distinct colony regions-uppermost (high irradiance), underside (low irradiance), and the colony base-representing microhabitats that vary in irradiance and water flow. Phylogenetic diversity (PD) values of coral SML bacteria communities were greater than surrounding seawater and lower than adjacent sediment. Bacterial diversity and community composition was consistent among the three microhabitats. Cyanobacteria, Bacteroidetes, Alphaproteobacteria, and Proteobacteria, respectively were the most abundant phyla represented in the samples. This is the first time spatial variability of the surface mucus layer of A. palmata has been studied. Homogeneity in the microbiome of A. palmata contrasts with SML heterogeneity found in other Caribbean corals. These findings suggest that, during non-stressful conditions, host regulation of SML microbiota may override diverse physiochemical influences induced by the topographical complexity of A. palmata. Documenting the spatial distribution of SML microbes is essential to understanding the functional roles these microorganisms play in coral health and adaptability to environmental perturbations.
Applied and environmental microbiology, Jan 24, 2015
White pox disease (WPD) affects the threatened elkhorn coral, Acropora palmata. Owing in part to ... more White pox disease (WPD) affects the threatened elkhorn coral, Acropora palmata. Owing in part to the lack of a rapid and simple diagnostic test, there have been few systematic assessments of the prevalence of acroporid serratiosis (caused specifically by Serratia marcescens) versus general WPD signs. Six reefs in the Florida Keys were surveyed between 2011 and 2013 to determine disease status of A. palmata and prevalence of S. marcescens. WPD was noted at 4 of the 6 reefs, with WPD lesions found on 8% - 40% of the surveyed colonies. No disease-associated mortality was observed. S. marcescens was detected in 26.9% (7/26) of WPD lesions and in mucus from apparently healthy colonies, both during and outside of disease events (9%; 18/201). S. marcescens was detected with greater frequency in A. palmata than in the overlying water column, regardless of disease status (P = 0.0177 ). S. marcescens could not be cultured from A. palmata but was isolated from healthy colonies of other coral s...
Applied and environmental microbiology, Jan 24, 2015
White pox disease (WPD) affects the threatened elkhorn coral, Acropora palmata. Owing in part to ... more White pox disease (WPD) affects the threatened elkhorn coral, Acropora palmata. Owing in part to the lack of a rapid and simple diagnostic test, there have been few systematic assessments of the prevalence of acroporid serratiosis (caused specifically by Serratia marcescens) versus general WPD signs. Six reefs in the Florida Keys were surveyed between 2011 and 2013 to determine disease status of A. palmata and prevalence of S. marcescens. WPD was noted at 4 of the 6 reefs, with WPD lesions found on 8% - 40% of the surveyed colonies. No disease-associated mortality was observed. S. marcescens was detected in 26.9% (7/26) of WPD lesions and in mucus from apparently healthy colonies, both during and outside of disease events (9%; 18/201). S. marcescens was detected with greater frequency in A. palmata than in the overlying water column, regardless of disease status (P = 0.0177 ). S. marcescens could not be cultured from A. palmata but was isolated from healthy colonies of other coral s...
Coral reefs of the Florida Keys typically experience seasonal temperatures of 20–31 °C. Deviation... more Coral reefs of the Florida Keys typically experience seasonal temperatures of 20–31 °C. Deviation outside of this range causes physiological impairment, potentially leading to colony death. In January and February 2010, two closely spaced cold fronts caused record-breaking cold temperatures producing sudden and severe seawater temperature declines in the Florida Keys. Inshore coral reefs (e.g., Admiral Reef) experienced lower sustained temperatures (i.e., <12 °C) than those further offshore (e.g., Little Grecian Reef, minimum temperature = 17.2 °C). During February and March 2010, we surveyed Admiral Reef and observed a mass die-off of reef-building corals, whereas 12 km away Little Grecian Reef did not exhibit coral mortality. Following this event, the physiological effects of low temperature stress on three common reef-building corals (Montastraea faveolata, Porites astreoides, Siderastrea siderea) were experimentally investigated over a range of temperatures that replicated the inshore cold-water anomaly (i.e., from 20 °C to 16 °C to 12 °C and back to 20 °C). Throughout the temperature modulation, coral respiration as well as endosymbiont gross photosynthesis and maximum PSII photosynthetic efficiency were measured. In addition to these physiological measurements, Symbiodinium genetic identity, cell densities and chlorophyll a content were quantified at the beginning and conclusion of the experiment. Although all corals were significantly affected at 12 °C, species-specific physiological responses were found indicating different coral and/or zooxanthellaSymbiodiniume cold tolerances. Montastraea faveolata and P. astreoides appeared to be most negatively impacted upon return to 20 °C, with significant reductions in gross photosynthesis and dark respiration. Under comparable temperature conditions, S. siderea recovered to pre-treatment rates of dark respiration and gross photosynthesis. Visual surveys of inshore reefs corroborated these results, with S. siderea being minimally affected by the cold-water anomaly whereas M. faveolata and P. astreoides experienced approximately nearly 100% mortality. This study highlights the importance of understanding genetically distinct coral-Symbiodinium symbioses and emphasizes potential physiological tolerance, recovery and consequences to an environmental perturbation. These data document a less studied environmental stressor that inshore Florida Key coral reefs are subjected to and highlight the importance of understanding how local weather and long-term global change will affect coral-Symbiodinium symbioses and coral reef communities.
Coral Reefs, 2010
Denaturing gradient gel electrophoresis (DGGE) is commonly utilized to identify and quantify micr... more Denaturing gradient gel electrophoresis (DGGE) is commonly utilized to identify and quantify microbial diversity, but the conditions required for different electrophoretic systems to yield equivalent results and optimal resolution have not been assessed. Herein, the influence of different DGGE system configuration parameters on microbial diversity estimates was tested using Symbiodinium, a group of marine eukaryotic microbes that are important constituents of coral reef ecosystems. To accomplish this, bacterial clone libraries were constructed and sequenced from cultured isolates of Symbiodinium for the ribosomal DNA internal transcribed spacer 2 (ITS2) region. From these, 15 clones were subjected to PCR with a GC clamped primer set for DGGE analyses. Migration behaviors of the resulting amplicons were analyzed using a range of conditions, including variation in the composition of the denaturing gradient, electrophoresis time, and applied voltage. All tests were conducted in parallel on two commercial DGGE systems, a C.B.S. Scientific DGGE-2001, and the Bio-Rad DCode system. In this context, identical nucleotide fragments exhibited differing migration behaviors depending on the model of apparatus utilized, with fragments denaturing at a lower gradient concentration and applied voltage on the Bio-Rad DCode system than on the C.B.S. Scientific DGGE-2001 system. Although equivalent PCR–DGGE profiles could be achieved with both brands of DGGE system, the composition of the denaturing gradient and application of electrophoresis time × voltage must be appropriately optimized to achieve congruent results across platforms.
Journal of Phycology, 2008
Coral Reefs, 2006
Coral bleaching, in which corals become visibly pale and typically lose their endosymbiotic zooxa... more Coral bleaching, in which corals become visibly pale and typically lose their endosymbiotic zooxanthellae (Symbiodinium spp.), increasingly threatens coral reefs worldwide. While the proximal environmental triggers of bleaching are reasonably well understood, considerably less is known concerning physiological and ecological factors that might exacerbate coral bleaching or delay recovery. We report a bleaching event in Belize during September 2004 in which Montastraea spp. corals that had been previously grazed by corallivorous parrotfishes showed a persistent reduction in symbiont density compared to intact colonies. Additionally, grazed corals exhibited greater diversity in the genetic composition of their symbiont communities, changing from uniform ITS2 type C7 Symbiodinium prior to bleaching to mixed assemblages of Symbiodinium types post-bleaching. These results suggest that chronic predation may exacerbate the influence of environmental stressors and, by altering the coral-zooxanthellae symbiosis, such abiotic-biotic interactions may contribute to spatial variation in bleaching processes.
Limnology and Oceanography, 2014
Journal of Phycology, 2008