SAR11 bacteria dominate the surface ocean and are major players in converting fixed carbon back t... more SAR11 bacteria dominate the surface ocean and are major players in converting fixed carbon back to atmospheric carbon dioxide. The SAR11 clade is comprised of niche-specialized ecotypes that display distinctive spatiotemporal transitions. We analysed SAR11 ecotype seasonality in two long-term 16S rRNA amplicon time series representing different North Atlantic regimes: the Sargasso Sea (subtropical ocean-gyre; BATS) and the temperate coastal Western English Channel (WEC). Using phylogenetically resolved amplicon sequence variants (ASVs), we evaluated seasonal environmental constraints on SAR11 ecotype periodicity. Despite large differences in temperature and nutrient availability between the two sites, at both SAR11 succession was defined by summer and winter clusters of ASVs. Summer cluster was dominated by ecotype Ia.3 in both sites. Winter clusters were dominated by ecotypes Ib and IIa.A at BATS and Ia.1 and IIa.B at WEC. A two-year weekly analysis within the WEC time series showe...
Map of study location in the Barents Sea, correlations between key geochemical, modeled and measu... more Map of study location in the Barents Sea, correlations between key geochemical, modeled and measured datasets. PCA axis 1 & 2 scores plotted against depth.
Settlement panels that incorporate gas permeable membranes were designed to study the impact of i... more Settlement panels that incorporate gas permeable membranes were designed to study the impact of increased CO<sub>2</sub> on biofilm formation and succession in the field. Each panel consisted of a 3 mm thick PVC backing panel, 5 mm gas space, 5 mm reinforced silicone polymer membrane and a 3 mm thick PVC gasket to seal the layers of the unit. The exact pressure required to produce a drop of 0.3 pH units was carefully calibrated in laboratory experiments under varying hydrodynamic regimes. The panels were immersed in a fully marine tidal embayment at a depth of 1 meter and randomly assigned one of three treatments: ambient pH (not supplied with gas), ambient pH (supplied with ambient atmospheric air) and 0.3 pH units below ambient (supplied with CO<sub>2</sub> at pressure). At 2, 4, 6, 8 and 12 weeks after deployment, 5 replicate panels of each treatment type were randomly selected and the microbial component analysed. Measurements of biofilm wet weight, biofi...
This data set contains incubations with sediment cores to assess the effect of bioturbating macro... more This data set contains incubations with sediment cores to assess the effect of bioturbating macrofauna on the abundance of genes and transcripts associated with nitrogen cycling. The data were collected between 01-April-2015 to 28-August-2015 over 3 cruises on board the RRS Discovery (DY021, DY030, and DY034) in the Celtic Sea. The authors do not have any concerns over the quality of the data set and values are consistent with similar data reported in the wider literature. Replicate sediment cores (n = 5) of size 20 cm by 20 cm and depth 12 cm were collected from NIOZ cores taken at 4 sites (Muddy, site A; Sandy Mud, site G; Muddy Sand, site H; and Sand, site I). These sediment cores were transferred to clear perspex mesocosms and luminophores, coloured sand which fluoresces under ultra-violet light, were added to guide the selection of undisturbed and bioturbated sediment samples for RNA and DNA molecular analysis. The data were collected as part of the Shelf Sea Biogeochemistry (S...
A custom-built flume (mesocosm) facility was used to manipulate CO2 and temperature in order to t... more A custom-built flume (mesocosm) facility was used to manipulate CO2 and temperature in order to test the impacts of seawater acidification and warming on microbial taxonomic marker and nitrogen cycling-gene abundances in both muddy and sandy coastal sediments. Experimental treatment levels contained representatives of present day CO2 and temperature levels and of those expected by 2100 under a 'business-as-usual' scenario (IPCC, 2007), with an emphasis on the interactive effects of reduced pH and increased sea water temperature on benthic microorganisms.
Process-based, mechanistic investigations of organic matter transformation and diagenesis directl... more Process-based, mechanistic investigations of organic matter transformation and diagenesis directly beneath the sediment–water interface (SWI) in Arctic continental shelves are vital as these regions are at greatest risk of future change. This is in part due to disruptions in benthic–pelagic coupling associated with ocean current change and sea ice retreat. Here, we focus on a high-resolution, multi-disciplinary set of measurements that illustrate how microbial processes involved in the degradation of organic matter are directly coupled with inorganic and organic geochemical sediment properties (measured and modelled) as well as the extent/depth of bioturbation. We find direct links between aerobic processes, reactive organic carbon and highest abundances of bacteria and archaea in the uppermost layer (0–4.5 cm depth) followed by dominance of microbes involved in nitrate/nitrite and iron/manganese reduction across the oxic-anoxic redox boundary (approx. 4.5–10.5 cm depth). Sulfate reducers dominate in the deeper (approx. 10.5–33 cm) anoxic sediments which is consistent with the modelled reactive transport framework. Importantly, organic matter reactivity as tracked by organic geochemical parameters (<i>n</i>-alkanes, <i>n</i>-alkanoic acids, <i>n</i>-alkanols and sterols) changes most dramatically at and directly below the SWI together with sedimentology and biological activity but remained relatively unchanged across deeper changes in sedimentology.This article is part of the theme issue 'The Changing Arctic Ocean: consequences for biological communities, biogeochemical processes and ecosystems'.
Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences, 2020
Process-based, mechanistic investigations of organic matter transformation and diagenesis directl... more Process-based, mechanistic investigations of organic matter transformation and diagenesis directly beneath the sediment–water interface (SWI) in Arctic continental shelves are vital as these regions are at greatest risk of future change. This is in part due to disruptions in benthic–pelagic coupling associated with ocean current change and sea ice retreat. Here, we focus on a high-resolution, multi-disciplinary set of measurements that illustrate how microbial processes involved in the degradation of organic matter are directly coupled with inorganic and organic geochemical sediment properties (measured and modelled) as well as the extent/depth of bioturbation. We find direct links between aerobic processes, reactive organic carbon and highest abundances of bacteria and archaea in the uppermost layer (0–4.5 cm depth) followed by dominance of microbes involved in nitrate/nitrite and iron/manganese reduction across the oxic-anoxic redox boundary (approx. 4.5–10.5 cm depth). Sulfate re...
There is increasing interest in the use of microalgae grown on wastewater to provide useful metab... more There is increasing interest in the use of microalgae grown on wastewater to provide useful metabolites. Several bacteria have been shown to affect the growth rate and quality of the algae, but it is not clear if this is specific to a particular group of bacteria or if nutrient conditions can also influence this interaction. The bacterial community associated with a freshwater Chlorella sp. isolated from open pond textile factory wastewater was characterised and a diverse group of bacteria isolated. We provide evidence that nutrient concentrations affect bacterial community composition. When grown in BG11 medium, the community was dominated by Pseudomonas sp., but when grown in Chu 10 medium (which contains lower nitrogen and phosphorus), the relative abundance of a Brevundimonas spp. increased. Several of the bacteria isolated were able to influence the growth of an axenic Chlorella vulgaris culture. The Pseudomonas sp. had a negative effect in all media tested whereas several isolates enhanced C. vulgaris growth, but only in Chu 10 medium. This supports the theory that bacterial stimulation of algal growth is not limited to species-specific interactions but is influenced by environmental conditions. In low nutrient conditions, Chlorella sp. may be increasingly dependent on bacteria for growth.
We evaluate the effects of nutrient limitation on cellular composition of polar lipid classes/spe... more We evaluate the effects of nutrient limitation on cellular composition of polar lipid classes/species in Chlorella sp. using modern polar lipidomic profiling methods (liquid chromatography–tandem mass spectrometry; LC-MS/MS). Total polar lipid concentration was highest in nutrient-replete (HN) cultures with a significant reduction in monogalactosyldiacylglycerol (MGDG), phosphatidylglycerol (PG), phosphatidylcholine (PC), and phosphatidylethanolamine (PE) class concentrations for nutrient-deplete (LN) cultures. Moreover, reductions in the abundance of MGDG relative to total polar lipids versus an increase in the relative abundance of digalactosyldiacylglycerol (DGDG) were recorded in LN cultures. In HN cultures, polar lipid species composition remained relatively constant throughout culture with high degrees of unsaturation associated with acyl moieties. Conversely, in LN cultures lipid species composition shifted towards greater saturation of acyl moieties. Multivariate analyses re...
Since the banning of several families of compounds in antifouling (AF) coatings, the search for e... more Since the banning of several families of compounds in antifouling (AF) coatings, the search for environmentally friendly AF compounds has intensified. Natural sources of AF compounds have been identified in marine organisms and can be used to create analogues in laboratory. In a previous study, we identified that dibromohemibastadin-1 (DBHB) is a promising AF molecule, leading to the inhibition of the activity of phenoloxidase, an enzyme involved in the attachment of mussels to surfaces. This paper describes the activity of the DBHB on biofilm formation and its detachment and on bacterial adhesion and communication: quorum sensing. DBHB has an anti-biofilm activity without affecting adhesion of marine and terrestrial bacteria at a dose of 10 µM. Moreover, DBHB activity on quorum sensing (QS) is demonstrated at doses of 8 and 16 µM. The activity of DBHB on QS is compared to kojic acid, a quorum sensing inhibitor already described. This compound is a promising environmentally friendly...
Trichodesmium, a colonial cyanobacterium typically associated with tropical waters, was observed ... more Trichodesmium, a colonial cyanobacterium typically associated with tropical waters, was observed between January and April 2014 in the western English Channel. Sequencing of the heterocyst differentiation (hetR) and 16S rRNA genes placed this community within the Clade IV Trichodesmium, an understudied clade previously found only in low numbers in warmer waters. Nitrogen fixation was not detected although measurable rates of nitrate uptake and carbon fixation were observed. Trichodesmium RuBisCO transcript abundance relative to gene abundance suggests the potential for viable and potentially active Trichodesmium carbon fixation. Observations of Trichodesmium when coupled with a numerical advection model indicate that Trichodesmium communities can remain viable for .3.5 months at temperatures lower than previously expected. The results suggest that Clade IV Trichodesmium occupies a different niche to other Trichodesmium species, and is a cold-or low-light-adapted variant.
The bacterial communities associated with healthy and diseased colonies of the cold-water gorgoni... more The bacterial communities associated with healthy and diseased colonies of the cold-water gorgonian coral Eunicella verrucosa at three sites off the south-west coast of England were compared using denaturing gradient gel electrophoresis (DGGE) and clone libraries. Significant differences in community structure between healthy and diseased samples were discovered, as were differences in the level of disturbance to these communities at each site; this correlated with depth and sediment load. The majority of cloned sequences from healthy coral tissue affiliated with the Gammaproteobacteria. The stability of the bacterial community and dominance of specific genera found across visibly healthy colonies suggest the presence of a specific microbial community. Affiliations included a high proportion of Endozoicomonas sequences, which were most similar to sequences found in tropical corals. This genus has been found in a number of invertebrates and is suggested to have a role in coral health...
Data set abstract: Results are reported for the analysis of water samples taken from the overlyin... more Data set abstract: Results are reported for the analysis of water samples taken from the overlying water column of 4 different study sites occupied on a bi-monthly basis, were possible, during a 3 year Benthic Study programme of Plymouth, on the south-west coast of England, United Kingdom. The analyses are reported for Nitrate+Nitrite, Nitrite, Silicate and Phosphate concentrations. Results show variations across the year with the main influence to particularly the upper water column being the output of the River Tamar and the nutrients fed out during periods of rainfall. Water column structure is seen for each site, with the sites varying from L4 which is an offshore coastal site, Rame Head which is a essentially a mud based strata, to Cawsand Bay and Jennicliff which are both situated within Plymouth Sound and hence are shallow and are greatly influenced by the river outputs. Sampling methodology and description of analytical techniques: The nutrient samples were taken from the re...
The geological storage of carbon dioxide (CO2) is expected to be an important component of future... more The geological storage of carbon dioxide (CO2) is expected to be an important component of future global carbon emission mitigation, but there is a need to understand the impacts of a CO2 leak on the marine environment and to develop monitoring protocols for leakage detection. In the present study, sediment cores were exposed to CO2-acidified seawater at one of five pH levels (8.0, 7.5, 7.0, 6.5 and 6.0) for 10 weeks. A bloom of Spirulina sp. and diatoms appeared on sediment surface exposed to pH 7.0 and 7.5 seawater. Quantitative PCR measurements of the abundance of 16S rRNA also indicated an increase within the pH 7.0 and 7.5 treatments after 10 weeks incubation. More detailed analysis of the microbial communities from the pH 7.0, 7.5 and 8.0 treatments confirmed an increase in the relative abundance of Spirulina sp. and Navicula sp. sequences, with changes in the relative abundance of major archaeal and bacterial groups also detected within the pH 7.0 treatment. A decreased flux of silicate from the sediment at this pH was also detected. Monitoring blooms of microphytobenthos may prove useful as an indicator of CO2 leakage within coastal areas.
International Journal of Greenhouse Gas Control, 2015
ABSTRACT A sub-seabed release of carbon dioxide (CO2) was conducted to assess the potential impac... more ABSTRACT A sub-seabed release of carbon dioxide (CO2) was conducted to assess the potential impacts of leakage from sub-seabed geological CO2 Capture and Storage CCS) on benthic macrofauna. CO2 gas was released 12 m below the seabed for 37 days, causing significant disruption to sediment carbonate chemistry. Regular macrofauna samples were collected from within the area of active CO2 leakage (Zone 1) and in three additional reference areas, 25 m, 75 m and 450 m from the centre of the leakage (Zones 2, 3 and 4 respectively). Macrofaunal community structure changed significantly in all zones during the study period. However, only the changes in Zone 1 were driven by the CO2 leakage with the changes in reference zones appearing to reflect natural seasonal succession and stochastic weather events. The impacts in Zone 1 occurred rapidly (within a few days), increased in severity through the duration of the leak, and continued to worsen after the leak had stopped. Considerable macrofaunal recovery was seen 18 days after the CO2 gas injection had stopped. In summary, small short-term CCS leakage events are likely to cause highly localised impacts on macrofaunal communities and there is the potential for rapid recovery to occur, depending on the characteristics of the communities and habitats impacted.
SAR11 bacteria dominate the surface ocean and are major players in converting fixed carbon back t... more SAR11 bacteria dominate the surface ocean and are major players in converting fixed carbon back to atmospheric carbon dioxide. The SAR11 clade is comprised of niche-specialized ecotypes that display distinctive spatiotemporal transitions. We analysed SAR11 ecotype seasonality in two long-term 16S rRNA amplicon time series representing different North Atlantic regimes: the Sargasso Sea (subtropical ocean-gyre; BATS) and the temperate coastal Western English Channel (WEC). Using phylogenetically resolved amplicon sequence variants (ASVs), we evaluated seasonal environmental constraints on SAR11 ecotype periodicity. Despite large differences in temperature and nutrient availability between the two sites, at both SAR11 succession was defined by summer and winter clusters of ASVs. Summer cluster was dominated by ecotype Ia.3 in both sites. Winter clusters were dominated by ecotypes Ib and IIa.A at BATS and Ia.1 and IIa.B at WEC. A two-year weekly analysis within the WEC time series showe...
Map of study location in the Barents Sea, correlations between key geochemical, modeled and measu... more Map of study location in the Barents Sea, correlations between key geochemical, modeled and measured datasets. PCA axis 1 & 2 scores plotted against depth.
Settlement panels that incorporate gas permeable membranes were designed to study the impact of i... more Settlement panels that incorporate gas permeable membranes were designed to study the impact of increased CO<sub>2</sub> on biofilm formation and succession in the field. Each panel consisted of a 3 mm thick PVC backing panel, 5 mm gas space, 5 mm reinforced silicone polymer membrane and a 3 mm thick PVC gasket to seal the layers of the unit. The exact pressure required to produce a drop of 0.3 pH units was carefully calibrated in laboratory experiments under varying hydrodynamic regimes. The panels were immersed in a fully marine tidal embayment at a depth of 1 meter and randomly assigned one of three treatments: ambient pH (not supplied with gas), ambient pH (supplied with ambient atmospheric air) and 0.3 pH units below ambient (supplied with CO<sub>2</sub> at pressure). At 2, 4, 6, 8 and 12 weeks after deployment, 5 replicate panels of each treatment type were randomly selected and the microbial component analysed. Measurements of biofilm wet weight, biofi...
This data set contains incubations with sediment cores to assess the effect of bioturbating macro... more This data set contains incubations with sediment cores to assess the effect of bioturbating macrofauna on the abundance of genes and transcripts associated with nitrogen cycling. The data were collected between 01-April-2015 to 28-August-2015 over 3 cruises on board the RRS Discovery (DY021, DY030, and DY034) in the Celtic Sea. The authors do not have any concerns over the quality of the data set and values are consistent with similar data reported in the wider literature. Replicate sediment cores (n = 5) of size 20 cm by 20 cm and depth 12 cm were collected from NIOZ cores taken at 4 sites (Muddy, site A; Sandy Mud, site G; Muddy Sand, site H; and Sand, site I). These sediment cores were transferred to clear perspex mesocosms and luminophores, coloured sand which fluoresces under ultra-violet light, were added to guide the selection of undisturbed and bioturbated sediment samples for RNA and DNA molecular analysis. The data were collected as part of the Shelf Sea Biogeochemistry (S...
A custom-built flume (mesocosm) facility was used to manipulate CO2 and temperature in order to t... more A custom-built flume (mesocosm) facility was used to manipulate CO2 and temperature in order to test the impacts of seawater acidification and warming on microbial taxonomic marker and nitrogen cycling-gene abundances in both muddy and sandy coastal sediments. Experimental treatment levels contained representatives of present day CO2 and temperature levels and of those expected by 2100 under a 'business-as-usual' scenario (IPCC, 2007), with an emphasis on the interactive effects of reduced pH and increased sea water temperature on benthic microorganisms.
Process-based, mechanistic investigations of organic matter transformation and diagenesis directl... more Process-based, mechanistic investigations of organic matter transformation and diagenesis directly beneath the sediment–water interface (SWI) in Arctic continental shelves are vital as these regions are at greatest risk of future change. This is in part due to disruptions in benthic–pelagic coupling associated with ocean current change and sea ice retreat. Here, we focus on a high-resolution, multi-disciplinary set of measurements that illustrate how microbial processes involved in the degradation of organic matter are directly coupled with inorganic and organic geochemical sediment properties (measured and modelled) as well as the extent/depth of bioturbation. We find direct links between aerobic processes, reactive organic carbon and highest abundances of bacteria and archaea in the uppermost layer (0–4.5 cm depth) followed by dominance of microbes involved in nitrate/nitrite and iron/manganese reduction across the oxic-anoxic redox boundary (approx. 4.5–10.5 cm depth). Sulfate reducers dominate in the deeper (approx. 10.5–33 cm) anoxic sediments which is consistent with the modelled reactive transport framework. Importantly, organic matter reactivity as tracked by organic geochemical parameters (<i>n</i>-alkanes, <i>n</i>-alkanoic acids, <i>n</i>-alkanols and sterols) changes most dramatically at and directly below the SWI together with sedimentology and biological activity but remained relatively unchanged across deeper changes in sedimentology.This article is part of the theme issue 'The Changing Arctic Ocean: consequences for biological communities, biogeochemical processes and ecosystems'.
Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences, 2020
Process-based, mechanistic investigations of organic matter transformation and diagenesis directl... more Process-based, mechanistic investigations of organic matter transformation and diagenesis directly beneath the sediment–water interface (SWI) in Arctic continental shelves are vital as these regions are at greatest risk of future change. This is in part due to disruptions in benthic–pelagic coupling associated with ocean current change and sea ice retreat. Here, we focus on a high-resolution, multi-disciplinary set of measurements that illustrate how microbial processes involved in the degradation of organic matter are directly coupled with inorganic and organic geochemical sediment properties (measured and modelled) as well as the extent/depth of bioturbation. We find direct links between aerobic processes, reactive organic carbon and highest abundances of bacteria and archaea in the uppermost layer (0–4.5 cm depth) followed by dominance of microbes involved in nitrate/nitrite and iron/manganese reduction across the oxic-anoxic redox boundary (approx. 4.5–10.5 cm depth). Sulfate re...
There is increasing interest in the use of microalgae grown on wastewater to provide useful metab... more There is increasing interest in the use of microalgae grown on wastewater to provide useful metabolites. Several bacteria have been shown to affect the growth rate and quality of the algae, but it is not clear if this is specific to a particular group of bacteria or if nutrient conditions can also influence this interaction. The bacterial community associated with a freshwater Chlorella sp. isolated from open pond textile factory wastewater was characterised and a diverse group of bacteria isolated. We provide evidence that nutrient concentrations affect bacterial community composition. When grown in BG11 medium, the community was dominated by Pseudomonas sp., but when grown in Chu 10 medium (which contains lower nitrogen and phosphorus), the relative abundance of a Brevundimonas spp. increased. Several of the bacteria isolated were able to influence the growth of an axenic Chlorella vulgaris culture. The Pseudomonas sp. had a negative effect in all media tested whereas several isolates enhanced C. vulgaris growth, but only in Chu 10 medium. This supports the theory that bacterial stimulation of algal growth is not limited to species-specific interactions but is influenced by environmental conditions. In low nutrient conditions, Chlorella sp. may be increasingly dependent on bacteria for growth.
We evaluate the effects of nutrient limitation on cellular composition of polar lipid classes/spe... more We evaluate the effects of nutrient limitation on cellular composition of polar lipid classes/species in Chlorella sp. using modern polar lipidomic profiling methods (liquid chromatography–tandem mass spectrometry; LC-MS/MS). Total polar lipid concentration was highest in nutrient-replete (HN) cultures with a significant reduction in monogalactosyldiacylglycerol (MGDG), phosphatidylglycerol (PG), phosphatidylcholine (PC), and phosphatidylethanolamine (PE) class concentrations for nutrient-deplete (LN) cultures. Moreover, reductions in the abundance of MGDG relative to total polar lipids versus an increase in the relative abundance of digalactosyldiacylglycerol (DGDG) were recorded in LN cultures. In HN cultures, polar lipid species composition remained relatively constant throughout culture with high degrees of unsaturation associated with acyl moieties. Conversely, in LN cultures lipid species composition shifted towards greater saturation of acyl moieties. Multivariate analyses re...
Since the banning of several families of compounds in antifouling (AF) coatings, the search for e... more Since the banning of several families of compounds in antifouling (AF) coatings, the search for environmentally friendly AF compounds has intensified. Natural sources of AF compounds have been identified in marine organisms and can be used to create analogues in laboratory. In a previous study, we identified that dibromohemibastadin-1 (DBHB) is a promising AF molecule, leading to the inhibition of the activity of phenoloxidase, an enzyme involved in the attachment of mussels to surfaces. This paper describes the activity of the DBHB on biofilm formation and its detachment and on bacterial adhesion and communication: quorum sensing. DBHB has an anti-biofilm activity without affecting adhesion of marine and terrestrial bacteria at a dose of 10 µM. Moreover, DBHB activity on quorum sensing (QS) is demonstrated at doses of 8 and 16 µM. The activity of DBHB on QS is compared to kojic acid, a quorum sensing inhibitor already described. This compound is a promising environmentally friendly...
Trichodesmium, a colonial cyanobacterium typically associated with tropical waters, was observed ... more Trichodesmium, a colonial cyanobacterium typically associated with tropical waters, was observed between January and April 2014 in the western English Channel. Sequencing of the heterocyst differentiation (hetR) and 16S rRNA genes placed this community within the Clade IV Trichodesmium, an understudied clade previously found only in low numbers in warmer waters. Nitrogen fixation was not detected although measurable rates of nitrate uptake and carbon fixation were observed. Trichodesmium RuBisCO transcript abundance relative to gene abundance suggests the potential for viable and potentially active Trichodesmium carbon fixation. Observations of Trichodesmium when coupled with a numerical advection model indicate that Trichodesmium communities can remain viable for .3.5 months at temperatures lower than previously expected. The results suggest that Clade IV Trichodesmium occupies a different niche to other Trichodesmium species, and is a cold-or low-light-adapted variant.
The bacterial communities associated with healthy and diseased colonies of the cold-water gorgoni... more The bacterial communities associated with healthy and diseased colonies of the cold-water gorgonian coral Eunicella verrucosa at three sites off the south-west coast of England were compared using denaturing gradient gel electrophoresis (DGGE) and clone libraries. Significant differences in community structure between healthy and diseased samples were discovered, as were differences in the level of disturbance to these communities at each site; this correlated with depth and sediment load. The majority of cloned sequences from healthy coral tissue affiliated with the Gammaproteobacteria. The stability of the bacterial community and dominance of specific genera found across visibly healthy colonies suggest the presence of a specific microbial community. Affiliations included a high proportion of Endozoicomonas sequences, which were most similar to sequences found in tropical corals. This genus has been found in a number of invertebrates and is suggested to have a role in coral health...
Data set abstract: Results are reported for the analysis of water samples taken from the overlyin... more Data set abstract: Results are reported for the analysis of water samples taken from the overlying water column of 4 different study sites occupied on a bi-monthly basis, were possible, during a 3 year Benthic Study programme of Plymouth, on the south-west coast of England, United Kingdom. The analyses are reported for Nitrate+Nitrite, Nitrite, Silicate and Phosphate concentrations. Results show variations across the year with the main influence to particularly the upper water column being the output of the River Tamar and the nutrients fed out during periods of rainfall. Water column structure is seen for each site, with the sites varying from L4 which is an offshore coastal site, Rame Head which is a essentially a mud based strata, to Cawsand Bay and Jennicliff which are both situated within Plymouth Sound and hence are shallow and are greatly influenced by the river outputs. Sampling methodology and description of analytical techniques: The nutrient samples were taken from the re...
The geological storage of carbon dioxide (CO2) is expected to be an important component of future... more The geological storage of carbon dioxide (CO2) is expected to be an important component of future global carbon emission mitigation, but there is a need to understand the impacts of a CO2 leak on the marine environment and to develop monitoring protocols for leakage detection. In the present study, sediment cores were exposed to CO2-acidified seawater at one of five pH levels (8.0, 7.5, 7.0, 6.5 and 6.0) for 10 weeks. A bloom of Spirulina sp. and diatoms appeared on sediment surface exposed to pH 7.0 and 7.5 seawater. Quantitative PCR measurements of the abundance of 16S rRNA also indicated an increase within the pH 7.0 and 7.5 treatments after 10 weeks incubation. More detailed analysis of the microbial communities from the pH 7.0, 7.5 and 8.0 treatments confirmed an increase in the relative abundance of Spirulina sp. and Navicula sp. sequences, with changes in the relative abundance of major archaeal and bacterial groups also detected within the pH 7.0 treatment. A decreased flux of silicate from the sediment at this pH was also detected. Monitoring blooms of microphytobenthos may prove useful as an indicator of CO2 leakage within coastal areas.
International Journal of Greenhouse Gas Control, 2015
ABSTRACT A sub-seabed release of carbon dioxide (CO2) was conducted to assess the potential impac... more ABSTRACT A sub-seabed release of carbon dioxide (CO2) was conducted to assess the potential impacts of leakage from sub-seabed geological CO2 Capture and Storage CCS) on benthic macrofauna. CO2 gas was released 12 m below the seabed for 37 days, causing significant disruption to sediment carbonate chemistry. Regular macrofauna samples were collected from within the area of active CO2 leakage (Zone 1) and in three additional reference areas, 25 m, 75 m and 450 m from the centre of the leakage (Zones 2, 3 and 4 respectively). Macrofaunal community structure changed significantly in all zones during the study period. However, only the changes in Zone 1 were driven by the CO2 leakage with the changes in reference zones appearing to reflect natural seasonal succession and stochastic weather events. The impacts in Zone 1 occurred rapidly (within a few days), increased in severity through the duration of the leak, and continued to worsen after the leak had stopped. Considerable macrofaunal recovery was seen 18 days after the CO2 gas injection had stopped. In summary, small short-term CCS leakage events are likely to cause highly localised impacts on macrofaunal communities and there is the potential for rapid recovery to occur, depending on the characteristics of the communities and habitats impacted.
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Papers by Karen Tait