pheophytin-a and dimethyl-sulfide

Microorganisms are but a few micrometers in diameter and are not visible to the naked eye. Yet, the large numbers of microorganisms present in the oceans and the global impact of their activities make it possible to observe them from space. Here a few examples of how microorganisms can be studied from satellites are presented. The first case is the best known: the main pigment used in photosynthesis (chlorophyll a) can be determined from satellites. These kinds of studies have contributed a tremendous amount of understanding about the distribution and dynamics of primary production in the oceans. Two other examples will concern analysis of heterotrophic prokaryotic production and estimates of dimethyl sulfide (DMS) concentration and flux to the atmosphere. These three processes are of fundamental importance for the functioning of the biosphere. Marine microbes carry out about half of the total primary production in the planet. A substantial fraction of the respiration in the oceans is due to the activity of heterotrophic prokaryotes. Finally, the flux of DMS to the atmosphere is believed to constitute one of the mechanisms by which the biota can regulate climate. The global implications of microbial processes in the oceans can only be addressed with the help of satellites.

Topics: Chlorophyll; Chlorophyll A; Computer Simulation; Electronic Data Processing; Extraterrestrial Environment; Prokaryotic Cells; Seawater; Solar Energy; Spacecraft; Sulfides; Water Microbiology

In two Icelandic Sea spring blooms (May 2018 and 2019) in the North Atlantic Ocean (62.9-68.0°N, 9.0-28.0°W), chlorophyll-a and dimethylsulfoniopropionate (DMSP) concentrations and DMSP lyase activity (the DMSP-to-dimethyl sulfide (DMS) conversion efficiency) were measured at 67 stations, and the hourly atmospheric DMS mixing ratios were concurrently measured only in May 2019 at Storhofdi on Heimaey Island, located south of Iceland (63.4°N, 20.3°W). The ocean parameters for biology (i.e., chlorophyll-a, DMSP, and DMSP lyase activity) were broadly associated in distribution; however, the statistical significance of the association differed among four ocean domains and also between 2018 and 2019. Specifically, the widespread dominance of Phaeocystis, coccolithophores, and dinoflagellates (all rich in DMSP and high in DMSP lyase activity) across the study area is a compelling indication that variations in DMSP-rich phytoplankton were likely a main cause of the variations in statistical significance. For all the ocean domains defined here, we found that the DMS production capacity (calculated using the exposures of air masses to ocean biology prior to their arrivals at Heimaey and the atmospheric DMS mixing ratios of those air masses at Heimaey) was surprisingly consistent with in situ ocean S data (i.e., DMSP and DMSP lyase activity). Our study shows that the proposed computational approach enabled the detection of changes in DMS production and emission in association with changes in ocean primary producers.

Topics: Atlantic Ocean; Chlorophyll; Chlorophyll A; Iceland; Phytoplankton; Seawater; Sulfides; Sulfur Compounds

Dimethyl sulfide (DMS) serves as an anti-greenhouse gas, plays multiple roles in aquatic ecosystems, and contributes to the global sulfur cycle. The chlorophyll a (CHL, an indicator of phytoplankton biomass)-DMS relationship is critical for estimating DMS emissions from aquatic ecosystems. Importantly, recent research has identified that the CHL-DMS relationship has a breakpoint, where the relationship is positive below a CHL threshold and negative at higher CHL concentrations. Conventionally, mean regression methods are employed to characterize the CHL-DMS relationship. However, these approaches focus on the response of mean conditions and cannot illustrate responses of other parts of the DMS distribution, which could be important in order to obtain a complete view of the CHL-DMS relationship. In this study, for the first time, we proposed a novel Bayesian change point quantile regression (BCPQR) model that integrates and inherits advantages of Bayesian change point models and Bayesian quantile regression models. Our objective was to examine whether or not the BCPQR approach could enhance the understanding of shifting CHL-DMS relationships in aquatic ecosystems. We fitted BCPQR models at five regression quantiles for freshwater lakes and for seas. We found that BCPQR models could provide a relatively complete view on the CHL-DMS relationship. In particular, it quantified the upper boundary of the relationship, representing the limiting effect of CHL on DMS. Based on the results of paired parameter comparisons, we revealed the inequality of regression slopes in BCPQR models for seas, indicating that applying the mean regression method to develop the CHL-DMS relationship in seas might not be appropriate. We also confirmed relationship differences between lakes and seas at multiple regression quantiles. Further, by introducing the concept of DMS emission potential, we found that pH was not likely a key factor leading to the change of the CHL-DMS relationship in lakes. These findings cannot be revealed using piecewise linear regression. We thereby concluded that the BCPQR model does indeed enhance the understanding of shifting CHL-DMS relationships in aquatic ecosystems and is expected to benefit efforts aimed at estimating DMS emissions. Considering that shifting (threshold) relationships are not rare and that the BCPQR model can easily be adapted to different systems, the BCPQR approach is expected to have great potential for generalization in other enviro

Topics: Bayes Theorem; Chlorophyll; Chlorophyll A; Ecosystem; Oceans and Seas; Phytoplankton; Sulfides

Dimethylsulfoniopropionate (DMSP) is an important marine osmolyte. Aphotic environments are only recently being considered as potential contributors to global DMSP production. Here, our Mariana Trench study reveals a typical seawater DMSP/dimethylsulfide (DMS) profile, with highest concentrations in the euphotic zone and decreased but consistent levels below. The genetic potential for bacterial DMSP synthesis via the dsyB gene and its transcription is greater in the deep ocean, and is highest in the sediment.s DMSP catabolic potential is present throughout the trench waters, but is less prominent below 8000 m, perhaps indicating a preference to store DMSP in the deep for stress protection. Deep ocean bacterial isolates show enhanced DMSP production under increased hydrostatic pressure. Furthermore, bacterial dsyB mutants are less tolerant of deep ocean pressures than wild-type strains. Thus, we propose a physiological function for DMSP in hydrostatic pressure protection, and that bacteria are key DMSP producers in deep seawater and sediment.

Topics: Bacteria; Chlorophyll A; Genes, Bacterial; Geologic Sediments; Hydrostatic Pressure; Marinobacter; Metagenome; Mutation; Oceans and Seas; Prochlorococcus; RNA, Ribosomal, 16S; Seawater; Sulfides; Sulfonium Compounds; Synechococcus

Dimethylsulfoniopropionate (DMSP) is mainly produced by marine phytoplankton but is released into the microbial food web and degraded by marine bacteria to dimethyl sulfide (DMS) and other products. To reveal the abundance and distribution of bacterial DMSP degradation genes and the corresponding bacterial communities in relation to DMS and DMSP concentrations in seawater, we collected surface seawater samples from DMS hot spot sites during a cruise across the Pacific Ocean. We analyzed the genes encoding DMSP lyase (dddP) and DMSP demethylase (dmdA), which are responsible for the transformation of DMSP to DMS and DMSP assimilation, respectively. The averaged abundance (±standard deviation) of these DMSP degradation genes relative to that of the 16S rRNA genes was 33% ± 12%. The abundances of these genes showed large spatial variations. dddP genes showed more variation in abundances than dmdA genes. Multidimensional analysis based on the abundances of DMSP degradation genes and environmental factors revealed that the distribution pattern of these genes was influenced by chlorophyll a concentrations and temperatures. dddP genes, dmdA subclade C/2 genes, and dmdA subclade D genes exhibited significant correlations with the marine Roseobacter clade, SAR11 subgroup Ib, and SAR11 subgroup Ia, respectively. SAR11 subgroups Ia and Ib, which possessed dmdA genes, were suggested to be the main potential DMSP consumers. The Roseobacter clade members possessing dddP genes in oligotrophic subtropical regions were possible DMS producers. These results suggest that DMSP degradation genes are abundant and widely distributed in the surface seawater and that the marine bacteria possessing these genes influence the degradation of DMSP and regulate the emissions of DMS in subtropical gyres of the Pacific Ocean.

Topics: Bacteria; Carbon-Sulfur Lyases; Chlorophyll; Chlorophyll A; DNA, Bacterial; Genes, Bacterial; Microbial Consortia; Oxidoreductases; Pacific Ocean; Phylogeny; RNA, Ribosomal, 16S; Roseobacter; Seawater; Sequence Analysis, DNA; Sulfides; Sulfonium Compounds; Temperature

Dimethylsulfide (DMS), dimethylsulfoniopropionate (DMSP) and dimethylsulfoxide (DMSO) are the most important biogenic organic dimethylated sulfur compounds in the ocean. The spatial distributions of these three sulfur compounds and their influencing factors were investigated in the East China Sea in June 2013. The mean concentrations of DMS, DMSPd, DMSPp, DMSOd and DMSOp in the surface seawater were 4.70, 7.00, 27.83, 13.66 and 10.78 nmol x L(-1), respectively. The horizontal distributions of DMS, DMSP and DMSO exhibited the similar patterns to that of chlorophyll a (Chl-a), with high values in coastal regions and low values in the open sea. DMS, DMSPd and DMSOp concentrations were significantly correlated with the levels of Chl-a, indicating that phytoplankton biomass might play an important role in controlling the concentrations of these sulfur compounds in the East China Sea. Moreover, positive relationships were observed between DMS and DMSPd and between DMSOd and DMS in the study area, which implied that the microbial degradation of DMSPd was the main source of DMS and DMSOd came mostly from the oxidation of DMS. The sea-to-air flux of DMS from the East China Sea in summer ranged from 0.62 to 33.98 micromol x (m2 x d)(-1), with an average of 9.71 micromol x (m2 x d)(-1).

Topics: Biomass; China; Chlorophyll; Chlorophyll A; Oceans and Seas; Phytoplankton; Seasons; Seawater; Sulfides; Sulfonium Compounds

The concentrations of dimethylsulfide (DMS) and dimethylsulfoniopropionate (DMSP) were measured in situ in the East China Sea and the Southern Yellow Sea during December 2011 and January 2012 to study their horizontal distributions and influencing factors. Besides, the size distribution of DMSPp and the sea-to-air flux of DMS were also investigated. The concentrations of DMS, dissolved DMSP (DMSPd) and particulate DMSP (DMSPp) ranged from 0.58 to 4.14, from 0.37 to 7.86 and from 4.29 to 25.76 nmol x L(-1), respectively, with the average values of (2.20 +/- 0.82), (2.12 +/- 1.66) and (11.98 +/- 6.23) nmol x L(-1). In addition, significantly positive correlations were found between DMS, DMSPp and chlorophyll a, and their diel variations followed the same trend, implying that phytoplankton biomass might play an important role in controlling the production and distributions of DMS and DMSP. A negative correlation was found between DMSPd and total bacterial abundance, probably because DMSPd was transferred into DMS under the action of DMSP lyase released from bacteria. Moreover, the larger nanophytoplankton (5-20 microm) contributed to the vast majority of Chl-a and DMSPp in the study area. The sea-to-air fluxes of DMS during the investigation were estimated to be from 0.61 to 25.52 micromol x (m2 x d)(-1), with an average of (8.30 +/- 5.92) micromol x (m2 x d)(-1).

Topics: Biomass; China; Chlorophyll; Chlorophyll A; Phytoplankton; Seasons; Seawater; Sulfides; Sulfonium Compounds

Spatial variations in dimethylsulfide (DMS) and dimethylsulfoniopropionate (DMSP) were surveyed in the surface microlayer and in the subsurface waters of the low productivity South China Sea in May 2005. Overall, average subsurface water concentrations of DMS and DMSP of dissolved (DMSPd) and particulate (DMSPp) fractions were 1.74 (1.00-2.50), 3.92 (2.21-6.54) and 6.06 (3.40-8.68) nM, respectively. No enrichment in DMS and DMSPp was observed in the microlayer. In contrast, the microlayer showed a DMSPd enrichment, with an average enrichment factor (EF, defined as the ratio of the microlayer concentration to subsurface water concentration) of 1.40. In the study area, none of the sulfur components were correlated with chlorophyll a. An important finding in this study was that DMS, DMSP and chlorophyll a concentrations in the surface microlayer were respectively correlated with those in the subsurface water, suggesting a close linkage between these two water bodies. The ratios of DMS:Chl-a and DMSPp:Chl-a showed a gradually increasing trend from North to South. This might be due to changes in the proportion of DMSP producers in the phytoplankton community with the increased surface seawater temperature. A clear diurnal variation in the DMS and DMSP concentrations was observed at an anchor station with the highest concentrations appearing during the day and the lowest concentrations during the night. The higher DMS and DMSP concentrations during daytime might be attributed to the light-induced increase in both algal synthesis and exudation of DMSP and biological production of DMS. The mean flux of DMS from the investigated area to the atmosphere was estimated to be 2.06 micromo lm(-2)d(-1). This low DMS emission flux, together with the low DMS surface concentrations was attributed to the low productivity in this sea.

Topics: China; Chlorophyll; Chlorophyll A; Environmental Monitoring; Oceans and Seas; Seasons; Seawater; Sulfides; Sulfonium Compounds; Time Factors; Wind

Nearshore water is one of the most important emission area of dimethylsulfide(DMS), at the same time, nearshore water is highly disturbed by human activities. The objectives of this study were to investigate the DMS concentration of coastal water and try to analyze the factors governing its distribution. Four situ investigations were made in the coastal water of Qingdao, which is located at west coast of Yellow Sea. DMS concentrations of surface water showed a clear seasonal variation with peak values during the summer. Spatial and temporal distributions of DMS in three studied areas(havey polluted area, light polluted area, and clean area) were irregular, but when the concentrations of DMS were moralized to chlorophyll a as a measure of phytoplankton biomass, there was significant difference of DMS/Chl a among the three areas, with the nutrient concentration improved, the DMS/Chl a decreased. And there was the positive relation between transparency and DMS/Chl a, especially in summer.

Topics: Biomass; Chlorophyll; Chlorophyll A; Nitrogen; Phosphorus; Phytoplankton; Seasons; Seawater; Sulfides; Water Pollutants, Chemical

This study of the origin and fate of dimethyl sulphide (DMS) in a particular and complex lagoon ecosystem such as that of the Venice lagoon focuses on the temporal evolutions of DMS concentrations in surface water together with those of dimethylsulphoniopropionate (DMSP), carbon disulphide (CS2), nutrients (nitrate, nitrite, ammonium, phosphate, silicate), sulphate, chlorophyll a, chlorinity, water temperature and phytoplankton (composition and density). Measurements were made from 3 March 1997 to 23 July 1998 at three stations in the central part of the Venice lagoon. The temporal trends of DMS concentration showed an absolute maximum concentration in winter (65 nmol S/l, 19/2/1998, Stn. 1; 119 nmol S/l, 19/2/1998, Stn. 2; 29 nmol S/l, 17/2/1998, Stn. 3) and two relative maxima in the spring-summer period. The spring-summer secondary maxima of DMS concentration were related to the maxima of DMSP and chlorophyll a concentrations and consequently to phytoplanktonic abundance while the winter DMS maximum showed no relation to DMSP or to chlorophyll a suggesting that the production and the fate of DMS could be different for the two periods. According to previous studies the CS2 concentration increased in the spring, achieved its maximum in summer, decreased in autumn and fell to its minimum in winter.

Topics: Carbon Disulfide; Chlorine; Chlorophyll; Chlorophyll A; Ecosystem; Geologic Sediments; Italy; Nitrates; Phosphates; Phytoplankton; Quaternary Ammonium Compounds; Seasons; Seawater; Silicates; Sulfides; Sulfonium Compounds; Water Pollutants, Chemical

We investigated the distribution of phytoplankton species and the associated dimethyl sulfur species, dimethylsulfoniopropionate (DMSP) and dimethylsulfide (DMS) on a cruise into the spring bloom region of the northern North Atlantic (near 47 degrees N, 19 degrees W). The cruise was timed to characterize the relationship between plankton dynamics and sulfur species production during the spring plankton bloom period. At the same time, we measured the DMS concentrations in the atmospheric boundary layer and determined the abundance and composition of the atmospheric aerosol. The water column studies showed that the interplay of wind-driven mixing and stratification due to solar heating controlled the evolution of the plankton population, and consequently the abundance of particulate and dissolved DMSP and DMS. The sea-to-air transfer of DMS was modulated by strong variations in wind speed, and was found to be consistent with currently available transfer parameterizations. The atmospheric concentration of DMS was strongly dependent on the sea surface emission, the depth of the atmospheric boundary layer and the rate of photooxidation as inferred from UV irradiance. Sea-salt and anthropogenic sulfate were the most abundant components of the atmospheric aerosol. On two days, a strong dust episode was observed bringing mineral dust aerosol from the Sahara desert to our northerly study region. The background concentrations of marine biogenic sulfate aerosol were low, near 30-60 ppt. These values were consistent with the rate of sulfate production estimated from the abundance of DMS in the marine boundary layer.

Topics: Aerosols; Atlantic Ocean; Atmosphere; Chlorophyll; Chlorophyll A; Minerals; Phytoplankton; Salts; Seasons; Seawater; Sulfates; Sulfides; Sulfonium Compounds; Sulfur; Sulfur Compounds