Arsenic compounds in tropical marine ecosystems: similarities between mangrove forest and coral reef

2009 ◽  
Vol 6 (3) ◽  
pp. 226 ◽  
Author(s):  
Somkiat Khokiattiwong ◽  
Narumol Kornkanitnan ◽  
Walter Goessler ◽  
Sabine Kokarnig ◽  
Kevin A. Francesconi

Environmental context. Despite the widespread occurrence of arsenobetaine in marine animals the origin of this arsenic compound remains unknown. A current hypothesis is that arsenobetaine is formed from more complex arsenic compounds found in marine algae. To test this hypothesis, we examined the arsenic compounds in a mangrove ecosystem where algae play a limited role in primary productivity. Abstract. Marine algae are known to bioaccumulate arsenic and transform it into arsenosugars, which are thought to be precursors of the major arsenic compound, arsenobetaine, found in marine animals. Marine ecosystems based on mangrove forests have high nutrient input from mangrove leaves, and thus provide a unique opportunity to study the cycling of arsenic in a marine system where algae are not the dominant food source. Two mangrove forests in Phuket, Thailand were selected as sampling sites for this study. For comparison, samples were also collected from two coral reef sites at and near Phuket. The samples collected included mangrove leaves, corals, algae, molluscs, fish and crustaceans. Arsenic contents in the samples and in aqueous extracts of the samples were determined by hydride generation atomic absorption spectrometry following a dry-ashing mineralisation procedure, and arsenic species were determined in the aqueous extracts by HPLC-MS (mainly ICPMS). Mangrove leaves contained only low concentrations of total arsenic (0.10–0.73 mg kg–1 dry mass) and the aqueous extracts thereof contained inorganic arsenic species, methylarsonate and dimethylarsinate, but arsenosugars were not detected. The total mean arsenic contents (3.2–86 mg kg–1 dry mass) of the animals from the mangrove ecosystem, however, were typical of those found in animal samples from other marine ecosystems. Similarly the arsenic compounds present were typical of those in animals from other marine ecosystems comprising mainly arsenobetaine with smaller quantities of other common arsenicals including arsenosugars, arsenocholine, tetramethylarsonium ion, trimethylarsine oxide and dimethylarsinate. A trimethylated arsenosugar, which is not commonly reported in marine organisms, was a significant arsenical (6–8% of total As) in some gastropod species from the mangrove ecosystem. The coral samples contained mainly arsenosugars and arsenobetaine, and the other animals collected from the coral ecosystem contained essentially the same pattern of arsenicals found for the mangrove animals. The data suggest that food chains based on algae are not necessary for animals to accumulate large concentrations of arsenobetaine.

2009 ◽  
Vol 60 (9) ◽  
pp. 885 ◽  
Author(s):  
W. Maher ◽  
S. Foster ◽  
F. Krikowa

Although over 50 arsenic species have been identified in marine organisms, the biochemical pathways by which these species are formed are not known. In this paper, we present an overview of bioconversions of arsenic species that occur in marine food chains based on studies conducted by our laboratory as well as the work of others. Phytoplankton and macroalgae only contain dimethylarsenoribosides or simple methylated arsenic compounds such as dimethylarsenate and dimethylarsenoethanol. Marine animals contain mostly arsenobetaine and a range of other arsenic species that may be precursors of arsenobetaine formation. The formation of arsenobetaine in marine animals from dimethylarsenoribosides may occur through a two-stage conversion pathway: arsenoriboside or trimethylarsonioriboside degradation to arsenocholine followed by quantitative oxidation to arsenobetaine. The minor arsenic species found in marine organisms are sulfur analogues of compounds found in the S-adenosylmethionine-methionine salvage and the dimethylsulfoniopropionate metabolic pathway of animals. A key intermediate in these pathways would be arsenomethionine, which could possibly be formed from dimethylarsinite, dimethylarsenoribosides or an arsenic-containing analogue of S-adenosylmethionine. Examining arsenic species in whole ecosystems has the advantage of using the pattern of arsenic species found to postulate the biochemical pathways of their formation.


2011 ◽  
Vol 8 (1) ◽  
pp. 44 ◽  
Author(s):  
Jana Navratilova ◽  
Georg Raber ◽  
Steven J. Fisher ◽  
Kevin A. Francesconi

Environmental context Despite high levels of complex organoarsenic compounds in marine organisms, arsenic in seawater is present almost entirely as inorganic species. We examine the arsenic products from a marine alga allowed to decompose under simulated natural coastal conditions, and demonstrate a multi-step conversion of organic arsenicals to inorganic arsenic. The results support the hypothesis that the arsenic marine cycle begins and ends with inorganic arsenic. Abstract Time series laboratory experiments were performed to follow the degradation of arsenic compounds naturally present in marine algae. Samples of the brown alga Ecklonia radiata, which contains three major arsenosugars, were packed into 12 tubes open to air at one end only, and allowed to naturally decompose under moist conditions. During the subsequent 25 days, single tubes were removed at intervals of 1–4 days; their contents were cut into four sections (from open to closed end) and analysed for arsenic species by HPLC/ICPMS following an aqueous methanol extraction. In the sections without direct contact with air, the original arsenosugars were degraded primarily to arsenate via two major intermediates, dimethylarsinoylethanol (DMAE) and dimethylarsinate (DMA). The section with direct contact with air degraded more slowly and significant amounts of arsenosugars remained after 25 days. We also report preliminary data suggesting that the amount of non-extractable or recalcitrant arsenic (i.e. insoluble after sequential extractions with water/methanol, acetone, and hexane) increased with time. Furthermore, we show that treatment of the pellet with 0.1-M trifluoroacetic acid at 95°C solubilises a significant amount of this recalcitrant arsenic, and that the arsenic is present mainly as a cationic species of currently unknown structure.


2008 ◽  
Vol 5 (3) ◽  
pp. 171 ◽  
Author(s):  
Marco Grotti ◽  
Francesco Soggia ◽  
Cristina Lagomarsino ◽  
Walter Goessler ◽  
Kevin A. Francesconi

Environmental context. Although arsenic occurs in marine animals at high concentrations, the pathways by which it is biotransformed and accumulated remain largely unknown. The observation that some species of algae can contain significant concentrations of arsenobetaine, a major marine arsenic species, is relevant to explanations of the source of this compound to marine animals and its transport through the marine food web. Abstract. Significant amounts of arsenobetaine (up to 0.80 μg As g–1 dry mass, representing 17% of the extractable arsenic) were found in the extracts of all four samples of the red alga Phyllophora antarctica collected from two sites in Antarctica (Terra Nova Bay and Cape Evans). The assignment was made with high performance liquid chromatography–inductively coupled plasma mass spectrometry (HPLC-ICPMS) based on exact cochromatography with a standard compound with two chromatographic systems (cation-exchange and ion-pairing reversed-phase), each run under two sets of mobile phase conditions. Particular care was taken during sample preparation to ensure that the arsenobetaine was of algal origin and did not result from epiphytes associated with the alga. Another red alga, Iridaea cordata, collected from Terra Nova Bay, did not contain detectable concentrations of arsenobetaine. For both algal species, the majority of the extractable arsenic was present as arsenosugars. Confirmation that marine algae can contain significant amounts of arsenobetaine allows a simpler explanation for the widespread occurrence of this arsenical in marine animals.


2016 ◽  
Vol 13 (4) ◽  
pp. 577 ◽  
Author(s):  
Shin-ichi Miyashita ◽  
Chisato Murota ◽  
Keisuke Kondo ◽  
Shoko Fujiwara ◽  
Mikio Tsuzuki

Environmental context Cyanobacteria are ecologically important, photosynthetic organisms that are widely distributed throughout the environment. They play a central role in arsenic transformations in terms of both mineralisation and formation of organoarsenic species as the primary producers in aquatic ecosystems. In this review, arsenic resistance, transport and biotransformation in cyanobacteria are reviewed and compared with those in other organisms. Abstract Arsenic is a toxic element that is widely distributed in the lithosphere, hydrosphere and biosphere. Some species of cyanobacteria can grow in high concentrations of arsenate (pentavalent inorganic arsenic compound) (100mM) and in low-millimolar concentrations of arsenite (trivalent inorganic arsenic compound). Arsenate, which is a molecular analogue of phosphate, is taken up by cells through phosphate transporters, and inhibits oxidative phosphorylation and photophosphorylation. Arsenite, which enters the cell through a concentration gradient, shows higher toxicity than arsenate by binding to sulfhydryl groups and impairing the functions of many proteins. Detoxification mechanisms for arsenic in cyanobacterial cells include efflux of intracellular inorganic arsenic compounds, and biosynthesis of methylarsonic acid and dimethylarsinic acid through methylation of intracellular inorganic arsenic compounds. In some cyanobacteria, ars genes coding for an arsenate reductase (arsC), a membrane-bound protein involved in arsenic efflux (arsB) and an arsenite S-adenosylmethionine methyltransferase (arsM) have been found. Furthermore, cyanobacteria can produce more complex arsenic species such as arsenosugars. In this review, arsenic metabolism in cyanobacteria is reviewed, compared with that in other organisms. Knowledge gaps remain regarding both arsenic transport (e.g. uptake of methylated arsenicals and excretion of arsenate) and biotransformation (especially production of lipid-soluble arsenicals). Further studies in these areas are required, not only for a better understanding of the role of cyanobacteria in the circulation of arsenic in aquatic environments, but also for their application to arsenic bioremediation.


2019 ◽  
Vol 5 ◽  
pp. 104
Author(s):  
Suhendra Purnawan ◽  
Subari Yanto ◽  
Ernawati S.Kaseng

This study aims to describe the profile of vegetation diversity in the mangrove ecosystem in Tamuku Village, Bone-Bone-Bone District, North Luwu Regency. This research is a qualitative research using survey methods. The data collection technique uses the Quadrant Line Transect Survey technique. The data analysis technique uses the thinking flow which is divided into three stages, namely describing phenomena, classifying them, and seeing how the concepts that emerge are related to each other. The results of this study are the profile of mangrove vegetation in Tamuku Village, which is still found 16 varieties of true mangrove vegetation and 7 varieties of mangrove vegetation joined in the coastal area of Tamuku Village, Bone-Bone District, North Luwu Regency, South Sulawesi. The condition of mangrove vegetation in Tamuku Village is currently very worrying due to human activities that cause damage such as the project of normalization of flow, opening of new farms, disposal of garbage, water pollution due to chemicals, and exploitation of mangrove forests for living needs. The impact is ecosystem damage and reduced vegetation area as a place to grow and develop mangroves.


Pollutants ◽  
2021 ◽  
Vol 1 (1) ◽  
pp. 18-28
Author(s):  
Davide Seveso ◽  
Yohan Didier Louis ◽  
Simone Montano ◽  
Paolo Galli ◽  
Francesco Saliu

In light of the recent marine oil spill that occurred off the coast of Mauritius (Indian Ocean), we comment here the incident, the containment method used by the local population, the biological impact of oil spill on two sensitive tropical marine ecosystems (coral reefs and mangrove forests), and we suggest monitoring and restoration techniques of the impacted ecosystems based on recent research advancements.


Author(s):  
J.S. Edmonds ◽  
Y. Shibata ◽  
R.I.T. Prince ◽  
K.A. Francesconi ◽  
M. Morita

Examination of extracts of tissues of a leatherback turtle, Dermochelys coriacea (L.) (Reptilia: Dermochelyidae) by high-performance liquid chromatography inductively coupled plasma-mass spectrometry has demonstrated the presence of arsenobetaine, arsenocholine and inorganic arsenate in heart muscle and liver, and arsenobetaine and inorganic arsenate in pectoral muscle. Although arsenobetaine was the major form in all tissues, inorganic arsenate and arsenocholine accounted for 50% and 15% respectively of arsenic in aqueous extracts of the liver.


1983 ◽  
Vol 40 (8) ◽  
pp. 1254-1257 ◽  
Author(s):  
M. D. Baker ◽  
P. T. S. Wong ◽  
Y. K. Chau ◽  
C. I. Mayfield ◽  
W. E. Inniss

Isolates from four genera of freshwater green algae were capable of methylating sodium arsenite in lake water and Bold's basal medium. Analysis of the liquid phase of the methylation flasks revealed the presence of methylarsonic acid, dimethylarsinic acid, and trimethylarsine oxide. Volatile arsine and methylarsines were not detected in the headspace gases presumably because of the inability of the algae to reduce completely the methylated–arsenic species. Although the algae varied with respect to their methylating abilities, the levels of methylated–arsenic compounds were always significantly higher when the algae were grown in lake water. This may have been due to the lower phosphate concentration in the lake water. We suggest that arsenic methylation by green algae constitutes an additional source for the formation and cycling of organo-arsenic compounds in freshwater ecosystems.


2012 ◽  
Vol 9 (2) ◽  
pp. 130 ◽  
Author(s):  
Vivien F. Taylor ◽  
Brian P. Jackson ◽  
Matthew R. Siegfried ◽  
Jana Navratilova ◽  
Kevin A. Francesconi ◽  
...  

Environmental contextArsenic occurs in marine organisms at high levels and in many chemical forms. A common explanation of this phenomenon is that algae play the central role in accumulating arsenic by producing arsenic-containing sugars that are then converted into simpler organic arsenic compounds found in fish and other marine animals. We show that animals in deep-sea vent ecosystems, which are uninhabited by algae, contain the same organic arsenic compounds as do pelagic animals, indicating that algae are not the only source of these compounds. AbstractArsenic concentration and speciation were determined in benthic fauna collected from the Mid-Atlantic Ridge hydrothermal vents. The shrimp species, Rimicaris exoculata, the vent chimney-dwelling mussel, Bathymodiolus azoricus, Branchipolynoe seepensis, a commensal worm of B. azoricus and the gastropod Peltospira smaragdina showed variations in As concentration and in stable isotope (δ13C and δ15N) signature between species, suggesting different sources of As uptake. Arsenic speciation showed arsenobetaine to be the dominant species in R. exoculata, whereas in B. azoricus and B. seepensis arsenosugars were most abundant, although arsenobetaine, dimethylarsinate and inorganic arsenic were also observed, along with several unidentified species. Scrape samples from outside the vent chimneys covered with microbial mat, which is a presumed food source for many vent organisms, contained high levels of total As, but organic species were not detectable. The formation of arsenosugars in pelagic environments is typically attributed to marine algae, and the pathway to arsenobetaine is still unknown. The occurrence of arsenosugars and arsenobetaine in these deep sea organisms, where primary production is chemolithoautotrophic and stable isotope analyses indicate food sources are of vent origin, suggests that organic arsenicals can occur in a foodweb without algae or other photosynthetic life.


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