Assessing indicators of arsenic toxicity using variable fluorescence in a commercially valuable microalgae: Physiological and toxicological aspects
Graphical Abstract
Introduction
Trace metal contamination has posed serious threats to aquatic and terrestrial organisms since the time of heavy industrialisation and globalisation [20], [29]. Some trace metals prove to have essential roles in the metabolism of organisms, but only up to a certain concentration, beyond which, it is often toxic [28], [31], [51], [91]. Arsenic (As) is one such element that shows no evidence for its essentiality in functioning of organisms and has been globally regarded as a serious threat to life in general, from microbes to mammals [48], [63], [87]. It is often described as a ubiquitous metal that can originate from anthropogenic, geo-genic and/or natural pathways like erosion of soil, volcanic eruptions, etc. (Z. [86]). Industries such as fossil fuel, agricultural factories using arsenic based pesticides, smelting or metal extraction factories are some examples of the man-made sources of As [63], [74]. In comparison to terrestrial animals, marine organisms have higher load of total As concentration ranging from 1 to 1000 µg/g in dry weight which is almost 100 times more than land creatures ranging from 0.1 − 10 µg/g in dry weight [22], [34].
Being the primary producer of the marine ecosystem, phytoplankton are often the earliest or the primary target that bear the consequences of arsenic toxicity in marine coastal areas, which are often perceived as heavily impacted zones due to the active commercial and industrial pursuits for decades [2], [34]. Marine algal species forms the basis of the trophic energy flow of the ecosystem and has profoundly proved its role as great indicators of the health of an ecosystem in many ecotoxicological studies [29], [38], [48], [55], [59]. Previous literatures concerning algal toxicity, have laid theories and explanation on the processes adapted by marine algae to combat the incessant exposure to arsenic, discussing the detoxification pathways, bio-transformation of metal states, etc. Hasegawa et al., ($year$) [34], [41], [42], [56], [63]. Biotransformation is the process that involves uptake of inorganic metal forms which then is either oxidized, reduced or methylated to organic states through an algal cell or other organisms [89]. Such studies mostly reflected the changes in the growth rate, pigment contents, morphological changes, biochemical alterations, and bioaccumulation capacity highlighting on metabolic activities and population structure [23], [29], [48], [55]. However, the effect of trace metal exposure and its consequences on the photosynthetic machinery and the associated physiological variables of an alga has not been much explored in the literature and such reports can shed light on valuable physiological indicators when exposed to metal stress. Variable fluorescence (VF) is such a technique that can be used for assessing physiological condition/state of the algal photosynthetic apparatus often used in studies related to limnology and laboratory cultures [75], [77], [78], [81]. However, variable fluorescence can also be used in the detection of toxicity or any form of stress providing prompt and efficacious physiological indicators to evaluate the risk factors prevailing in the marine habitats [38], [7], [8], [83]. This technique makes it possible to study in a non-intrusive way the efficiency of the photosynthetic processes of microalgae, in situ natural environment or in experiments whether or not related to water quality issues. The key parameters concerning the functioning of the photosynthetic apparatus used in previous studies were: the maximum quantum yield (Fv/Fm) of photochemistry in photosystem II (PSII), the maximum electron transport rate (ETRmax) in relative (rETRmax) or absolute units (ETRmax(II)), the absorption cross section of PSII photochemistry (σPSII) and the non-photochemical quenching (NPQ) [38], [46], [8], [83]. Identification of new indicators specific to highly toxic contaminants like arsenic can assist the environmental management and risk assessment groups to analyse the varied threats posed on the marine ecosystem with much rapidity and precision by using variable fluorescence methods for stress physiology [38].
In this work, we studied the marine algal species Diacronema lutheri, characterised with phytosterol richness and a variety of mostly type A pigments (chla, c1, chlorophyllides) with two dissimilar (in length) flagella [29], [3]. Diacronema lutheri is an eco-friendly source for producing valuable compounds like phytosterol due to its natural richness and is also majorly used in the sector of aquaculture especially as a feed for bivalves, copepods which in turn are fed to fish larvae, shrimps in farms and other cultured organisms, making it ecologically and economically valuable ([16], [27], [32]). Previous literatures reported that D. lutheri is a bioindicator species, signalling stress from trace metals by lowering photosynthetic pigment, cell density and by exemplifying capacity of bioaccumulating and bioconcentrating varied amount of essential and non-essential trace metals ([29]a). In this study our objective was to comprehend the physiological anomalies caused due to arsenic exposure in D. lutheri using the variable fluorescence technique through Fast Repetition Rate fluorometer (FRRf) in linkage with pigment analyses by high-performance liquid chromatography (HPLC). Thus, the goal is not only to characterize the impact of toxic metal on physiology of this species but to have a functional understanding of the phenomenon of toxicity. The VF technique was implemented to compare the photosynthetic processes occurring in photosystem II (PSII) apart from which the monitoring of cell density, pigment contents and the bioaccumulation capacity of D. lutheri was also analysed in control group and arsenic-exposed algal cells. In natural environments, a complex and often a cocktail of metal exists and previous studies reported that such coexistence of multiple trace metals can influence the toxicity and/or the absorption of metals in the body of the organisms, such as Iron (Fe) or Manganese (Mn) oxides influence the mobility of As. Hence, a range of trace metals were studied in order to comprehend the bioaccumulation of other trace metals apart from As ([15]; [4]. Hence, studies on such issues are warranted for the rapidity to detect As contamination which can further aid on the risk assessment of utilising such ecologically and economically important algal species in the medicinal or aquaculture farms, concerning the pollutants present in the environment.
Section snippets
Test organism- Diacronema lutheri
The initial stock of the microalgae D. lutheri was acquired from the Roscoff Culture Collection in France (RCC-1537). Laboratory cultures were then initiated in 6 L flasks using artificial seawater prepared from osmosed water and artificial salt (coral salt-pro). All the cultures were maintained under controlled laboratory conditions in an incubator with a 12 h: 12 h light/dark regime at 18 °C with salinity 33. The cultures were supplemented or enriched by adding vitamins and the Conway medium
Chlorophyll a content and growth curve of D. lutheri
Chl a content displayed on Fig. 1 (control, As (11.25 µg/L) and As (22.5 µg/L)) measured at each interval of time from T3 until T21 shows an initial increase and then a declination in all the treatments. The chl a increased from T3 to T9 significantly for control (p < 0.05). The treatment As (11.25 µg/L) increased chl a from T3 to T9 and further to T15 significantly (<0.01). Lastly, for the treatment As (22.5 µg/L) increased chl a significantly from T3 to T15. At the lysis phase no significant
Toxicity of Arsenic to D. lutheri
The growth curve of D. lutheri in this study, showed a clear and strong slowdown in arsenic exposed cells, consistently explained from all the parameters measured, like the cell density, pigments and photo-physiology by variable fluorescence. The cell density of D. lutheri showed a significant difference from the control after 9 days of As exposure irrespective of the concentration. Non-essential trace metal exposures often caused a significant drop in cell density or growth rates at the post
Conclusion
This study shows the effect of As contamination on the physiology, pigment concentrations and cell density of the algal species D. lutheri throughout the algal growth curve. The cell density, chl a concentration decreased significantly in As exposed cells from day 9 until the lysis phase day 21 when compared to the control. The maximum quantum efficiency (Fv/Fm) showed coherence with the growth parameters whereas the photo-physiological parameters like the functional [Sigma (σPSII)] and the
Environmental implication
Arsenic is ubiquitous and hazardous to human health in trace amounts, given the dreadful record of lethal cases from arsenic contamination, worldwide. Hence, new tools are warranted for this compelling necessity to monitor effects of arsenic in nature. This study proposes new indicators of arsenic contamination through physiology of a microalgae (Diacronema lutheri) using variable fluorescence. Furthermore, a linkage of physiological markers with ecotoxicology using non-destructive, rapid and a
CRediT authorship contribution statement
Shagnika Das: Performed the experiment, analysis and drafted the manuscript. Fabrice Lizon: Supervised the physiological measurements and analyses. Reviewed and helped in drafting the manuscript. Francois Gevaert: Analyzed the pigment concentrations, reviewed the manuscript. Capucine Bialais: Helped during experiments. Gwendoline Duong: Performed the analyses in HPLC for pigments. Baghdad Ouddane: Performed heavy metals analyses. Sami Souissi: Conceived the project and reviewed the manuscript.
Declaration of Competing Interest
The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
Acknowledgement
We are thankful to the project Valgorize (Interreg 2 Seas programme) co-funded by the European Regional Development Fund under the subsidy contract No ValgOrize 2S05017 for providing the necessary fellowship to perform this study. Our earnest gratitude to the past and present members of our laboratory for maintaining the mass-cultures of planktons for years. This work has been supported by the European Union (ERDF), the French State, the French Region Hauts-de-France and Ifremer, in the
References (93)
- et al.
Pavlova lutheri is a high-level producer of phytosterols
Algal Res
(2015) - et al.
Arsenic-phosphorus interactions in the soil-plant-microbe system: Dynamics of uptake, suppression and toxicity to plants
Environ Pollut
(2018) Chlorophyll fluorescence as a tool to identify drought stress in Acer genotypes
Environ Exp Bot
(2018)- et al.
Adverse effects of atrazine, DCMU and metolachlor on phytoplankton cultures and communities at environmentally relevant concentrations using Fast Repetition Rate Fluorescence
Sci Total Environ
(2020) - et al.
Cadmium inhibits epoxidation of diatoxanthin to diadinoxanthin in the xanthophyll cycle of the marine diatom Phaeodactylum tricornutum
FEBS Lett
(2001) - et al.
Chlorophyll fluorescence – A tool to assess photosynthetic performance and stress photophysiology in symbiotic marine invertebrates and seaplants
Mar Pollut Bull
(2021) - et al.
Effective strategy to recycle arsenic-accumulated biomass of Pteris vittata with high benefits
Sci Total Environ
(2021) - et al.
Regulation of electron transport in microalgae
Biochim Biophys Acta BBA Bioenerg
(2011) - et al.
Efficient removal of arsenic from aqueous solution by continuous adsorption onto iron-coated cork granulates
J Hazard Mater
(2022) - et al.
Screening of trace metal elements for pollution tolerance of freshwater and marine microalgal strains: Overview and perspectives
Algal Res
(2020)
The effects of mining tailings in the physiology of benthic algae: Understanding the relation between mud’s inductive acidification and the heavy metal’s toxicity
Environ Exp Bot
Effects of lead on two green microalgae Chlorella and Scenedesmus: photosystem II activity and heterogeneity
Algal Res
Effects of lead on growth, photosynthetic characteristics and production of reactive oxygen species of two freshwater green algae
Chemosphere
Intergenerational effects of resuspended sediment and trace metal mixtures on life cycle traits of a pelagic copepod
Environ Pollut
Single toxicity of arsenic and combined trace metal exposure to a microalga of ecological and commercial interest: Diacronema lutheri
Chemosphere
Trace metals exposure in three different coastal compartments show specific morphological and reproductive traits across generations in a sentinel copepod
Sci Total Environ
Heavy metal induced physiological alterations in Salvinia natans
Ecotoxicol Environ Saf
A model for the relationship between light intensity and the rate of photosynthesis in phytoplankton
Ecol Model
Optimal chlorophyll fluorescence parameter selection for rapid and sensitive detection of lead toxicity to marine microalgae Nitzschia closterium based on chlorophyll fluorescence technology
J Photochem Photobiol B
Cadmium ion-chlorophyll interaction – Examination of spectral properties and structure of the cadmium-chlorophyll complex and their relevance to photosynthesis inhibition
Chemosphere
Biosynthesis and release of methylarsenic compounds during the growth of freshwater algae
Chemosphere
Role of Fe plaque on arsenic biotransformation by marine macroalgae
Sci Total Environ
Absorption and speciation of arsenic by microalgae under arsenic-copper Co-exposure
Ecotoxicol Environ Saf
Arsenic speciation and biotransformation pathways in the aquatic ecosystem: The significance of algae
J Hazard Mater
Acute and chronic toxicity of cadmium on the copepod Pseudodiaptomus annandalei: A life history traits approach
Chemosphere
Herbicide toxicity on river biofilms assessed by pulse amplitude modulated (PAM) fluorometry
Aquat Toxicol
Hydrothermal liquefaction accelerates the toxicity and solubility of arsenic in biowaste
J Hazard Mater
Comparative biotransformation and detoxification potential of arsenic by three macroalgae species in seawater: Evidence from laboratory culture studies
Chemosphere
Arsenic speciation and biotransformation by the marine macroalga Undaria pinnatifida in seawater: A culture medium study
Chemosphere
Antioxidant enzymes are induced by phenol in the marine microalga Lingulodinium polyedrum
Ecotoxicol Environ Saf
Study of dynamics of phytoplankton and photosynthetic parameters using opportunity ships in the western English Channel
J Mar Syst
Copper excess detoxification is mediated by a coordinated and complementary induction of glutathione, phytochelatins and metallothioneins in the green seaweed Ulva compressa
Plant Physiol Biochem
Integrated environmental factor-dependent growth and arsenic biotransformation by aquatic microalgae: A review
Chemosphere
Freshwater phytoplankton: Salinity stress on arsenic biotransformation
Environ Pollut
Truncated chlorophyll antenna size of the photosystems—a practical method to improve microalgal productivity and hydrogen production in mass culture. Int. J. Hydrog
Energy, BIOHYDROGEN
A review on sources, identification and treatment strategies for the removal of toxic Arsenic from water system
J Hazard Mater
Coupling high frequency monitoring and bioassay experiments to investigate a harmful algal bloom in the Bay of Seine (French-English Channel)
Mar Pollut Bull
Algal photosynthetic responses to toxic metals and herbicides assessed by chlorophyll a fluorescence
Ecotoxicol Environ Saf
Acute toxicity, uptake and accumulation kinetics of nickel in an invasive copepod species: Pseudodiaptomus marinus
Chemosphere
The interactions between microplastic polyvinyl chloride and marine diatoms: Physiological, morphological, and growth effects
Ecotoxicol Environ Saf
Spatial distribution of benthic toxicity and sediment-bound metals and arsenic in Guangzhou urban waterways: Influence of land use
J Hazard Mater
Thioredoxin-like protein CDSP32 alleviates Cd-induced photosynthetic inhibition in tobacco leaves by regulating cyclic electron flow and excess energy dissipation
Plant Physiol Biochem
Arsenic bioaccumulation and biotransformation in aquatic organisms
Environ Int
High copper and UVR synergistically reduce the photochemical activity in the marine diatom Skeletonema costatum
J Photochem Photobiol B
Population response of the estuarine copepod Eurytemora affinis to its bioaccumulation of trace metals
Chemosphere
Effects of polystyrene microplastic on uptake and toxicity of copper and cadmium in hydroponic wheat seedlings (Triticum aestivum L.)
Ecotoxicol Environ Saf
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