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Agarwal V, Sonnet V, Inomura K, Ciochetto AB, Mouw CB. Image-derived indicators of phytoplankton community responses to Pseudo-nitzschia blooms. HARMFUL ALGAE 2024; 138:102702. [PMID: 39244237 DOI: 10.1016/j.hal.2024.102702] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/21/2024] [Revised: 07/18/2024] [Accepted: 07/24/2024] [Indexed: 09/09/2024]
Abstract
Phytoplankton populations in the natural environment interact with each other. Despite rising global concern with Pseudo-nitzschia blooms, which can produce the potent neurotoxin domoic acid, we still do not fully understand how other phytoplankton genera respond to the presence of Pseudo-nitzschia. Here, we used a 4-year high-resolution imaging dataset for 9 commonly found phytoplankton genera in Narragansett Bay, alongside environmental data, to identify potential interactions between phytoplankton genera and their response to elevated Pseudo-nitzschia abundance. Our results indicate that Pseudo-nitzschia tends to bloom either concurrently with or right after other phytoplankton genera. Such bloom periods coincide with higher water temperatures and lower salinity. Pseudo-nitzschia image abundance tends to increase the most from March-May and peaks during May-Jun, whereas the image-derived biovolume and width of Pseudo-nitzschia chains increase the most during Jan-Feb. For most phytoplankton genera, their relationship with Pseudo-nitzschia abundance is noticeably different from their relationship with Pseudo-nitzschia image features. Despite the complexity in the phytoplankton community, our analysis suggests several ecological indicators that may be used to determine the risk of harmful algal blooms.
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Affiliation(s)
- Vitul Agarwal
- Graduate School of Oceanography, University of Rhode Island, Narragansett, USA.
| | - Virginie Sonnet
- Graduate School of Oceanography, University of Rhode Island, Narragansett, USA; Laboratoire d'Océanographie de Villefanche, Sorbonne Université, CNRS, Villefranche-sur-mer, France
| | - Keisuke Inomura
- Graduate School of Oceanography, University of Rhode Island, Narragansett, USA
| | - Audrey B Ciochetto
- Graduate School of Oceanography, University of Rhode Island, Narragansett, USA
| | - Colleen B Mouw
- Graduate School of Oceanography, University of Rhode Island, Narragansett, USA.
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2
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Lou Y, Wang Y, Li S, Yu F, Liu X, Cong Y, Li Z, Jin F, Zhang M, Yao Z, Wang J. Different responses of marine microalgae Phaeodactylum tricornutum upon exposures to WAF and CEWAF of crude oil: A case study coupled with stable isotopic signatures. JOURNAL OF HAZARDOUS MATERIALS 2024; 468:133833. [PMID: 38401215 DOI: 10.1016/j.jhazmat.2024.133833] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/18/2023] [Revised: 02/16/2024] [Accepted: 02/17/2024] [Indexed: 02/26/2024]
Abstract
Increasing use of chemical dispersants for oil spills highlights the need to understand their adverse effects on marine microalgae and nutrient assimilation because the toxic components of crude oil can be more bioavailable. We employed the crude oil water-accommodated fraction (WAF) and chemically enhanced WAF (CEWAF) to compare different responses in marine microalgae (Phaeodactylum tricornutum) coupled with stable isotopic signatures. The concentration and proportion of high-molecular-weight polycyclic aromatic hydrocarbons (HMW PAHs), which are key toxic components in crude oil, increased after dispersant addition. CEWAF exposure caused higher percent growth inhibition and a lower chlorophyll-a level of microalgae than those after WAF exposure. Compared with WAF exposure, CEWAF led to an enhancement in the self-defense mechanism of P. tricornutum, accompanied by an increased content of extracellular polymeric substances. 13C-depletion and carbon assimilation were altered in P. tricornutum, suggesting more HMW PAHs could be utilized as carbon sources by microalgae under CEWAF. CEWAF had no significant effects on the isotopic fractionation or assimilation of nitrogen in P. tricornutum. Our study unveiled the impact on the growth, physiological response, and nutrient assimilation of microalgae upon WAF and CEWAF exposures. Our data provide new insights into the ecological effects of dispersant applications for coastal oil spills.
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Affiliation(s)
- Yadi Lou
- Key Laboratory for Ecological Environment in Coastal Areas (Ministry of Ecology and Environment), Marine Debris and Microplastic Research Center, Department of Marine Chemistry, National Marine Environmental Monitoring Center, Dalian 116023, China
| | - Ying Wang
- Key Laboratory for Ecological Environment in Coastal Areas (Ministry of Ecology and Environment), Marine Debris and Microplastic Research Center, Department of Marine Chemistry, National Marine Environmental Monitoring Center, Dalian 116023, China.
| | - Shiyue Li
- Key Laboratory for Ecological Environment in Coastal Areas (Ministry of Ecology and Environment), Marine Debris and Microplastic Research Center, Department of Marine Chemistry, National Marine Environmental Monitoring Center, Dalian 116023, China; College of Marine Ecology and Environment, Shanghai Ocean University, Shanghai 201306, China
| | - Fuwei Yu
- Key Laboratory for Ecological Environment in Coastal Areas (Ministry of Ecology and Environment), Marine Debris and Microplastic Research Center, Department of Marine Chemistry, National Marine Environmental Monitoring Center, Dalian 116023, China; School of Chemical, Dalian University of Technology, Dalian 116024, China
| | - Xing Liu
- Key Laboratory for Ecological Environment in Coastal Areas (Ministry of Ecology and Environment), Marine Debris and Microplastic Research Center, Department of Marine Chemistry, National Marine Environmental Monitoring Center, Dalian 116023, China
| | - Yi Cong
- Key Laboratory for Ecological Environment in Coastal Areas (Ministry of Ecology and Environment), Marine Debris and Microplastic Research Center, Department of Marine Chemistry, National Marine Environmental Monitoring Center, Dalian 116023, China
| | - Zhaochuan Li
- Key Laboratory for Ecological Environment in Coastal Areas (Ministry of Ecology and Environment), Marine Debris and Microplastic Research Center, Department of Marine Chemistry, National Marine Environmental Monitoring Center, Dalian 116023, China
| | - Fei Jin
- Key Laboratory for Ecological Environment in Coastal Areas (Ministry of Ecology and Environment), Marine Debris and Microplastic Research Center, Department of Marine Chemistry, National Marine Environmental Monitoring Center, Dalian 116023, China
| | - Mingxing Zhang
- Key Laboratory for Ecological Environment in Coastal Areas (Ministry of Ecology and Environment), Marine Debris and Microplastic Research Center, Department of Marine Chemistry, National Marine Environmental Monitoring Center, Dalian 116023, China
| | - Ziwei Yao
- Key Laboratory for Ecological Environment in Coastal Areas (Ministry of Ecology and Environment), Marine Debris and Microplastic Research Center, Department of Marine Chemistry, National Marine Environmental Monitoring Center, Dalian 116023, China
| | - Juying Wang
- Key Laboratory for Ecological Environment in Coastal Areas (Ministry of Ecology and Environment), Marine Debris and Microplastic Research Center, Department of Marine Chemistry, National Marine Environmental Monitoring Center, Dalian 116023, China
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Ben Othman H, Pick FR, Sakka Hlaili A, Leboulanger C. Effects of polycyclic aromatic hydrocarbons on marine and freshwater microalgae - A review. JOURNAL OF HAZARDOUS MATERIALS 2023; 441:129869. [PMID: 36063709 DOI: 10.1016/j.jhazmat.2022.129869] [Citation(s) in RCA: 17] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/31/2022] [Revised: 07/18/2022] [Accepted: 08/26/2022] [Indexed: 06/15/2023]
Abstract
The first synthetic review of the PAHs effects on microalgae in experimental studies and aquatic ecosystems is provided. Phytoplankton and phytobenthos from marine and freshwaters show a wide range of sensitivities to PAHs, and can accumulate, transfer and degrade PAHs. Different toxicological endpoints including growth, chlorophyll a, in vivo fluorescence yield, membrane integrity, lipid content, anti-oxidant responses and gene expression are reported for both freshwater and marine microalgal species exposed to PAHs in culture and in natural assemblages. Photosynthesis, the key process carried out by microalgae appears to be the most impacted by PAH exposure. The effect of PAHs is both dose- and species-dependent and influenced by environmental factors such as UV radiation, temperature, and salinity. Under natural conditions, PAHs are typically present in mixtures and the toxic effects induced by single PAHs are not necessarily extrapolated to mixtures. Natural microalgal communities appear more sensitive to PAH contamination than microalgae in monospecific culture. To further refine the ecological risks linked to PAH exposure, species-sensitivity distributions (SSD) were analyzed based on published EC50s (half-maximal effective concentrations during exposure). HC5 (harmful concentration for 5% of the species assessed) was derived from SSD to provide a toxicity ranking for each of nine PAHs. The most water-soluble PAHs naphthalene (HC5 = 650 µg/L), acenaphthene (HC5 = 274 µg/L), and fluorene (HC5 = 76.8 µg/L) are the least toxic to microalgae, whereas benzo[a]pyrene (HC5 = 0.834 µg/L) appeared as the more toxic. No relationship between EC50 and cell biovolume was established, which does not support assumptions that larger microalgal cells are less sensitive to PAHs, and calls for further experimental evidence. The global PAHs HC5 for marine species was on average higher than for freshwater species (26.3 and 1.09 µg/L, respectively), suggesting a greater tolerance of marine phytoplankton towards PAHs. Nevertheless, an important number of experimental exposure concentrations and reported toxicity thresholds are above known PAHs solubility in water. The precise and accurate assessment of PAHs toxicity to microalgae will continue to benefit from more rigorously designed experimental studies, including control of exposure duration and biometric data on test microalgae.
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Affiliation(s)
- Hiba Ben Othman
- Laboratoire de Phytoplanctonologie, Faculté des Sciences de Bizerte, Université de Carthage, Zarzouna, 7021 Bizerte, Tunisia; MARBEC, Univ Montpellier, IRD, Ifremer, CNRS, Sète, France
| | - Frances R Pick
- Department of Biology, University of Ottawa, Ottawa K1N 6N5, Canada
| | - Asma Sakka Hlaili
- Laboratoire de Phytoplanctonologie, Faculté des Sciences de Bizerte, Université de Carthage, Zarzouna, 7021 Bizerte, Tunisia; Université de Tunis El Manar, Faculté des Sciences de Tunis, LR18ES41 Sciences de l'Environnement, Biologie et Physiologie des Organismes Aquatiques, Tunis, Tunisia
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Kamalanathan M, Mapes S, Prouse A, Faulkner P, Klobusnik NH, Hillhouse J, Hala D, Quigg A. Core metabolism plasticity in phytoplankton: Response of Dunaliella tertiolecta to oil exposure. JOURNAL OF PHYCOLOGY 2022; 58:804-814. [PMID: 36056600 PMCID: PMC10087180 DOI: 10.1111/jpy.13286] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/06/2022] [Accepted: 08/23/2022] [Indexed: 06/15/2023]
Abstract
Human alterations to the marine environment such as an oil spill can induce oxidative stress in phytoplankton. Exposure to oil has been shown to be lethal to most phytoplankton species, but some are able to survive and grow at unaffected or reduced growth rates, which appears to be independent of the class and phylum of the phytoplankton and their ability to consume components of oil heterotrophically. The goal of this article is to test the role of core metabolism plasticity in the oil-resisting ability of phytoplankton. Experiments were performed on the oil- resistant chlorophyte, Dunaliella tertiolecta, in control and water accommodated fractions of oil, with and without metabolic inhibitors targeting the core metabolic pathways. We observed that inhibiting pathways such as photosynthetic electron transport (PET) and pentose-phosphate pathway were lethal; however, inhibition of pathways such as mitochondrial electron transport and cyclic electron transport caused growth to be arrested. Pathways such as photorespiration and Kreb's cycle appear to play a critical role in the oil-tolerating ability of D. tertiolecta. Analysis of photo-physiology revealed reduced PET under inhibition of photorespiration but not Kreb's cycle. Further studies showed enhanced flux through Kreb's cycle suggesting increased energy production and photorespiration counteract oxidative stress. Lastly, reduced extracellular carbohydrate secretion under oil exposure indicated carbon and energy conservation, which together with enhanced flux through Kreb's cycle played a major role in the survival of D. tertiolecta under oil exposure by meeting the additional energy demands. Overall, we present data that suggest the role of phenotypic plasticity of multiple core metabolic pathways in accounting for the oxidative stress tolerating ability of certain phytoplankton species.
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Affiliation(s)
- Manoj Kamalanathan
- Department of Marine BiologyTexas A&M University at GalvestonGalvestonTexas77573USA
- Present address:
Bigelow Laboratory for Ocean SciencesEast BoothbayMaine04544USA
| | - Savannah Mapes
- Department of Marine BiologyTexas A&M University at GalvestonGalvestonTexas77573USA
- Present address:
Virginia Institute of Marine ScienceGloucester PointVirginia23062USA
| | - Alexandra Prouse
- Department of Marine BiologyTexas A&M University at GalvestonGalvestonTexas77573USA
| | - Patricia Faulkner
- Department of Marine BiologyTexas A&M University at GalvestonGalvestonTexas77573USA
| | | | - Jessica Hillhouse
- Department of Marine BiologyTexas A&M University at GalvestonGalvestonTexas77573USA
| | - David Hala
- Department of Marine BiologyTexas A&M University at GalvestonGalvestonTexas77573USA
| | - Antonietta Quigg
- Department of Marine BiologyTexas A&M University at GalvestonGalvestonTexas77573USA
- Department of OceanographyTexas A&M UniversityCollege StationTexas77845USA
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From Surface Water to the Deep Sea: A Review on Factors Affecting the Biodegradation of Spilled Oil in Marine Environment. JOURNAL OF MARINE SCIENCE AND ENGINEERING 2022. [DOI: 10.3390/jmse10030426] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Over the past century, the demand for petroleum products has increased rapidly, leading to higher oil extraction, processing and transportation, which result in numerous oil spills in coastal-marine environments. As the spilled oil can negatively affect the coastal-marine ecosystems, its transport and fates captured a significant interest of the scientific community and regulatory agencies. Typically, the environment has natural mechanisms (e.g., photooxidation, biodegradation, evaporation) to weather/degrade and remove the spilled oil from the environment. Among various oil weathering mechanisms, biodegradation by naturally occurring bacterial populations removes a majority of spilled oil, thus the focus on bioremediation has increased significantly. Helping in the marginal recognition of this promising technique for oil-spill degradation, this paper reviews recently published articles that will help broaden the understanding of the factors affecting biodegradation of spilled oil in coastal-marine environments. The goal of this review is to examine the effects of various environmental variables that contribute to oil degradation in the coastal-marine environments, as well as the factors that influence these processes. Physico-chemical parameters such as temperature, oxygen level, pressure, shoreline energy, salinity, and pH are taken into account. In general, increase in temperature, exposure to sunlight (photooxidation), dissolved oxygen (DO), nutrients (nitrogen, phosphorous and potassium), shoreline energy (physical advection—waves) and diverse hydrocarbon-degrading microorganisms consortium were found to increase spilled oil degradation in marine environments. In contrast, higher initial oil concentration and seawater pressure can lower oil degradation rates. There is limited information on the influences of seawater pH and salinity on oil degradation, thus warranting additional research. This comprehensive review can be used as a guide for bioremediation modeling and mitigating future oil spill pollution in the marine environment by utilizing the bacteria adapted to certain conditions.
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Sweet JA, Bargu S, Morrison WL, Parsons M, Pathare MG, Roberts BJ, Soniat TM, Stauffer BA. Phytoplankton dynamics in Louisiana estuaries: Building a baseline to understand current and future change. MARINE POLLUTION BULLETIN 2022; 175:113344. [PMID: 35124379 DOI: 10.1016/j.marpolbul.2022.113344] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/08/2021] [Revised: 01/04/2022] [Accepted: 01/09/2022] [Indexed: 06/14/2023]
Abstract
Louisiana estuaries are important habitats in the northern Gulf of Mexico, a region undergoing significant and sustained human- and climate-driven changes. This paper synthesizes data collected over multiple years from four Louisiana estuaries - Breton Sound, Terrebonne Bay, the Atchafalaya River Delta Estuary, and Vermilion Bay - to characterize trends in phytoplankton biomass, community composition, and the environmental factors influencing them. Results highlight similarities in timing and composition of maximum chlorophyll, with salinity variability often explaining biomass trends. Distinct drivers for biomass versus community structure were observed in all four estuarine systems. Systems shared a lack of significant correlation between river discharge and overall phytoplankton biomass, while discharge was important for understanding community composition. Temperature was a significant explanatory variable for both biomass and community composition in only one system. These results provide a regional view of phytoplankton dynamics in Louisiana estuaries critical to understanding and predicting the effects of ongoing change.
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Affiliation(s)
- Julia A Sweet
- Department of Biology, University of Louisiana at Lafayette, Lafayette, LA 70503, USA.
| | - Sibel Bargu
- Department of Oceanography and Coastal Sciences, Louisiana State University, Baton Rouge, LA 70803, USA
| | - Wendy L Morrison
- Louisiana Universities Marine Consortium, Cocodrie, LA 70344, USA
| | - Michael Parsons
- Coastal Watershed Institute, Florida Gulf Coast University, Fort Myers, FL 33965, USA
| | - Mrunmayee G Pathare
- Department of Biology, University of Louisiana at Lafayette, Lafayette, LA 70503, USA
| | - Brian J Roberts
- Louisiana Universities Marine Consortium, Cocodrie, LA 70344, USA
| | - Thomas M Soniat
- Department of Biological Sciences, University of New Orleans, New Orleans, LA 70148, USA
| | - Beth A Stauffer
- Department of Biology, University of Louisiana at Lafayette, Lafayette, LA 70503, USA
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Remote Sensing of Dispersed Oil Pollution in the Ocean-The Role of Chlorophyll Concentration. SENSORS 2021; 21:s21103387. [PMID: 34067967 PMCID: PMC8152263 DOI: 10.3390/s21103387] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/30/2021] [Revised: 05/08/2021] [Accepted: 05/10/2021] [Indexed: 11/17/2022]
Abstract
In the contrary to surface oil slicks, dispersed oil pollution is not yet detected or monitored on regular basis. The possible range of changes of the local optical properties of seawater caused by the occurrence of dispersed oil, as well as the dependencies of changes on various physical and environmental factors, can be estimated using simulation techniques. Two models were combined to examine the influence of oceanic water type on the visibility of dispersed oil: the Monte Carlo radiative transfer model and the Lorenz-Mie model for spherical oil droplets suspended in seawater. Remote sensing reflectance, Rrs, was compared for natural ocean water models representing oligotrophic, mesotrophic and eutrophic environments (characterized by chlorophyll-a concentrations of 0.1, 1 and 10 mg/m3, respectively) and polluted by three different kinds of oils: biodiesel, lubricant oil and crude oil. We found out that dispersed oil usually increases Rrs values for all types of seawater, with the highest effect for the oligotrophic ocean. In the clearest studied waters, the absolute values of Rrs increased 2-6 times after simulated dispersed oil pollution, while Rrs band ratios routinely applied in bio-optical models decreased up to 80%. The color index, CI, was nearly double reduced by dispersed biodiesel BD and lubricant oil CL, but more than doubled by crude oil FL.
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Quigg A, Parsons M, Bargu S, Ozhan K, Daly KL, Chakraborty S, Kamalanathan M, Erdner D, Cosgrove S, Buskey EJ. Marine phytoplankton responses to oil and dispersant exposures: Knowledge gained since the Deepwater Horizon oil spill. MARINE POLLUTION BULLETIN 2021; 164:112074. [PMID: 33540275 DOI: 10.1016/j.marpolbul.2021.112074] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/06/2020] [Revised: 10/16/2020] [Accepted: 01/15/2021] [Indexed: 06/12/2023]
Abstract
The Deepwater Horizon oil spill of 2010 brought the ecology and health of the Gulf of Mexico to the forefront of the public's and scientific community's attention. Not only did we need a better understanding of how this oil spill impacted the Gulf of Mexico ecosystem, but we also needed to apply this knowledge to help assess impacts from perturbations in the region and guide future response actions. Phytoplankton represent the base of the food web in oceanic systems. As such, alterations of the phytoplankton community propagate to upper trophic levels. This review brings together new insights into the influence of oil and dispersant on phytoplankton. We bring together laboratory, mesocosm and field experiments, including insights into novel observations of harmful algal bloom (HAB) forming species and zooplankton as well as bacteria-phytoplankton interactions. We finish by addressing knowledge gaps and highlighting key topics for research in novel areas.
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Affiliation(s)
- Antonietta Quigg
- Texas A&M University at Galveston, 200 Seawolf Parkway, Galveston, TX 77553, USA.
| | - Michael Parsons
- Florida Gulf Coast University, 10501 FGCU Blvd South, Fort Myers, FL 33965, USA.
| | - Sibel Bargu
- Louisiana State University, 1235 Energy, Coast & Environment Building, Baton Rouge, LA 70803, USA.
| | - Koray Ozhan
- Middle East Technical University, P.O. Box 28, 33731 Erdemli, Mersin, Turkey.
| | - Kendra L Daly
- University of South Florida, 140 Seventh Ave S., St. Petersburg, FL 33701, USA.
| | - Sumit Chakraborty
- Mote Marine Laboratory, 1600 Ken Thompson Parkway, Sarasota, FL 34236, USA.
| | - Manoj Kamalanathan
- Texas A&M University at Galveston, 200 Seawolf Parkway, Galveston, TX 77553, USA.
| | - Deana Erdner
- University of Texas Marine Science Institute, 750 Channel View Drive, Port Aransas, TX 78373, USA.
| | - Sarah Cosgrove
- University of Texas Marine Science Institute, 750 Channel View Drive, Port Aransas, TX 78373, USA.
| | - Edward J Buskey
- University of Texas Marine Science Institute, 750 Channel View Drive, Port Aransas, TX 78373, USA.
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Liu Y, Li N, Lou Y, Liu Y, Zhao X, Wang G. Effect of water accommodated fractions of fuel oil on fixed carbon and nitrogen by microalgae: Implication by stable isotope analysis. ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY 2020; 195:110488. [PMID: 32200143 DOI: 10.1016/j.ecoenv.2020.110488] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/28/2019] [Revised: 03/14/2020] [Accepted: 03/15/2020] [Indexed: 06/10/2023]
Abstract
Effect of water accommodated fractions (WAF) of #180 fuel oil on fixed carbon and nitrogen in microalgae was studied by stable isotopes. Platymonas helgolandica, Heterosigma akashiwo and Nitzschia closterium were exposed to five WAF concentrations for 96 h. The δ13C value of microalgae was significantly lower than that of the control group, indicated that carbon was limited in the WAF concentrations. The δ13C value of microalgae appeared peak valley at 48 h in control group, corresponding to the enhanced capacity in carbon fixation during microalgae photosynthesis. The physiological acclimation capacity of microalgae was revealed by the occurrence time when the δ13C value was in peak valley, and thus the physiological acclimation capacity of microalgae decreased in the order of Nitzschia closterium > Heterosigma akashiwo > Platymonas helgolandica. Principal component analysis (PCA) were applied to the δ13C value in order to verify the "hormesis" phenomenon in microalgae. The δ13C value could discriminate between stimulatory effects at low doses and inhibitory effects at high doses. In addition, the present study also investigated the effect of the nitrogen on microalgae growth. Because microalgae could still absorb the NO3-N and release of NO2-N and NH4-N in present study, the nitrogen cycle in microalgae was in the equilibrium status. The δ15N value in microalgae exhibited no obvious change with the increasing of WAF concentrations at the same time. However, due to the enrichment of nitrogen, the δ15N value first increased gradually with the time and finally was stable. Overall, the fractionation of carbon and nitrogen stable isotopes illustrated that the effect of carbon on the growth of microalgae was more prominent than nitrogen. Stable isotopes was used to investigate the influence of WAF on fixed carbon and nitrogen in microalgae growth, providing a fundamental theoretical guidance for risk assessment of marine ecological environment.
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Affiliation(s)
- Yu Liu
- College of Environmental Science and Engineering, Dalian Maritime University, Dalian, China; Environmental Information Institute, Dalian Maritime University, Dalian, China.
| | - Na Li
- College of Environmental Science and Engineering, Dalian Maritime University, Dalian, China
| | - Yadi Lou
- College of Environmental Science and Engineering, Dalian Maritime University, Dalian, China
| | - Yuxin Liu
- College of Environmental Science and Engineering, Dalian Maritime University, Dalian, China
| | - Xinda Zhao
- College of Environmental Science and Engineering, Dalian Maritime University, Dalian, China
| | - Guoguang Wang
- College of Environmental Science and Engineering, Dalian Maritime University, Dalian, China.
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