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Liu Y, Mao Y, Gui J, Long Y, Wen Y, Xie S, Sun J. Stratification of dissolved organic matter in the upper 5000 m water column in the western Pacific Ocean. MARINE ENVIRONMENTAL RESEARCH 2024; 194:106346. [PMID: 38215625 DOI: 10.1016/j.marenvres.2024.106346] [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: 09/26/2023] [Revised: 12/12/2023] [Accepted: 01/07/2024] [Indexed: 01/14/2024]
Abstract
Marine dissolved organic matter (DOM) is a principal reservoir involved in biogeochemical cycles and exerts a pivotal influence on global carbon flux dynamics. In this study, excitation-emission matrix fluorescence spectroscopy combined with parallel factor analysis (EEM-PARAFAC) was conducted on 230 DOM samples collected from 21 sites between February and April 2022 in the Western Pacific Ocean (WPO). We identified five distinct fluorescence peaks (peaks B, T, A, C, and M), predominantly protein-like and humic-like components. These findings, marked by significant differences (p < 0.01) in fluorescence intensities and spectral indices, characterized the transformation of DOM with ocean depth, illustrating a transition from active to recalcitrant forms. Additionally, random forest analysis (RFA) identified depth as a key factor influencing marine dissolved organic carbon (DOC), with a 32.59% importance value. Correlations between hydrological and fluorescent parameters underscored the complexity of DOM sources and influencing processes. Overall, this work broadens our understanding of DOM variability in the upper 5000 m of the WPO, enhancing our knowledge of the marine environment's role in the global carbon cycle.
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Affiliation(s)
- Yang Liu
- School of Life Science, Shanxi University, Taiyuan, 030006, China; Research Centre for Indian Ocean Ecosystem, Tianjin University of Science and Technology, Tianjin, 300457, China
| | - Yingjie Mao
- College of Marine Science and Technology, China University of Geosciences (Wuhan), Wuhan 430074, PR China; Research Centre for Indian Ocean Ecosystem, Tianjin University of Science and Technology, Tianjin, 300457, China
| | - Jiang Gui
- College of Marine Science and Technology, China University of Geosciences (Wuhan), Wuhan 430074, PR China; Research Centre for Indian Ocean Ecosystem, Tianjin University of Science and Technology, Tianjin, 300457, China
| | - Yi Long
- College of Marine Science and Technology, China University of Geosciences (Wuhan), Wuhan 430074, PR China; Research Centre for Indian Ocean Ecosystem, Tianjin University of Science and Technology, Tianjin, 300457, China
| | - Yujian Wen
- Research Centre for Indian Ocean Ecosystem, Tianjin University of Science and Technology, Tianjin, 300457, China
| | - Shulian Xie
- School of Life Science, Shanxi University, Taiyuan, 030006, China
| | - Jun Sun
- College of Marine Science and Technology, China University of Geosciences (Wuhan), Wuhan 430074, PR China; Research Centre for Indian Ocean Ecosystem, Tianjin University of Science and Technology, Tianjin, 300457, China.
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Kholssi R, Lougraimzi H, Moreno-Garrido I. Effects of global environmental change on microalgal photosynthesis, growth and their distribution. MARINE ENVIRONMENTAL RESEARCH 2023; 184:105877. [PMID: 36640723 DOI: 10.1016/j.marenvres.2023.105877] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/24/2022] [Revised: 01/06/2023] [Accepted: 01/08/2023] [Indexed: 06/17/2023]
Abstract
Global climate change (GCC) constitutes a complex challenge posing a serious threat to biodiversity and ecosystems in the next decades. There are several recent studies dealing with the potential effect of increased temperature, decrease of pH or shifts in salinity, as well as cascading events of GCC and their impact on human-environment systems. Microalgae as primary producers are a sensitive compartment of the marine ecosystems to all those changes. However, the potential consequences of these changes for marine microalgae have received relatively little attention and they are still not well understood. Thus, there is an urgent need to explore and understand the effects generated by multiple climatic changes on marine microalgae growth and biodiversity. Therefore, this review aimed to compare and contrast mechanisms that marine microalgae exhibit to directly respond to harsh conditions associated with GCC and the potential consequences of those changes in marine microalgal populations. Literature shows that microalgae responses to environmental stressors such as temperature were affected differently. A stress caused by salinity might slow down cell division, reduces size, ceases motility, and triggers palmelloid formation in microalgae community, but some of these changes are strongly species-specific. UV irradiance can potentially lead to an oxidative stress in microalgae, promoting the production of reactive oxygen species (ROS) or induce direct physical damage on microalgae, then inhibiting the growth of microalgae. Moreover, pH could impact many groups of microalgae being more tolerant of certain pH shifts, while others were sensitive to changes of just small units (such as coccolithophorids) and subsequently affect the species at a higher trophic level, but also total vertical carbon transport in oceans. Overall, this review highlights the importance of examining effects of multiple stressors, considering multiple responses to understand the complexity behind stressor interactions.
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Affiliation(s)
- Rajaa Kholssi
- Composting Research Group, Faculty of Sciences, University of Burgos, Burgos, Spain; Ecology and Coastal Management, Institute of Marine Sciences of Andalusia (ICMAN-CSIC), Campus Río San Pedro, 11510, Puerto Real, Cádiz, Spain.
| | - Hanane Lougraimzi
- Laboratory of Plant, Animal and Agro-Industry Productions, Faculty of Sciences, Ibn Tofail University, BP: 242, 14000, Kenitra, Morocco
| | - Ignacio Moreno-Garrido
- Ecology and Coastal Management, Institute of Marine Sciences of Andalusia (ICMAN-CSIC), Campus Río San Pedro, 11510, Puerto Real, Cádiz, Spain
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Li H, Gao K. Deoxygenation enhances photosynthetic performance and increases N 2 fixation in the marine cyanobacterium Trichodesmium under elevated pCO 2. Front Microbiol 2023; 14:1102909. [PMID: 36876059 PMCID: PMC9975739 DOI: 10.3389/fmicb.2023.1102909] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2022] [Accepted: 01/27/2023] [Indexed: 02/17/2023] Open
Abstract
Effects of changed levels of dissolved O2 and CO2 on marine primary producers are of general concern with respect to ecological effects of ongoing ocean deoxygenation and acidification as well as upwelled seawaters. We investigated the response of the diazotroph Trichodesmium erythraeum IMS 101 after it had acclimated to lowered pO2 (~60 μM O2) and/or elevated pCO2 levels (HC, ~32 μM CO2) for about 20 generations. Our results showed that reduced O2 levels decreased dark respiration significantly, and increased the net photosynthetic rate by 66 and 89% under the ambient (AC, ~13 μM CO2) and the HC, respectively. The reduced pO2 enhanced the N2 fixation rate by ~139% under AC and only by 44% under HC, respectively. The N2 fixation quotient, the ratio of N2 fixed per O2 evolved, increased by 143% when pO2 decreased by 75% under the elevated pCO2. Meanwhile, particulate organic carbon and nitrogen quota increased simultaneously under reduced O2 levels, regardless of the pCO2 treatments. Nevertheless, changed levels of O2 and CO2 did not bring about significant changes in the specific growth rate of the diazotroph. Such inconsistency was attributed to the daytime positive and nighttime negative effects of both lowered pO2 and elevated pCO2 on the energy supply for growth. Our results suggest that Trichodesmium decrease its dark respiration by 5% and increase its N2-fixation by 49% and N2-fixation quotient by 30% under future ocean deoxygenation and acidification with 16% decline of pO2 and 138% rise of pCO2 by the end of this century.
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Affiliation(s)
- He Li
- State Key Laboratory of Marine Environmental Science, College of Ocean and Earth Sciences, Xiamen University, Xiamen, China
| | - Kunshan Gao
- State Key Laboratory of Marine Environmental Science, College of Ocean and Earth Sciences, Xiamen University, Xiamen, China.,Co-Innovation Center of Jiangsu Marine Bio-industry Technology, Jiangsu Ocean University, Lianyungang, China
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Piscoya E, von Dassow P, Aldunate M, Vargas CA. Physical-chemical factors influencing the vertical distribution of phototrophic pico-nanoplankton in the Oxygen Minimum Zone (OMZ) off Northern Chile: The relative influence of low pH/low O 2 conditions. MARINE ENVIRONMENTAL RESEARCH 2022; 180:105710. [PMID: 35932510 DOI: 10.1016/j.marenvres.2022.105710] [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: 01/17/2022] [Revised: 07/21/2022] [Accepted: 07/23/2022] [Indexed: 06/15/2023]
Abstract
The vertical distribution of phytoplankton is of fundamental importance in the structure, dynamic, and biogeochemical pathways in marine ecosystems. Nevertheless, what are the main factors determining this distribution remains as an open question. Here, we evaluated the relative influence of environmental factors that might control the coexistence and vertical distribution of pico-nanoplankton associated with the OMZ off northern Chile. Our results showed that in the upper layer Synechococcus-like cells were numerically important at all sampling stations. Pico-nano eukaryotes and phototrophic nanoflagellates (PNF) also showed high abundances in the upper layer decreasing in abundance down to the upper oxycline, while only Prochlorococcus showed high abundances under oxycline and within the oxygen-depleted layer. Statistical analyses evidenced that temperature, oxygen, and carbonate chemistry parameters (pH and dissolved inorganic carbon, DIC) influenced significantly the vertical distribution of phototrophic pico-nanoplankton. Additionally, we experimentally-evaluated the combined effect of low pH/low O2 conditions on a nanophytoplankton species, the haptophyte Imantonia sp. Under control conditions (pH = 8.1; O2 = 287.5 μM, light = 169.6 μEm-2s-1), Imantonia sp. in vivo fluorescence increased over fifty times, inducing supersaturated O2 conditions (900 μM) and an increasing pH (8.5), whereas upon an experimental treatment mimicking OMZ conditions (pH = 7.5; O2 = 55.6 μM; light = 169.6 μEm-2s-1), in vivo fluorescence declined dramatically, suggesting that Imantonia sp. did not survive. Although preliminary, our study provides evidence about the role of low pH/low O2 conditions on the vertical distribution of nanophytoplankton, which deserve future attention through both fieldwork and more extended experimental experiences.
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Affiliation(s)
- Edson Piscoya
- Graduate Program in Oceanography, Department of Oceanography, Universidad de Concepción, Casilla 160-C, Concepcion, Chile; Millennium Institute of Oceanography (IMO), Concepción, Chile; Coastal Ecosystems & Global Environmental Change Lab (ECCALab), Department of Aquatic Systems, Faculty of Environmental Sciences, Universidad de Concepción, Concepcion, Chile
| | - Peter von Dassow
- Millennium Institute of Oceanography (IMO), Concepción, Chile; Department of Ecology, P. Universidad Católica de Chile, Alameda 340, Santiago, Chile; Research Fellow, Stazione Zoologica Anton Dohrn Napoli, Naples, Italy
| | - Montserrat Aldunate
- Millennium Institute of Oceanography (IMO), Concepción, Chile; Coastal Ecosystems & Global Environmental Change Lab (ECCALab), Department of Aquatic Systems, Faculty of Environmental Sciences, Universidad de Concepción, Concepcion, Chile
| | - Cristian A Vargas
- Millennium Institute of Oceanography (IMO), Concepción, Chile; Coastal Ecosystems & Global Environmental Change Lab (ECCALab), Department of Aquatic Systems, Faculty of Environmental Sciences, Universidad de Concepción, Concepcion, Chile; Coastal Socio-ecological Millennium Institute (SECOS), P. Universidad Católica de Chile, Chile.
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