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Huguet A, Barillé L, Soudant D, Petitgas P, Gohin F, Lefebvre A. Identifying the spatial pattern and the drivers of the decline in the eastern English Channel chlorophyll-a surface concentration over the last two decades. MARINE POLLUTION BULLETIN 2024; 199:115870. [PMID: 38134868 DOI: 10.1016/j.marpolbul.2023.115870] [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: 03/31/2023] [Revised: 11/25/2023] [Accepted: 11/29/2023] [Indexed: 12/24/2023]
Abstract
It has been established from previous studies that chlorophyll-a surface concentration has been declining in the eastern English Channel. This decline has been attributed to a decrease in nutrient concentrations in the rivers. However, the decrease in river discharge could also be a cause. In our study, rivers outflows and in-situ data have been compared to time series of satellite-derived chlorophyll-a concentrations. Dynamic Linear Model has been used to extract the dynamic and seasonally adjusted trends of several environmental variables. The results showed that, for the 1998-2019 period, chlorophyll-a levels stayed significantly lower than average and satellite images revealed a coast to offshore gradient. Chlorophyll-a concentration of coastal stations appeared to be related to the declining fluxes of phosphate while offshore stations were more related to nitrate-nitrite. Therefore, we can exclude that the climate variability, through river flows alone, has a dominant effect on the decline of chlorophyll-a concentration.
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Affiliation(s)
- Antoine Huguet
- IFREMER, Service Valorisation de l'Information pour la Gestion Intégrée Et la Surveillance, Rue de l'ïle d'Yeu, B.P. 21105, 44311 Nantes Cedex 3, France.
| | - Laurent Barillé
- Nantes Université, Institut des Substances et Organismes de la Mer, ISOMer, UR 2160, 2 rue de la Houssinière, B.P. 92208, 44322 Nantes Cedex 3, France
| | - Dominique Soudant
- IFREMER, Service Valorisation de l'Information pour la Gestion Intégrée Et la Surveillance, Rue de l'ïle d'Yeu, B.P. 21105, 44311 Nantes Cedex 3, France
| | - Pierre Petitgas
- IFREMER, Département Ressources Biologiques et Environnement, Rue de l'ïle d'Yeu, B.P. 21105, 44311 Nantes Cedex 3, France
| | - Francis Gohin
- IFREMER, Laboratoire d'écologie pélagique, DYNECO PELAGOS, CS 10070, 29280 Plouzané, France
| | - Alain Lefebvre
- IFREMER, Laboratoire Environnement côtier et Ressources Aquacoles, 150 quai Gambetta, BP 699, Boulogne-sur-Mer 62321, France
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Chen YH, Gao YH, Chen CP, Liang JR, Sun L, Zhen Y, Qiao L. Seasonal variations of phytoplankton assemblages and its relation to environmental variables in a scallop culture sea area of Bohai Bay, China. MARINE POLLUTION BULLETIN 2016; 113:362-370. [PMID: 27771098 DOI: 10.1016/j.marpolbul.2016.10.025] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/03/2016] [Revised: 10/07/2016] [Accepted: 10/08/2016] [Indexed: 06/06/2023]
Abstract
Seasonal variations of phytoplankton assemblages were examined in a scallop culture sea area of Bohai Bay (China) with regard to some major physical and chemical variables. Samples were collected at three stations from July 2011 to September 2013. A total of 134 species belong to 4 phyla were identified, of which 104 were diatoms, 27 were dinoflagellates, 1 was euglenophyte and 2 were chrysophytes. The cells abundance in autumn (55.44×103cells/L) was higher than that in summer (6.99×103cells/L), spring (3.46×103cells/L) and winter (2.69×103cells/L). The Shannon-Wiener diversity index was higher in summer (3.06), followed by spring (3.02) and winter (2.91), and low in autumn (1.40). Results of canonical correspondence analysis showed that phosphate, salinity, temperature, silicate and DIN/SiO2 ratio were the most important environmental factors influencing the variation of phytoplankton community structure. It is suggested that eutrophication resulted from scallop culture would cause a potential red tide risk.
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Affiliation(s)
- Yang-Hang Chen
- School of Life Sciences, Xiamen University, Xiamen 361102, China
| | - Ya-Hui Gao
- School of Life Sciences, Xiamen University, Xiamen 361102, China; State Key Laboratory of Marine Environmental Science, Xiamen University, Xiamen 361102, China; Key Laboratory of the Ministry of Education for Coastal and Wetland Ecosystems, Xiamen University, Xiamen 361102, China.
| | - Chang-Ping Chen
- School of Life Sciences, Xiamen University, Xiamen 361102, China; Key Laboratory of the Ministry of Education for Coastal and Wetland Ecosystems, Xiamen University, Xiamen 361102, China
| | - Jun-Rong Liang
- School of Life Sciences, Xiamen University, Xiamen 361102, China; Key Laboratory of the Ministry of Education for Coastal and Wetland Ecosystems, Xiamen University, Xiamen 361102, China
| | - Lin Sun
- School of Life Sciences, Xiamen University, Xiamen 361102, China; State Key Laboratory of Marine Environmental Science, Xiamen University, Xiamen 361102, China
| | - Yu Zhen
- Key Laboratory of Marine Environment and Ecology, Ministry of Education, Qingdao 266100, China; Laboratory for Marine Ecology and Environmental Science, Qingdao National Laboratory for Marine Science and Technology, Qingdao 266071, China
| | - Ling Qiao
- Key Laboratory of Marine Environment and Ecology, Ministry of Education, Qingdao 266100, China; Laboratory for Marine Ecology and Environmental Science, Qingdao National Laboratory for Marine Science and Technology, Qingdao 266071, China
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Cunliffe M. Purine catabolic pathway revealed by transcriptomics in the model marine bacterium Ruegeria pomeroyi DSS-3. FEMS Microbiol Ecol 2015; 92:fiv150. [PMID: 26613749 DOI: 10.1093/femsec/fiv150] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/24/2015] [Indexed: 11/13/2022] Open
Abstract
Purines are nitrogen-rich compounds that are widely distributed in the marine environment and are an important component of the dissolved organic nitrogen (DON) pool. Even though purines have been shown to be degraded by bacterioplankton, the identities of marine bacteria capable of purine degradation and their underlying catabolic mechanisms are currently unknown. This study shows that Ruegeria pomeroyi, a model marine bacterium and Marine Roseobacter Clade (MRC) representative, utilizes xanthine as a source of carbon and nitrogen. The R. pomeroyi genome contains putative genes that encode xanthine dehydrogenase (XDH), which is expressed during growth with xanthine. RNAseq-based analysis of the R. pomeroyi transcriptome revealed that the transcription of an XDH-initiated catabolic pathway is up-regulated during growth with xanthine, with transcription greatest when xanthine was the only available carbon source. The RNAseq-deduced pathway indicates that glyoxylate and ammonia are the key intermediates from xanthine degradation. Utilising a laboratory model, this study has identified the potential genes and catabolic pathway active during xanthine degradation. The ability of R. pomeroyi to utilize xanthine provides novel insights into the capabilities of the MRC that may contribute to their success in marine ecosystems and the potential biogeochemical importance of the group in processing DON.
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Affiliation(s)
- Michael Cunliffe
- Marine Biological Association of the United Kingdom, The Laboratory, Citadel Hill, Plymouth PL1 2PB, UK Marine Biology and Ecology Research Centre, Marine Institute, Plymouth University, Drake Circus, Plymouth PL4 8AA, UK
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Samanta B, Bhadury P. Analysis of diversity of chromophytic phytoplankton in a mangrove ecosystem using rbcL gene sequencing. JOURNAL OF PHYCOLOGY 2014; 50:328-340. [PMID: 26988190 DOI: 10.1111/jpy.12163] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/21/2013] [Accepted: 11/21/2013] [Indexed: 06/05/2023]
Abstract
Phytoplankton forms the basis of primary production in mangrove environments. The phylogeny and diversity based on the amplification and sequencing of rbcL, the large subunit encoding the key enzyme ribulose-1, 5-bisphosphate carboxylase/oxygenase was investigated for improved understanding of the community structure and temporal trends of chromophytic eukaryotic phytoplankton assemblages in Sundarbans, the world's largest continuous mangrove. Diatoms (Bacillariophyceae) were by far the most frequently detected group in clone libraries (485 out of 525 clones), consistent with their importance as a major bloom-forming group. Other major chromophytic algal groups including Cryptophyceae, Haptophyceae, Pelagophyceae, Eustigmatophyceae, and Raphidophyceae which are important component of the assemblages were detected for the first time from Sundarbans based on rbcL approach. Many of the sequences from Sundarbans rbcL clone libraries showed identity with key bloom forming diatom genera namely Thalassiosira, Skeletonema and Nitzschia. Similarly, several rbcL sequences which were diatom-like were also detected highlighting the need to explore diatom communities from the study area. Some of the rbcL sequences detected from Sundarbans were ubiquitous in distribution showing 100% identities with uncultured rbcL sequences targeted previously from the Gulf of Mexico and California upwelling system that are geographically separated from study area. Novel rbcL lineages were also detected highlighting the need to culture and sequence phytoplankton from the ecoregion. Principal component analysis revealed that nitrate is an important variable that is associated with observed variation in phytoplankton assemblages (operational taxonomic units). This study applied molecular tools to highlight the ecological significance of diatoms, in addition to other chromophytic algal groups in Sundarbans.
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Affiliation(s)
- Brajogopal Samanta
- Integrative Taxonomy and Microbial Ecology Research Group, Department of Biological Sciences, Indian Institute of Science Education and Research-Kolkata, Mohanpur Campus, Mohanpur-741252, Nadia, West Bengal, India
| | - Punyasloke Bhadury
- Integrative Taxonomy and Microbial Ecology Research Group, Department of Biological Sciences, Indian Institute of Science Education and Research-Kolkata, Mohanpur Campus, Mohanpur-741252, Nadia, West Bengal, India
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Peng S, Zhou R, Qin X, Shi H, Ding D. Application of macrobenthos functional groups to estimate the ecosystem health in a semi-enclosed bay. MARINE POLLUTION BULLETIN 2013; 74:302-310. [PMID: 23849956 DOI: 10.1016/j.marpolbul.2013.06.037] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/18/2013] [Revised: 05/31/2013] [Accepted: 06/18/2013] [Indexed: 06/02/2023]
Abstract
In this study, the functional group concept was first applied to evaluate the ecosystem health of Bohai Bay. Macrobenthos functional groups were defined according to feeding types and divided into five groups: a carnivorous group (CA), omnivorous group (OM), planktivorous group (PL), herbivorous group (HE), and detritivorous group (DE). Groups CA, DE, OM, and PL were identified, but the HE group was absent from Bohai Bay. Group DE was dominant during the study periods. The ecosystem health was assessed using a functional group evenness index. The functional group evenness values of most sampling stations were less than 0.40, indicating that the ecosystem health was deteriorated in Bohai Bay. Such deterioration could be attributed to land reclamation, industrial and sewage effluents, oil pollution, and hypersaline water discharge. This study demonstrates that the functional group concept can be applied to ecosystem health assessment in a semi-enclosed bay.
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Affiliation(s)
- Shitao Peng
- Laboratory of Environmental Protection in Water Transport Engineering, Tianjin Research Institute for Water Transport Engineering, Tianjin 300456, China; First Institute of Oceanography, SOA, Qingdao 266061, China
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Peng S, Qin X, Shi H, Zhou R, Dai M, Ding D. Distribution and controlling factors of phytoplankton assemblages in a semi-enclosed bay during spring and summer. MARINE POLLUTION BULLETIN 2012; 64:941-948. [PMID: 22472788 DOI: 10.1016/j.marpolbul.2012.03.004] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/11/2011] [Revised: 03/06/2012] [Accepted: 03/08/2012] [Indexed: 05/31/2023]
Abstract
The phytoplankton assemblages' patterns and their correlation to environmental factors were studied in Bohai Bay during spring and summer. Two zones, the northern (NWA) and southern (SWA) water area, were identified by cluster analysis based on their physical and chemical properties. Principal component analysis (PCA) showed that more phytoplankton species was found in the SWA with low nutrient concentration, while high phytoplankton abundance occurred in the NWA with high nutrient concentration. The seasonal variability in phytoplankton can be explained by water temperature, nutrient, and hydrodynamic conditions (includes mixing during spring and stratification during summer). Results of redundancy analysis (RDA) showed that silicate (SiO(4)) and soluble reactive phosphorus (SRP) were the most important environmental factors influencing the phytoplankton distribution during spring and summer, respectively. Hydrodynamics condition plays a key role in controlling variation of the environmental factors, which determined phytoplankton distribution in Bohai Bay.
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Affiliation(s)
- Shitao Peng
- The First Institute of Oceanography, State Oceanic Administration (SOA), Qingdao 266061, China
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