First Record of the Centric Diatom Pleurosira laevis (Ehrenberg) Compère, 1982 from the Ganga River at Prayagraj, India: Implications of Mass Gathering Events
DOI:
https://doi.org/10.21276/pt.2026.v3.i2.9Keywords:
Pleurosira laevis, Centrale diatoms, Mahakumbh, River Ganga, PrayagrajAbstract
Pleurosira laevis (Ehrenberg) Compère is a cosmopolitan, euryhaline, centric diatom species documented in diverse aquatic habitats worldwide. This study reports the first documented occurrence of P. laevis in the Ganga River at the Triveni Sangam, Prayagraj, Uttar Pradesh, India, during the Mahakumbh 2025 mass-gathering event. The planktonic and periphytic samples (18 samples) were collected in three distinct parts: Pre-Mahakumbh (15 to 25 December 2024), Peak Mahakumbh (14 January to 26 February 2025), and Post-Mahakumbh (15 to 25 March 2025). Pleurosira laevis was exclusively detected during the Peak Mahakumbh period, coinciding with observable elevations in total dissolved solids (395.0 ± 84.5 mg/L, +34.0% increase), chloride concentrations (63 ± 11.9 mg/L, +58.5% increase), and electrical conductivity (634.0 ± 162.2 µS/cm, +35.2% increase) compared to optimal conditions. The presence of this species was not recorded in pre-Mahakumbh samples despite intensive sampling (6 samples), indicating its occurrence was affected by the temporary ionic enrichment and anthropogenic salinization associated with mass bathing activities. Light microscopy revealed diagnostic morphological features, including oval to elliptical shapes of valves (40.7 to 71.8 µm length, 38.1 to 56.9 µm width), a pair of protuberant ocelli (9.36 to 15.53 µm length), and the presence of 2-3 rimoportulae. This first record is insightful in understanding the distribution of P. laevis across the Indian subcontinent. The record also demonstrates its importance as a bioindicator of episodic anthropogenic salinization in freshwater ecosystems. The study highlights the intensity and effects of large-scale pilgrimage events on freshwater ecosystems, as they can create temporary ecological windows that facilitate the establishment of halophilic diatom taxa in otherwise oligohaline river systems
References
Pal V, Kumar J, Dwivedi AC, Kumar D. Diversity of phytoplankton from the Ganga River at Rasulabad Ghat and Sangam, Prayagraj, Uttar Pradesh. J Inland Fish Soc India. 2024;56(2):145-154. https://doi.org/10.56093/jifsi.v56i2.163176
Srivastava K, Jha DN, Mishra S, Kumar V, Das SCS, Alam A, Srivastava RS, Das BK. Impact of Prayagraj Kumbh-2019 on water quality and plankton communities of the River Ganga. J Fish Life Sci. 2020;5(1):44-48.
Venkatachalapathy R, Karthikeyan P. Diatom indices and water quality index of the Cauvery River, India: implications on the suitability of bio-indicators for environmental impact assessment. In: Environmental Management of River Basin Ecosystems. Springer; 2015:707-724.
Compère P. Pleurosira laevis (Ehrenberg) Compère, a new name for Biddulphia laevis Ehrenberg. Bacillaria. 1982;5:177-190.
Johnson LM, Rosowski JR. Valve and band morphology of some freshwater diatoms. V. Variations in the cingulum of Pleurosira laevis (Bacillariophyceae). J Phycol. 1992;28(2):247-255.
Sharifinia M, Ramezanpour Z, Namin JI. Distribution of benthic centric diatom Pleurosira laevis (Compère, 1982) in different substrate types and physicochemical parameters. Braz J Biol. 2016;76(4):891-900. https://doi.org/10.1590/1519-6984.02515
Mamanazarova KS, Gololobova MA. First record of diatom species Pleurosira laevis (Ehrenberg) Compère for Uzbekistan and Central Asia. Russ J Biol Invasions. 2017;8(1):69-74. https://doi.org/10.1134/S2075111717010072
Parikhani F, Atazadeh E, Razeghi J, Mosaferi M, Kulikovskiy M. Using algal indices to assess the ecological conditions of the Aras River, Northwestern Iran. J Mar Sci Eng. 2023;11(10):1867. https://doi.org/10.3390/jmse11101867
Zalat A, Al Wosabi S. Diatom assemblages in surface sediments from the coastal and deep basins of the southern Oceanography, Yemen. Oceanologia. 2011;53(1):129-154.
Fai PBA, Kenko DBN, Tchamadeu NN, Mbida M, Nola M, Ben Boubaker EA. Use of multivariate analysis to identify phytoplankton bioindicators of stream water quality in the monomodal equatorial agroecological zone of Cameroon. Environ Monit Assess. 2023;195(3):436.
El Awamri AF. Studies on the morphology of different valve types of the centric diatom species Pleurosira laevis (Ehr.) Compère. Aust J Basic Appl Sci. 2008;2(1):22-29.
Da Rocha Filho FV, Oliveira JS, Terra BF, Cavalcante KP. Masses of periphytic diatoms in an intermittent stream from the northwestern region of Ceará. Int J Semiarid. 2024;7(7):57-68.
Fránková Kozáková M, Marvan P, Geriš R. Halophilous diatoms in Czech running waters: Pleurosira laevis and Bacillaria paxillifera. In: Proceedings of the 1st Central European Diatom Meeting. Berlin, Germany; 2007:39-44.
Kociolek JP, Spaulding SA, Sabbe K, Vyverman W. New species and combinations in the diatom genus Pleurosira. Diatom Res. 2011;26(2):137-150.
John J. The Diatom Flora of the Swan River Estuary, Western Australia. Doctoral dissertation. University of Western Australia; 1983.
Kamakura S, Ashworth M, Yamada K, Mikami D, Kobayashi A, Idei M, Sato S. Morphological plasticity in response to salinity change in the euryhaline diatom Pleurosira laevis (Bacillariophyta). J Phycol. 2022;58(4):247-260. https://doi.org/10.1111/jpy.13258
del Giorgio PA, Vinocur AL, Lombardo RJ, Tell G. Progressive changes in the structure and dynamics of the phytoplankton community along a pollution gradient in a lowland river: a multivariate approach. Hydrobiologia. 1991;224(2):129-153.
Singh A, Kumar P, Sharma R. Phytoplankton diversity and water quality assessment of River Ganga at Varanasi. J Environ Biol. 2020;41(3):567-574.
Kumar J, Srivastava K, Jha DN. Phytoplankton community structure of River Ganga at Patna. J Inland Fish Soc India. 2021;53(2):45-52.
Sharma R, Singh A, Mishra S. Diatom community structure as bioindicators of water quality in River Ganga at Kanpur. Int J Environ Sci Technol. 2022;19(4):2341-2350.
Jaiswal RK, Singh A, Kumar P, Sharma S. Diatom based water quality assessment of the Yamuna River at Allahabad. Int J Curr Microbiol Appl Sci. 2022;11(1):1234-1245.
Nautiyal P, Verma J. Taxonomic richness and diversity of the epilithic diatom flora of the two biogeographic regions of the Indian subcontinent. Bull Natl Inst Ecol. 2009;19:1-4.
Central Pollution Control Board. Water Quality Status of Ganga River 2019-2020. Ministry of Environment, Forest and Climate Change, Government of India; 2020.
Mishra M, Ahuja K, Rawat R. Assessment of physicochemical, heavy metal, and microbial contamination in the Ganga River at Prayagraj across Maha Kumbh phases. Int J Life Sci. 2025;11(5):8320-8326. https://doi.org/10.21276/SSR-IIJLS.2025.11.5.18
Garg A, Singh U, Singh SK. Integrated engineering, environmental, and socio-economic impacts of Ganga river channelization for Maha Kumbh 2025, Prayagraj, India: a case study. Sci Cult. 2026;12(1.1):4251-4583. https://doi.org/10.5281/zenodo.121126316
Hasle GR, Fryxell GA. The marine diatoms Thalassiosira oceanica sp. nov. and T. partheneia. Phycologia. 1978;17(3):263-272.
American Public Health Association. Standard Methods for the Examination of Water and Wastewater. 23rd ed. American Public Health Association; 2017.
Krammer K, Lange-Bertalot H. Bacillariophyceae. Teil 3: Centrales, Fragilariaceae, Eunotiaceae. Vols 2-3. Gustav Fischer Verlag; 1991.
Compère P. Taxonomic revision of the diatom genus Pleurosira (Eupodiscaceae). Bacillaria. 1982;5:87-118.
Spaulding SA, Jovanoska E, Bishop I, Wolfe AP, Chambless S, Esser SC, Otu MK. Diatoms.org: supporting taxonomists, connecting communities. Diatom Res. 2021;36(4):291-304.
Guiry MD, Guiry GM. AlgaeBase. World-wide electronic publication, National University of Ireland, Galway. Accessed April 28, 2026. https://www.algaebase.org
Round FE, Crawford RM, Mann DG. The Diatoms: Biology and Morphology of the Genera. Cambridge University Press; 1990.
Kim SY, Kim HS. Morphology and ecology of Pleurosira laevis (Bacillariophyceae) from South Korea. Korean J Phycol. 2012;27(2):89-96.
Li Y, Nagumo T, Xu K. Morphology and molecular phylogeny of Pleurosira nanjiensis sp. nov., a new marine benthic diatom from the Nanji Islands, China. Acta Oceanol Sin. 2018;37(10):33-39.
Cavalcante KP, Tremarin PI, Ludwig TAV. Taxonomic studies of centric diatoms (Diatomeae): unusual nanoplanktonic forms and new records for Brazil. Acta Bot Bras. 2013;27(2):237-251.
Kociolek JP, Lamb MA, Lowe RL. Notes on the growth and ultrastructure of Biddulphia laevis Ehr. (Bacillariophyceae) in the Maumee River, Ohio. Ohio J Sci. 1983;83(3):125-130.
Bilous OP, Genkal SI, Zimmermann J, Kusber WH, Jahn R. Centric diatom diversity in the lower part of the Southern Bug River (Ukraine): the transitional zone at Mykolaiv city. PhytoKeys. 2021;178:31-58.
Seckbach J, Kociolek P, eds. The Diatom World. Vol 19. Springer Science & Business Media; 2011.
Karthick B, Kociolek JP. Four new centric diatoms (Bacillariophyceae) from the Western Ghats, South India. Phytotaxa. 2011;22:25-40.
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