Seasonal variation, habitat complexity, and trophic structure of fish assemblages in the Irrawaddy Delta, Myanmar
DOI:
https://doi.org/10.17017/j.fish.1280Keywords:
DNA barcoding, fish diversity, Irrawaddy mangrove, seasonal variation, species compositionAbstract
The Irrawaddy mangrove ecosystem in Myanmar is a crucial habitat for aquatic biodiversity, yet its ecological dynamics remain understudied. This research explored the seasonal variation, spatial dynamics, and trophic structure of fish assemblages in Pyapon and Bogale townships, Myanmar. Seasonal and market surveys recorded 129 fish species from 64 families, with Mystus gulio, Oryzias dancena, Coilia dussumieri, and Glossogobius giuris dominating the community. Seasonal shifts significantly influenced species diversity. Winter exhibited the highest species richness and diversity, while summer displayed the lowest. Nevertheless, species evenness remained highly stable across all seasons, suggesting a consistently balanced community. Moving beyond basic water parameters, multivariate analyses demonstrated that habitat complexity and food web dynamics are likely key drivers of community structuring. Permutational multivariate analysis of variance revealed a highly significant spatial separation of fish assemblages between mangrove and agricultural land habitats. Furthermore, indicator species analysis identified specific taxa driving this divergence, while functional feeding guild analysis revealed a marked dominance of benthivores and detritivores in mangrove sites. This highlights the critical role of mangrove-derived organic matter in supporting the estuarine food web. The presence of four threatened species, including the Endangered Eleutheronema tetradactylum and Johnius macrorhynus, demonstrates that preserving the physical integrity and trophic inputs of mangroves is paramount for sustaining estuarine fish diversity and supporting sustainable local fisheries management.
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References
Allan JD (2004) Landscapes and riverscapes: the influence of land use on stream ecosystems. Annual Review of Ecology, Evolution, and Systematics 35(1): 257–284.
Aziz MSB, Hasan NA, Mondol MMR, Alam MM, Haque MM (2021) Decline in fish species diversity due to climatic and anthropogenic factors in Hakaluki Haor, an ecologically critical wetland in northeast Bangladesh. Heliyon 7(1): e05977.
Baran E, Myschowoda C (2009) Dams and fisheries in the Mekong Basin. Aquatic Ecosystem Health and Management 12(3): 227–234.
Boettiger C, Lang DT, Wainwright PC (2012) rfishbase: exploring, manipulating and visualizing FishBase data from R. Journal of Fish Biology 81(6): 2030–2039.
BOLD (2025) Identifying species through DNA barcodes. University of Guelph. https://boldsystems.org
Bucklin A, Steinke D, Blanco-Bercial L (2011) DNA barcoding of marine metazoa. Annual Review of Marine Science 3(1): 471–508.
Casatti L (2005) Fish assemblage structure in a first order stream, southeastern Brazil: longitudinal distribution, seasonality, and microhabitat diversity. Biota Neotropica 5(1): 75–83.
Chea R, Pool TK, Chevalier M, Ngor P, So N, … Grenouillet G (2020) Impact of seasonal hydrological variation on tropical fish assemblages: abrupt shift following an extreme flood event. Ecosphere 11(12): e03303.
Chong VC (2007) Mangroves-fisheries linkages—The Malaysian perspective. Bulletin of Marine Science 80(3): 755–772.
Elliott M, Whitfield AK (2011) Challenging paradigms in estuarine ecology and management. Estuarine, Coastal and Shelf Science 94(4): 306–314.
Faunce CH, Serafy JE (2006) Mangroves as fish habitat: 50 years of field studies. Marine Ecology Progress Series 318: 1–18.
Forest Department (2020) Forest resource assessment [Map]. Forest Department, Naypyitaw, Myanmar.
Fricke R, Eschmeyer WN, Van der Laan R (2024) Eschmeyer's catalog of fishes: genera, species, references. California Academy of Sciences. https://researcharchive.calacademy.org
Frissell CA, Liss WJ, Warren CE, Hurley MD (1986) A hierarchical framework for stream habitat classification: viewing streams in a watershed context. Environmental Management 10(2): 199–214.
Froese R, Pauly D (2024) FishBase. World Wide Web electronic publication. https://www.fishbase.org
GBIF (2024) Global Biodiversity Information Facility. Free and open access to biodiversity data. https://www.gbif.org
Gusmao ACB, van Dijk RL, Girard EB, Peijnenburg KT, Macher J, … Morard R (2025) Exploring the potential of the COI gene marker for DNA barcoding of planktonic foraminifera. Scientific Reports 15(1): 19205.
Hebert PD, Ratnasingham S, De Waard JR (2003) Barcoding animal life: cytochrome c oxidase subunit 1 divergences among closely related species. Proceedings of the Royal Society of London. Series B: Biological Sciences 270(suppl_1): S96–S99.
Hendy IW, Burt O, Clough S, Young L, Cragg SM (2020) Mosquitofish avoid thermal stress by moving from open water to the shade of the mangrove Rhizophora mangle. Marine Ecology Progress Series 637: 103–116.
Hubbs CL, Lagler KF, Smith GR (2004) Fishes of the Great Lakes region. Revised Edition. University of Michigan Press.
IUCN (2024) The IUCN Red List of threatened species (Version 2024-1). https://www.iucnredlist.org
Li Y, Qin T, Tun YY, Chen X (2021) Fishes of the Irrawaddy River: diversity and conservation. Aquatic Conservation: Marine and Freshwater Ecosystems 31(8): 1945–1955.
Nagelkerken I, Van der Velde G, Gorissen M, Meijer G, Van't Hof T, Den Hartog C (2000) Importance of mangroves, seagrass beds and the shallow coral reef as a nursery for important coral reef fishes, using a visual census technique. Estuarine, Coastal and Shelf Science 51(1): 31–44.
NCBI (2025) GenBank overview. National Institutes of Health. https://www.ncbi.nlm.nih.gov/genbank/
Neiff JJ, Neiff APd, Verón MBC (2009) The role of vegetated areas on fish assemblage of the Paraná River floodplain: effects of different hydrological conditions. Neotropical Ichthyology 7(1): 39–48.
Okey TA, Pauly D, Allen J, Anderson PD, Bechtol BE, ... Zeiner K (1999) Trophic mass-balance model of Alaska's Prince William sound ecosystem, for the post-spill period 1994–1996. Fisheries Centre, University of British Columbia, Vancouver BC, Canada.
Oksanen J, Simpson GL, Blanchet FG, Kindt R, Legendre P, … Weedon J (2022) Vegan: community ecology package. R package version 2.6–4.
Psomadakis PN, Thein H, Russell BC, Tun MT (2019) Field identification guide to the living marine resources of Myanmar. FAO Species Identification Guide for Fishery Purposes. Rome, FAO and MOALI.
Pusey BJ, Arthington AH (2003) Importance of the riparian zone to the conservation and management of freshwater fish: a review. Marine and Freshwater Research 54(1): 1–16.
R Core Team (2023) R: a language and environment for statistical computing. R Foundation for Statistical Computing, Vienna, Austria. https://www.R-project.org/
RStudio Team (2023) RStudio: integrated development for R. Posit Software, PBC, Boston, MA. https://www.rstudio.com
Silva PB, Arantes CC, Freitas CE, Petrere M Jr, Ribeiro FR (2021) Seasonal hydrology and fish assemblage structure in the floodplain of the lower Amazon River. Ecology of Freshwater Fish 30(2): 162–173.
Tun MT (2021) Marine creatures of Myanmar. WCS Myanmar, Yangon, Myanmar.
Ullah MR, Hasan MM, Alam MA, Neela JN, Islam M, … Alam MA (2023) Diversity of fish species in relation to climatological fluctuations in a coastal river of Bangladesh. Journal of Marine Sciences 2023(1): 6662387.
Vidthayanon C, Termvidchakorn A, Pe M (2005) Inland fishes of Myanmar. Southeast Asian Fisheries Development Center, 160 pp.
Win ML, Myint T (2020) Species composition, seasonal occurrence and abundance of freshwater fishes in Ayeyarwady River segment, Sagaing region, Upper Myanmar. IOP Conference Series: Earth and Environmental Science 416: 012015.
Yang ML, Jiang WS, Wang WY, Pan XF, Kong DP, … Yang JX (2016) Fish assemblages and diversity in three tributaries of the Irrawaddy River in China: changes, threats and conservation perspectives. Knowledge and Management of Aquatic Ecosystems 417: 9.
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The data that support the findings of this study are avail-able on request from the corresponding author.
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Copyright (c) 2026 Ko Ko Tun Thwin, Jiang Bai, Htet Naing Nay, Htet Zaw Phyo, Thaung Naing Oo, Xiao Yong Chen
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