Distance-decay relationship reveals both horizontal and vertical dispersal limitation and source–sink relationships of phytoplankton in a deep channel-type reservoir

Abstract

Elucidating the spatiotemporal distribution of phytoplankton in reservoirs is crucial for both water supply security and the protection of riverine ecosystems. In this study, the spatiotemporal characteristics of phytoplankton community diversity in a typical deep, channel-type reservoir were investigated to quantify the contributions of top-down and bottom-up phytoplankton inputs to adjacent water layers and to identify key factors influencing diversity. The Shannon–Wiener and Margalef indices gradually increased from the main channel flowing into the reservoir to the surface water and then decreased toward deeper layers. The Fast Expectation–Maximization Microbial Source Tracking (FEAST) model was applied to quantify contributions from upstream phytoplankton to downstream communities and among different vertical layers within the reservoir. The results revealed that the bottom-up contribution rates of the phytoplankton communities in July, August, and January were significantly higher than the top-down contribution rates, which were driven primarily by increasing numbers of cyanobacteria, whereas the top-down contribution rates were associated with water column overturning. Significant distance-decay patterns of phytoplankton community similarity were observed in summer and autumn in the horizontal dimension and in all seasons except spring in the vertical dimension. Variation partitioning analysis revealed that spatial position exerted a substantially stronger influence on phytoplankton community diversity than nutrient concentration. Overall, this study highlights the source–sink dynamics of phytoplankton and indicates that spatial position is the primary driver of diversity, outweighing local environmental factors such as nutrient availability.

Graphical abstract

Keywords

Phytoplankton / Reservoir / FEAST / Source-sink relationship / Dispersal limitation

Highlight

	● The FEAST model revealed source–sink relationships among phytoplankton communities.
	● Phytoplankton community showed significant horizontal and vertical distance-decay.
	● Spatial position was the primary driver of phytoplankton diversity in reservoirs.

References

[1] APHA (2005). Standard Methods for the Examination of Water and Wastewater. 21st ed. Washington: American Public Health Association, American Water Works Association, Water Environment Federation

[2] Baek S H , Shimode S , Han M S , Kikuchi T . (2008). Growth of dinoflagellates, Ceratium furca and Ceratium fusus in Sagami Bay, Japan: the role of nutrients. Harmful Algae, 7(6): 729–739

[3] Bicudo D C , Tremarin P I , Almeida P D , Zorzal-Almeida S , Wengrat S , Faustino S B , Costa L F , Bartozek E C R , Rocha A C R , Bicudo C E M . et al. (2016). Ecology and distribution of Aulacoseira species (Bacillariophyta) in tropical reservoirs from Brazil. Diatom Research, 31(3): 199–215

[4] Borics G , Abonyi A , Salmaso N , Ptacnik R . (2021). Freshwater phytoplankton diversity: models, drivers and implications for ecosystem properties. Hydrobiologia, 848(1): 53–75

[5] Chen J , Wang P F , Wang C , Wang X , Miao L Z , Liu S , Yuan Q S , Sun S H . (2020). Distinct assembly mechanisms underlie similar biogeographic patterns of rare and abundant bacterioplankton in cascade reservoirs of a large river. Frontiers in Microbiology, 11: 158

[6] Chen J P , Chen H Y , Liu C , Huan H , Teng Y G . (2023). Evaluation of FEAST for metagenomics-based source tracking of antibiotic resistance genes. Journal of Hazardous Materials, 442: 130116

[7] Coles J F , Jones R C . (2000). Effect of temperature on photosynthesis-light response and growth of four phytoplankton species isolated from a tidal freshwater river. Journal of Phycology, 36(1): 7–16

[8] Dixon P . (2003). VEGAN, a package of R functions for community ecology. Journal of Vegetation Science, 14(6): 927–930

[9] Edwards K F , Thomas M K , Klausmeier C A , Litchman E . (2016). Phytoplankton growth and the interaction of light and temperature: a synthesis at the species and community level. Limnology and Oceanography, 61(4): 1232–1244

[10] Fonseca B M , de Mattos Bicudo C E . (2011). Phytoplankton seasonal and vertical variations in a tropical shallow reservoir with abundant macrophytes (Ninféias Pond, Brazil). Hydrobiologia, 665(1): 229–245

[11] Forsblom L , Engström-Öst J , Lehtinen S , Lips I , Lindén A . (2019). Environmental variables driving species and genus level changes in annual plankton biomass. Journal of Plankton Research, 41(6): 925–938

[12] Gamito S . (2010). Caution is needed when applying Margalef diversity index. Ecological Indicators, 10(2): 550–551

[13] Gaur S , Bhattacharjee R , Chander S , Ohri A , Srivastava P K. . (2025). Globally validated non-unique inversion framework to estimate optically active water quality indicators using in situ and space-borne hyperspectral data sets. Frontiers of Environmental Science & Engineering, 19(1): 10

[14] Hajdu S , Höglander H , Larsson U . (2007). Phytoplankton vertical distributions and composition in Baltic Sea cyanobacterial blooms. Harmful Algae, 6(2): 189–205

[15] Hall N S , Paerl H W . (2011). Vertical migration patterns of phytoflagellates in relation to light and nutrient availability in a shallow microtidal estuary. Marine Ecology Progress Series, 425: 1–19

[16] Heino J , Melo A S , Siqueira T , Soininen J , Valanko S , Bini L M . (2015). Metacommunity organisation, spatial extent and dispersal in aquatic systems: patterns, processes and prospects. Freshwater Biology, 60(5): 845–869

[17] Hu Y X , Liu X D , Xing W Y , Hu Z Y , Liu G X . (2019). Marker gene analysis reveals the spatial and seasonal variations in the eukaryotic phytoplankton community composition in the Yangtze River, Three Gorges Reservoir, China. Journal of Plankton Research, 41(6): 835–848

[18] Hunter P R , Gaston M A . (1988). Numerical index of the discriminatory ability of typing systems: an application of Simpson’s index of diversity. Journal of Clinical Microbiology, 26(11): 2465–2466

[19] Ives A R , Carpenter S R . (2007). Stability and diversity of ecosystems. Science, 317(5834): 58–62

[20] Jin L , Chen H H , Xue Y Y , Soininen J , Yang J . (2022). The scale-dependence of spatial distribution of reservoir plankton communities in subtropical and tropical China. Science of the Total Environment, 845: 157179

[21] Johnson N , Revenga C , Echeverria J . (2001). Managing water for people and nature. Science, 292(5519): 1071–1072

[22] Jost L . (2010). The relation between evenness and diversity. Diversity, 2(2): 207–232

[23] Kim B R , Shin J , Guevarra R B , Lee J H , Kim D W , Seol K H , Lee J H , Kim H B , Isaacson R E . (2017). Deciphering diversity indices for a better understanding of microbial communities. Journal of Microbiology and Biotechnology, 27(12): 2089–2093

[24] Lee T A , Rollwagen-Bollens G , Bollens S M . (2015). The influence of water quality variables on cyanobacterial blooms and phytoplankton community composition in a shallow temperate lake. Environmental Monitoring and Assessment, 187(6): 315

[25] Lewis W M Jr . (1983). A revised classification of lakes based on mixing. Canadian Journal of Fisheries and Aquatic Sciences, 40(10): 1779–1787

[26] Li S Z , Ren K X , Yan X , Tsyganov A N , Mazei Y , Smirnov A , Mazei N , Zhang Y Y , Rensing C , Yang J . (2023a). Linking biodiversity and ecological function through extensive microeukaryotic movement across different habitats in six urban parks. iMeta, 2(2): e103

[27] Li S Z , Yan X , Chen H H , Jeppesen E , Xiao P , Jin L , Xu Z J , Zuo J , Ren K X , Yang J . (2025). Cyanobacterial blooms specifically alter the dispersal-mediated taxonomic and functional vertical similarity of microbial communities in a subtropical reservoir. Water Research, 281: 123574

[28] Li T C , Liu G L , Yuan H T , Chen J W , Lin X , Li H F , Yu L Y , Wang C , Li L , Zhuang Y Y . et al. (2023b). Eukaryotic plankton community assembly and influencing factors between continental shelf and slope sites in the northern South China Sea. Environmental Research, 216: 114584

[29] Lu L H , Zou X , Yang J X , Xiao Y , Wang Y C , Guo J S , Li Z . (2020). Biogeography of eukaryotic plankton communities along the upper Yangtze River: the potential impact of cascade dams and reservoirs. Journal of Hydrology, 590: 125495

[30] Lu Y A , Tuo Y , Zhang L L , Hu X Y , Huang B , Chen M , Li Z H . (2023). Vertical distribution rules and factors influencing phytoplankton in front of a drinking water reservoir outlet. Science of the Total Environment, 902: 166512

[31] Magadza C H D . (2010). Environmental state of Lake Kariba and Zambezi River Valley: lessons learned and not learned. Lakes & Reservoirs: Science, Policy and Management for Sustainable Use, 15(3): 167–192

[32] McGillicuddy D J Jr , Signell R P , Stock C A , Keafer B A , Keller M D , Hetland R D , Anderson D M . (2003). A mechanism for offshore initiation of harmful algal blooms in the coastal Gulf of Maine. Journal of Plankton Research, 25(9): 1131–1138

[33] Nyirabuhoro P , Liu M , Xiao P , Liu L M , Yu Z , Wang L N , Yang J . (2020). Seasonal variability of conditionally rare taxa in the water column bacterioplankton community of subtropical reservoirs in China. Microbial Ecology, 80(1): 14–26

[34] Olli K , Nyman E , Tamminen T . (2023). Half-century trends in alpha and beta diversity of phytoplankton summer communities in the Helsinki Archipelago, the Baltic Sea. Journal of Plankton Research, 45(1): 146–162

[35] Peres-Neto P R , Legendre P , Dray S , Borcard D . (2006). Variation partitioning of species data matrices: estimation and comparison of fractions. Ecology, 87(10): 2614–2625

[36] Qu Y MWu N CGuse BFohrer N (2018). Riverine phytoplankton shifting along a lentic-lotic continuum under hydrological, physiochemical conditions and species dispersal. Science of the Total Environment, 619–620: 619–620

[37] Rangel L M , Silva L H S , Rosa P , Roland F , Huszar V L M . (2012). Phytoplankton biomass is mainly controlled by hydrology and phosphorus concentrations in tropical hydroelectric reservoirs. Hydrobiologia, 693(1): 13–28

[38] Salmaso N . (2003). Life strategies, dominance patterns and mechanisms promoting species coexistence in phytoplankton communities along complex environmental gradients. Hydrobiologia, 502(1−3): 13–36

[39] Shenhav L , Thompson M , Joseph T A , Briscoe L , Furman O , Bogumil D , Mizrahi I , Pe’er I , Halperin E . (2019). FEAST: fast expectation-maximization for microbial source tracking. Nature Methods, 16(7): 627–632

[40] Smayda T J . (1997). Harmful algal blooms: their ecophysiology and general relevance to phytoplankton blooms in the sea. Limnology and Oceanography, 42(5part2): 1137–1153

[41] Spellerberg I F , Fedor P J . (2003). A tribute to Claude Shannon (1916–2001) and a plea for more rigorous use of species richness, species diversity and the ‘Shannon–Wiener’ Index. Global Ecology and Biogeography, 12(3): 177–179

[42] Tang X FZhang C YXu SHu EChang CMa Y HXi D PLi M (2025). Spatial and temporal dynamics of the complexity, stability and community assembly of phytoplankton community in a deep channel-type reservoir. Journal of Environmental Sciences, 165: 107–118

[43] Viner A B . (1985). Thermal stability and phytoplankton distribution. Hydrobiologia, 125(1): 47–69

[44] Wang J, Sun F H, Guo Y D, Zhao Q Y, Huang N N, Wang Z T, Wu F C (2024a). Spatial and temporal pattern of phytoplankton community assembly processes in the largest tributary of the Yangtze River, China, 05 December 2024, PREPRINT (Version 1) available at Research Square

[45] Wang L , Liu J R , Bao Z , Ma X F , Shen H , Xie P , Chen J . (2024b). Thermocline stratification favors phytoplankton spatial overlap and species diversity in a subtropical deep reservoir. Science of the Total Environment, 913: 169712

[46] Wang L , Tan L , Cai Q H . (2024c). Distinct differences of vertical phytoplankton community structure in mainstream and a tributary bay of the Three Gorges Reservoir, China. Frontiers in Plant Science, 15: 1381798

[47] Wang X L , Sun J , Lin B L , Shi L D , Zuo X Y , Li Y Y . (2024d). Investigation on phytoplankton dynamics and its environmental correlates in the Xiangjiaba channel-type reservoir. Journal of Hydrology, 641: 131745

[48] Williams O J , Beckett R E , Maxwell D L . (2016). Marine phytoplankton preservation with Lugol’s: a comparison of solutions. Journal of Applied Phycology, 28(3): 1705–1712

[49] Xiao X Y , Chen C L , Li H R , Li L H , Yu X. . (2024). The variation of microbiological characteristics in surface waters during persistent precipitation. Frontiers of Environmental Science & Engineering, 18(9): 111

[50] Xiao Z , Li H , Li X C , Li R H , Huo S L , Yu G L . (2022). Geographic pattern of phytoplankton community and their drivers in lakes of middle and lower reaches of Yangtze River floodplain, China. Environmental Science and Pollution Research, 29(55): 83993–84005

[51] Xu H , Yan M , Long L H , Ma J , Ji D B , Liu D F , Yang Z J . (2021). Modeling the effects of hydrodynamics on thermal stratification and algal blooms in the Xiangxi Bay of Three Gorges Reservoir. Frontiers in Ecology and Evolution, 8: 610622

[52] Yang F , Chang C , Wen L , Hao Z N , Pang Y , Yi Y B , He D , Li M . (2025). Unravelling riverine dissolved organic matter sources using molecular fingerprints and FEAST model in a multi-tributary mountain river basin. Water Research, 280: 123478

[53] Ye S S , Chang C , Xiao M , Li B C , Hu E , Li M . (2025). Water travel time shapes the biogeography of riverine phytoplankton under the influence of dam and tributary. Limnology and Oceanography, 70(12): 3576–3591

[54] Ye S S , Wen L , Gao L , Zhang J Y , Zhang H H , Yang S Q , Hu E , Deng J M , Xiao M , Zamyadi A . et al. (2024). Exploring intrinsic distribution of phytoplankton relative abundance and biomass in combination with continental-scale field investigation and microcosm experiment. Water Research, 248: 120853

[55] Zhang B , Chen J , Wang C , Wang P F , Cui G , Gao H , Feng B B , Sheng S , Fu J J. . (2025). Increasing flow velocity promotes nitrification and denitrification in benthic biofilms via enhancing the diversity and potential predation behavior among multi-trophic microorganisms. Frontiers of Environmental Science & Engineering, 19(10): 136

[56] Znachor P , Nedoma J , Hejzlar J , Seďa J , Komárková J , Kolář V , Mrkvička T , Boukal D S . (2020). Changing environmental conditions underpin long-term patterns of phytoplankton in a freshwater reservoir. Science of the Total Environment, 710: 135626

RIGHTS & PERMISSIONS

Higher Education Press 2026