Ecological assessment of fish habitat connectivity across lotic–lentic boundaries in regulated hydrological systems
Main Article Content
Abstract
The connection of habitats is critical to support freshwater biodiversity, especially in regulated hydrological systems where the occurrence of natural flow regimes is disturbed. The paper examines fish habitat connectivity at lotic-lentic boundaries, based on an integrated multi-layered model, which integrates structural, hydrological, and ecological indicators. An experiment on a dataset of different levels of connectivity was conducted to determine the effects of fragmentation on fish diversity and ecosystem well-being. The analysis incorporates global-scale geospatial data and connectivity metrics to quantify fragmentation patterns and hydrological alterations. The statistical analysis indicated that there are a lot of differences in the species richness among the connectivity gradients, with high connectivity areas having a maximum of 45 species and low connectivity areas having 18 species, representing nearly a 60% reduction in biodiversity. The percentage of migratory species decreased significantly between highly connected habitats (62) and fragmented systems (19). Correlation analysis showed that barrier density and species richness had a good negative relationship (r = -0.78, p < 0.01), and hydrological connectivity index had a good positive relationship with biodiversity (r = +0.74, p < 0.01). Regression results further demonstrated strong predictive relationships, with a high coefficient of determination (R² ≈ 0.96), confirming the influence of connectivity on ecological responses. The results of the regression further supported the hypothesis that an increase in fragmentation causes significant loss of biodiversity, and better hydrological connectivity creates stability in the ecosystems. The conclusions stress that physical obstacles, as well as a change in flow processes, have a significant impact on aquatic ecosystems. The suggested framework is able to represent these intricate interactions and give a detailed connectivity measurement tool. The paper concludes that the restoration of hydrological connectivity and structural fragmentation reduction are the key measures to preserve fish diversity and ecological balance of the regulated river systems.
Article Details
Section
How to Cite
References
Ahmad, H., Miranda, L.E., Dunn, C.G., Boudreau, M.R. and Colvin, M.E., 2025. Hydrologic connectivity in floodplain systems: a multiscale review of concepts, metrics and management. Hydrological Processes, 39(9), p.e70260. https://doi.org/10.1002/hyp.70260
Anand, V., Oinam, B., Singh, S.K. and Wieprecht, S., 2025. Assessment of freshwater ecosystem health condition based on fish habitats using a holistic modelling approach. Discover Water, 5(1), p.11. https://doi.org/10.1111/fwb.14181
Besson, J.C., Neary, J.J., Stafford, J.D., Dunn, C.G. and Miranda, L.E., 2023. Fish functional gradients along a reservoir cascade. Freshwater Biology, 68(6), pp.1079-1091. https://doi.org/10.1111/fwb.14087
Blackburn‐Desbiens, P., Grosbois, G., Power, M., Culp, J. and Rautio, M., 2023. Integrating connectivity and hydrological zooplankton composition in Arctic ponds and lakes. Freshwater Biology, 68(12), pp.2131-2150. https://doi.org/10.1111/fwb.14181
Chang, T., Li, M. and Gao, X., 2025. Dispersal-based processes as drivers of fish communities and species distributions in the Yangtze River-Poyang Lake riverine floodplain of China. Ecological Processes, 14(1), pp.1-13. https://doi.org/10.1186/s13717-025-00616-x
Chaparro, G., O’Farrell, I. and Hein, T., 2023. Hydrological conditions determine shifts of plankton metacommunity structure in riverine floodplains without affecting patterns of species richness along connectivity gradients. Aquatic Sciences, 85(2), p.41. https://doi.org/10.1007/s00027-023-00937-z
Chen, Q., Li, Q., Lin, Y., Zhang, J., Xia, J., Ni, J., Cooke, S.J., Best, J., He, S., Feng, T. and Chen, Y., 2023. River damming impacts on fish habitat and associated conservation measures. Reviews of Geophysics, 61(4), p.e2023RG000819. https://doi.org/10.1029/2023RG000819
Cheng, G., Tao, J., Wang, J., Zhang, W., Zhang, X., Tang, B., Tao, J. and Ding, C., 2025. Drivers of nonnative fish invasion patterns differ by species origin and waterbody type. Reviews in Fish Biology and Fisheries, 35(4), pp.2175-2189. https://doi.org/10.1007/s11160-025-09998-9
Dutta, J., Haidar, I.K.A., Noman, M. and Chowdhury, M.A.W., 2024. Conservation Priorities for Threatened Fish to Withstand Climate Crisis: Sustainable Capture and Protection of Inland Hydrographic Ecosystems. Ecologies, 5(2), pp.155-169. https://doi.org/10.3390/ecologies5020010
Fu, H., Xu, J., Zhang, H., Molinos, J.G., Zhang, M., Klaar, M. and Brown, L.E., 2023. A meta-analysis of environmental responses to freshwater ecosystem restoration in China (1987–2018). Environmental Pollution, 316, p.120589. https://doi.org/10.1016/j.envpol.2022.120589
Gonçalves-Silva, M., D’Bastiani, E., Datry, T. and Rezende, C.F., 2025. Hydrological fluctuations determine predator–prey interactions in a semi-arid non-perennial river. Hydrobiologia, pp.1-18. https://doi.org/10.1007/s10750-025-05968-1
Jovičić, K., Đikanović, V., Subotić, S., Dimitrijević, M., Kovačević, S., Miljanović, B. and Vranković, J.S., 2025. Assessment of Hepatic Enzyme Biomarkers in Northern Pike (Esox lucius) from Lotic and Lentic Freshwater Habitats: Implications for Monitoring Metal Pollution and Ecological Stress in Aquatic Ecosystems. Fishes, 10(11), p.541. https://doi.org/10.3390/fishes10110541
Lehner, B., Beames, P., Mulligan, M., Zarfl, C., De Felice, L., van Soesbergen, A., Thieme, M., Garcia de Leaniz, C., Anand, M., Belletti, B. and Brauman, K.A., 2024. The Global Dam Watch database of river barrier and reservoir information for large-scale applications. Scientific Data, 11(1), pp.1-18. https://doi.org/10.1038/s41597-024-03752-9
Lew, S., Burandt, P. and Glińska-Lewczuk, K., 2025. Microbial Communities Drive Methane Fluxes from Floodplain Lakes—A Hydrological Gradient Perspective. Environmental Microbiology, 27(6), pp.1-16. https://doi.org/10.1111/1462-2920.70127
Michie, L.E., Harrisson, K.A., Rourke, M.L., Crook, D.A., Stuart, I., Ellis, I., Sharpe, C.P., Butler, G.L. and Thiem, J.D., 2025. Dispersal and Kinship Patterns of a Pelagic-Spawning Riverine Fish Highlight the Value of Connectivity Over Large Spatial Scales. Ecohydrology, 18(3), pp.1-13. https://doi.org/10.1002/eco.70032
O’Mara, K., Venarsky, M., Stewart-Koster, B., McGregor, G.B., Schulz, C., Marshall, J. and Bunn, S.E., 2024. Hydrological connectivity and environment characteristics explain spatial variation in fish assemblages in a wet–dry tropical river. Hydrobiologia, 851(21), pp.5207-5221. https://doi.org/10.1007/s10750-024-05676-2
Petriki, O. and Bobori, D.C., 2025. Ecological Assessment and SWOT-AHP Integration for Sustainable Management of a Mediterranean Freshwater Lake. Sustainability, 17(11), p.4950. https://doi.org/10.3390/su17114950
Regolin, A.L., Bressan, R., Kunz, T.S., Martello, F., Ghizoni‐Jr, I.R., Cherem, J.J., Capela, D.J.V., Oliveira‐Santos, L.G.R., Collevatti, R.G. and Sobral‐Souza, T., 2023. hydrological connectivity models to assess the impacts of hydropower plants on an endemic and imperilled freshwater turtle. Journal of Applied Ecology, 60(8), pp.1734-1748. https://doi.org/10.1111/1365-2664.14436
Taylor, P., Carvalho, L., Chapman, D., Law, A., Miller, C., Scott, M., Siriwardena, G., Thackeray, S.J., Ward, C., Wilkie, C. and Willby, N., 2025. Understanding the hydrological and landscape connectivity of lakes. Landscape Ecology, 40(7), p.140. https://doi.org/10.1007/s10980-025-02153-6
Thiem, J.D., Michie, L.E., Butler, G.L., Ebner, B.C., Sharpe, C.P., Stuart, I. and Townsend, A., 2023. A protected flow breaks the drought for golden perch (Macquaria ambigua) spawning along an extensive semi‐arid river system. Ecohydrology, 16(7), p.e2576. https://doi.org/10.1002/eco.2576
Tiwari, S., Brizuela, S.R., Hein, T., Turnbull, L., Wainwright, J. and Funk, A., 2024. Water‐controlled ecosystems as complex networks: Evaluation of network‐based approaches to quantify patterns of connectivity. Ecohydrology, 17(7), pp.1-22. https://doi.org/10.1002/eco.2690
Verhelst, P., Brys, R., Cooke, S.J., Pauwels, I., Rohtla, M. and Reubens, J., 2023. Enhancing our understanding of fish movement ecology through interdisciplinary and cross-boundary research. Reviews in Fish Biology and Fisheries, 33(1), pp.111-135. https://doi.org/10.1007/s11160-022-09741-8
Widén, Å., Renöfält, B.M. and Jansson, R., 2024. Environmental flows in a future climate: balancing hydropower production and ecosystem rehabilitation in the Ume river system, Sweden. Science of the Total Environment, 955, p.176622. https://doi.org/10.1016/j.scitotenv.2024.176622
Xiang, C., Huang, W., Yao, C., Zhou, H., Wang, Z., Wang, J. and Yang, P., 2025. A Habitat Model for Assessing the Impact of the Three Gorges Project on Phytophilic Spawners. Ecology and Evolution, 15(9), pp.1-13. https://doi.org/10.1002/ece3.72166