{"title":"Trophic dynamics and ecosystem health of a young tropical reservoir in Northeast India","authors":"Sanjenbam Bidyasagar, Keisham Sushma, Prajna Ritambhara Swain, Giri Bhavan Sreekanth, Yumnam Bedajit, Karankumar Ramteke, Ch. Basudha Devi, Pranab Gogoi, Sukham Monalisha, Gusheinzed Waikhom","doi":"10.1007/s10661-025-14003-8","DOIUrl":null,"url":null,"abstract":"<div><p>Small reservoirs are recognised as the most productive man-made ecosystem inhabiting diverse flora and fauna, having a scope for small-scale fisheries to support food security, livelihood, and many other ecological services. This study aimed to determine the trophic structure and ecosystem functioning of the Maphou Reservoir, located in the Northeastern Hill region, India, using the Ecopath mass-balance modelling approach, to figure out the strategic scientific ecosystem-based fisheries management. Ten functional groups were identified, most of which were confined in trophic level II (low order primary consumer). Exotic fish was the most utilized group based on ecotrophic efficiency (EE = 0.782), followed by herbivorous fish (EE = 0.623), and carnivorous fish group are found to be the keystone species. Based on the mixed trophic index (MTI), lower trophic level functional groups (detritus and phytoplankton) had a positive impact on the higher trophic levels, manifesting a ‘bottom-up control’ ecosystem. The reservoir is a primary producer-driven ecosystem (transfer efficiency from primary producer, PP = 4.864%), and mean transfer efficiency is low (4.732%), indicating scope for enhancing the fish stock sizes. The total primary producer/total respiration (TPP/TR) (3.629) and total primary producer/total biomass (TPP/TB) (70.70) suggested that the reservoir is in immature and developing ecosystem with high resilience against external perturbations (Overhead = 63.25%). The reservoir shows a moderately complex food web structure (connectance index = 0.457). The study recommended management measures for stocking enhancement of detritivores (<i>Cirrhinus mrigala</i>, <i>Cyprinus carpio</i>) and phyto-planktivorous fishes (<i>Hypophthalmichthys molitrix</i>, <i>H. nobilis</i>) to improve ecosystem efficiency; both groups have fairly low EE (detritus EE = 0.105 and phytoplankton EE = 0.379). These findings will be an essential input for policy formulation and scientific management of the small reservoir ecosystems in the tropics.</p><h3>Graphical abstract</h3>\n<div><figure><div><div><picture><source><img></source></picture></div></div></figure></div></div>","PeriodicalId":544,"journal":{"name":"Environmental Monitoring and Assessment","volume":"197 5","pages":""},"PeriodicalIF":2.9000,"publicationDate":"2025-04-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Environmental Monitoring and Assessment","FirstCategoryId":"93","ListUrlMain":"https://link.springer.com/article/10.1007/s10661-025-14003-8","RegionNum":4,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q3","JCRName":"ENVIRONMENTAL SCIENCES","Score":null,"Total":0}
引用次数: 0
Abstract
Small reservoirs are recognised as the most productive man-made ecosystem inhabiting diverse flora and fauna, having a scope for small-scale fisheries to support food security, livelihood, and many other ecological services. This study aimed to determine the trophic structure and ecosystem functioning of the Maphou Reservoir, located in the Northeastern Hill region, India, using the Ecopath mass-balance modelling approach, to figure out the strategic scientific ecosystem-based fisheries management. Ten functional groups were identified, most of which were confined in trophic level II (low order primary consumer). Exotic fish was the most utilized group based on ecotrophic efficiency (EE = 0.782), followed by herbivorous fish (EE = 0.623), and carnivorous fish group are found to be the keystone species. Based on the mixed trophic index (MTI), lower trophic level functional groups (detritus and phytoplankton) had a positive impact on the higher trophic levels, manifesting a ‘bottom-up control’ ecosystem. The reservoir is a primary producer-driven ecosystem (transfer efficiency from primary producer, PP = 4.864%), and mean transfer efficiency is low (4.732%), indicating scope for enhancing the fish stock sizes. The total primary producer/total respiration (TPP/TR) (3.629) and total primary producer/total biomass (TPP/TB) (70.70) suggested that the reservoir is in immature and developing ecosystem with high resilience against external perturbations (Overhead = 63.25%). The reservoir shows a moderately complex food web structure (connectance index = 0.457). The study recommended management measures for stocking enhancement of detritivores (Cirrhinus mrigala, Cyprinus carpio) and phyto-planktivorous fishes (Hypophthalmichthys molitrix, H. nobilis) to improve ecosystem efficiency; both groups have fairly low EE (detritus EE = 0.105 and phytoplankton EE = 0.379). These findings will be an essential input for policy formulation and scientific management of the small reservoir ecosystems in the tropics.
期刊介绍：
Environmental Monitoring and Assessment emphasizes technical developments and data arising from environmental monitoring and assessment, the use of scientific principles in the design of monitoring systems at the local, regional and global scales, and the use of monitoring data in assessing the consequences of natural resource management actions and pollution risks to man and the environment.
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