Changes of the copepod community of Ganges estuary following tropical cyclone Yass

Changes of the copepod community of Ganges estuary following tropical cyclone Yass | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Changes of the copepod community of Ganges estuary following tropical cyclone Yass Sourav Paul, Samya Karan, Bhaskar Deb Bhattacharya This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-4862370/v1 This work is licensed under a CC BY 4.0 License Status: Posted Version 1 posted You are reading this latest preprint version Abstract Tropical cyclones (TCs) are straining the lower food web of Indian estuaries but regular institutional monitoring of those changes is rare. For that the ‘Cyclone Ecology’ research program was established in February 2019 on the Muriganga stretch of the Ganges estuary. On 26 May 2021, a category-1 TC Yass disrupted the ‘Cyclone Ecology’ research program sites. A before-after impact assessment was conducted of the cyclone-mediated changes. Water and copepod samples were collected in the pre-Yass (November 2020 to March 2021) and the post-Yass (June 2021) periods. The aim was to assess changes in diversity and dominance of the copepod community following TC Yass. Post-Yass, estuary became polyhaline for a while losing its usual meso-haline characteristic. Species richness of the copepod community was higher during post-Yass than the pre-Yass period. During the pre-Yass, calanoid copepods Bestiolina similis , Paracalanus parvus and Acartiella tortaniformis co-dominated the community and Bestiolina similis was the most abundant species. Post-Yass abundances of the cyclopoid copepods were considerably higher than the pre-Yass. Further, Oithona brevicornis replaced Bestiolina similis as the most abundant species of the community. Spatial heterogeneity of the copepod community of the pre-Yass period temporarily lost in the post-Yass. Changed species richness, abundances, dominance and spatial heterogeneity of the copepod community even for a short-term may have consequences for the ecology of the lower food web of an estuary. Keeping United Nations Ocean Decade (2021-2030) as the baseline, a nation-wide cyclone impact monitoring and resilience plan of the lower food web of Indian estuaries is recommended. Diversity and dominance Cyclopoid copepods salinity estuarine monitoring Indian estuaries Figures Figure 1 Figure 2 Introduction Tropical cyclones (TCs) are discreate and destructive events that temporarily disrupts the lives and livelihoods of ecological communities (Needham et al. 2015 ). Researchers have focused on the genesis of TCs, causes and consequences of their rising intensities and frequencies across the world, and on their impacts on biodiversity (Woodruff et al. 2013 ; Kang & Elsner 2015 ; Mondal et al. 2022 ; Thompson et al. 2023 ). Lack of predictability of a TC track, immediate mobility of the scientific infrastructures and human resources following a TC are the barriers before cyclone research programme of estuaries unless regular institutional monitoring plans are in place (Rogers 2021 ; Paul et al. 2020a , b , 2023 ). Furthermore, estuaries are of diverse shapes, sizes, physical, chemical and biological attributes; therefore, an assessment of a TC mediated changes of a specific type of estuary (e.g., open river, intermittently open/close river, lagoon, tidal lakes) may not be accurate for other types of estuaries; therefore, to some extent such a monitoring plan has to have estuary type specific requirements (Whitfield 1992 ; Wetz & Yoskowitz 2013 ; Phlips et al. 2020 ). A few TC research programmes that are running in North America are tracking the impacts of the hurricanes on the estuaries and their inhabitants including biogeochemical cycles, plankton and other forms of lower food web for a considerably long period of time (Paerl et al. 2019 ; Walker et al. 2021 ). Cyclone research conducted in India, Sri Lanka, China, Taiwan, South Africa have studied the impacts of the TCs on different types of estuaries such as river-estuary, coastal lagoons, brackish lakes (Martin et al. 1992 ; Beyrend-Dur et al. 2013 ; Mishra et al. 2021 ; Xia et al. 2022 ). Those studies demonstrated many extreme and abrupt changes of the water quality of an estuary that follows a TC as well as the vulnerability of the various food web components including plankton that have triggered or could potentially trigger trophic cascades (Bhattacharya et al. 2014 ; Srichandan et al. 2015 ; Kumar et al. 2020 ; Paul et al. 2020a , b ; Acharyya et al. 2021 ; Paul et al. 2023 ). A cyclone ecology research program of a river-estuary is rare (Paerl et al. 2019 ; Paul et al. 2023 ). Cyclone research of estuaries is mostly focused on intermittently open/close estuaries, coastal lagoons and tidal lakes (Srichandan et al. 2015 ; Xia et al. 2022 ; Thompson et al. 2023 ). Results of those research programs suggest that the intensity of the floods associated with a TC causes the major disruptions of the plankton communities and the windspeed of a TC has less to do with that (Peierls et al. 2003 ; Wetz & Paerl 2008 ). The distance to the landfall site of a TC does affect the extent of the disruption that a plankton community of an estuary may suffer after a TC (Kumar et al. 2017 ). Those observation may be less applicable for the plankton communities of a river-estuary such as the Ganges estuary (GE), India (Paul et al. 2020a , b , 2023 ). The intensity of the TCs are increasing in the Bay of Bengal (BoB) and the region is possibly going to receive more frequent and intense cyclones in the 21 Century (Balaguru et al. 2014 ; Mondal et al. 2022 ). It is almost inevitable that in future the structures and functions of the estuarine communities of India would be stressed from the cyclone-mediated changes (Paul et al. 2020a , b , 2023 ). If the TCs are going to be frequent than the estuarine communities would have less time to recover the impacts of those TCs (Paul et al. 2020b ); therefore, evaluations of such impacts on various scales (e.g., immediate (a few days), short-term (a few week to a month or so), medium-term (a few months to a few years) and long-term (decadal or more)) are essential for finding effective monitoring and management plans for the components of the lower food web of an estuary (Paul et al. 2023 ). Indian estuaries are not institutionally monitored on a regular basis for research programs; therefore, medium to long-term datasets are absent (Paul et al. 2023 , 2024 ). Considering those needs of the country, the ‘Cyclone Ecology (CE)’ was established on February 2019 on the GE (Paul et al. 2020a , b , 2023 ). That research programme runs on the Muriganga stretch of the GE and takes a before-after sampling approach considering the various categories of the TCs which landfall in the region (Paul et al. 2023 ). The Muriganga runs beside the Namkhana of West Bengal and it meets the BoB within a few kilometer; therefore, it is prone to face storm surges, depressions and TCs (Bhattacharya et al. 2014 ; Paul et al. 2020a , b , 2023 ). The CE programme uses the copepods as a model community and it studies the resilience and vulnerability of that community in face of a TC and/or successive TCs (Paul et al. 2020a , b , 2023 ). From the CE programme sites on the Muriganga 36 species of copepods are reported (Paul et al. 2019 , 2024 ) on various occasions and among them Bestiolina similis , Acartiella tortaniformis , Pseudodiaptomus serricaudatus , Paracalanus parvus and Acartia spinicauda are estuarine specialists which persist throughout the year (Paul et al. 2019 , 2023 , 2024 ). The programme has already studied the impacts of the TCs such as the Fani (May 2019), BulBul (November 2019) and Amphan (May 2020) which had varying intensities (Category-2 to 5); those studies suggested that the copepod community of the Muriganga suffered from the mechanical forcing that follows a TC rather from the extreme and abrupt changes of the abiotic conditions (Paul et al. 2020a , b , 2023 ). Those observation also include a short-term depression of species richness and abundance of the copepod community (Paul et al. 2020a , b , 2023 ). Even within a few days to a few weeks after a TC mediated disruption those copepods recolonize their microhabitats in the Muriganga often led by estuarine specialists (Paul et al. 2020a , b , 2023 ). Their spatial niches are segregated only by a few hundred meter stretch of the Muriganga stretch of the GE (Paul et al. 2019 , 2024 ). The TCs in the recent past such as the Aila (a Category-1 TC that landfall on 25 May 2009) severely affected the composition of the copepod community of the Indian Sundarbans (Bhattacharya et al. 2014 ). The Fani a Category-4 TC that landfall on Puri coast of Orissa about 350 K.M. away from the CE programme sites passed it on 5 May 2019 in capacity of a major depression (Paul et al. 2020b ). The post-Fani destructions and floods were limited and the copepod community of the CE programme sites is less affected by that (Paul et al. 2020b ). A Category-2 TC Bulbul landfall on 9 November 2019 on the Dhanchi forest of the Indian Sundarbans which is not far from the CE programme sites (Paul et al. 2020a ). The post-Bulbul floods were limited and the copepod community of the CE programme sites recovered with a few weeks from its immediate decline of abundance and richness that followed shortly after the TC (Paul et al. 2020a ). On the 20 May 2020, a Category-5 TC Amphan landfall only a few kilometer from the CE programme sites on the Muriganga and it caused severe destruction of the entire region as well as floods (Halder et al. 2021 ; Kumar et al. 2021 ; Paul et al. 2023 ). The copepod community composition, abundance and dominance hierarchy changed after the TC Amphan passed the CE programme sites and it took months to recover the state that existed before the Amphan; however, in some cases (e.g., dominance hierarchy) neo-normal ecological trends were observed (Paul et al. 2023 , 2024 ). The category-1 TC Yass landfall on 26 May 2021near the Dhamra Port of the Balasore region, Odisha state of India with a maximum sustained wind speed of 130–140 K.M./h gusting up to 155 K.M./hour (Paul & Chowdhury 2021 ). On the same day, after its landfall the TC Yass progressed towards the coastal regions of the West Bengal that include the CE programme sites.In that time the BoB sea surface temperature dropped about 3°C, salinity and density had raised by 1 psu and ~ 2 kg/m 3 , respectively (Varma et al. 2023 ). Indian Tide Table 2021 published by the order of the Surveyor General of India in 2020, predicted astronomical high tide on 26 May 2021 of Sagar Island (which is only a few kilometer from the CE programme sites) could reach as high as 5.71 meter. The TC Yass brought with it a high storm surge of 3.5 to 5 ​meters in the coasts of the Odisha and West Bengal and the tidal waves of height 1 to 2 meters above the astronomical tide were observed (Mondal et al. 2022 ; Varma et al. 2023 ). During that cyclonic period 11,405.21km 2 of the West Bengal’s coastal regions were inundated because about 1195 mm of rainfall occurred in short-time (Paul & Chowdhury 2021 ; Halder & Bandyopadhyay 2022 ). Within a short time, massive inundation occurred in the Namkhana (78.1 km 2 ), Sagar Island (37.1 km 2 ) and Kakdwip (32.6 km 2 ) blocks of the South 24 Parganas of the West Bengal which are besides the GE and are close to CE programme sites and their 43.6%, 28.3% and 19.2% human populations, respectively were affected (Paul & Chowdhury 2021 ). The current study hypothesized that in short-term the copepod community structure is affected (in terms of diversity, dominance, distribution) by the TC Yass which may have consequences for the lower food web of the Muriganga stretch of the GE. This study would be useful for conceptualizing a short-term monitoring plan of the zooplankton community of the river-estuaries of India against a Category-1 TC. Methods Study site The study was conducted from the CE programme sites (i.e., S1, S2 and S3) which have been established in February 2019 on the Muriganga stretch of the GE (Fig.1). The present study is a part of the monitoring of the CE programme sites so for the details related to study site see Paul et al. (2023). Sampling during the pre- and post-Yass periods The inundation that followed the TC Yass (landfall: 26 May 2021) caused a massive damage to infrastructure including roads to the Namkhana region of the West Bengal. The COVID-19 pandemic related lockdown had made it even more difficult to mobilise scientific resources immediately after the TC Yass. The sampling begun on 4 June 2021 and the sampling went till 22 June 2021. During that period the CE programme sites were sampled on 4 occasions (once in 6 days interval). Those are samples of the post-Yass period. On 21 November 2020, 29 January 2021 and 19 April 2021 water and copepod assemblages were sampled from the CE programme sites. During that period estuary was not perturbed by any TC for a considerable period. Those samples are assumed as the samples of the pre-Yass period. Field sampling of water and copepods, and laboratory processes Field sampling of the water and copepod assemblages related to the current study followed the similar methods which were deployed on the CE programme sites during the studies of the TC Fani, Bulbul and Amphan so for the details please refer to Paul et al. (2020a,b, 2023). By adopting the methods of the Paul et al. (2023) the copepod assemblages were collected in triplicate, preserved in 4% formalin and brought to the laboratory for species level identification by following Kasturirangan (1963) under the microscope (Bestscope-BS30T, China) and their abundances were expressed as individual(s) per cubic metre (i.e. ind.m -3 ). On the each occasion of the field sampling abiotic parameters such as the salinity (PSU), water temperature (°C) and pH of the estuary were measured from the sub-surface water by a hand held multi-parameter probe (YSI-1030; YSI, USA). Data structure, presentation and analysis Abiotic data of the pre- and post-Yass periods are presented in Table 1. Diversity indices such as the Shannon-diversity and the dominance (i.e., Simpson index) and the Pielou’s evenness index were calculated by using the ‘vegan’ package (version 2.6-4) using CRAN-R 4.3.2 (R Core Team 2023). Site-specific relative abundances of the copepods during the pre- and post-Yass periods were calculated (Table 3). Ordination analysis (on species abundance data after square root transformation) was conducted. At first a cluster analysis was done (see annexure 1) of both the pre- and post-Yass data using PRIMER-e version 7 (Clarke & Gorle 2015). Then a Non-metric Multidimensional Scaling (NMDS) was conducted using the Bray–Curtis measure of dissimilarity (‘Vegan’ package version 2.5.6). Finally NMDS biplots (see Figure 2) of both the pre- and post-Yass periods were drawn using PRIMER-e version 7 (Clarke & Gorle 2015). Permutational Multivariate Analysis of Variance (PERMANOVA) was conducted (i.e. Adonis test, permutations = 999, method = Bray-Curtis, package: ‘Vegan’ version: 2.5.6) to evaluate the variability of the copepod assemblages among sampling sites. Such a test was performed separately for the pre- and post-Yass periods. For PERMANOVA an assumption of homogeneity of multi-variate dispersion was tested by conducting Analysis of variance (ANOVA). Similarity percentage analysis (i.e. SIMPER) were conducted for the assessment of similarity and dissimilarity of the copepod assemblages sampled in the pre-Yass and post-Yass periods using the package ‘Vegan’ version: 2.5.6 of the CRAN-R 4.3.2 (R Core Team 2023). Results Abiotic conditions of the CE program sites During the pre-Yass period the salinity regime of the Muriganga was in between mesohaline to polyhaline ranged from 7.50 to 17.90 (Table 1). After the TC Yass the salinity of the Muriganga remained consistently in the polyhaline zone (ranged 15.90 to 20.80) for a few weeks (Table 1). Both in the pre- and post-Yass the pH of the Muriganga mostly remained slightly alkaline (Table 1). The water temperature in the post-Yass period varied within a narrow range i.e., 29.10 to 31.20°C; however, on the occasions of the pre-Yass sampling a considerable variability (range 21.40 to 30.30°C) of the water temperature was observed (Table 1). Copepod community structure and its changes Irrespective of the sampling sites, in the post-Yass period the species richness of the copepod community was higher than the pre-Yass period (Table 2). During the pre-Yass the species richness ranged 17 to 20 whereas in the post-Yass that was 20 to 24 (Table 2). Consequently, in the post-Yass period the Shannon Diversity, Simpson dominance and Pielou’s evenness indices of the copepod community showed higher values in comparison to the pre-Yass period (Table 2). In respect to relative abundance, during the pre-Yass period copepod species such as the Bestiolina similis , Paracalanus parvus and Acartiella tortaniformis co-dominated the community and among them Bestiolina similis was the most abundant species contributing up to 20.52% of the total community (Table 3). After the TC Yass, Bestiolina similis , Paracalanus parvus , Acartiella tortaniformis and Acartia spinicauda co-dominated the copepod community by virtue of their higher relative abundances but a noticeable decline in the relative abundances were observed for Bestiolina similis , Paracalanus parvus and Acartiella tortaniformis (Table 3). Post-Yass relative abundances of Canthocalanus pauper , Temora turbinata , Corycaeus crassiusculus Dana and different species of Oithona were higher than the pre-Yass period (Table 3). In the post-Yass period the copepod species that dominated the community in terms of its relative abundance is Oithona brevicornis (Table 3). Species such the Labidocera euchaeta and Oithona nana were not present in the copepod assemblages which were sampled in the pre-Yass period but those species were present in the post-Yass period (Table 3). During pre-Yass copepods of the Paracalanidae (cumulative abundance 49 to 59 %) family dominated the community followed by Acartiidae (cumulative abundance 27 – 33 %) and Oithonidae (cumulative abundance 3 – 8 %). After Yass Paracalindae contribution decreased to 28 to 35% and Acartiidae decreased to 17 to 29%; however, Oithonidae increased significantly to13 to 19% of the total copepod abundance. The Shannon diversity index correlating with species number also showed the trend of increased diversity in post- Yass period in all the three sites (Table 2). The NMDS analysis and the biplot of the pre-Yass period revealed the site specific variability of the copepod assemblages (Fig.2), which was found to be significant (PERMANOVA: DF = 2, Pseudo-F = 17.66, R 2 = 0.85, P = 0.005; homogeneity of multivariate dispersion test ANOVA: DF = 2, F = 0.4, P = 0.95). On contrary, the NDMS and the biplot (Fig.2) suggested that during the post-Yass period the spatial variability of the copepod assemblages of the Muriganga was not significant (PERMANOVA: DF = 2, Pseudo-F = 0.41, R 2 = 0.08, P = 0.95; homogeneity of multivariate dispersion test ANOVA: DF = 2, F = 0.28, P = 0.76). Results of the SIMPER analysis suggested that in the pre-Yass the average similarity of the copepods sampled on various occasions was 37.04% (chiefly contributed by the species such as B. similis 18.94%, P. parvus 17.82% and A. tortaniformis 14.83% and A. spinicauda 10.35%). Results further showed that the average similarity within the copepod assemblages did rise to 77.09% in the post-Yass period (chiefly contributed by the species such as A. tonsa 10.7%, O. similis 9.43; P. parvus 8.56% and A. longicornis 8.13%). Further, the average dissimilarity between the copepod assemblages sampled in the pre-and the post-Yass periods was 66.21% chiefly contributed by the species such as A. tonsa 10.84%, O. similis 9.34; A. longicornis 7.74% and B. similis 6.98%. Discussion Habitat conditions during the pre- and post-Yass periods Results of the abiotic variability demonstrated that the Muriganga stretch of the GE is a true estuary, which agree with previous studies conducted in the region (Mukhopadhyay et al. 2006 ; Chowdhury et al. 2015; Bhattacharya & Paul 2023; Paul et al. 2024 ). Due to the large influx of freshwater from the upstream of the Muriganga, it often remains mesohaline (Mitra et al. 2009 ; Paul et al. 2019 ; Bhattacharya & Paul 2023; Paul et al. 2024 ). Shortly after TC Yass, salt water intrusion from the adjacent Bay of Bengal had turned the estuary from a mesohaline to a polyhaline one and the estuary maintained such a characteristics for a few weeks which was not observed after TC Fani, Bulbul and Amphan (Paul et al. 2020a , b , 2023 , 2024 ). After TC Aila the Muriganga did remain polyhaline for a considerable time (Mitra et al. 2011 ; Bhattacharya et al. 2014 ). The Muriganga experiences macro-tidal environment and its pH profile remains slightly alkaline throughout the year unless there is an excessive rain for a few days which lowers the pH specially in monsoon (Chowdhury et al. 2015; Paul et al. 2024 ). Even after TC Yass, alkalinity of the estuary remained higher. High alkaline condition of the Muriganga was observed after the TC Phailin which caused sudden influx of salt near the mouth of the estuary (Das et al. 2016 ). The water temperature of the Muriganga follows the typical seasonal characteristics of a tropical estuary (Mukhopadhyay et al. 2006 ; Chowdhury et al. 2015; Paul et al. 2024 ). Post-Yass the water temperature of the Muriganga did not exhibits any drastic change. Absence of drastic change in water temperature of the Muriganga was also not observed after the TC Fani, Bulbul and Amphan (Paul et al. 2020a , b , 2023 ). Such was the case for TC Domoina which hit the lake St. Lucia and northern estuarine systems of the Natal, South Africa (Forbes & Cyrus 1992 ). On contrary, a considerable decline in the water temperature of the Muriganga was observed within a few days after the TC Aila (Bhattacharya et al. 2014 ). Previous studies on the TCs conducted on the lagoons, tidal lakes and intermittently open/close estuaries of India and across the world have suggested that a sudden change of the salinity regime of an estuary could influence diversity and distribution of its biological communities including the copepods (Forbes & Cyrus 1992 ; Reay & Moore 2005 ; Mitra et al. 2011 ; Beyrend-Dur et al. 2013 ; Bhattacharya et al. 2014 ; Srichandan et al. 2021 ; Mishra et al. 2023a , b ; Thompson et al. 2023 ). It was also suggested that the post-cyclone flood often exert mechanical forcing which subsequently temporarily disrupts plankton communities (Srichandan et al. 2021 ; Paul et al. 2023 ). Copepod community of the pre- and post-Yass periods Post TC Yass the number of species increased within the sampled copepod assemblages, the community had more cyclopoid copepods than the pre-Yass period. Species such as the A. tortaniformis had replaced the B. similis as the most dominant species of the copepod community, and the abundances of a few dominant species such as P. parvus , A. spinicauda had considerably declined. The O. brevicornis abundance had risen in the post-Yass period, and the species such as L. euchaeta and O. nana were observed in the post-Yass period which were absent in the pre-Yass period. It is, therefore, evident that in short-term the copepod community of the Muriganga is impacted and underwent several changes. Those changes in the community structure of the copepods of the Muriganga were not observed after TC Fani, Bulbul and Amphan (Paul et al. 2020a , b , 2023 ). The Oithona are generally omnivores that mostly eat organic debris, dinoflagellates, diatoms, and proto-zooplankton (Pond & Ward 2011 ; Wang et al. 2017 ). The sudden increment of Oithonidae family in the post- Yass samples could be attributed to the increased organic debris in the water which is common after a TC (Bhattacharya et al. 2014 ). The increased number of Oithonidae family is mainly due to the increment of O. brevicornis abundance in the post-Yass samples, such a phenomenon was observed after cyclone “Aila” (Bhattacharya et al. 2014 ) but not after TC Fani, Bulbul and Amphan (Paul et al. 2020a , b , 2023 ). The dominance of Oithonidae suggested their high adaptability to trophic and hydrologic conditions in the post- Yass period. After each of the TC Aila, Fani, Bulbul and Amphan there were an immediate decline in the species richness and the total abundance of the copepods (Paul et al. 2020a , b , 2023 ). Within a week or so after TC Fani and Bulbul about 50% of the species richness recovered (Paul et al. 2020a , b ). Decline in the total abundance of the copepod community as well as in the abundances of the individual species is not that uncommon after a TC mediated disruption of estuaries of India, South Africa and Taiwan (Forbes & Cyrus 1992 ; Lopez-Lopez et al. 2012 ; Beyrend-Dur et al. 2013 ; Bhattacharya et al. 2014 ; Srichandan et al. 2021 ). Results of the NMDS and SIMPER analysis suggested that the TC Yass for a while had washed away some of the spatial heterogeneity within the copepod community that existed in the pre-Yass period. This is not unexpected because floods and or incessant rainfall (often associated with a TC) often temporarily wash way environmental gradients of an estuary and impact the spatial niche segregations of many estuarine biota including plankton (Payne et al. 2015 , Nandy et al. 2018 ); therefore, the community becomes more homogenous at least for a short-term (Paul et al. 2023 ). Later when the environmental gradients become again prominent in an estuary that in consequence help many estuarine specialist copepods to recolonize their vacant spatial niches (Paul et al. 2020a , b , 2023 ). Cyclone ecology research of Indian estuaries In total 61 TCs of various intensities have disrupted the nine coastal states of India from 2006 to 2020; the highest numbers were recorded in Odisha (20), West Bengal (14) and Andhra Pradesh (11) (Kantamaneni et al. 2022 ). The cyclone ecology research of the Indian estuaries is relatively new as its roots could be traced in last two decades (Kumar et al. 2010 ; Joseph et al. 2011 ; Mitra et al. 2011 ; Mukherjee et al. 2012 ; Bhattacharya et al. 2014 ; Kumar et al. 2017 ). Literature is mostly focused on Indian Sundarbans, West Bengal and on the estuaries (e.g., Chilika lagoon) of Odisha (Mitra et al. 2011 ; Mukherjee et al. 2012 ; Bhattacharya et al. 2014 ; Paul et al. 2020a , b , 2023 ; Kumar et al. 2017 ; Srichandan et al. 2021 ; Mishra et al. 2023a , b ). Little is known about the impact of TCs on the ecology of other estuaries, backwaters and lagoons of India (Joseph et al. 2011 ; Mangesh et al. 2016 ; Gunasekaran et al. 2021 ; Sachithanandam et al. 2022 ). Traditionally, the frequency of cyclones in India is higher on the eastern coast than on the western coast; however, in the recent years, the frequency of cyclones over the Arabian sea is on the rise (Baburaj et al. 2021; Kar & Banerjee 2021 ); therefore, cyclone ecology research would become more relevant than ever for Indian estuaries. India has no institutional mechanism placed for regular monitoring of its estuaries for cyclone-mediated changes (Paul et al. 2019 , 2020a , b , 2023 ). Except the Chilika lagoon and mangrove estuaries of Indian Sundarbans including the GE, drawing a baseline for different types of Indian estuaries and predicting their fates facing TCs; therefore, are difficult. The other major issue is the previous studies conducted in India and elsewhere have documented the disturbance and recovery of estuaries from one or a few locations or storm events, limiting generalizations about the TC impacts and characteristic patterns of ecosystem response and recovery (Buelo et al. 2024 ). Considering the scarcity of scientific resources, unpredictability of a TC track and mobilization of scientific infrastructure and human resources immediately after a TC or successive TCs there shall be focus on geo-spatial science and remotely operated in-situ recordings and periodic ecological surveys for monitoring the baselines and stochastic disturbances of Indian estuaries (Mishra et al. 2023a ; Paul et al. 2023 ; Varma et al. 2023 ). The Sundarbans (including the GE), Chilika lagoon, Godavari estuary, Cochin-estuary, Mandovi-Zuari estuary are some of the iconic estuaries of India that are serving millions of Indians daily by providing ecosystem services (Sarkar & Bhattacharya 2003 ; Bhavan et al. 2023 ). Those services may get seriously jeopardised if the lower food web of the Indian estuaries are strained from the periodic TCs (Paul et al. 2020a ; Mishra et al. 2021 ; Rasquinha & Mishra 2021 ; Mishra et al. 2023a ). United Nations Ocean Decade (2021–2030) may serve as the baseline to initiate a cyclone impact monitoring and resilience plan of the lower food web of Indian estuaries. Declarations Acknowledgements Dr. Paul thanks DST Inspire Faculty Award [Sanction no: DST/INSPIRE/04/2016/0000036] of the Government of India for his fellowship and funding the research. Dr. Paul further extends his gratitude to the Core Research Grant sanctioned by the Science and Engineering Research Board (SERB) [Sanction: EMR/2017/001111 dated 24 July 2018] of the Government of India which met the fellowship of Mr. Karan. Dr. Bhattacharya extends his gratitude to the Estuarine and Coastal Studies Foundation for financial assistance received during the course of the study. Thanks to the Head of Department of Zoology, University of Calcutta and the Director of Estuarine and Coastal Studies Foundation, West Bengal for providing facilities related to this research. Dr. Paul thanks the Intergovernmental Oceanographic Commission, UNESCO for endorsing the present study as a part of the (Decade Action: No. 122.2 –‘Periodic cyclone effects on Gangetic food web) United Nation Decade of Ocean Science for Sustainable Development (2021-2030). Financial Support DST Inspire Faculty Award [Sanction no: DST/INSPIRE/04/2016/0000036] of the Government of India met fellowship of Dr. Sourav Paul and partial funding the research. Core Research Grant sanctioned by the Science and Engineering Research Board (SERB) [Sanction: EMR/2017/001111 dated 24 July 2018] of the Government of India met the fellowship of Mr. Karan and partial funding for the research. Estuarine and Coastal Studies Foundation, India provided financial assistance to Dr. Bhaskar Deb Bhattacharya during the course of the study. Competing interest All authors declare that they have no competing interest on connection with this study. Ethical approval No ethical standards were required to execute the study. Data availability Data would be provided with a reasonable request for non-commercial purpose. Author Contributions Sourav Paul: Conceptualization,Methodology,Formal analysis and investigation,writing original draft, writing - review and editing, Funding acquisition , Resources, Supervision; Samya Karan: Methodology; Bhaskar Deb Bhattacharya: Methodology, writing - review and editing. References Acharyya T, Sudatta BP, Srichandan S, Baliarsingh SK, Lotliker AA, Raulo S, Singh S and Samanta A (2021) Deciphering long-term seasonal and tidal water quality trends in the Mahanadi estuary. Journal of Coastal Conservation 25,1-16. Baburaj PP, Abhilash S, Nirmal CA, Sreenath AV, Mohankumar K and Sahai AK (2022) Increasing incidence of Arabian Sea cyclones during the monsoon onset phase: Its impact on the robustness and advancement of Indian summer monsoon. Atmospheric Research 267, 105915. Balaguru K, Taraphdar S, Leung LR and Foltz GR (2014) Increase in the intensity of postmonsoon Bay of Bengal tropical cyclones. Geophysical Research Letters 41, 3594-3601. 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Environmental Hazards 22, 65-78. Mishra M, Acharyya T, Santos CAG, da Silva RM, Kar PK, Mohanty PK, Rout NR, Beja SK, Bhattacharyya D, Behera B and Barik S (2023b) Impact assessment of severe cyclonic storm Asani on the nesting grounds of Olive Ridley turtle, Rushikulya Estuary and spit in Odisha state, India. Ocean and Coastal Management 238,106572. Mitra A, Gangopadhyay A, Dube A, Schmidt AC and Banerjee K (2009) Observed changes in water mass properties in the Indian Sundarbans (northwestern Bay of Bengal) during 1980–2007. Current Science 97, 1445-1452. Mitra A, Halder P and Banerjee K (2011) Changes of selected hydrological parameters in Hooghly estuary in response to a severe tropical cyclone (Aila). Indian Journal of Geo-Marine Science 40, 32-36. Mitra A, Mondal K, and Banerjee K (2011) Spatial and tidal variations of physico-chemical parameters in the lower Gangetic delta region, West Bengal, India. Journal of Spatial Hydrology 11, 52-69. Mondal M, Biswas A, Haldar S, Mandal S, Bhattacharya S and Paul S (2022) Spatio-temporal behaviours of tropical cyclones over the bay of Bengal Basin in last five decades. Tropical Cyclone Research and Review 11, 1-15. Mukherjee S, Chaudhuri A, Sen S and Homechaudhuri S (2012) Effect of Cyclone Aila on estuarine fish assemblages in the Matla River of the Indian Sundarbans. Journal of Tropical Ecology 28, 405-415. Mukhopadhyay SK, Biswas HD, De TK and Jana TK (2006) Fluxes of nutrients from the tropical River Hooghly at the land–ocean boundary of Sundarbans, NE Coast of Bay of Bengal, India. Journal of Marine Systems 62, 9-21. Nandy T, Mandal S, and Chatterjee M (2018) Intra-monsoonal variation of zooplankton population in the Sundarbans Estuarine System, India. Environmental Monitoring and Assessment 190, 1-20. Needham HF, Keim BD and Sathiaraj D (2015) A review of tropical cyclone‐generated storm surges: Global data sources, observations, and impacts. Reviews of Geophysics 53, 545-591. Nunn AD, Tewson LH and Cowx IG (2012) The foraging ecology of larval and juvenile fishes. Reviews in Fish Biology and Fisheries 22, 377-408. Ortiz AMD, Chua PL, Salvador Jr, D, Dyngeland C, Albao Jr, JDG and Abesamis RA (2023) Impacts of tropical cyclones on food security, health and biodiversity. Bulletin of the World Health Organization 101, 152. Paerl HW, Hall NS, Hounshell AG, Luettich Jr RA, Rossignol KL, Osburn CL and Bales J (2019) Recent increase in catastrophic tropical cyclone flooding in coastal North Carolina, USA: Long-term observations suggest a regime shift. Scientific Reports 9, 10620. Paul S and Chowdhury S (2021) Investigation of the character and impact of tropical cyclone Yaas: a study over coastal districts of West Bengal, India. Safety in Extreme Environments 3, 219-235. Paul S, Karan S, Ghosh S and Bhattacharya BD (2019) Hourly variation of environment and copepod community of the Ganges River Estuary of India: Perspectives on sampling estuarine zooplankton. Estuarine, Coastal and Shelf Science 230,106441. Paul S, Karan S and Bhattacharya BD (2020a) Daily variability of copepods after successive tropical cyclones in the Ganges River estuary of India. Estuarine, Coastal and Shelf Science 246, 107048. Paul S, Karan S and Bhattacharya BD (2020b) Effects of cyclone Fani on the copepod community of the Ganges River estuary of India. Environmental Monitoring and Assessment 192, 1-16. Paul S, Karan S and Bhattacharya BD (2023) Effects of tropical cyclone Amphan on the copepods of the Ganges estuary. Marine Biology Research 19, 342-354. Paul S, Karan S and Bhattacharya BD (2024) Copepods (Zooplankton) of Muriganga Estuary, at West Bengal Coast, India. Proceedings of the Zoological Society. doi.org/10.1007/s12595-024-00515-7. Payne NL, van der Meulen DE, Suthers IM, Gray CA, Walsh CT and Taylor MD (2015) Rain-driven changes in fish dynamics: a switch from spatial to temporal segregation. Marine Ecology Progress Series 528, 267-275. Peierls BL, Christian RR and Paerl HW (2003) Water quality and phytoplankton as indicators of hurricane impacts on a large estuarine ecosystem. Estuaries 26, 1329-1343. Phlips EJ, Badylak S, Nelson NG and Havens KE (2020) Hurricanes, El Niño and harmful algal blooms in two sub-tropical Florida estuaries: Direct and indirect impacts. Scientific Reports 10, 1910. Pond DW and Ward P (2011) Importance of diatoms for Oithona in Antarctic waters. Journal of Plankton Research 33,105-118. R Core Team (2023). R: A language and environment for statistical computing. R Foundation for Statistical Computing, Vienna, Austria. URL https://www.R-project.org/. Rasquinha DN and Mishra DR (2021) Tropical cyclones shape mangrove productivity gradients in the Indian subcontinent. Scientific Reports 11, 17355. Reay WG and Moore K (2005) Impacts of tropical cyclone Isabel on shallow water quality of the York River Estuary. VIMS Books and Book Chapters. 6. https://scholarworks.wm.edu/vimsbooks/6 Rogers RF (2021) Recent advances in our understanding of tropical cyclone intensity change processes from airborne observations. Atmosphere 12, 650. Sachithanandam V, Bonthu S, Mageswaran T, Singh KS, Vimala J, Sridhar R, Purvaja R and Ramesh R (2022) Effect of hydrodynamic conditions on seagrass ecosystems during Cyclone Lehar in the South Andaman Islands, India. Ecohydrology and Hydrobiology 22, 640-659. Sarkar SK and Bhattacharya AK (2003) Conservation of biodiversity of the coastal resources of Sundarbans, Northeast India: an integrated approach through environmental education. Marine Pollution Bulletin 47, 260-264. Srichandan S, Kim JY, Kumar A, Mishra DR, Bhadury P, Muduli PR, Pattnaik AK and Rastogi G (2015) Interannual and cyclone-driven variability in phytoplankton communities of a tropical coastal lagoon. Marine Pollution Bulletin 101, 39-52. Srichandan S, Tarafdar L, Muduli PR and Rastogi G (2021) Spatiotemporal patterns and impact of a cyclone on the zooplankton community structure in a brackish coastal lagoon. Regional Studies in Marine Science 44, 101743. Thompson PA, Paerl HW, Campbell L, Yin K and McDonald KS (2023) Tropical cyclones: what are their impacts on phytoplankton ecology?. Journal of Plankton Research 45, 180-204. Varma AK, Jaiswal N, Das A, Kumar M, Lele NV, Tripathy R, Maity S, Pandya M, Bhattacharya B, Mandal AK and Jishad M (2023) A pathway for multi-stage cyclone-induced hazard tracking—case study for Yaas. Natural Hazards 117, 1035-1067. Wang L, Du F, Wang, X, Li Y and Ning J (2017) Distribution and role of the genus Oithona (Copepoda: Cyclopoida) in the South China Sea. Oceanologia 59, 300-310. Walker LM, Montagna PA, Hu X and Wetz MS (2021) Timescales and magnitude of water quality change in three Texas estuaries induced by passage of Hurricane Harvey. Estuaries and Coasts 44, 960-971. Wetz MS and Paerl HW (2008) Estuarine phytoplankton responses to hurricanes and tropical storms with different characteristics (trajectory, rainfall, winds). Estuaries and Coasts 31, 419-429. Wetz MS and Yoskowitz DW (2013) An ‘extreme’ future for estuaries? Effects of extreme climatic events on estuarine water quality and ecology. Marine Pollution Bulletin 69, 7-18. Whitfield AK (1992) A characterization of southern African estuarine systems. Southern African Journal of Aquatic Science 18, 89-103. Woodruff JD, Irish JL and Camargo SJ (2013) Coastal flooding by tropical cyclones and sea-level rise. Nature 504, 44-52. Xia C, Ge X, Haibin LÜ, Zhang H, Xing X and Cui Y (2022) A phytoplankton bloom with a cyclonic eddy enhanced by the tropical cyclone Phethai in eastern Sir Lanka. Regional Studies in Marine Science 51, 102217. Tables Tables 1 to 3 are available in the Supplementary Files section Additional Declarations No competing interests reported. Supplementary Files Annexture1.tif Table1.docx Table2.docx Table3.docx Cite Share Download PDF Status: Posted Version 1 posted You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. 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Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-4862370","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":344975163,"identity":"e3cc4004-8cf9-48d2-8b69-3c9a21332e9f","order_by":0,"name":"Sourav Paul","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAA60lEQVRIiWNgGAWjYFADdobEB0CKh494LcwMjw1AWthI0ML4TAJEE9Qi395j9uFn2x15g8PMaZVfc+xk2BiYHz66gUeLwZkzxjN7254ZbjjMlnZbdlsy0GFsxsY5+LRI5Bgz8Jw5zLjhME/abcltzEAtPGzS+LTIz8gxZvxz5rD9hsP834olt9UT1sJwI8eYmaficOKGwwxpjB+3HSasxeDMsWJmmYpnyTMPMyRLM247zsPGTMAv8u3NmxnfGNyx7TvekPjx57Zqe3725oeP8ToMAg6ASWYeMElYOUIL4w/iVI+CUTAKRsEIAwDgLkdXoP9VzgAAAABJRU5ErkJggg==","orcid":"","institution":"University of Calcutta","correspondingAuthor":true,"submittingAuthor":false,"prefix":"","firstName":"Sourav","middleName":"","lastName":"Paul","suffix":""},{"id":344975164,"identity":"04ff7d35-290e-4958-ab8b-4520bc785ff3","order_by":1,"name":"Samya Karan","email":"","orcid":"","institution":"University of 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1","display":"","copyAsset":false,"role":"figure","size":440602,"visible":true,"origin":"","legend":"\u003cp\u003eMap of the study area, track of tropical cyclone Yass and the cyclone ecology program sites (i.e., S1, S2 and S3) on the Muriganga stretch of the Ganges estuary, India (after Paul et al. 2023).\u003c/p\u003e","description":"","filename":"OnlineFig.1.png","url":"https://assets-eu.researchsquare.com/files/rs-4862370/v1/40839122137cfb7b7c900808.png"},{"id":63762204,"identity":"dc98bc67-3536-4e84-9f90-f5cfa273f912","added_by":"auto","created_at":"2024-09-02 06:31:26","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":64649,"visible":true,"origin":"","legend":"\u003cp\u003eSpatial variability of the copepod community sampled during the pre-Yass and post-Yass periods from the cyclone ecology program sites (i.e., S1, S2 and S3) on the Muriganga stretch of the Ganges estuary, India.\u003c/p\u003e","description":"","filename":"OnlineFig.2.png","url":"https://assets-eu.researchsquare.com/files/rs-4862370/v1/f0d0d8910e92b25b62499ea7.png"},{"id":66244927,"identity":"d4989ff8-20ae-4287-bb31-2eb9fb106bbc","added_by":"auto","created_at":"2024-10-09 07:32:30","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":1224983,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-4862370/v1/fe9ec5e1-18b2-41e5-8838-9c6663c82261.pdf"},{"id":63762207,"identity":"20c87e67-94ab-4efe-b95b-1417ff6f401a","added_by":"auto","created_at":"2024-09-02 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06:31:26","extension":"docx","order_by":3,"title":"","display":"","copyAsset":false,"role":"supplement","size":15839,"visible":true,"origin":"","legend":"","description":"","filename":"Table2.docx","url":"https://assets-eu.researchsquare.com/files/rs-4862370/v1/0d9975cbdf27e5769ff77e06.docx"},{"id":63762678,"identity":"01eba7a2-44ae-4261-8093-c18bd23d7f24","added_by":"auto","created_at":"2024-09-02 06:39:26","extension":"docx","order_by":4,"title":"","display":"","copyAsset":false,"role":"supplement","size":18170,"visible":true,"origin":"","legend":"","description":"","filename":"Table3.docx","url":"https://assets-eu.researchsquare.com/files/rs-4862370/v1/cec4bc673f6fb839641b7cbc.docx"}],"financialInterests":"No competing interests reported.","formattedTitle":"Changes of the copepod community of Ganges estuary following tropical cyclone Yass","fulltext":[{"header":"Introduction","content":"\u003cp\u003eTropical cyclones (TCs) are discreate and destructive events that temporarily disrupts the lives and livelihoods of ecological communities (Needham et al. \u003cspan citationid=\"CR38\" class=\"CitationRef\"\u003e2015\u003c/span\u003e). Researchers have focused on the genesis of TCs, causes and consequences of their rising intensities and frequencies across the world, and on their impacts on biodiversity (Woodruff et al. \u003cspan citationid=\"CR68\" class=\"CitationRef\"\u003e2013\u003c/span\u003e; Kang \u0026amp; Elsner \u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e2015\u003c/span\u003e; Mondal et al. \u003cspan citationid=\"CR34\" class=\"CitationRef\"\u003e2022\u003c/span\u003e; Thompson et al. \u003cspan citationid=\"CR61\" class=\"CitationRef\"\u003e2023\u003c/span\u003e). Lack of predictability of a TC track, immediate mobility of the scientific infrastructures and human resources following a TC are the barriers before cyclone research programme of estuaries unless regular institutional monitoring plans are in place (Rogers \u003cspan citationid=\"CR56\" class=\"CitationRef\"\u003e2021\u003c/span\u003e; Paul et al. \u003cspan citationid=\"CR44\" class=\"CitationRef\"\u003e2020a\u003c/span\u003e,\u003cspan citationid=\"CR45\" class=\"CitationRef\"\u003eb\u003c/span\u003e, \u003cspan citationid=\"CR46\" class=\"CitationRef\"\u003e2023\u003c/span\u003e). Furthermore, estuaries are of diverse shapes, sizes, physical, chemical and biological attributes; therefore, an assessment of a TC mediated changes of a specific type of estuary (e.g., open river, intermittently open/close river, lagoon, tidal lakes) may not be accurate for other types of estuaries; therefore, to some extent such a monitoring plan has to have estuary type specific requirements (Whitfield \u003cspan citationid=\"CR67\" class=\"CitationRef\"\u003e1992\u003c/span\u003e; Wetz \u0026amp; Yoskowitz \u003cspan citationid=\"CR66\" class=\"CitationRef\"\u003e2013\u003c/span\u003e; Phlips et al. \u003cspan citationid=\"CR50\" class=\"CitationRef\"\u003e2020\u003c/span\u003e). A few TC research programmes that are running in North America are tracking the impacts of the hurricanes on the estuaries and their inhabitants including biogeochemical cycles, plankton and other forms of lower food web for a considerably long period of time (Paerl et al. \u003cspan citationid=\"CR41\" class=\"CitationRef\"\u003e2019\u003c/span\u003e; Walker et al. \u003cspan citationid=\"CR64\" class=\"CitationRef\"\u003e2021\u003c/span\u003e). Cyclone research conducted in India, Sri Lanka, China, Taiwan, South Africa have studied the impacts of the TCs on different types of estuaries such as river-estuary, coastal lagoons, brackish lakes (Martin et al. \u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e1992\u003c/span\u003e; Beyrend-Dur et al. \u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e2013\u003c/span\u003e; Mishra et al. \u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e2021\u003c/span\u003e; Xia et al. \u003cspan citationid=\"CR69\" class=\"CitationRef\"\u003e2022\u003c/span\u003e). Those studies demonstrated many extreme and abrupt changes of the water quality of an estuary that follows a TC as well as the vulnerability of the various food web components including plankton that have triggered or could potentially trigger trophic cascades (Bhattacharya et al. \u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e2014\u003c/span\u003e; Srichandan et al. \u003cspan citationid=\"CR59\" class=\"CitationRef\"\u003e2015\u003c/span\u003e; Kumar et al. \u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e2020\u003c/span\u003e; Paul et al. \u003cspan citationid=\"CR44\" class=\"CitationRef\"\u003e2020a\u003c/span\u003e,\u003cspan citationid=\"CR45\" class=\"CitationRef\"\u003eb\u003c/span\u003e; Acharyya et al. \u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e2021\u003c/span\u003e; Paul et al. \u003cspan citationid=\"CR46\" class=\"CitationRef\"\u003e2023\u003c/span\u003e). A cyclone ecology research program of a river-estuary is rare (Paerl et al. \u003cspan citationid=\"CR41\" class=\"CitationRef\"\u003e2019\u003c/span\u003e; Paul et al. \u003cspan citationid=\"CR46\" class=\"CitationRef\"\u003e2023\u003c/span\u003e). Cyclone research of estuaries is mostly focused on intermittently open/close estuaries, coastal lagoons and tidal lakes (Srichandan et al. \u003cspan citationid=\"CR59\" class=\"CitationRef\"\u003e2015\u003c/span\u003e; Xia et al. \u003cspan citationid=\"CR69\" class=\"CitationRef\"\u003e2022\u003c/span\u003e; Thompson et al. \u003cspan citationid=\"CR61\" class=\"CitationRef\"\u003e2023\u003c/span\u003e). Results of those research programs suggest that the intensity of the floods associated with a TC causes the major disruptions of the plankton communities and the windspeed of a TC has less to do with that (Peierls et al. \u003cspan citationid=\"CR49\" class=\"CitationRef\"\u003e2003\u003c/span\u003e; Wetz \u0026amp; Paerl \u003cspan citationid=\"CR65\" class=\"CitationRef\"\u003e2008\u003c/span\u003e). The distance to the landfall site of a TC does affect the extent of the disruption that a plankton community of an estuary may suffer after a TC (Kumar et al. \u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e2017\u003c/span\u003e). Those observation may be less applicable for the plankton communities of a river-estuary such as the Ganges estuary (GE), India (Paul et al. \u003cspan citationid=\"CR44\" class=\"CitationRef\"\u003e2020a\u003c/span\u003e,\u003cspan citationid=\"CR45\" class=\"CitationRef\"\u003eb\u003c/span\u003e, \u003cspan citationid=\"CR46\" class=\"CitationRef\"\u003e2023\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eThe intensity of the TCs are increasing in the Bay of Bengal (BoB) and the region is possibly going to receive more frequent and intense cyclones in the 21 Century (Balaguru et al. \u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e2014\u003c/span\u003e; Mondal et al. \u003cspan citationid=\"CR34\" class=\"CitationRef\"\u003e2022\u003c/span\u003e). It is almost inevitable that in future the structures and functions of the estuarine communities of India would be stressed from the cyclone-mediated changes (Paul et al. \u003cspan citationid=\"CR44\" class=\"CitationRef\"\u003e2020a\u003c/span\u003e,\u003cspan citationid=\"CR45\" class=\"CitationRef\"\u003eb\u003c/span\u003e, \u003cspan citationid=\"CR46\" class=\"CitationRef\"\u003e2023\u003c/span\u003e). If the TCs are going to be frequent than the estuarine communities would have less time to recover the impacts of those TCs (Paul et al. \u003cspan citationid=\"CR45\" class=\"CitationRef\"\u003e2020b\u003c/span\u003e); therefore, evaluations of such impacts on various scales (e.g., immediate (a few days), short-term (a few week to a month or so), medium-term (a few months to a few years) and long-term (decadal or more)) are essential for finding effective monitoring and management plans for the components of the lower food web of an estuary (Paul et al. \u003cspan citationid=\"CR46\" class=\"CitationRef\"\u003e2023\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eIndian estuaries are not institutionally monitored on a regular basis for research programs; therefore, medium to long-term datasets are absent (Paul et al. \u003cspan citationid=\"CR46\" class=\"CitationRef\"\u003e2023\u003c/span\u003e, \u003cspan citationid=\"CR47\" class=\"CitationRef\"\u003e2024\u003c/span\u003e). Considering those needs of the country, the \u0026lsquo;Cyclone Ecology (CE)\u0026rsquo; was established on February 2019 on the GE (Paul et al. \u003cspan citationid=\"CR44\" class=\"CitationRef\"\u003e2020a\u003c/span\u003e,\u003cspan citationid=\"CR45\" class=\"CitationRef\"\u003eb\u003c/span\u003e, \u003cspan citationid=\"CR46\" class=\"CitationRef\"\u003e2023\u003c/span\u003e). That research programme runs on the Muriganga stretch of the GE and takes a before-after sampling approach considering the various categories of the TCs which landfall in the region (Paul et al. \u003cspan citationid=\"CR46\" class=\"CitationRef\"\u003e2023\u003c/span\u003e). The Muriganga runs beside the Namkhana of West Bengal and it meets the BoB within a few kilometer; therefore, it is prone to face storm surges, depressions and TCs (Bhattacharya et al. \u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e2014\u003c/span\u003e; Paul et al. \u003cspan citationid=\"CR44\" class=\"CitationRef\"\u003e2020a\u003c/span\u003e,\u003cspan citationid=\"CR45\" class=\"CitationRef\"\u003eb\u003c/span\u003e, \u003cspan citationid=\"CR46\" class=\"CitationRef\"\u003e2023\u003c/span\u003e). The CE programme uses the copepods as a model community and it studies the resilience and vulnerability of that community in face of a TC and/or successive TCs (Paul et al. \u003cspan citationid=\"CR44\" class=\"CitationRef\"\u003e2020a\u003c/span\u003e,\u003cspan citationid=\"CR45\" class=\"CitationRef\"\u003eb\u003c/span\u003e, \u003cspan citationid=\"CR46\" class=\"CitationRef\"\u003e2023\u003c/span\u003e). From the CE programme sites on the Muriganga 36 species of copepods are reported (Paul et al. \u003cspan citationid=\"CR43\" class=\"CitationRef\"\u003e2019\u003c/span\u003e, \u003cspan citationid=\"CR47\" class=\"CitationRef\"\u003e2024\u003c/span\u003e) on various occasions and among them \u003cem\u003eBestiolina similis\u003c/em\u003e, \u003cem\u003eAcartiella tortaniformis\u003c/em\u003e, \u003cem\u003ePseudodiaptomus serricaudatus\u003c/em\u003e, \u003cem\u003eParacalanus parvus\u003c/em\u003e and \u003cem\u003eAcartia spinicauda\u003c/em\u003e are estuarine specialists which persist throughout the year (Paul et al. \u003cspan citationid=\"CR43\" class=\"CitationRef\"\u003e2019\u003c/span\u003e, \u003cspan citationid=\"CR46\" class=\"CitationRef\"\u003e2023\u003c/span\u003e, \u003cspan citationid=\"CR47\" class=\"CitationRef\"\u003e2024\u003c/span\u003e). The programme has already studied the impacts of the TCs such as the Fani (May 2019), BulBul (November 2019) and Amphan (May 2020) which had varying intensities (Category-2 to 5); those studies suggested that the copepod community of the Muriganga suffered from the mechanical forcing that follows a TC rather from the extreme and abrupt changes of the abiotic conditions (Paul et al. \u003cspan citationid=\"CR44\" class=\"CitationRef\"\u003e2020a\u003c/span\u003e,\u003cspan citationid=\"CR45\" class=\"CitationRef\"\u003eb\u003c/span\u003e, \u003cspan citationid=\"CR46\" class=\"CitationRef\"\u003e2023\u003c/span\u003e). Those observation also include a short-term depression of species richness and abundance of the copepod community (Paul et al. \u003cspan citationid=\"CR44\" class=\"CitationRef\"\u003e2020a\u003c/span\u003e,\u003cspan citationid=\"CR45\" class=\"CitationRef\"\u003eb\u003c/span\u003e, \u003cspan citationid=\"CR46\" class=\"CitationRef\"\u003e2023\u003c/span\u003e). Even within a few days to a few weeks after a TC mediated disruption those copepods recolonize their microhabitats in the Muriganga often led by estuarine specialists (Paul et al. \u003cspan citationid=\"CR44\" class=\"CitationRef\"\u003e2020a\u003c/span\u003e,\u003cspan citationid=\"CR45\" class=\"CitationRef\"\u003eb\u003c/span\u003e, \u003cspan citationid=\"CR46\" class=\"CitationRef\"\u003e2023\u003c/span\u003e). Their spatial niches are segregated only by a few hundred meter stretch of the Muriganga stretch of the GE (Paul et al. \u003cspan citationid=\"CR43\" class=\"CitationRef\"\u003e2019\u003c/span\u003e, \u003cspan citationid=\"CR47\" class=\"CitationRef\"\u003e2024\u003c/span\u003e). The TCs in the recent past such as the Aila (a Category-1 TC that landfall on 25 May 2009) severely affected the composition of the copepod community of the Indian Sundarbans (Bhattacharya et al. \u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e2014\u003c/span\u003e). The Fani a Category-4 TC that landfall on Puri coast of Orissa about 350 K.M. away from the CE programme sites passed it on 5 May 2019 in capacity of a major depression (Paul et al. \u003cspan citationid=\"CR45\" class=\"CitationRef\"\u003e2020b\u003c/span\u003e). The post-Fani destructions and floods were limited and the copepod community of the CE programme sites is less affected by that (Paul et al. \u003cspan citationid=\"CR45\" class=\"CitationRef\"\u003e2020b\u003c/span\u003e). A Category-2 TC Bulbul landfall on 9 November 2019 on the Dhanchi forest of the Indian Sundarbans which is not far from the CE programme sites (Paul et al. \u003cspan citationid=\"CR44\" class=\"CitationRef\"\u003e2020a\u003c/span\u003e). The post-Bulbul floods were limited and the copepod community of the CE programme sites recovered with a few weeks from its immediate decline of abundance and richness that followed shortly after the TC (Paul et al. \u003cspan citationid=\"CR44\" class=\"CitationRef\"\u003e2020a\u003c/span\u003e). On the 20 May 2020, a Category-5 TC Amphan landfall only a few kilometer from the CE programme sites on the Muriganga and it caused severe destruction of the entire region as well as floods (Halder et al. \u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e2021\u003c/span\u003e; Kumar et al. \u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e2021\u003c/span\u003e; Paul et al. \u003cspan citationid=\"CR46\" class=\"CitationRef\"\u003e2023\u003c/span\u003e). The copepod community composition, abundance and dominance hierarchy changed after the TC Amphan passed the CE programme sites and it took months to recover the state that existed before the Amphan; however, in some cases (e.g., dominance hierarchy) neo-normal ecological trends were observed (Paul et al. \u003cspan citationid=\"CR46\" class=\"CitationRef\"\u003e2023\u003c/span\u003e, \u003cspan citationid=\"CR47\" class=\"CitationRef\"\u003e2024\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eThe category-1 TC Yass landfall on 26 May 2021near the Dhamra Port of the Balasore region, Odisha state of India with a maximum sustained wind speed of 130\u0026ndash;140 K.M./h gusting up to 155 K.M./hour (Paul \u0026amp; Chowdhury \u003cspan citationid=\"CR42\" class=\"CitationRef\"\u003e2021\u003c/span\u003e). On the same day, after its landfall the TC Yass progressed towards the coastal regions of the West Bengal that include the CE programme sites.In that time the BoB sea surface temperature dropped about 3\u0026deg;C, salinity and density had raised by 1 psu and ~\u0026thinsp;2 kg/m\u003csup\u003e3\u003c/sup\u003e, respectively (Varma et al. \u003cspan citationid=\"CR62\" class=\"CitationRef\"\u003e2023\u003c/span\u003e). Indian Tide Table\u0026nbsp;2021 published by the order of the Surveyor General of India in 2020, predicted astronomical high tide on 26 May 2021 of Sagar Island (which is only a few kilometer from the CE programme sites) could reach as high as 5.71 meter. The TC Yass brought with it a high storm surge of 3.5 to 5 ​meters in the coasts of the Odisha and West Bengal and the tidal waves of height 1 to 2 meters above the astronomical tide were observed (Mondal et al. \u003cspan citationid=\"CR34\" class=\"CitationRef\"\u003e2022\u003c/span\u003e; Varma et al. \u003cspan citationid=\"CR62\" class=\"CitationRef\"\u003e2023\u003c/span\u003e). During that cyclonic period 11,405.21km\u003csup\u003e2\u003c/sup\u003e of the West Bengal\u0026rsquo;s coastal regions were inundated because about 1195 mm of rainfall occurred in short-time (Paul \u0026amp; Chowdhury \u003cspan citationid=\"CR42\" class=\"CitationRef\"\u003e2021\u003c/span\u003e; Halder \u0026amp; Bandyopadhyay \u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e2022\u003c/span\u003e). Within a short time, massive inundation occurred in the Namkhana (78.1 km\u003csup\u003e2\u003c/sup\u003e), Sagar Island (37.1 km\u003csup\u003e2\u003c/sup\u003e) and Kakdwip (32.6 km\u003csup\u003e2\u003c/sup\u003e) blocks of the South 24 Parganas of the West Bengal which are besides the GE and are close to CE programme sites and their 43.6%, 28.3% and 19.2% human populations, respectively were affected (Paul \u0026amp; Chowdhury \u003cspan citationid=\"CR42\" class=\"CitationRef\"\u003e2021\u003c/span\u003e). The current study hypothesized that in short-term the copepod community structure is affected (in terms of diversity, dominance, distribution) by the TC Yass which may have consequences for the lower food web of the Muriganga stretch of the GE. This study would be useful for conceptualizing a short-term monitoring plan of the zooplankton community of the river-estuaries of India against a Category-1 TC.\u003c/p\u003e"},{"header":"Methods","content":"\u003cp\u003e\u003cem\u003eStudy site\u003c/em\u003e\u003c/p\u003e\n\u003cp\u003eThe study was conducted from the CE programme sites (i.e., S1, S2 and S3) which have been established in February 2019 on the Muriganga stretch of the GE (Fig.1). The present study is a part of the monitoring of the CE programme sites so for the details related to study site see Paul et al. (2023).\u003c/p\u003e\n\u003cp\u003e\u003cem\u003eSampling during the pre- and post-Yass periods\u003c/em\u003e\u003c/p\u003e\n\u003cp\u003eThe inundation that followed the TC Yass (landfall: 26 May 2021) caused a massive damage to infrastructure including roads to the Namkhana region of the West Bengal. The COVID-19 pandemic related lockdown had made it even more difficult to mobilise scientific resources immediately after the TC Yass. The sampling begun on 4 June 2021 and the sampling went till 22 June 2021. During that period the CE programme sites were sampled on 4 occasions (once in 6 days interval). Those are samples of the post-Yass period. On 21 November 2020, 29 January 2021 and 19 April 2021 water and copepod assemblages were sampled from the CE programme sites. During that period estuary was not perturbed by any TC for a considerable period. Those samples are assumed as the samples of the pre-Yass period.\u003c/p\u003e\n\u003cp\u003e\u003cem\u003eField sampling of water and copepods, and laboratory processes\u003c/em\u003e\u003c/p\u003e\n\u003cp\u003eField sampling of the water and copepod assemblages related to the current study followed the similar methods which were deployed on the CE programme sites during the studies of the TC Fani, Bulbul and Amphan so for the details please refer to Paul et al. (2020a,b, 2023). By adopting the methods of the Paul et al. (2023) the copepod assemblages were collected in triplicate, preserved in 4% formalin and brought to the laboratory for species level identification by following Kasturirangan (1963) under the microscope (Bestscope-BS30T, China) and their abundances were expressed as individual(s) per cubic metre (i.e. ind.m\u003csup\u003e-3\u003c/sup\u003e). On the each occasion of the field sampling abiotic parameters such as the salinity (PSU), water temperature (°C) and pH of the estuary were measured from the sub-surface water by a hand held multi-parameter probe (YSI-1030; YSI, USA).\u003c/p\u003e\n\u003cp\u003eData structure, presentation and analysis\u003c/p\u003e\n\u003cp\u003eAbiotic data of the pre- and post-Yass periods are presented in Table 1. Diversity indices such as the Shannon-diversity and the dominance (i.e., Simpson index) and the Pielou’s evenness index were calculated by using the ‘vegan’ package (version 2.6-4) using CRAN-R 4.3.2 (R Core Team 2023). Site-specific relative abundances of the copepods during the pre- and post-Yass periods were calculated (Table 3). Ordination analysis (on species abundance data after square root transformation) was conducted. At first a cluster analysis was done (see annexure 1) of both the pre- and post-Yass data using PRIMER-e version 7 (Clarke \u0026amp; Gorle 2015). Then a Non-metric Multidimensional Scaling (NMDS) was conducted using the Bray–Curtis measure of dissimilarity (‘Vegan’ package version 2.5.6). Finally NMDS biplots (see Figure \u0026nbsp;2) of both the pre- and post-Yass periods were drawn using PRIMER-e version 7 (Clarke \u0026amp; Gorle 2015). Permutational Multivariate Analysis of Variance (PERMANOVA) was conducted (i.e. Adonis test, permutations = 999, method = Bray-Curtis, package: ‘Vegan’ version: 2.5.6) to evaluate the variability of the copepod assemblages among sampling sites. Such a test was performed separately for the pre- and post-Yass periods. For PERMANOVA an assumption of homogeneity of multi-variate dispersion was tested by conducting Analysis of variance (ANOVA). Similarity percentage analysis (i.e. SIMPER) were conducted for the assessment of similarity and dissimilarity of the copepod assemblages sampled in the pre-Yass and post-Yass periods using the package ‘Vegan’ version: 2.5.6 of the CRAN-R 4.3.2 (R Core Team 2023).\u003c/p\u003e"},{"header":"Results","content":"\u003cp\u003e\u003cem\u003eAbiotic conditions of the CE program sites\u003c/em\u003e\u003c/p\u003e\n\u003cp\u003eDuring the pre-Yass period the salinity regime of the Muriganga was in between mesohaline to polyhaline ranged from 7.50 to 17.90 (Table 1). After the TC Yass the salinity of the Muriganga remained consistently in the polyhaline zone (ranged 15.90 to 20.80) for a few weeks (Table 1). Both in the pre- and post-Yass the pH of the Muriganga mostly remained slightly alkaline (Table 1). The water temperature in the post-Yass period varied within a narrow range i.e., 29.10 to 31.20°C; however, on the occasions of the pre-Yass sampling a considerable variability (range 21.40 to 30.30°C) of the water temperature was observed (Table 1).\u003c/p\u003e\n\u003cp\u003e\u003cem\u003eCopepod community structure and its changes\u003c/em\u003e\u003c/p\u003e\n\u003cp\u003eIrrespective of the sampling sites, in the post-Yass period the species richness of the copepod community was higher than the pre-Yass period (Table 2). During the pre-Yass the species richness ranged 17 to 20 whereas in the post-Yass that was 20 to 24 (Table 2). Consequently, in the post-Yass period the Shannon Diversity, Simpson dominance and Pielou’s evenness indices of the copepod community showed higher values in comparison to the pre-Yass period (Table 2). In respect to relative abundance, during the pre-Yass period copepod species such as the \u003cem\u003eBestiolina similis\u003c/em\u003e, \u003cem\u003eParacalanus parvus\u003c/em\u003e and \u003cem\u003eAcartiella tortaniformis\u003c/em\u003e co-dominated the community and among them \u003cem\u003eBestiolina similis\u003c/em\u003e was the most abundant species contributing up to 20.52% of the total community (Table 3). After the TC Yass, \u003cem\u003eBestiolina similis\u003c/em\u003e, \u003cem\u003eParacalanus parvus\u003c/em\u003e, \u003cem\u003eAcartiella tortaniformis\u003c/em\u003e and \u003cem\u003eAcartia spinicauda\u0026nbsp;\u003c/em\u003eco-dominated the copepod community by virtue of their higher relative abundances but a noticeable decline in the relative abundances were observed for \u003cem\u003eBestiolina similis\u003c/em\u003e, \u003cem\u003eParacalanus parvus\u003c/em\u003e and \u003cem\u003eAcartiella tortaniformis\u003c/em\u003e (Table 3). Post-Yass relative abundances of\u0026nbsp;\u003cem\u003eCanthocalanus pauper\u003c/em\u003e, \u003cem\u003eTemora turbinata\u003c/em\u003e, \u003cem\u003eCorycaeus crassiusculus\u0026nbsp;\u003c/em\u003eDana and different species of \u003cem\u003eOithona\u003c/em\u003e were higher than the pre-Yass period (Table 3). In the post-Yass period the copepod species that dominated the community in terms of its relative abundance is \u003cem\u003eOithona brevicornis\u003c/em\u003e (Table 3). Species such the \u003cem\u003eLabidocera euchaeta\u0026nbsp;\u003c/em\u003eand \u003cem\u003eOithona nana\u003c/em\u003e were not present in the copepod assemblages which were sampled in the pre-Yass period but those species were present in the post-Yass period (Table 3).\u0026nbsp;During pre-Yass copepods of the Paracalanidae (cumulative abundance 49 to 59 %) family dominated the community followed by Acartiidae (cumulative abundance 27 – 33 %) and Oithonidae (cumulative abundance 3 – 8 %). After Yass Paracalindae contribution decreased to 28 to 35% and Acartiidae decreased to 17 to 29%; however, Oithonidae increased significantly to13 to 19% of the total copepod abundance. The Shannon diversity index correlating with species number also showed the trend of increased diversity in post- Yass period in all the three sites (Table 2).\u0026nbsp;The NMDS analysis and the biplot of the pre-Yass period revealed the site specific variability of the copepod assemblages (Fig.2), which was found to be significant (PERMANOVA: DF = 2, Pseudo-F = 17.66, R\u003csup\u003e2\u003c/sup\u003e = 0.85, P = 0.005; homogeneity of multivariate dispersion test ANOVA: DF = 2, F = 0.4, P = 0.95). On contrary, the NDMS and the biplot (Fig.2) suggested that during the post-Yass period the spatial variability of the copepod assemblages of the Muriganga was not significant (PERMANOVA: DF = 2, Pseudo-F = 0.41, R\u003csup\u003e2\u003c/sup\u003e = 0.08, P = 0.95; homogeneity of multivariate dispersion test ANOVA: DF = 2, F = 0.28, P = 0.76). Results of the SIMPER analysis suggested that in the pre-Yass the average similarity of the copepods sampled on various occasions was 37.04% (chiefly contributed by the species such as \u003cem\u003eB. similis\u003c/em\u003e 18.94%, \u003cem\u003eP. parvus\u003c/em\u003e 17.82% and \u003cem\u003eA. tortaniformis\u003c/em\u003e 14.83% and \u003cem\u003eA. spinicauda\u003c/em\u003e 10.35%). Results further showed that the average similarity within the copepod assemblages did rise to 77.09% in the post-Yass period (chiefly contributed by the species such as \u003cem\u003eA. tonsa\u003c/em\u003e 10.7%, \u003cem\u003eO. similis\u003c/em\u003e 9.43;\u003cem\u003e\u0026nbsp;P. parvus\u003c/em\u003e 8.56% and \u003cem\u003eA. longicornis\u003c/em\u003e 8.13%). Further, the average dissimilarity between the copepod assemblages sampled in the pre-and the post-Yass periods was 66.21% chiefly contributed by the species such as \u003cem\u003eA. tonsa\u003c/em\u003e 10.84%, \u003cem\u003eO. similis\u003c/em\u003e 9.34;\u003cem\u003e\u0026nbsp;A. longicornis\u003c/em\u003e 7.74% and \u003cem\u003eB. similis\u003c/em\u003e 6.98%.\u003c/p\u003e"},{"header":"Discussion","content":"\u003cdiv id=\"Sec10\" class=\"Section2\"\u003e \u003ch2\u003eHabitat conditions during the pre- and post-Yass periods\u003c/h2\u003e \u003cp\u003eResults of the abiotic variability demonstrated that the Muriganga stretch of the GE is a true estuary, which agree with previous studies conducted in the region (Mukhopadhyay et al. \u003cspan citationid=\"CR36\" class=\"CitationRef\"\u003e2006\u003c/span\u003e; Chowdhury et al. 2015; Bhattacharya \u0026amp; Paul 2023; Paul et al. \u003cspan citationid=\"CR47\" class=\"CitationRef\"\u003e2024\u003c/span\u003e). Due to the large influx of freshwater from the upstream of the Muriganga, it often remains mesohaline (Mitra et al. \u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e2009\u003c/span\u003e; Paul et al. \u003cspan citationid=\"CR43\" class=\"CitationRef\"\u003e2019\u003c/span\u003e; Bhattacharya \u0026amp; Paul 2023; Paul et al. \u003cspan citationid=\"CR47\" class=\"CitationRef\"\u003e2024\u003c/span\u003e). Shortly after TC Yass, salt water intrusion from the adjacent Bay of Bengal had turned the estuary from a mesohaline to a polyhaline one and the estuary maintained such a characteristics for a few weeks which was not observed after TC Fani, Bulbul and Amphan (Paul et al. \u003cspan citationid=\"CR44\" class=\"CitationRef\"\u003e2020a\u003c/span\u003e,\u003cspan citationid=\"CR45\" class=\"CitationRef\"\u003eb\u003c/span\u003e, \u003cspan citationid=\"CR46\" class=\"CitationRef\"\u003e2023\u003c/span\u003e, \u003cspan citationid=\"CR47\" class=\"CitationRef\"\u003e2024\u003c/span\u003e). After TC Aila the Muriganga did remain polyhaline for a considerable time (Mitra et al. \u003cspan citationid=\"CR32\" class=\"CitationRef\"\u003e2011\u003c/span\u003e; Bhattacharya et al. \u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e2014\u003c/span\u003e). The Muriganga experiences macro-tidal environment and its pH profile remains slightly alkaline throughout the year unless there is an excessive rain for a few days which lowers the pH specially in monsoon (Chowdhury et al. 2015; Paul et al. \u003cspan citationid=\"CR47\" class=\"CitationRef\"\u003e2024\u003c/span\u003e). Even after TC Yass, alkalinity of the estuary remained higher. High alkaline condition of the Muriganga was observed after the TC Phailin which caused sudden influx of salt near the mouth of the estuary (Das et al. \u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e2016\u003c/span\u003e). The water temperature of the Muriganga follows the typical seasonal characteristics of a tropical estuary (Mukhopadhyay et al. \u003cspan citationid=\"CR36\" class=\"CitationRef\"\u003e2006\u003c/span\u003e; Chowdhury et al. 2015; Paul et al. \u003cspan citationid=\"CR47\" class=\"CitationRef\"\u003e2024\u003c/span\u003e). Post-Yass the water temperature of the Muriganga did not exhibits any drastic change. Absence of drastic change in water temperature of the Muriganga was also not observed after the TC Fani, Bulbul and Amphan (Paul et al. \u003cspan citationid=\"CR44\" class=\"CitationRef\"\u003e2020a\u003c/span\u003e,\u003cspan citationid=\"CR45\" class=\"CitationRef\"\u003eb\u003c/span\u003e, \u003cspan citationid=\"CR46\" class=\"CitationRef\"\u003e2023\u003c/span\u003e). Such was the case for TC Domoina which hit the lake St. Lucia and northern estuarine systems of the Natal, South Africa (Forbes \u0026amp; Cyrus \u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e1992\u003c/span\u003e). On contrary, a considerable decline in the water temperature of the Muriganga was observed within a few days after the TC Aila (Bhattacharya et al. \u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e2014\u003c/span\u003e). Previous studies on the TCs conducted on the lagoons, tidal lakes and intermittently open/close estuaries of India and across the world have suggested that a sudden change of the salinity regime of an estuary could influence diversity and distribution of its biological communities including the copepods (Forbes \u0026amp; Cyrus \u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e1992\u003c/span\u003e; Reay \u0026amp; Moore \u003cspan citationid=\"CR54\" class=\"CitationRef\"\u003e2005\u003c/span\u003e; Mitra et al. \u003cspan citationid=\"CR32\" class=\"CitationRef\"\u003e2011\u003c/span\u003e; Beyrend-Dur et al. \u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e2013\u003c/span\u003e; Bhattacharya et al. \u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e2014\u003c/span\u003e; Srichandan et al. \u003cspan citationid=\"CR60\" class=\"CitationRef\"\u003e2021\u003c/span\u003e; Mishra et al. \u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e2023a\u003c/span\u003e,\u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003eb\u003c/span\u003e; Thompson et al. \u003cspan citationid=\"CR61\" class=\"CitationRef\"\u003e2023\u003c/span\u003e). It was also suggested that the post-cyclone flood often exert mechanical forcing which subsequently temporarily disrupts plankton communities (Srichandan et al. \u003cspan citationid=\"CR60\" class=\"CitationRef\"\u003e2021\u003c/span\u003e; Paul et al. \u003cspan citationid=\"CR46\" class=\"CitationRef\"\u003e2023\u003c/span\u003e).\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec11\" class=\"Section2\"\u003e \u003ch2\u003eCopepod community of the pre- and post-Yass periods\u003c/h2\u003e \u003cp\u003ePost TC Yass the number of species increased within the sampled copepod assemblages, the community had more cyclopoid copepods than the pre-Yass period. Species such as the \u003cem\u003eA. tortaniformis\u003c/em\u003e had replaced the \u003cem\u003eB. similis\u003c/em\u003e as the most dominant species of the copepod community, and the abundances of a few dominant species such as \u003cem\u003eP. parvus\u003c/em\u003e, \u003cem\u003eA. spinicauda\u003c/em\u003e had considerably declined. The \u003cem\u003eO. brevicornis\u003c/em\u003e abundance had risen in the post-Yass period, and the species such as \u003cem\u003eL. euchaeta\u003c/em\u003e and \u003cem\u003eO. nana\u003c/em\u003e were observed in the post-Yass period which were absent in the pre-Yass period. It is, therefore, evident that in short-term the copepod community of the Muriganga is impacted and underwent several changes. Those changes in the community structure of the copepods of the Muriganga were not observed after TC Fani, Bulbul and Amphan (Paul et al. \u003cspan citationid=\"CR44\" class=\"CitationRef\"\u003e2020a\u003c/span\u003e,\u003cspan citationid=\"CR45\" class=\"CitationRef\"\u003eb\u003c/span\u003e, \u003cspan citationid=\"CR46\" class=\"CitationRef\"\u003e2023\u003c/span\u003e). The \u003cem\u003eOithona\u003c/em\u003e are generally omnivores that mostly eat organic debris, dinoflagellates, diatoms, and proto-zooplankton (Pond \u0026amp; Ward \u003cspan citationid=\"CR51\" class=\"CitationRef\"\u003e2011\u003c/span\u003e; Wang et al. \u003cspan citationid=\"CR63\" class=\"CitationRef\"\u003e2017\u003c/span\u003e). The sudden increment of Oithonidae family in the post- Yass samples could be attributed to the increased organic debris in the water which is common after a TC (Bhattacharya et al. \u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e2014\u003c/span\u003e). The increased number of Oithonidae family is mainly due to the increment of \u003cem\u003eO. brevicornis\u003c/em\u003e abundance in the post-Yass samples, such a phenomenon was observed after cyclone \u0026ldquo;Aila\u0026rdquo; (Bhattacharya et al. \u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e2014\u003c/span\u003e) but not after TC Fani, Bulbul and Amphan (Paul et al. \u003cspan citationid=\"CR44\" class=\"CitationRef\"\u003e2020a\u003c/span\u003e,\u003cspan citationid=\"CR45\" class=\"CitationRef\"\u003eb\u003c/span\u003e, \u003cspan citationid=\"CR46\" class=\"CitationRef\"\u003e2023\u003c/span\u003e). The dominance of Oithonidae suggested their high adaptability to trophic and hydrologic conditions in the post- Yass period. After each of the TC Aila, Fani, Bulbul and Amphan there were an immediate decline in the species richness and the total abundance of the copepods (Paul et al. \u003cspan citationid=\"CR44\" class=\"CitationRef\"\u003e2020a\u003c/span\u003e,\u003cspan citationid=\"CR45\" class=\"CitationRef\"\u003eb\u003c/span\u003e, \u003cspan citationid=\"CR46\" class=\"CitationRef\"\u003e2023\u003c/span\u003e). Within a week or so after TC Fani and Bulbul about 50% of the species richness recovered (Paul et al. \u003cspan citationid=\"CR44\" class=\"CitationRef\"\u003e2020a\u003c/span\u003e,\u003cspan citationid=\"CR45\" class=\"CitationRef\"\u003eb\u003c/span\u003e). Decline in the total abundance of the copepod community as well as in the abundances of the individual species is not that uncommon after a TC mediated disruption of estuaries of India, South Africa and Taiwan (Forbes \u0026amp; Cyrus \u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e1992\u003c/span\u003e; Lopez-Lopez et al. \u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e2012\u003c/span\u003e; Beyrend-Dur et al. \u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e2013\u003c/span\u003e; Bhattacharya et al. \u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e2014\u003c/span\u003e; Srichandan et al. \u003cspan citationid=\"CR60\" class=\"CitationRef\"\u003e2021\u003c/span\u003e). Results of the NMDS and SIMPER analysis suggested that the TC Yass for a while had washed away some of the spatial heterogeneity within the copepod community that existed in the pre-Yass period. This is not unexpected because floods and or incessant rainfall (often associated with a TC) often temporarily wash way environmental gradients of an estuary and impact the spatial niche segregations of many estuarine biota including plankton (Payne et al. \u003cspan citationid=\"CR48\" class=\"CitationRef\"\u003e2015\u003c/span\u003e, Nandy et al. \u003cspan citationid=\"CR37\" class=\"CitationRef\"\u003e2018\u003c/span\u003e); therefore, the community becomes more homogenous at least for a short-term (Paul et al. \u003cspan citationid=\"CR46\" class=\"CitationRef\"\u003e2023\u003c/span\u003e). Later when the environmental gradients become again prominent in an estuary that in consequence help many estuarine specialist copepods to recolonize their vacant spatial niches (Paul et al. \u003cspan citationid=\"CR44\" class=\"CitationRef\"\u003e2020a\u003c/span\u003e,\u003cspan citationid=\"CR45\" class=\"CitationRef\"\u003eb\u003c/span\u003e, \u003cspan citationid=\"CR46\" class=\"CitationRef\"\u003e2023\u003c/span\u003e).\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec12\" class=\"Section2\"\u003e \u003ch2\u003eCyclone ecology research of Indian estuaries\u003c/h2\u003e \u003cp\u003eIn total 61 TCs of various intensities have disrupted the nine coastal states of India from 2006 to 2020; the highest numbers were recorded in Odisha (20), West Bengal (14) and Andhra Pradesh (11) (Kantamaneni et al. \u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e2022\u003c/span\u003e). The cyclone ecology research of the Indian estuaries is relatively new as its roots could be traced in last two decades (Kumar et al. \u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e2010\u003c/span\u003e; Joseph et al. \u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e2011\u003c/span\u003e; Mitra et al. \u003cspan citationid=\"CR32\" class=\"CitationRef\"\u003e2011\u003c/span\u003e; Mukherjee et al. \u003cspan citationid=\"CR35\" class=\"CitationRef\"\u003e2012\u003c/span\u003e; Bhattacharya et al. \u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e2014\u003c/span\u003e; Kumar et al. \u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e2017\u003c/span\u003e). Literature is mostly focused on Indian Sundarbans, West Bengal and on the estuaries (e.g., Chilika lagoon) of Odisha (Mitra et al. \u003cspan citationid=\"CR32\" class=\"CitationRef\"\u003e2011\u003c/span\u003e; Mukherjee et al. \u003cspan citationid=\"CR35\" class=\"CitationRef\"\u003e2012\u003c/span\u003e; Bhattacharya et al. \u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e2014\u003c/span\u003e; Paul et al. \u003cspan citationid=\"CR44\" class=\"CitationRef\"\u003e2020a\u003c/span\u003e,\u003cspan citationid=\"CR45\" class=\"CitationRef\"\u003eb\u003c/span\u003e, \u003cspan citationid=\"CR46\" class=\"CitationRef\"\u003e2023\u003c/span\u003e; Kumar et al. \u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e2017\u003c/span\u003e; Srichandan et al. \u003cspan citationid=\"CR60\" class=\"CitationRef\"\u003e2021\u003c/span\u003e; Mishra et al. \u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e2023a\u003c/span\u003e,\u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003eb\u003c/span\u003e). Little is known about the impact of TCs on the ecology of other estuaries, backwaters and lagoons of India (Joseph et al. \u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e2011\u003c/span\u003e; Mangesh et al. \u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e2016\u003c/span\u003e; Gunasekaran et al. \u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e2021\u003c/span\u003e; Sachithanandam et al. \u003cspan citationid=\"CR57\" class=\"CitationRef\"\u003e2022\u003c/span\u003e). Traditionally, the frequency of cyclones in India is higher on the eastern coast than on the western coast; however, in the recent years, the frequency of cyclones over the Arabian sea is on the rise (Baburaj et al. 2021; Kar \u0026amp; Banerjee \u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e2021\u003c/span\u003e); therefore, cyclone ecology research would become more relevant than ever for Indian estuaries. India has no institutional mechanism placed for regular monitoring of its estuaries for cyclone-mediated changes (Paul et al. \u003cspan citationid=\"CR43\" class=\"CitationRef\"\u003e2019\u003c/span\u003e, \u003cspan citationid=\"CR44\" class=\"CitationRef\"\u003e2020a\u003c/span\u003e,\u003cspan citationid=\"CR45\" class=\"CitationRef\"\u003eb\u003c/span\u003e, \u003cspan citationid=\"CR46\" class=\"CitationRef\"\u003e2023\u003c/span\u003e). Except the Chilika lagoon and mangrove estuaries of Indian Sundarbans including the GE, drawing a baseline for different types of Indian estuaries and predicting their fates facing TCs; therefore, are difficult. The other major issue is the previous studies conducted in India and elsewhere have documented the disturbance and recovery of estuaries from one or a few locations or storm events, limiting generalizations about the TC impacts and characteristic patterns of ecosystem response and recovery (Buelo et al. \u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e2024\u003c/span\u003e). Considering the scarcity of scientific resources, unpredictability of a TC track and mobilization of scientific infrastructure and human resources immediately after a TC or successive TCs there shall be focus on geo-spatial science and remotely operated \u003cem\u003ein-situ\u003c/em\u003e recordings and periodic ecological surveys for monitoring the baselines and stochastic disturbances of Indian estuaries (Mishra et al. \u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e2023a\u003c/span\u003e; Paul et al. \u003cspan citationid=\"CR46\" class=\"CitationRef\"\u003e2023\u003c/span\u003e; Varma et al. \u003cspan citationid=\"CR62\" class=\"CitationRef\"\u003e2023\u003c/span\u003e). The Sundarbans (including the GE), Chilika lagoon, Godavari estuary, Cochin-estuary, Mandovi-Zuari estuary are some of the iconic estuaries of India that are serving millions of Indians daily by providing ecosystem services (Sarkar \u0026amp; Bhattacharya \u003cspan citationid=\"CR58\" class=\"CitationRef\"\u003e2003\u003c/span\u003e; Bhavan et al. \u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e2023\u003c/span\u003e). Those services may get seriously jeopardised if the lower food web of the Indian estuaries are strained from the periodic TCs (Paul et al. \u003cspan citationid=\"CR44\" class=\"CitationRef\"\u003e2020a\u003c/span\u003e; Mishra et al. \u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e2021\u003c/span\u003e; Rasquinha \u0026amp; Mishra \u003cspan citationid=\"CR53\" class=\"CitationRef\"\u003e2021\u003c/span\u003e; Mishra et al. \u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e2023a\u003c/span\u003e). United Nations Ocean Decade (2021\u0026ndash;2030) may serve as the baseline to initiate a cyclone impact monitoring and resilience plan of the lower food web of Indian estuaries.\u003c/p\u003e \u003c/div\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eAcknowledgements\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eDr. Paul thanks DST Inspire Faculty Award [Sanction no: DST/INSPIRE/04/2016/0000036] of the Government of India for his fellowship and funding the research. Dr. Paul further extends his gratitude to the Core Research Grant sanctioned by the Science and Engineering Research Board (SERB) [Sanction: EMR/2017/001111 dated 24 July 2018] of the Government of India which met the fellowship of Mr. Karan. Dr. Bhattacharya extends his gratitude to the Estuarine and Coastal Studies Foundation for financial assistance received during the course of the study. Thanks to the Head of Department of Zoology, University of Calcutta and the Director of Estuarine and Coastal Studies Foundation, West Bengal for providing facilities related to this research. Dr. Paul thanks the Intergovernmental Oceanographic Commission, UNESCO for endorsing the present study as a part of the (Decade Action: No. 122.2 –‘Periodic cyclone effects on Gangetic food web) United Nation Decade of Ocean Science for Sustainable Development (2021-2030).\u003cbr\u003e\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFinancial Support\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eDST Inspire Faculty Award [Sanction no: DST/INSPIRE/04/2016/0000036] of the Government of India met fellowship of Dr. Sourav Paul and partial funding the research. Core Research Grant sanctioned by the Science and Engineering Research Board (SERB) [Sanction: EMR/2017/001111 dated 24 July 2018] of the Government of India met the fellowship of Mr. Karan and partial funding for the research. Estuarine and Coastal Studies Foundation, India provided financial assistance to Dr. Bhaskar Deb Bhattacharya during the course of the study.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCompeting interest\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eAll authors declare that they have no competing interest on connection with this study.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eEthical approval\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eNo ethical standards were required to execute the study.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eData availability\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eData would be provided with a reasonable request for non-commercial purpose.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAuthor Contributions\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eSourav Paul:\u0026nbsp;\u003c/strong\u003eConceptualization,Methodology,Formal analysis and investigation,writing original draft, writing - review and editing, Funding acquisition\u003cstrong\u003e,\u0026nbsp;\u003c/strong\u003eResources, Supervision; \u003cstrong\u003eSamya Karan:\u003c/strong\u003e\u0026nbsp; Methodology; \u003cstrong\u003eBhaskar Deb Bhattacharya:\u003c/strong\u003e Methodology, writing - review and editing.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n \u003cli\u003eAcharyya T, Sudatta BP, Srichandan S, Baliarsingh SK, Lotliker AA, Raulo S, Singh S and Samanta A (2021) Deciphering long-term seasonal and tidal water quality trends in the Mahanadi estuary. \u003cem\u003eJournal of Coastal Conservation\u003c/em\u003e 25,1-16.\u003c/li\u003e\n \u003cli\u003eBaburaj PP, Abhilash S, Nirmal CA, Sreenath AV, Mohankumar K and Sahai AK (2022) Increasing incidence of Arabian Sea cyclones during the monsoon onset phase: Its impact on the robustness and advancement of Indian summer monsoon. \u003cem\u003eAtmospheric Research\u003c/em\u003e 267, 105915.\u003c/li\u003e\n \u003cli\u003eBalaguru K, Taraphdar S, Leung LR and Foltz GR (2014) Increase in the intensity of postmonsoon Bay of Bengal tropical cyclones. \u003cem\u003eGeophysical Research Letters\u003c/em\u003e 41, 3594-3601.\u003c/li\u003e\n \u003cli\u003eBeyrend-Dur D, Souissi S and Hwang JS (2013) Population dynamics of calanoid copepods in the subtropical mesohaline Danshuei Estuary (Taiwan) and typhoon effects. \u003cem\u003eEcological Research\u003c/em\u003e 28, 771-780.\u003c/li\u003e\n \u003cli\u003eBhattacharya BD, Bhattacharya AK, Rakshit D and Sarkar SK (2014) Impact of the tropical cyclonic storm \u0026lsquo;Aila\u0026rsquo; on the water quality characteristics and mesozooplankton community structure of Sundarban mangrove wetland, India. \u003cem\u003eIndian Journal of Geo-Marine Science\u0026nbsp;\u003c/em\u003e43, 216-223.\u003c/li\u003e\n \u003cli\u003eBhattacharya P and Paul S (2024) Effects of abiotic changes on a pelagic Chaetognath \u003cem\u003eZonosagitta bedoti\u0026nbsp;\u003c/em\u003epopulation of the Ganges estuary, India. \u003cem\u003eJournal of Aquatic Biology and Fisheries\u003c/em\u003e 11, 12-18.\u003c/li\u003e\n \u003cli\u003eBhavan SG, Bhat S, Mujawar S, Velayudhan PK, Mayekar T, Patil A, Lal DM, Naik G, Ingole, B, Rajkumar S and Kumar P (2023) Seen from the Stakeholder\u0026rsquo;s revelation\u0026mdash;valuation of ecosystem services in a small tropical Indian estuary. \u003cem\u003eRegional Studies in Marine Science\u003c/em\u003e 62,102905.\u003c/li\u003e\n \u003cli\u003eBuelo CD, Besterman AF, Walter JA, Pace ML, Ha DT and Tassone SJ (2024) Quantifying disturbance and recovery in estuaries: Tropical cyclones and high-frequency measures of oxygen and salinity. \u003cem\u003eEstuaries and Coasts\u003c/em\u003e 47, 18-31.\u003c/li\u003e\n \u003cli\u003eChoudhury AK, Das M, Philip P and Bhadury P (2015) An assessment of the implications of seasonal precipitation and anthropogenic influences on a mangrove ecosystem using phytoplankton as proxies. \u003cem\u003eEstuaries and Coasts\u003c/em\u003e 38, 854-872.\u003c/li\u003e\n \u003cli\u003eClarke KR and Gorley RN (2015) Getting started with PRIMER v7. 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Effects of extreme climatic events on estuarine water quality and ecology. \u003cem\u003eMarine Pollution Bulletin\u003c/em\u003e 69, 7-18.\u003c/li\u003e\n \u003cli\u003eWhitfield AK (1992) A characterization of southern African estuarine systems. \u003cem\u003eSouthern African Journal of Aquatic Science\u003c/em\u003e 18, 89-103.\u003c/li\u003e\n \u003cli\u003eWoodruff JD, Irish JL and Camargo SJ (2013) Coastal flooding by tropical cyclones and sea-level rise. \u003cem\u003eNature\u003c/em\u003e 504, 44-52.\u003c/li\u003e\n \u003cli\u003eXia C, Ge X, Haibin L\u0026Uuml;, Zhang H, Xing X and Cui Y (2022) A phytoplankton bloom with a cyclonic eddy enhanced by the tropical cyclone Phethai in eastern Sir Lanka. \u003cem\u003eRegional Studies in Marine Science\u003c/em\u003e 51, 102217.\u003c/li\u003e\n\u003c/ol\u003e"},{"header":"Tables","content":"\u003cp\u003eTables 1 to 3 are available in the Supplementary Files section\u003c/p\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":true,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true},"keywords":"Diversity and dominance, Cyclopoid copepods, salinity, estuarine monitoring, Indian estuaries","lastPublishedDoi":"10.21203/rs.3.rs-4862370/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-4862370/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eTropical cyclones (TCs) are straining the lower food web of Indian estuaries but regular institutional monitoring of those changes is rare. For that the ‘Cyclone Ecology’ research program was established in February 2019 on the Muriganga stretch of the Ganges estuary. On 26 May 2021, a category-1 TC Yass disrupted the ‘Cyclone Ecology’ research program sites. A before-after impact assessment was conducted of the cyclone-mediated changes. Water and copepod samples were collected in the pre-Yass (November 2020 to March 2021) and the post-Yass (June 2021) periods. The aim was to assess changes in diversity and dominance of the copepod community following TC Yass. Post-Yass, estuary became polyhaline for a while losing its usual meso-haline characteristic. Species richness of the copepod community was higher during post-Yass than the pre-Yass period. During the pre-Yass, calanoid copepods \u003cem\u003eBestiolina similis\u003c/em\u003e, \u003cem\u003eParacalanus parvus\u003c/em\u003e and \u003cem\u003eAcartiella tortaniformis\u003c/em\u003e co-dominated the community and \u003cem\u003eBestiolina similis\u003c/em\u003e was the most abundant species. Post-Yass abundances of the cyclopoid copepods were considerably higher than the pre-Yass. Further, \u003cem\u003eOithona brevicornis\u003c/em\u003e replaced \u003cem\u003eBestiolina similis\u003c/em\u003eas the most abundant species of the community. Spatial heterogeneity of the copepod community of the pre-Yass period temporarily lost in the post-Yass. Changed species richness, abundances, dominance and spatial heterogeneity of the copepod community even for a short-term may have consequences for the ecology of the lower food web of an estuary. Keeping United Nations Ocean Decade (2021-2030) as the baseline, a nation-wide cyclone impact monitoring and resilience plan of the lower food web of Indian estuaries is recommended.\u003c/p\u003e","manuscriptTitle":"Changes of the copepod community of Ganges estuary following tropical cyclone Yass","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2024-09-02 06:31:21","doi":"10.21203/rs.3.rs-4862370/v1","editorialEvents":[{"type":"communityComments","content":0}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"5d6c1e40-0815-4e0b-acc9-3f721016ffd9","owner":[],"postedDate":"September 2nd, 2024","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[],"tags":[],"updatedAt":"2024-10-09T07:24:19+00:00","versionOfRecord":[],"versionCreatedAt":"2024-09-02 06:31:21","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-4862370","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-4862370","identity":"rs-4862370","version":["v1"]},"buildId":"-HB7Z8yhvgn0wM9Nzuekk","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}