Theses and Dissertations
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Item Understanding Aggregations Sites of Elasmobranchs in selected islands of the Lakshadweep archipelago(Wildlife Institute of India, Dehradun, 2025) Sawant, Chinmay Prakash; Ghanekar, Chinmaya; Johnson, J.A.This Study shows the identification of the aggregation sites of the elasmobranchs, i.e., sharks, rays, and skates, belonging to the Lakshadweep archipelago, emphasising the identification of aggregation places and traditional knowledge regarding related habitats and species. The presence of elasmobranch aggregations is biologically important as it addresses essential life processes like feeding, reproduction, and nursery grounds. Semi-structured interviews were conducted with 120 respondents, including fisherfolks and scuba divers at four selected Islands of Kavaratti, Kadmat, Bitra, and Agatti on traditional ecological knowledge and information about the presence of elasmobranch species and their aggregation sites. Sixteen aggregation sites were reported, nine for rays and eight for sharks. These aggregations occurred most frequently during the post-monsoon season and the early morning hours. The major habitats ecountered with these aggregations were shallow sandy lagoon, coral and rocky reef, sand, and open ocean pelagic zone. The interviews conducted for assessing species composition included a collective 24 species of sharks and 13 species of rays, with dominant encountered species such as the Whale shark, Blacktip Reef Shark and Tawny nurse shark, for rays Spotted eagle ray, Porcupine ray and Oceanic manta ray. 14 species of sharks are aggregating: Whitetip reef shark, Blacktip shark, and Blacktip reef shark are dominant in the aggregation sites. For the ray aggregation site total of 10 species were reported as they formed aggregations from the Porcupine ray, Spotted eagle ray, Cowtail Ray, and Indian Ocean blue-spotted mask ray. Key aggregation sites are such as Cheriyapani, Valiyapani, and Suheli Par, were identified as key elasmobranch aggregation hotspots. Pole and line, hook and line the traditional fishing practices in the islands. The result of the habitat surveys confirmed these findings, showing that lagoon areas are particularly important for the aggregation of rays, whereas coral reefs in Kadmat, Kavaratti, and Bitra host potential shark populations. In Bitra, rays were observed feeding on a locally frequent prey species called "Muchroli," suggesting distinctive trophic interactions. Moreover, drone surveys validated the presence of huge aggregations of rays in pristine reef habitats, such as Cheriyapani, Valiyapani, and submerged banks offshore, including Suheli Par and Perumal Par. These locations are likely to serve as refugia, with the best possible conditions for feeding, resting, and potential nursery grounds, primarily due to minimal human disturbance. This research provides the first comprehensive understanding of the ecological knowledge of sharks and rays, including their species and key habitats. The results highlight the imperative necessity for continuous long-term monitoring, understanding their ecology of specific fisheries management and habitat, to protect these ecologically specialised and at-risk species in the Lakshadweep archipelago.Item Tadpoles with a Trick : Overwintering Ecology of Tadpoles in a Himalayan Stream, Uttarakhand India(Wildlife Institute of India, Dehradun, 2021) Jithin, V.; Das, Abhijit; Johnson, J.A.Overwintering is a unique phenomenon of delaying metamorphosis in amphibian larvae at low temperature conditions prevailing at high elevation and latitude. This study is first of its kind in India to look at selected ecological aspects of overwintering tadpoles of Nanorana spp. in a Himalayan streamItem Ecology and conservation of Ichthyofauna in the Godavari River Restuarine Ecosystem (EGREE) Andhra Pradesh(Wildlife Institute of India, Dehradun, 2022) Paromita Ray; Johnson, J.A.; Sivakumar, K.This study was conducted to understand the ecological processes and functions of the estuary, including studying the role of the Godavari mangroves as fish habitats, is needed to maintain the various ecosystem services of EGREE. The three main objectives of this thesis are: 1. To study the spatio-temporal changes in fish assemblage across the different habitats in East Godavari Riverine Estuary Ecosystem (EGREE) 2. To study the trophic ecology of ichthyofauna in East Godavari Riverine Estuary Ecosystem (EGREE). 3. To study the role of mangrove forests in structuring the ichthyofauna in Coringa Wildlife Sanctuary. This study was conducted between June 2014 and May 2017 in the estuarine zone of the Godavari delta and the mangroves of Coringa Wildlife Sanctuary in Andhra Pradesh.Item Ecology of Seagrass Habitats and its associated macrobenthic invertebrates in Andaman islands, India(Wildlife Institute of India, Dehradun, 2024) Gole, Swapnali; Sivakumar, K.; Johnson, J.A.; Das, HimansuThe diversity, composition, and growth of species in plant communities are shaped mainly by their complex interactions with local environmental settings. Owing to the unprecedented global decline of seagrasses, it is crucial to understand in-situ ecological interactions for informing mitigation measures. However, several ecological aspects of seagrass ecosystems are under-studied in the tropical Indian waters, which fall in the highly productive Indo-Pacific seagrass distribution bioregion, offering many socio-ecological services. In this context, my study aimed to address the ecological gaps in India's unique seagrass biodiversity hotspot, the insular archipelago called the Andaman and Nicobar Islands (ANI). Objectives of the study were 1) To assess the spatial distribution patterns of seagrass habitats and associated macrobenthic invertebrates in the Andaman Islands, 2) To understand the seasonal variation in seagrass meadows and associated macrobenthic invertebrates, 3) To understand the structural diversity of seagrass meadows and its influence on associated macrobenthic invertebrates, and 4) To document the Traditional Ecological Knowledge on seagrass habitats. The field study was carried out between 2018 and 2022, with a significant sampling period between January and May, as it is the best feasible season for fieldwork in ANI. The spatial diversity, distribution, and growth of seagrasses in the present study were primarily governed by the water depth, habitat heterogeneity, substrate types, and availability. The study suggests that any alterations in the benthic habitat profile of these meadows are likely to affect the species distribution patterns and overall ecological services offeredItem Ecology and Migratory patterns of the Golden Mahseer, Top Putitora (Hamilton,1822), in Western Himalayas using Radio Telemetry Techniques(Wildlife Institute of India, Dehradun, 2023) Dhawan, Bhawana; Johnson, J.A.; Sivakumar, K.This work is one of the most important and iconic freshwater fish species, golden mahseer Tor putitora (Hamilton, 1822), that provides crucial insights into the assemblage structure, food and space resource of the species, habitat ecology, life-history characteristics and movement ecology of the species. This study is the detailed study of any freshwater fish species in which movement patterns in the streams have been studied using radio telemetry techniques in the Himalayan streams.Item The Effect of Land-use Changes on Odonate Assemblages in the Central Western Ghats(Wildlife Institute of India, Dehradun, 2024) Gowda, H.N. Rakshit; Gautam, Ritesh; Johnson, J.A.Odonata, the only apex insect predator in both terrestrial and aquatic life forms, are widely used as biological indicators of the health of aquatic ecosystems across the globe. The Riparian land uses such as commercial plantations negatively impact the Odonata assemblages, causing the homogenisation of habitats with generalist species and the extinction of specialist species. These land uses affect the riparian vegetation, habitat structure, and water quality parameters, which are crucial for Odonates to complete their life cycle. To understand the impact of commercial plantations on stream-associated Odonata assemblages at the sub-order level, three treatments comprising a combination of forest and areca plantations on either bank of streams were selected. The habitat variables, such as ambient temperature and canopy cover, along with stream parameters like flow and water quality parameters such as pH and water temperature, significantly influenced the Odonate assemblages. The sub-orders, Dragonflies and Damselflies, differed in their response to altered (Areca plantations and plantation-forest edge) and preserved sites (forested sites). These outcomes highlight the importance of the dependency of Odonata on particular sets of variables and the consideration of suborders of Odonata separately as indicator groups for the quality of aquatic ecosystems.Item RISK ASSESSMENT OF POTENTIALLY TOXIC ELEMENTS IN THE HABITAT, AND DIET OF SMOOTH-COATED OTTER (Lutrogale perspicillata) IN TUNGABHADRA OTTER CONSERVATION RESERVE (TOCR), KARNATAKA(Wildlife Institute of India, Dehradun, 2024) Ahmed K., Niyaz; Johnson, J.A.; Hussain, S.A.; Sah, RuchikaSmooth-coated otter (Lutrogale perspicillata), is a vital indicator species for freshwater ecosystems, playing a crucial role in maintaining ecological balance. Despite their essential place in the food web, they are always neglected compared to other terrestrial carnivores. This study explores the distribution, diet, and, ecotoxicological exposures to smooth-coated otters in Tungabhadra Otter Conservation Reserve, Karnataka. The study area, encompassing a 36km stretch of the Tungabhadra River (TOCR), is a unique habitat facing significant anthropogenic pressures, including mining activities and pollution, which threaten the local biodiversity and otter populations. The distribution of smooth-coated otters in TOCR was assessed through intensive sign surveys, revealing a clumped distribution pattern. Otter signs, including spraints, pugmarks, and grooming sites were dominant signs found in the landscape. Dietary analysis was examined by analysing the spraints (scat), using two methods frequency of occurrence method, and the score bulk estimate method revealing a predominantly piscivorous diet. The diet consisted of about 14 species out of which 69.53% is constituted of non–native fish species (Oreochromis mossambicus, Labeo rohita, Cyprinus carpio, and Cirrhinus cirrhosus). Ecotoxicological assessments were performed on water, sediment, fish, and spraint samples to evaluate the presence of potentially toxic elements (PTEs). While PTE concentrations in water and sediment were generally below harmful thresholds, their presence poses a long-term risk through bioaccumulation. Risk assessment indicated significant potential health risks from metals like mercury and arsenic, which could impact otter healItem See Through Sound : Understanding the Pattern of Habitat use by Ganetic River Dolphin in the Kaziranga Part of Brahmaputra River(Wildlife Institute of India, Dehradun, 2019) Abhishek, B.; Qureshi, Qamar; Johnson, J.A.Studying the habitat and its associated features is important because of its driving factors that limits the abundance and distribution of a species. This study mainly focuses upon the abundance, distribution, activity and habitat use pattern of Gangetic river dolphins in part of the Brahmaputra River that flows through Kaziranga National Park. The abundance of Gangetic river dolphin and its relatedness to the different habitat features of the river and fish species were studied. The 92 km length of river in the study area was divided in to 43 segments, which were further broadly classified in to different river morphology.Item Ecological responses of Intertidal Benthic communities to certain abiotic factors in Nancowry islands, Nicobar(Wildlife Institute of India, Dehradun, 2017) Kandregula, Samyukta Rao; Sivakumar, K.; Johnson, J.A.The intertidal zone is the amphibious niche between the high and low tides. The invertebrate taxa present here lay bare to several influencing factors and facilitate the flow of energy by participating at each trophic level in the marine ecosystem. This study was carried out in order to assess the community structure of intertidal benthic macro invertebrates. Their associations with various factors known to affect intertidal zones were looked into, in the remote islands of Kamorta and Nancowry in Central Nicobar, Andaman and Nicobar archipelago. Three study sites of varying beach profiles (reflective, intermediate and dissipative) were studied across spatio-temporal scales. Baseline information was drawn 'on the key players of the macrofauna community signals. Replicates need to be studied to confirm the patterns observed. Comprehensive community level analyses (at species) need to be done along with supplementary data through Total Organic Carbon (TOC) analysis and heavy metal analysis (ICP-MS analysis) needs to be done to ascertain the sources and magnitudes of the signals of influencing factors.Item Riverine Habitats Under Changing Land-use : A Resource Selection Study of Smooth-Coated Otter (Lutrogale perspicillata Geoffroy Saint-Hilaire 1826) in Kabini River and Tributaries(Wildlife Institute of India, Dehradun, 2015) Aneesh, C.R.; Hussain, S.A.; Johnson, J.A.; Talukdar, G.Habitat selection is an important part of the ecology of semi-aquatic mammals since they are highly specialized animals. River otters are especially vulnerable animals in the present situation due to increasing human disturbance, altering riparian vegetation damming and channelization in river basins. This study looked at the effect of land-use pattern on the habitat selection by otters with special reference to smooth-coated otter (Lutrogale perspicillata) in Kabini river, South India. The study showed fewer presence sites of smooth-coated otter inside the protected areas, due to naturally unsuitable habitats for the species, with shallower stream habitats in hilly terrains. These sites were occupied by Asian small-clawed otters (Aonyx cinerea). However the sign intensity was more in presence locations inside protected area and least in urbanized area. The detailed study in presence only sites revealed that anthropogenic disturbance primarily increasing human presence, fishing and grazing is the most important factor affecting selection of habitat by smooth-coated otter. The intensity of usage of habitat is also governed by disturbance factors. Other environmental factors are only secondary to disturbance factors affecting habitat selection which includes a set of factors pertaining to land and water summarized as slow, deep waters with intact bank cover and/or grassy banks with close escape cover distance. Prey fish species of medium size class (21-40cm) affects the habitat selection. Although Asian small-clawed otter and smooth-coated otter occur in same river system , there is a clear niche partitioning between these two species. The study also Looked at the effect of dams on otters which is the primary factor negatively affecting otter habitats. Yet flow regimes are mostly compensated due to more streams joining the main river channel. Increasing degree of habitat disturbance in different land-uses seems to negatively influence the fluvial functionality which is positively associated with otter habitat. The combined effect of isolation due to reservoir and increasing disturbances in downstream area pushes smooth-coated otters to select habitats upstream that are marginal to them and more suitable for small-clawed otters.