Theses and Dissertations
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Item 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 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 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.