PhD Theses (WII)
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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 Spatial modelling of critical dugong habitats (CDHs) in India(Wildlife Institute of India, Dehradun, 2024) Seal, Sohom; Sivakumar, K.; Raman, ManiIn India, there is a scarcity of comprehensive data on dugong distribution and their habitat suitability, complicating the development of effective conservation strategies. Baseline data on priority areas for dugong conservation was provided by the Wildlife Institute of India back in 2012. Therefore, a temporal data gap exists for a re-evaluation study of CDHs through collating recent dugong occurrences and fishing pressure collected through primary surveys. Further, this study could fill the data gaps by employing advanced spatial modelling techniques and integrating primary and secondary data collected through multi-stakeholder involvement, thereby providing a robust understanding of recent and more accurate CDHs. The study focused on four key dugong ranges along the Indian coast: the Andaman and Nicobar Islands (ANI), Palk Bay and the Gulf of Mannar (PB-GoM) in Tamil Nadu, and the Gulf of Kutch (GoK) in Gujarat. These regions are recognised for their rich marine biodiversity and extensive seagrass meadows, which are critical for dugong survival. The ANI features relatively pristine marine environments, while PB-GoM and GoK are heavily impacted by fishing activities and coastal development, making them significant areas for conservation focus. The primary objectives of this study are: 1) To understand the distribution status of seagrass meadows in selected dugong habitats using in situ and remote sensing data, 2) Mapping the interface between dugong distribution and fisheries in selected dugong habitats, 3) Mapping the environmental governing factors that determine dugong distribution, and 4) Integrating environmental and habitat parameters in GIS platform to classify Critical Dugong Habitats (CDHs). The study employed a combination of in-situ surveys and remote sensing techniques to map seagrass meadows. Intertidal and subtidal surveys were conducted using the line-intercept transect method, and satellite imagery from Sentinel-2A and 2B was utilised for classification in the Google Earth Engine platform. The study highlights the challenges of mapping in turbid waters and identifies suitable classification algorithms curated for different water conditions for better mapping accuracy.Item The Spatial Ecology and Conservation of Seagrasses of the Gulf of Kachchh, Gujarat(Wildlife Institute of India, Dehradun, 2024) Pathan, Sameeha Vahedkhan; Sivakumar, K.Seagrass ecosystems provide ecosystem services that rank among the highest in economic valuation worldwide. They also provide a range of economic, social, and environmental goods and services, which greatly increase coastal communities' resilience to the impacts of climate change. As unique marine habitats, seagrass ecosystems provide shelter and food for marine species during different life stages and contribute to sediment accretion and primary production. The high diversity of marine plant and animal life supports tourism activities and provides the raw materials for medicinal, agricultural, and structural applications. Furthermore, the physical structure of seagrass ecosystems attenuates wave height and speed, protecting coastlines from erosion and storm surges. Threats to seagrass ecosystems in the coastal areas of the Gulf of Kachchh include pollution, rising sea levels, eutrophication, reduction of light intensity and die-back. These all negatively impact seagrass ecosystems, such as increasing growth of epiphytes, sediment anoxia, or increased prevalence of diseases. Further, the effects of climate change on seagrass ecosystems will be additional stressors. The underlying factors affecting seagrass ecosystems are direct human pressures such as pollution, disturbances, and eutrophication. The combined stressors – human pressures and climate change impacts – are likely to exceed the thresholds for seagrasses, leading to, among other things, i) redistribution (reduction and coastal migration) of existing habitats and ii) widespread seagrass ecosystem die-off. In this context, this study was conducted between January 2018- March 2022 and aimed to understand the phenology, biomass and spatial distribution patterns of seagrasses of the GoK, using which I attempted to understand the foraging behaviour, habitat use and movement ecology of dugongs in the Gulf of Kachchh. The major objectives of the study include a) Mapping the distributional characteristics and patterns of seagrass meadows in the southwestern GoK, b) understanding the seasonal variations in the abundance of seagrasses on topographically distinct meadows, c) investigating fine-scale and topographical determinants of dugong habitat preferences and d) to assess the role of semi-diurnal tides' influence on dugong foraging habitats.Item 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.