Theses and Dissertations

Permanent URI for this communityhttp://192.168.202.180:4000/handle/123456789/1

Browse

Subject: search.filters.subject.Seagrass

Search Results

Now showing 1 - 3 of 3
  • No Thumbnail Available
    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, Himansu
    The 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 offered
  • No Thumbnail Available
    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.
  • No Thumbnail Available
    Item
    An Investigation of the Relationship Between Green Turtle (Chelonia mydas herbibory and Seagrass in the Agtti Lagoon, Lakshadweep
    (Wildlife Institute of India, Dehradun, 2007) Lal, Aparna; Choudhury, B.C.; Sivakumar, K.
    Globally, nearshore ecosystems are being increasingly impacted upon by expanding coastal development. The almost complete dependence of marine mega herbivores like Green Turtles (Chelonia mydas) on these habitats for food together with their current low population levels in many regions highlights the need to understand this vital relationship. This study was an attempt within this framework. It aimed to quantify the intensity and potential impacts of Green Turtle grazing on the seagrass Cymodocea rotundata in the Agatti Lagoon, Lakshadweep. To map the habitat types in the lagoon, points generated from a grid were used, while 23 transects, perpendicular to the shore, formed the basic sampling unit to assess turtle density and map their distribution patterns across the lagoon. The study recorded exceptionally high turtle abundances within the lagoon with their distribution patterns being restricted to certain areas within the seagrass meadow. The magnitude and potential impacts of herbivory were quantified across the established gradient of turtle density in the lagoon. It was found that C. rotundata plant parameters like morphology, life history strategies, population dynamics and meadow level characteristics were significantly different in areas with less turtles, indicative of a response to turtle grazing, results supported by experimental evidence. It was found that increased shoot recruitment rather than increased shoot production could be a mechanism whereby seagrass deals with intense herbivory. This study shows that grazing intensity is an important factor potentially regulating the response of seagrasses to grazing.