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| Abstract: | In the present thesis entitled” Implications of Hydrobiology and Nutrient dynamics on Trophic structure and Interactions in Cochin backwaters”, an attempt has been made to assess the influence of general hydrography, nutrients and other environmental factors on the abundance, distribution and trophic interactions in Cochin backwater system. The study was based on five seasonal sampling campaigns carried out at 15 stations spread along the Cochin backwater system. The thesis is presented in the following 5 chapters. Salient features of each chapter are summarized below: Chapter 1- General Introduction: Provides information on the topic of study, environmental factors, back ground information, the significance, review of literature, aim and scope of the present study and its objectives.Chapter 2- Materials and Methods: This chapter deals with the description of the study area and the methodology adopted for sample collection and analysis. Chapter 3- General Hydrograhy and Sediment Characteristics: Describes the environmental setting of the study area explaining seasonal variation in physicochemical parameters of water column and sediment characteristics. Data on hydrographical parameters, nitrogen fractionation, phosphorus fractionation and biochemical composition of the sediment samples were assessed to evaluate the trophic status. Chapter 4- Nutrient Dynamics on Trophic Structure and Interactions: Describes primary, secondary and tertiary production in Cochin backwater system. Primary production related to cell abundance, diversity of phytoplankton that varies seasonally, concentration of various pigments and primary productivitySecondary production refers to the seasonal abundance of zooplankton especially copepod abundance and tertiary production deals with seasonal fish landings, gut content analysis and proximate composition of dominant fish species. The spatiotemporal variation, interrelationships and trophic interactions were evaluated by statistical methods. Chapter 5- Summary: The results and findings of the study are summarized in the fifth chapter of the thesis. |
| Description: | Department of Chemical Oceanography, School of Marine Sciences, Cochin University of Science and Technology, |
| URI: | http://dyuthi.cusat.ac.in/purl/3225 |
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| Dyuthi-T1199.pdf | (9.418Mb) |
| Abstract: | The work was carried out with an objective to know the quantitative and qualitative nature of the macrobenthos in relation to the existing hydrographical parameters and sediment characteristics. With the above two cruises were conducted to collect materials. Representative samples were collected from each degree square of the western continental shelf. The study deals with the hydrographic parameters. The bottom water temperature, salinity and dissolved oxygen were measured. The findings showed variations according to depth and latitude. The study gives the details of sediment characteristics of the study area. 7 different types of substrata were noticed. It also explains the macro faunal composition and diversity, and the standing stock of macrobenthos. The wet-weight and numerical abundance of macrobenthic groups are included. The thesis discusses the relation between hydrography and macrobenthos, and sediment characteristics and macrobenthos, based on the results obtained by statistical analysis of the data. It also investigates the relation between macrobenthos and fishery. |
| URI: | http://dyuthi.cusat.ac.in/purl/84 |
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| Dyuthi-T0191.pdf | (14.19Mb) |
| Abstract: | The source, fate and diagentic pathway of sedimentary organic matter in estuaries are difficult to delineate due to the complexity of organic matter sources, intensive physical mixing and biological processes. A combination of bulk organic matter techniques and molecular biomarkers are found to be successful in explaining organic matter dynamics in estuaries. The basic requirement for these multi-proxy approaches are (i) sources have significantly differing characteristics, (ii) there are a sufficient number of tracers to delineate all sources and (iii) organic matter degradation and processing have little, similar or predictable effects on end member characteristics. Although there have been abundant researches that have attempted to tackle difficulties related to the source and fate of organic matter in estuarine systems, our understanding remains limited or rather inconsistent regarding the Indian estuaries. Cochin estuary is the largest among many extensive estuarine systems along the southwest coast of India. It supports as much biological productivity and diversity as tropical rain forests. In this study, we have used a combination of bulk geochemical parameters and different group of molecular biomarkers to define organic matter sources and thereby identifying various biogeochemical processes acting along the salinity gradient of the Cochin estuary |
| Description: | Department of Chemical Oceanography School of Marine Sciences Cochin University of Science and Technology |
| URI: | http://dyuthi.cusat.ac.in/purl/3753 |
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| Dyuthi-T1715.pdf | (5.601Mb) |
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