english final - Birbal Sahni Institute of Palaeobotany

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BIRBAL SAHNI INSTITUTE OF PALAEOBOTANY Annual Report 2004-2005 Component 5 : History of mangrove vegetation in India: Mahanadi Delta Pollen analysed 10 samples from profile (BS-1152 ±30,625 yrs. BP) collected from Bhagwanpur (Orissa). The samples exhibited varying frequency of palynodebris, such as pollen, spores, dinoflagellate cysts, microforaminifera, pseudoschizea, etc. The encountered core mangroves taxa included Rhizophora, Sonneratia, Heritiera, Avicennia, Excoecaria, etc. The hinterland taxa, such as Holoptelca, Salvadora, Emblica, Oleaceae, and Fabaceae were recorded along with Poaceae, Chenopodiaceae/Amaranthaceae, Cyperaceae, etc. Asha Khandelwal Component 6 : Climate and vegetational succession in tropical forests of Mikir plateau and upper Assam plain, North East India during Quaternary Pollen analysis of 10 moss cushion and subsurface soil samples from across the Dilli river around Dilli Colliery, Dibrugarh District signifies the existing of tropical deciduous forest as evidenced by the palynoassemblage recovered from the sediment. Occurrence of degraded pollen-spores along with adequate fungal spores and filaments in the sediments indicates the microbial activity during sedimentation. The further palynological study of two onemeter soil sections exposed near Dilli river is in progress. A manuscript entitled ‘Pollen rain in and around Dilli Colliery, Assam’ is finalized. S.K. Bera A view of Independence Day Celebrations 2004 19
BIRBAL SAHNI INSTITUTE OF PALAEOBOTANY Annual Report 2004-2005 Birbal Sahni Institute of Palaeobotany Project 11: Proxy climatic signals from Marine and Coastal sediments during Late Quaternary Component 1: Dinoflagellate cysts from marine sediments as proxy indicators of palaeoenvironmental changes along the western shelf of India during Late Quaternary Study of low frequency organic walled dinoflagellate cyst assemblages from surface sediment samples from shallow depths (~50 m) revealed enhanced proportion of Tuberculodinium vancomoae having preference for lower salinity and warm water. It may be useful as indicator of warm and humid conditions with enhanced precipitation (related to rainfall/monsoon). Processing of 5.5 m core samples (Gravity core GC 7; 2 cm interval), (provided by Dr. Rajiv Nigam, NIO ,Goa) was taken up to study down core variations in specific dinoflagellate cyst associations, especially Protoperidinioid group and open marine forms (belonging to Gonyaulacoids), besides allocthonous terrestrially derived organic matter. Rahul Garg & Khowaja Ateequzzaman Component 2: Algal evidence for Late Quaternary palaeoenvironment changes in the Bengal Basin Processed 73 samples belonging to 7 profiles of Sarsanka lake, East Midnapur district for algal remains. A total of 53 diatom taxa belonging to 22 genera were identified in the sediments. Significant constituents of the assemblages are Amphora spp. Nitzschia spp., Rhopalodia spp., Mastogloia spp., Synedra spp., Surirella spp., Cyclotella spp., Cocscinodiscus spp., Biddulphia spp., Thalssiosera spp. Several species of diatoms were examined under SEM. Continued analysis of surface sediment diatom assemblages in depth profiles along the Ramnagar Khal towards Mohana to describe the relationship between species distribution and salinity and waterdepth of deposition. Preliminary data interpretation was made. The diversity of the diatom flora in the surface sediments is much lower near the mouth of Mohana than the inner part of the Ramnagar Khal. The decrease in number of species is related to the increase in salinity southward. The composition of the diatom assemblages varies significantly from Ramnagar towards Mohana. According to their distribution in the sediments three main ecological groups have been distinguished. Also undertook a field trip to Digha and Sarsanka areas and collected 3 cores from Sarsanka Lake. For the understanding of modern algal distribution pattern in the region, 29 surface soil samples as well as water samples from different depth and salinity level were collected. Hydrological data were also collected from 10 different environmental setups using soil and water analysis kit Samir Sarkar Component 3: Quaternary mangrove vegetation, environment, climate, ecology and sea level changes in south-east coast of India Studied two sedimentary soil profiles from Kolleru lake area. The lake is separated from the Bay of Bengal in the east by about 11 km stretch of Kaikalur sand ridges and swales extending between the Krishna and Godavari river delta. The soil sediments from Kolleru lake area ranging from 1.5 to 2 m depth from the ground surface dates back to 2600 ±100 yrs. BP. Palynological results show Late Holocene lacustrine deposition and no mangrove pollen or any other marine forms were recorded. The north-eastern flank of the lake joins the sea through a narrow 20 km long Upputeru channel. Near its mouth, the mangroves are only a millennium old. A 7 m soil section from Annamalainagar dates back to 5640 =/- 100 yrs. BP. Evidences of mangroves here are at 3.5 m below mean sea level indicating a paleoshoreline 18 km inland from the present shoreline. The mangrove line receded 8 km seawards reaching Natarajapuram in ~2000 yrs. span. Therefore, in the beginning of Late Holocene mangroves occupied a larger area than present. Deterioration of mangroves since Late Holocene was also accompanied by its migration towards the northeast of the estuary. Also surveyed and collected surface soil and core samples from Adyar/ Cooum estuary, Ennore Creek and environs (Chennai), Cuddalore and adjoining Pichavaram estuary. Anjum Farooqui 20
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