Anjum Farooqui

Evidence of Late Palaeocene-Early Eocene equatorial rain forest refugia in southern Western Ghats, India

Equatorial rain forests that maintain a balance between speciation and extinction are hot-spots for studies of biodiversity. Western Ghats in southern India have gained attention due to high tropical biodiversity and endemism in their southern most area. We attempted to track the affinities of the pollen flora of the endemic plants of Western Ghat area within the fossil palynoflora of late Palaeocene-early Eocene (∼55–50 Ma) sedimentary deposits of western and northeastern Indian region. The study shows striking similarity of extant pollen with twenty eight most common fossil pollen taxa of the early Palaeogene. Widespread occurrences of coal and lignite deposits during early Palaeogene provide evidence of existence of well diversified rain forest community and swampy vegetation in the coastal low lying areas all along the western and northeastern margins of the Indian subcontinent. Prevalence of excessive humid climate during this period has been seen as a result of equatorial positioning of Indian subcontinent, superimposed by a long term global warming phase (PETM and EECO) during the early Palaeogene. The study presents clear evidence that highly diversified equatorial rain forest vegetation once widespread in the Indian subcontinent during early Palaeogene times, are now restricted in a small area as a refugia in the southernmost part of the Western Ghat area. High precipitation and shorter periods of dry months seem to have provided suitable environment to sustain lineages of ancient tropical vegetation in this area of Western Ghats in spite of dramatic climatic changes subsequent to the post India-Asia collision and during the Quaternary and Recent times.

Early Permian glacio-marine thecamoebian assemblages from the northwest Himalayas, India

Diverse assemblages of thecamoebians are reported here from the Early Permian Manjir Formation of the northwest Himalaya in India. These thecamoebian tests were found in palynological preparations and are assigned an Early Permian age based on co-occurrence of age-diagnostic palynomorphs. Several of them show very close morphological affinity with extant thecamoebian genera, such as Amphitrema, Arcella, Centropyxis, Cyclopyxis, Cucurbitella, Difflugia and Trinema. This fauna lived in shallow-marine environments during the Early Permian deglacial phase of the widespread Late Carboniferous–Early Permian glaciation of Gondwana. The extant forms used for morphological comparison with the fossil forms were recorded from lakes and ponds in various parts of India. This study supports the current hypothesis of minimal evolution in thecamoebian lineages through geological time, and this group of protists has survived through long geological time and several mass extinction events without any significant morphological change. Stratigraphical and palaeontological evidence indicates that this fauna lived in the shallow-marine environments along the northwestern margin of Indian Gondwana during the deglacial phase of Late Carboniferous–Early Permian glaciation.

Early-Holocene to present palaeoenvironmental shifts and short climate events from the tropical wetland and lake sediments, Kukkal Lake, Southern India: Geochemistry and palynology

The Kukkal basin, Tamil Nadu, India, receives most of its rain from the southwest monsoon (SWM). A sediment core from Kukkal Lake preserves a continuous sediment record from the early-Holocene to present (9000 yr BP to present). The present lake is situated at an elevation of ~1887 m a.s.l., in a small basin that appears to have alternated between a and wetland depositional environment. Climate proxies, including sediment texture, total organic carbon (TOC), total nitrogen (TN), C/N, pollen and geochemical composition indicate a steady progression to wetter conditions, with two stepwise changes at about 8000, and between 3200 and 1800 yr BP. The change at 8000 yr BP appears to correspond to a brief (100–150 years) dry spell recorded elsewhere in India. The change at 3200–1800 yr BP consisted in a rapid intensification of the SWM, and may correlate with the initiation of the ‘Roman Warm Period’. There is no clear evidence of changes at the times of the ‘Medieval Warm Period’ (‘MWP’) and the ‘Little Ice Age’ (‘LIA’). The C/N ratio of the sediments ranges from 14.02 to 8.31, indicating that the organic matter originated from a mixture of lacustrine algae, vascular and terrestrial plants. Chemical weathering indices (Chemical Index of Alteration (CIA), Chemical Index of Weathering (CIW), and Plagioclase Index of Alteration (PIA)) are consistent with extreme silicate weathering. Pollen data show a development from savanna vegetation prior to about 8000 yr BP, followed by grassland with palms, the appearance of ferns just prior to 3200 yr BP and the establishment of the tropical humid forest between 3200 and about 1800 yr BP.

Biogenic arsenopyrite in holocene peat sediment, India

The plant organic matter in the peat layer deposited around 6650+/-110 and 4800+/-80 years BP, during the transgressive and regressive phases of sea level changes, respectively in the dried part (playa) of the present Pulicat lagoon in Palar Basin (southeast coast of India) was studied to elucidate the biogenic pyrite generation and associated trace elements. The scanning electron microscopic (SEM) observations show strongly curved unique C-shaped bacteria of uniform coccoidal shape and size (1 microm) freely scattered on the plant epidermal microfragments. These form spheroidal microcolonies 8-15 microm in diameter attached to the epidermis in a linear fashion or haphazardly enclosed in the translucent sheath as observed in surface view. These colonies are dense with a number of toxic trace elements as analyzed under an SEM-EDX spectrometer indicating its affinity toward metal binding. On maturity the sheath ruptures disseminating tetrad form of bacteria along with some C-shaped bacteria and few rhombohedral crystals of framboidal pyrite. The pyrite crystals intact in spheroidal shape in cavities on the epidermal fragments indicate its biogenic precipitation mediated by the bacteria. The pyrite crystals are rich in sulfur, iron, and traces of arsenic when analyzed by the SEM-EDX spectrometer. It is suggested that cubic and pyritohedran forms of crystals are perhaps arsenopyrite precipitated biogenically in saturated coastal wetland ecosystem in the past mediated by tetrad strain of the observed coccoid bacteria. Thus, the strata-bound peat layer could be the potent residing place for arsenopyrite or other toxic trace elements that may contaminate the groundwater aquifer.

Deltaic land subsidence and sea level fluctuations along the east coast of India since 8 ka: A palynological study

The consequences of climate change and land subsidence are often related to sea level rise/fall. Mangrove extinction and migration were assessed through palynological studies in two sedimentary cores in order to address climate, Relative Sea level (RSL) and its relation to geomorphology since 8420 cal. yr BP from Kanuru (500 cm deep) and since 5850 cal. yr BP from Machilipatnam (118 cm deep), Krishna delta, India. Four units/nine phases of sediment depositional environment were identified on the basis of marine/terrestrial palynomorphs. In Unit 1, the marine palynomorphs indicate palaeoshoreline in Kanuru from 8420 to 8300 cal. yr BP which is now ~4–5 km from the present-day shoreline, but after a short span a retreat in sea level took place between 8300 and 7040 cal. yr BP. About three to four short-term intermittent rise/fall in RSL were recorded in Unit 2 between 7040 and 3980 cal. yr BP in Kanuru and between 5225 and 3240 cal. yr BP in Machilipatnam. During this period, the diversity of mangroves was more in Machilipatnam and only salt-tolerant mangroves were present in Kanuru. Unit 3 is characterized by non-estuarine sediment deposition since 3920–240 cal. yr BP in Kanuru and since 3240–950 cal. yr BP in Machilipatnam. Unit 4 shows a rise in RSL in both the studied sites which began much earlier in Machilipatnam than in Kanuru. Loss of mangrove diversity and dominance of salt-tolerant mangroves were recorded in Unit 4. Results indicate climate-induced RSL fluctuations highlighting the cooling event of 8.2 ka BP from Kanuru site and duration of intermittent rise/fall of RSL during middle Holocene transgression. The rate of sea level rise during the period was not continuous but interrupted by three to four retreats. At present, the evidence of these are at different depths in both the sites and in other contemporary sites along the east coast of India, suggesting neo-tectonics in the vertical stack of Holocene sediment. The geomorphology of the studied sector is tectonically controlled which may increase deltaic instability in future.

Plants foraged by bees for honey production in northern India: The diverse flora of India and its implications for apiculture

Abstract The plants foraged by bees for honey production vary from place to place in the diverse flora of India. This paper reports a palynological study of honey from eight sites of agriculture and urbanisation in the Gangetic Plain of Uttar Pradesh (UP), and presents data from similar studies done in India. Pollen grains of 55 species were recorded in the honey from south-western, central and eastern parts of Uttar Pradesh, where Ageratum conyzoides, a noxious invasive weed, is a very dominant plant taxon. The second plant community used for foraging by honeybees consists of Syzygium cumini, Feronia limonia, Eucalyptus globulus, Prosopis spicigera, Prosopis juliflora, Brassica campestris, Pimpinella tomentosa, Xanthium strumarium, and Ziziphus sp. The third plant community foraged by honeybees includes diverse plant species such as Capparis sp., Ficus sp., Murraya koenigii, Aegle marmelos, and Tinospora cordifolia, as well as Caryophyllaceae and nectarless families. The last group of plants foraged by honeybees comprises ca 37 species sparsely present in the vicinity. If honeybees have access to their preferred plant species they rarely visit non-preferred species, but in the urban and rural agricultural areas where the vegetation is sparse they are forced to forage several other plants including invasive species. The quality and character of honey, whether multifloral, monofloral, or bifloral, largely indicates the changing pattern of vegetation in a particular area, and can furnish decadal to century-scale information about the vegetational changes induced by climate or anthropopression. Palynological data also shed light on medicinally important or allergenic pollen protein present in honey (valuable information for consumers) and the details about plant taxa foraged by honeybees can be used for branding and marketing particular types of honey.

Pollen-vegetation relationship in surface sediments, Coringa mangrove ecosystem, India: palaeoecological applications

Abstract Pollen in the surface sediment collected in a transect from sea to land in the Coringa mangrove wetland was analysed to determine the spatial and quantitative composition of the pollen record for palaeoecological interpretation. Autochthonous pollen preservation of the existing mangrove species was predominant in the sediments and serves as a potential indicator of coastal wetlands. The low quantity of allochthonous and parautochthonous pollen in the sediment reflects the regional plant community. Statistical analysis of the palynological data shows a high association between pollen from Avicennia marina and Clerodendrum inerme and their vegetation. Aegiceras corniculatum, Sonneratia, Ceriops decandra, Xylocarpus mekongenesis, Cocos nucifera, Azadirachta indica, Syzygium, Chenopodiaceae, Poaceae and Cyperaceae show overrepresentation. Ordination techniques for individual species using fidelity and dispersibility indices and regression analyses suggest four different floristic groups, of (i) high dispersibility-moderate fidelity taxa; (ii) high dispersibility-low fidelity taxa; (iii) moderate dispersibility-low fidelity taxa; and (iv) low dispersibility-high fidelity taxa. Species with high fidelity and moderate-low dispersibility indices could be used to identify the vegetation types in sedimentary sequences. The presence of discriminatory taxa (Avicennia marina, Sonneratia sp.), even in small quantities, helps in accurate identification of the local vegetation. Results indicate that while mangrove pollen is transported over short distances, non-mangrove pollen and spores are transported from longer distances. Thus, the status of mangrove and non-mangrove pollen in the sediments provides a clue to the (palaeo)coastal ecology and the (palaeo)climatic conditions.

Environmental impact on coastal wetlands since 4 ka in Cauvery Delta: Palynology and thecamoebian study

Palaeoclimate and Palaeoecological study was carried out in ∼2 m sediment core deposited since 4 ka in an estuarine environment along Uppanar River mouth, Cauvery Delta. Palynological and thecamoebian evidences indicate (1) a basal fluvial lacustrine depositional environment (∼4–3 ka) characterized by sandy sediment, with low salinity and dominance of non-pollen forms like foraminiferal linings and thecamoebians with a low percentage of pollen and spores and (2) an estuarine environment (since 3 ka) characterized by clayey sediment with high salinity and a good percentage of mangrove and terrestrial pollen along with non-pollen forms. A shift in the depositional environment since ∼3 ka indicates monsoonal and geomorphological changes in the coastal wetland. During this period dominance of Avicennia and Cheno/Ams indicate low freshwater runoff from land suggesting a weakened monsoon condition enhanced by anthropogenic activity.