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63
Non-Pollen Palynomorphs from
the Late-Holocene Sediments of Majuli
Island, Assam (Indo-Burma Region):
Implications to Palaeoenvironmental
Studies
Arya Pandey, Swati Tripathi, and Sadhan Kumar Basumatary
Abstract A total 31 sediment samples from a 150 cm deep sedimentary core was
examined for the Non-Pollen Palynomorphs (NPPs) analysis from the Sakali wet-
land in order to provide an overview of palaeoenvironment in Majuli Island (world
largest river island), Assam for the late Holocene. About 25 varieties of non-pollen
palynomorphs were reported, out of which fungal spores were at high abundance
along with scanty occurrence of zoological remains reflecting the past climate
vegetation and faunal interactions in the region. The dominance of coprophilous
fungi like Sordaria, Podospora, Ascodesmis, Coniochaeta (almost 40%) indicates
the past occurrence of vast open-land areas with grazing activities of herbivorous
animals. Some non-coprophilous fungi like Tetraploa, Dictyosporium, Cookeina
indicates the rich floral diversity around the study site. Other fungal remains like
Valsaria, Alternaria, Geastrum and Diploidia along with the presence of zoological
remains like Neorhabdocoela are indicative of the freshwater ecosystem with diver-
sified rich flora indicating warm and humid climate conditions in the region. The
presence of Entophlyctis lobata at the bottom of the sedimentary core indicates the
relatively dry climatic conditions in the island because this fungal spore is specificof
the temperate region. The frequent soil erosional activities could be evident through
the dominance of branched and solitary Glomus, attributable to the high flood-prone
region resulting in the mixing of local vegetation with the outlandish vegetation. The
scanty occurrence of Botryococcus, supports the high energy levels in wetland water,
attributed to frequent flood activities. All these NPP varieties of fungal, algal and
zoological affinities collectively display the past forest cover, palaeo-depositional
environment, past climatic conditions, anthropogenic response and grazing activities
in Majuli Island of Assam.
A. Pandey · S. Tripathi (*) · S. K. Basumatary
Quaternary Palynology Laboratory, Birbal Sahni Institute of Palaeosciences, Lucknow, Uttar
Pradesh, India
©The Author(s), under exclusive license to Springer Nature Switzerland AG 2022
B. Phartiyal et al. (eds.), Climate Change and Environmental Impacts: Past, Present
and Future Perspective, Society of Earth Scientists Series,
https://doi.org/10.1007/978-3-031-13119-6_5
Keywords Late-Holocene · Non-pollen palynomorphs · Palaeoenvironment ·
Ecology, fungal spores · Majuli Island · Assam
64 A. Pandey et al.
1 Introduction
The Quaternary was a period of major environmental changes that were possibly
greater than any other time in the last 60 million years (Prell and Kutzbach 1987;
Clement et al. 1999) and the Holocene is a major epoch that had been the witness of
some major rapid climatic events, like Holocene climatic optimum (HCO), Medieval
Warm Period (MWP) and Little Ice Age (LIA) (Alley et al. 1997; Mayewski et al.
2004). The climatic changes that occurred during the Quaternary can be elaborated
by biotic and abiotic proxies and records. Pollen and spores analysis may lead to
strong inferences about the past climate and have a great role to reflect the vegetation
due to their extreme resistant sporoderm and high production with wide distribution
(Bradley 1985). However, owing to some taphonomic issues, such as bioturbation,
translocation, sorting destruction (Birks and Birks 1980; Moore and Webb 1978), as
well as differences in pollen production and dispersal between taxa, which depend
on the plant species themselves and climatic conditions (Hicks 2001; Spieksma et al.
2003), the past ecological inferences are not possible to reconstruct accurately.
Therefore, there is a dire need to look after an auxiliary proxy tool which could
complement the pollen-inferred past climatic and depositional signals.
The utility of NPPs as paleoecological indicators has grown rapidly during the
last decase or so, because of their frequent occurrence in palynological slides and
potential to improve the reconstruction of past communities and environments, local
grazing pressure and fire and human pressure (van Geel et al. 1994; van Geel and
Aptroot 2006). Their fast germination and reproductive ability maintain their pres-
ence in the high amount in the sediments, even for a thousand years. Some of the
fungal and algal remain often found in a mycorrhizal form, pathogenic form, or in a
symbiotic relationship and they apprise about the presence of those co-occurred
specific taxa around that area. Though many NPPs are still not properly identified but
some of them can be used as palaeoecological indicators. In the present investiga-
tion, 25 different and distinguished NPP types, grouped comprehensively under
three classifications as fungal, algal and zoological remains, have been considered,
archived and represented from the Sakali wetland of Majuli Island, alongside their
palaeoecological implications.
The Majuli is the largest river island in the world which is located on the
Brahmaputra River in the state of Assam, northeast India (falls under the Indo-
Burma biodiversity hot spot). The geographical and physiographic conditions of
Majuli Island makes it a sensitive region for any natural calamities such as flood, soil
erosion, cyclone, etc. Therefore, to overcome these natural calamities posing threats
of physiographic disturbances and ecological imbalances, which would have serious
consequences in Assam state, the present study could provide an insight to identify
and demonstrate the Non-Pollen Paynomorphs (NPPs) especially fungal and zoo-
logical remains in tracing the palaeoenvironment in the Majuli Island.
Non-Pollen Palynomorphs from the Late-Holocene Sediments of Majuli Island,... 65
The palyno-investigations provide valuable insights concerning changes in the
vegetation and contemporaneous climatic oscillation on the Indian subcontinent
since the Quaternary epoch. The few published records on vegetation succession
and past climatic oscillations in Assam include studies of reserve forest of lower
Brahmaputra valley and upper Assam region (Bhattacharya and Chanda 1992; Bera
and Dixit 2011; Dixit and Bera 2012; Tripathi et al. 2020). However, despite the
frequent occurrence in pollen slides, the NPP studies have never been carried out on
the modern surface soil and Quaternary sediments from the Assam, except a solitary
publication from the Rhino dung samples of Kaziranga National Park of Assam
dealing with the coprophilous fungi (Basumatary and McDonald 2017). Neverthe-
less, the fungal spores have also been studied on the Holocene sediments of
Mizoram, northeast India, for the palaeoclimatic interpretation (Mandaokar et al.
2008). The present study thus assesses the behaviour of non-pollen palynomorphs
with the respective depositional and ecological setting around the Sakali wetland
which may further strengthen and substantiate the pollen-based palaeoclimatic
reconstruction in the Majuli Island and the surrounding region of northeast India.
2 Regional Setting
Majuli is the largest tropical river island in the Brahmaputra River located in the
Indian state of Assam. It is allocated between latitude 93300–94350E and longitude
26500–27100N at an elevation ranging from 60 to 85 m above mean sea level
(Basumatary et al. 2018). Majuli had a total area of 1250 square kilometres (483 sq.
mi), but having lost significantly to erosion it has an area of only 421.65 square
kilometres (163 sq. mi) in 2001. With a population of 1.6 Lakhs, the majority being
tribal have a very rich heritage and has been the abode of Assamese Vashnavite
culture with a tremendous option for spiritual and Eco-tourism. The island comprises
of many small endangered wetlands like Sakali, Duboi, Johai, Belguri, etc. The
sedimentary core for the present study has been retrieved from the Sakali wetland.
The Sakali wetland (26520N, 94120E) in the Majuli Island is located in close
vicinity to the Brahmaputra River (Fig. 1). The wetland is bordered by open area
and cultivated land. The wetland comprises approximately 0.70 km
2
but is much
larger during heavy summer rains. During heavy rainfall, the infiltration of more
rainwater from the Brahmaputra River results in flooding of the surrounding area.
During winter it becomes smaller due to low rainfall (Basumatary et al. 2018).
Majority of the research on Majuli has focused on bank erosion, rainfall pattern,
drainage discharge of the Brahmaputra river, geomorphic changes in the river basin
and vegetation (Das 2015). This island is one of the most dynamic landforms and
highly sensitive towards the natural calamities, like earthquake and floods.
66 A. Pandey et al.
Fig. 1 Location map showing the study area (after Basumatary et al. 2018)
3 Climate and Soil Type
Majuli Island has a subtropical monsoon climate, as is found in the other parts of
Assam, in general, the study area enjoys a warm and humid climate. The climate of
the region is controlled by the southwest and northeast monsoons since area pos-
sesses high rainfall i.e. the average annual rainfall in the area is around 215 cm. The
relative humidity is very high and ranges from 75% to 86%. During summers it is hot
and humid with the maximum temperature rise up to 37 C and cold and dry during
the winters. All the major festivals in the island are held in the winter season when it
is cool and pleasant. The average temperature hovers from 7 to 18 C.
The soil in the Sakali wetland and adjoining areas is largely characterized by the
moderately deep to very deep deposition of alluvium, with variation in colour from
grey to mottled grey. It is mostly composed of sandy to silty loams and slightly
acidic in nature. It is less acidic on the riverbanks and sometimes slightly alkaline.
The soil lacks in the development of intact profile and is deficient in phosphoric acid,
nitrogen and humus (Basumatary et al. 2018).
Non-Pollen Palynomorphs from the Late-Holocene Sediments of Majuli Island,... 67
4 Material and Methods
A 1.5 m deep sedimentary core has been procured from the centre of the Sakali
wetland through PVC pipe after the several trials coring (Fig. 2). The sedimentary
core was sub-sectioned at about 5 cm interval initially for the palynological assess-
ment. Fortunately, after the chemical processing and preparation of permanent slides
for the pollen analysis, we realized that the samples were rich in the diversity of
non-pollen palynomorphs and with this we started our studies on NPPs as an
auxiliary tool for the palaeoenvironmental reconstruction in Majuli Island. The soil
sediment of this region is composed of varied proportions of organic clay, silt and
sand (Fig. 2). The different types of Non-pollen palynomorphs with their affinity and
environmental implications are provided in Table 1. For the chemical processing,
acetolysis technique was utilized for the extraction of pollen, spores and NPPs
(Erdtman 1943). The step-wise chemical processing of soil samples are enumerated
below:
1. 10 g of soil sample was treated with 10% potassium hydroxide (KOH) and
boiled for up to 10–15 min until the effervesces comes.
2. After getting cool sieve the samples through 150-μm mesh size sieve for the
deflocculating of the organic matter.
3. Then pour the samples into a centrifuge tube and centrifuge until a speed of at
least 4500 rpm.
4. Wash the material with water and centrifuge until the supernatant is clear.
5. Dehydrate with 96% acetic acid and centrifuge.
6. Prepare an acetolysis mixture of acetic anhydride and sulphuric acid in (9:1)
ratio.
7. Acetolyse the material by heating the sample in the acetolysing mixture to
100 C for at least 10 min.
8. Cool the sample tubes at room temperature and then again centrifuge.
9. Wash the material with distilled water and centrifuge twice.
10. Pass the sample through 60-μm mesh size (0.56-μm pore size) sieve and the
residue (>10 μm) was collected and stored for NPP studies.
11. The counting with photo-documentation of NPPs was done using an Olympus
BX-50 Microscope with attached DP-26 Olympus camera (Plates 1and 2).
5 Results
Due to the high diversification and complex nature of Non-pollen palynomorphs in
palynological slides, most researchers often encounter difficulties in identification. It
is possible to observe NPPs with variable views and their counting tells us about
their abundance in a specific area. The identification and grouping of NPP types are
necessary to reflect the vegetation and ecological dynamics rather than assuming a
species entity based on their morphology alone (Adojoh et al. 2019). Description of
all the NPP types are strictly based on morphological features (size, shape, number,
68 A. Pandey et al.
Fig. 2 A litholog of 150 cm deep sedimentary core procured from the Sakali wetland of Majuli
Island, Assam
(continued)
Non-Pollen Palynomorphs from the Late-Holocene Sediments of Majuli Island,... 69
Table 1 The characteristic non-pollen palynomorphs and their affinities along with an environ-
mental implications
S. no Genus Affinity/family Environmental implication
1Helminthosporium Fungal spore
(Pleosporaceae)
Best indicator of cultivated land and
pathogen to members of Poaceae family
2Gelasinospora Non-coprophilous
fungi (Sordariaceae)
Found in highly decomposed peat, indi-
cate the human settlement around the
study site
3Nigrospora Coprophilous fungi
(Trichosphaeriaceae)
Frequently found at the cropland and
open-land. Pathogenic to grasses and
some other angiosperms like tea, palms
and banana.
4Ascodesmis Coprophilous fungi
(Ascodesmidaceae)
Found on dung of both wild and domes-
ticated animals, indicates the grazing
activity around the study site
5Podospora Coprophilous fungi
(Lasiosphaeriaceae)
Found on dung, indicates the animal
diversity and grazing activity
6Sordaria Coprophilous fungi
(Sordariaceae)
Found on dung, also occur on moulds
indicates grazing activity
7Telitia Pathogenic fungus
(Ustilaginaceae)
Plant pathogen, effects the members of
Poaceae family
8Delitschia Coprophilous fungi Dung loving fungi, indicates grazing
activity
9Entophlyctis
lobata
Non-coprophilous
fungi
(Chytriomycetaceae)
Specific of temperate region. Cold climate
loving fungi.
10 Dictyosporium Non-coprophilous
fungi
(Dictyosporiaceae)
Indicate warm and humid climate
11 Diporotheca Parasitic fungi
(Diporothecaceae)
Parasites on the roots of solanum species;
wet zone highly trampled by livestock.
12 Coniochaeta Coprophilous fungi
(Coniochaetaceae)
Widely found on dung of both wild and
domesticated animals; also grow on
decaying woods
13 Diploidia Non-coprophilous
fungi
(Botryosphaeriaceae)
Shows cosmopolitan distribution, and no
specifictemperature is needed for their
growth
14 Glomus Mycorrhizal fungi
(Glomeraceae)
Frequently found near the wetland and
open land area that indicate soil erosion.
15 Arnium type Coprophilous fungi
(Lasiosphaeriaceae)
Mostly occur on dung, but some species
are also abundant on rotting herbaceous
stems and wood
16 Alternaria Non-coprophilous
fungi
(Pleosporeaceae)
Shows cosmopolitan distribution, and no
specifictemperature is needed for their
growth
17 Valsaria Non-coprophilous
fungi (Valsariaceae)
Warm loving, occur on decayed bark or
woods
and characteristics of apertures and appendices, wall colour, surface structure)
provided by van Geel (1972,1986,2001) and others (e.g. Bakker and van Smeerdijk
1982; Vander Wiel 1982; Kuhry 1985; Haas 1996; Guy-Ohlson 1998) have system-
atically developed the practice of examining all fossils from a wide variety of
sediment types. High fungal abundance can be seen in the studied sediment samples
of Sakali wetland, a few algal, plant and animal remains were also retrieved. All the
identified NPPs that were spotted in the palynological slides have been elaborated
below.
70 A. Pandey et al.
Table 1 (continued)
S. no Genus Affinity/family Environmental implication
18 Geastrum Saprophytic fungi
(Geastraceae)
Cosmopolitan fungi, grow in tropical cli-
mate mainly found to grow scattered or
clustered in leaf litter or humus
19 Tetraploa Non-coprophilous
fungi
(Tetraplosphaeriaceae)
Indicate comparatively warm and humid
climatic condition but favourable habitat
is near water.
20 Ustilago Smut fungi
(Ustilaginaceae)
Indicate warm and humid climatic
condition
21 Cookeina Saprobic or parasitic
fungi (Pezizaceae)
Commonly found attached with woody
substrate may be living or dead. Indicate
the presence of woody plants.
22 Botryococcus Algal remain
(Dictyosphaeriaceae)
Typically found in tropical fresh water
wetlands
23 Biostructured
phytoclast
Organic remains It shows the presence of woody plants
24 Neorhabdocoela Zoological remain Found in fresh water ecosystem
25 Flatworm residue Zoological remain Mostly found near the wetland area that
represents the freshwater ecosystem near
around.
26 Fungal hyphae
(septate)
Fungal body part Bundle of hyphae ultimately results in
formation of the mycelium.
Mycelium is highly branched and plays an
important role in vegetative reproduction
in fungi. Warm and humid climatic con-
ditions are favourable for their growth.
5.1 Fungal Remains
Most of the fossil fungi recovered from the sedimentary core of Sakali wetland
appeared to be ascospores, conidia, and chlamydospores produced by 21 different
fungi belonging to 16 families like Sordariaceae, Pleosporaceae, Glomeraceae,
Ascodesmidaceae, Chytriomycetaceae, Dictyosporiaceae, Lasiosphaeriaceae,
Valsariaceae, etc.). Many of the recorded fungal spores were found in peat deposits,
especially in peat layers which were formed under relatively dry conditions. In lake
Non-Pollen Palynomorphs from the Late-Holocene Sediments of Majuli Island,... 71
Plate 1 Non-pollen palynomorphs retrieved from the sedimentary core of Sakali wetland of Majuli
Island, Assam. 1. Botryococcus,2.Nigrospora,3.Ascodesmis,4–5. Geastrum,6.Diporotheca,
7. Coniochaeta,8–9. Glomus, 10. Entophlyctis lobata,11. Arnium type, 12. Unidentified, 13.
Telitia,14–15. Valsaria,16. Ustilago, 17. Ascospore of Cookeina, 18. Delitschia, 19. Unidentified,
20. Diploidia, 21. Dictyosporium, 22. Segmented mycelium, 23. Alternaria
deposits, however, fungal remains normally are of rare occurrence (in open water
there is no strictly local production of fungal spores which do preserve as fossils).
Another factor that influences the fossil record is the fact that only relatively big
(heavy) fungal spores with thick walls are normally preserved. Most of the thin-
walled spores, which disperse better and which are known from the records of spores
in the present atmosphere, obviously do not fossilize. From the various studies of
72 A. Pandey et al.
Plate 2 Non-pollen palynomorphs retrieved from the sedimentary core of Sakali wetland of Majuli
Island, Assam. 24–26. Sordaria,27–28. Podospora, 29. Helminthosporium, 30. Tetraploa, 31.
Gelasinospora, 32. Unidentified, 33. Unidentified, 34. Unidentified, 35.Unidentified, 36.
Biostructured phytoclast, 37. Flatworm residue, 38. Neorhabdocoela
fossil fungal spores, it became clear that the recorded spores in most cases were of
strictly local occurrence. Some of the reported fungal remains are listed below with
details.
Non-Pollen Palynomorphs from the Late-Holocene Sediments of Majuli Island,... 73
Nigrospora [Plate 1, (2)]
It is a dark hyaline round-shaped spore, the diameter is about 25–32 μm. Nigrospora
is a ubiquitous, cosmopolitan fungus, especially abundant in a warm climate. It is
mostly found on decaying plant material and soil. It belongs to phylum Ascomycota
and class Trichosphaeriaceae. It is a common pathogen of grasses.
Ascodesmis [Plate 1, (3)]
It is a coprophilous fungus with a complex fruiting body. Its diameter is about
12–15 μm, round in shape, yellow colour body with several spins like outgrowth.
Widely found on the dung of both wild and domesticated animals, indicates the
grazing activity.
Geastrum [Plate 1, (4, 5)]
Its diameter is about 25 to 30 μm, spherical with an irregular outer surface having
some ridges all around the surface wall. The outer layer of the tissue splits like a star
(7–10 pointed rays) that eventually bends back to point downwards. It is a sapro-
phytic fungus which grows mainly in the tropical climate, cosmopolitan in nature
with proliferating growth in leaf litter or humus in scattered or clustered form. It
belongs to the earth star family of fungi.
Diporotheca [Plate 1, (6)]
These ascospores are one-celled, ellipsoidal, 32–49 18–25 μm in size, both ends
truncate with a wide germ pore of ca. 1.5 μm in diameter. Parasites on the roots of
Solanum species, wet zone highly trampled by livestock (Cugny et al. 2010).
Coniochaeta [Plate 1, (7)]
It is a coprophilous fungus with domb shape likes structure placed one above the
other, spherical shaped and very small in size (12 10 μm), and the measurement
fluctuates because of its complex structure. The edge of the spore is dark in colour,
rarely visible. The occurrence of Coniochaeta indicates the presence of dung and
peat. The species of Coniochaeta and their anamorphs occurs on dung, wood, or
bark of trees, soil, leaves, and leaf litter and rarely in non-woody host plants like
Poaceae.
Glomus [Plate 1,(8, 9)]
It is an Arbuscular mycorrhizal fungus, that dependent on their mycorrhizal associ-
ation with plant root to complete their life cycle. They are dark yellowish to light
brown in colour, about 10 μm in size and have a tail-like structure. They mostly
occur in soil in solitary form, rarely seen in the branched form. Glomus species are
found in nearly all terrestrial habitats, including arboreal land, deserts, grassland,
tropical forest, and tundras. The endomycorrhizal fungus Glomus occurs on a variety
of host plants, and chlamydospores are of a regular occurrence on pollen slides
(Cook et al. 2011).
74 A. Pandey et al.
Entophlyctis lobata [Plate 1, (10)]
It is an endobiotic fungus with multiple morphological variations among their
species (van Geel 1978): sporangia crenulate, 20–38 18–33 μm, about 6 μm
high, walls about 0.5 μm thick (Kuhry 1997): Crenulate sporangia, with a central
pore. Mostly found in the temperate region, reflecting the cold temperature.
Arnium [Plate 1, (11)]
These ascospores are oval-shaped with 38–45 20–25 μm in size, with some
ornamentation could be seen on the surface of the spore. These are coprophilous
fungi but some species are also abundant in rotten herbaceous wood and stem.
Telitia [Plate 1, (13)]
Fungal spore is globose, 11.8–18 μm in diameter, bi-layered with the reticulate body
surface, ca. 0.5 μm thick superficial sculpturing. Spines like outgrowth, with
5.6–10.4 μm long, ca. 0.3 μm in diameter. It is a plant pathogenic fungus that
generally affects the grasses, warm and humid climatic condition is favourable for
their growth.
Valsaria [Plate 1, (14, 15)]
Ascospores uniseptate, septum very pronounced and slightly protruding, bi-layered
thick verrucose wall, measuring ca. 32 22 μm. Warmer climatic condition is
favourable for its growth. An indication in this direction may be the observation that
species of Valsaria have become more common in warmer parts. In times of global
warming, it seems justified to expect that these fungi will enlarge their distribution
area (Jaklitsch et al. 2015).
Ustilago [Plate 1, (16)]
It is a round-shaped smut fungus, globose 16–24 μm in diameter (van Geel et al.
2011). It shows pathogenic characters, especially in maize and wheat.
Ascospore of Cookeina [Plate 1, (17)]
Spore is bi-celled with elliptical shaped body, measuring 30–35 5–20 μm, ends are
slightly pointed, surface provided with longitudinal striations; septum lanceolate and
distinct, (Mandaokar et al. 2008). Non-coprophilous fungus, mostly saprophytic and
parasitic taxon commonly associated with woody substrates like a living, dead or
decaying wood and leaves or litters. It indicates the dense forest under humid and
rainy climate.
Delitschia [Plate 1, (18)]
The spore is divided by a thick septum, ends are slightly conical, measuring
32–35 13–15 μm, the thickness of septa is around 0.41 μm; spore wall is neither
differentiated nor visible. It is a coprophilous fungus.
Diploidia [Plate 1, (20)]
The ascospore is an ellipsoidal, dark brown in colour. It indicates a warm and humid
climate.
Non-Pollen Palynomorphs from the Late-Holocene Sediments of Majuli Island,... 75
Dictyosporium [Plate 1, (21)]
Pale brown conidia of 36–41 11–14 μm, consisting of one truncate cell with
3 vertical straight or slightly curved cylindrical, septate arms of more or less similar
length, arranged close to each other. Mostly found in deadwood.
Alternaria [Plate 1, (23)]
The tri-septate spore is curved at the axis at one side and slightly pointed on the
other, around 5–6 longitudinal septa are present that divide the body of the spore into
chambers. It is a cosmopolitan fungus found generally in areas with a warm and
humid climate.
Sordaria [Plate 2, (24, 25, 26)]
Spores ellipsoidal, one-celled, brown, 18–20 10–11 μm with a protruding apical
pore of about 1.5 μm diameter at one end with a slight annulus (van Geel 1978), the
spore wall is thick and pigmented with high survival capacity. It is also a coproph-
ilous fungus which indicates grazing activity and sometimes grows on moulds
as well.
Podospora [Plate 2, (27, 28)]
A dark-pigmented upper cell and a hyaline lower cell (pedicel); they often have a
gelatinous sheath and gelatinous caudal, brown-to-black coloured upper cell. Spore
length is 17–34 μm, inflatable-type species (van Geel and Aptroot 2006). It is a very
common coprophilous fungus, representing a warm and humid climate with an
indication of grazing activities.
Helminthosporium [Plate 2, (29)]
Hyphae are septate. Multicellular conidia (six or more-celled), are brown to dark
brown, erect, parallel-walled, and ceasing to elongate when the terminal conidium is
formed. Large 40 9μm, solitary, club-shaped, and pale to dark brown.
Helminthosporium is an indicator of cultivated land.
Tetraploa [Plate 2, (30)]
Conidia ellipsoid to rectangular, 3–4 columns with 4 cells in each column,
yellowish-brown, 33–41 18–23 μm, verruculose, thick-walled; terminating in
septate appendages, 12–80 μm long (frequently broken), 5–8μm wide. Distributed
mainly in tropical and sub-tropical regions. Found as saprophytes, on decaying
wood, leaf litters, grasses and some monocotyledons as well (Gelorini et al. 2011).
Gelasinospora [Plate 2, (31)]
Ascospores ellipsoidal, 21–32 15–20 μm. Spore surface almost black, evenly
ornamented with ca. 1 μm wide round hyaline pits (van Geel 1978).
5.2 Algal Remains
Algal palynomorphs, observed in the pollen slides besides pollen grains and spores
of terrestrial and aquatic plants and fungal spores, are mainly represented by
Botryococcus, Pseudoschizia,Pediastrum,Spirogyra and Zygnema. However, in the
sediments of Majuli Island, we only noticed the trace occurrence of Botryococcus.
76 A. Pandey et al.
Botryococcus [Plate 1, (1)]
It is green algae, found in colonies of cells with irregular shape and size. The cell
body is oval-shaped folded in mucilage and about 8–10 μm long and 4–6μm wide.
Modern Botryococcus is widely dispersed in temperate and tropical regions and is
known to tolerate seasonally cold climates.
5.3 Zoological Remains
Neorhabdocoela [Plate 2, (38)]
Oocyte without operculum, yellow, funnel-shaped or oval, 123–147 119–150 μm,
with a smooth surface, stalk typical but often only partly preserved or not preserved,
with articulation just beneath the body (Gelorini et al. 2011). Found in pollen
preparations from Holocene freshwater lake sediments (Haas 1996).
Flatworm Residue [Plate 2, (37)]
Flatworm plays a major role in cultivations; hence their remains reflect the farming
activities in the respective field. The digestive cavity of the Flatworms has only one
opening for both ingestion (intake of nutrients) and egestion (removal of undigested
wastes); as a result, the food cannot be processed continuously (Zaborski 2002).
5.4 Organic Matter
Bio-structured Phytoclast [Plate 2, (36)]
Indicates the remaining part of the plant like cortex, epidermis, vascular bundles, etc.
6 Discussion
6.1 General View of NPPs Recorded from the Majuli
Sediments
Non-pollen palynomorphs play a very vital role in the prediction of past
palynostratigraphical and palaeoclimatic condition. Because of its wide variety and
distinguish characters they provide valuable information regarding the
palaeoenvironmental reconstruction. The NPPs recovered from the 31 sediment
samples of the 150 cm deep sedimentary core procured from the Sakali wetland of
Majuli Island have dissimilar origin and nature and include fungal spores, algal and
zoological remains of different environment. During our pollen-based late Holocene
climatic studies in the aforesaid sediment core, it seems that the vegetation was not
fully reflected by the available palynoassemblage, owing to the recurring floods and
massive soil erosion in the Majuli Island (Barman et al. 2013). Thus, there is a dire
need to look after the NPPs in the palynological slides, in order to provide an
auxiliary tool that corroborates the pollen data for inferring the past vegetation and
climate of this largest river island.
Non-Pollen Palynomorphs from the Late-Holocene Sediments of Majuli Island,... 77
6.2 Major Inferences Drawn from the Retrieval of Fungal
Spore from the Late-Holocene Sediment Samples
Majority of the research on Majuli has focused on climate change, disturbance in
vegetation, bank erosion, rainfall pattern, drainage discharge of the Brahmaputra
river, geomorphic changes in the river basin and the impact of the 1950 earthquake
on settlements and fluvial pattern of the river. The studied sedimentary core gives
variant forms of non-pollen palynomorphs especially the coprophilous and
non-coprophilous fungal remains that provide very valuable insight into the
palaeoenvironmental conditions. A total of 21 different fungal spore types were
reported in the present investigation from the late Holocene sediments of Sakali
wetland of Majuli Island, Assam. The coprophilous fungi have been broadly used to
unravel the presence of herbivores (van Geel and Aptroot 2006; Cugny et al. 2010;
Gelorini et al. 2011; Ghosh et al. 2017; Loughlin Nicholas et al. 2018). Their
presence could be used as indicators of the presence of the livestock, particularly
bovines. The Sordaria sp. is particularly found on cattle dung (Ejarque et al. 2011;
van Geel and Aptroot 2006) and is commonly used for indicating the grazing
activities (Ejarque et al. 2011). Moreover, the Podospora sp. and Delitschia
sp. are strictly coprophilous, whereas Coniochaeta sp. and ascospores of
Sordariaceae are saprophytic in nature, growing on dead plant parts and other
decaying substrates (Ghosh et al. 2017). Coprophilous fungi in surface and sedi-
mentary soil profile helps to document or infer the former presence and subsequent
decline of, herbivorous animals in a region. Many coprophilous fungi have rather
very narrow host range so; they can be indicator for a specific region which reflects
the climate and vegetation around the area. Apart from the coprophilous fungi, the
other non-coprophilous fungi like Alternaria,Dictyosporium,Telitia and Valsaria
were also reported consistently in the sample that shows the proliferation of dense
vegetation under warm and humid climate in the region (Ellis and Ellis 1985).
The Tetraploa and Glomus indicate rich plant diversity and availability of water
in the region. These fungi are commonly found as mycorrhizal fungi on roots, leaves
and stems of Poaceae and Cyperaceae (Tanaka et al. 2009). Glomus is mostly found
during the early phase of late Holocene, often used as an indicator of soil erosion,
and dry climatic conditions, since this fungus primarily lives underground
(Anderson et al. 1984; van Geel et al. 2003). The presence of Entophlyctis lobata
at the bottom of the sediment core reflects the cold and dry temperature since it is
specific of temperate regions. The fungal spores of Arnium and Gelasinospora
mostly occur in highly decomposed peat; formed under relatively dry, oligotrophic
conditions, also indicate layers with charred material.
78 A. Pandey et al.
Further, the other fungal spores like Nigrospora sp., and Tetraploa sp., could be
used as indicators of open-land vegetation which could be related to the human
pressure (Gelorini et al. 2011). The Helminthosporium (a key indicator of cultivated
land), and Telitia are grass pathogen and especially associated with the Poaceae
member’s example, Oryza sativa (rice), and Bambusa vulgaris (Bamboo) and these
taxa are abundant in the region that reflects the anthropogenic activities around the
area, whereas Diporotheca shows the symbiotic relationship with Solanum sp.
The corroboration of these NPPs helps us to reconstruct the past climate vegeta-
tion interaction. The NPPs collectively display the holistic information of mixed
settlement of domestic living, anthropogenic capacities and environmental elements
prevailing during the late Holocene in the Majuli Island.
6.3 Overall Inferences from the Algal and Zoological
Remains
The occurrence of Neorhabdocoela, a freshwater zoological remain demonstrates
the existence of cropland along with the presence of perennial water system around
it. We have also encountered the scanty amount of algal remain like Botryococcus,
where the flow of water would be in stagnant condition (Kumar et al. 2017). The
complete absence of algal remains and rare occurrence of Botryococcus in sediments
of Sakali wetland, supports the high energy levels in wetland water, attributed to
frequent flood activities, owing to the close vicinity of Brahmaputra river. The
overall NPP assemblage shows that this island possesses the grazing activities,
cultivation process and domestic settlement during the recent past.
Besides the aforesaid NPPs, there are large numbers of NPPs, which are still
unidentified and their ecological, as well as environmental values, are yet to be
established. Additionally, the unidentified NPPs particularly fungal spores and
conidia, which are in predominance, could be prescribing the probability to improve
the typification and knowing of new bio-markers for their future examinations in
palaeoecology, palaeoenvironment and palaeoclimate.
7 Conclusions
From the overall reviewing of the inferences discussed in the present paper, it can be
suggested that the generated database of Non-pollen palynomorphs could provide
baseline information for the precise reconstruction of past vegetation and climate in
this high flood and erosion-prone region of Majuli Island. Twenty-five different and
well-identified NPP types, classified broadly under three categories as fungal, algal
and zoological remains, have been studied, documented and illustrated from the
Sakali wetland of Majuli Island, along with their palaeoecological implications.
Based on the recovered NPPs we concluded that the study area is providing a
blend scenario of scattered forest near the wetland, and the presence of some
non-coprophilous fungi indicates the practice of cultivation around with adequate
signature of human settlement. The coprophilous fungi especially Sordaria and
Podospora could be used to decode the palaeoherbivory in the Majuli Island. In
future, the multiproxy analysis including both biotic and abiotic proxies would
definitely unfold the past hidden ambience of the region.
Non-Pollen Palynomorphs from the Late-Holocene Sediments of Majuli Island,... 79
Moreover, the vigorous dataset on NPPs aspect from sediment samples was
needed with a view to strengthen the palaeoclimatic and palaeoecological
interpretation.
Acknowledgments We thank, Dr. Vandana Prasad, Director, BSIP, Lucknow, India for the
encouragement and permission to publish the paper. We acknowledge the Forest Department,
Govt., of Assam for permission and necessary help during the field study. Here, we like to thank
Dr. Biswajeet Thakur for his kind support during the investigation. This research was supported by
the Science and Engineering Research Board (SERB), New Delhi, India under Women Excellence
Award (grant number SB/WEA-06/2019).
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