First Report of Diversity of Cyanobacteria of Broknes Peninsula of Larsemann Hills, East Antarctica

ABSTRACT Antarctica is an extreme environment and contains many unique geological, glaciological and biological features. However, due to changes in climatic conditions Antarctica is affected by Global warming. The Larsemann Hills area is located in East Antarctica approximately halfway between Vest fold Hills and Amery Ice Shelf on South-eastern coast of Prydz Bay which includes two main peninsulas, the western named Stornes and the eastern named Broknes. The Antarctic environment is highly sensitive and susceptible to the impacts of human activities and has much less natural ability to recover from disturbance than the environment of other continents. Due to coastal location and ice free landscape, Larsemann Hills is an attractive area for human activities which consit on scientific expeditions as well as touristic activities which are currently increasing. It is hypothesized that due to increase in land use pressure, the growth and diversity of Cyanobacteria in this area may be affected. The aim of this study was to record Cyanobacteria from freshwater bodies, rocks and terrestrial habitats. Considering the two main peninsulas, Stornes peninsula comes under the Antarctic Specially Protected Area (ACPA) so the samples were collected from diverse habitats of Broknes Peninsula. Altogether, 16 species of Cyanobacteria belonging to nine genera were recorded from diverse habitat of Broknes Peninsula of Larsemann Hills. This is the first Indian study report of Cyanobacteria of Broknes peninsula of Larsemann Hills. All species are reported for the first time and therefore constitutes new record from this area.


INTRODUCTION
Larsemann Hills (69°23'S, 76°53'E), in the Prydz Bay, is an ice-free oasis on the Ingrid Christensen Coast, Princess Elizabeth Land, located approximately midway between the eastern extremity of the Amery Ice Shelf and the southern boundary of the Vestfold Hills. This ice-free coastal oasis was named after Mr. Larsemann Christensen. It is the second largest (area of 50 square km) of only four major ice-free oases found along East Antarctica. The highest elevations are around 180 m above sea level (ANARE 2000). Larsemann Hills region includes two main peninsulas, the western named Stornes and the eastern named Broknes. In between these two peninsulas, there are number of islands of varying dimensions and some unnamed promontories. The satellite imagery of the area indicates open sea on the eastern edge of the Broknes Peninsula. Westwards, the Clemence Fjord separates Broknes Peninsula from Stinear Peninsula and Fisher Island.
There are several lakes in the Larsemann Hills (Gillieson et al. 1990), ranging from small ephemeral ponds to large water bodies. Some of these water bodies are ice free for the very short period of time or partially ice free in the summer months when the water temperature increase rapidly, reaching about + 8°C in some of the shallower ones. For the remainder of the year (8-10 months), they are covered with about 2.0 m of ice (Hodgson et al. 2001).
Cyanobacteria occurs in a wide range of habitats and are distributed all over land and water system often. They can also occur in rather extreme environments where there is no other vegetation possibly due to their adaptive capability to adverse environmental conditions with respect to different climatic/environmental factors, availability of nutrients. Their occurrence even in wide range of ecologically stress conditions and extreme habitats proves that they are very tolerant. In Antarctica it occurs in fresh-water ecosystem like lakes, ponds, and marine water system and ocean. Besides, it also occurs on stones, rocks, snow and in cold lakes (Zakhia et al. 2008) and presents interesting qualitative and quantitative variance in time and space.
In Antarctic oasis Cyanobacteria species composition was investigated in Schirmacher oasis in various environment including streams lakes, moss, soil and rock (Pandey et al. 2004). Antarctic environment supports the growth of diazotrophic Cyanobacteria which play a key role in nitrogen cycling (Coyne et al. 2020). Pandey et al. 1992 have studied nitrogen fixation by Cyanobacteria associated with moss communities in Schirmacher oasis, Antarctica. Pandey et al. 1995 described nutrient status, algal and Cyanobacteria flora diversity of freshwater streams of Schirmacher oasis, Antarctica (Gupta 2015).
Cyanobacteria studies, were carried out under the Indian Scientific Expedition and other Programmes in and around the Schirmacher oasis; however, hitherto on Cyanobacteria diversity study has been undertaken from Broknes Peninsula of Larsemann Hills, Antarctica.
Sampling of the coastal areas from the Vestfold Hills to the Larsemann Hills conducted by Dhargalkar (1990) indicates that the flora of the Ingrid Christensen Coast is relatively uniform and restricted to bryophytes, lichens and algae. Sabbe et al. (2003) have reported Diatom flora in the fresh and saline water Lakes of Larsemann Hills and Rauer Island. Ellis-Evans et al. 1998 reported phytoplankton comprises autotrophic nanoflagellates, dinoflagellates and Cosmarium from different water bodies and benthic communities of the deep water lakes are dominated by thick Cyanobacteria mats. However, as far as work on algal diversity of Larsemann Hills, Antarctica is concerned, Bharati & Niyogi (2015) have studied phytoplankton only up to class level. Therefore, taxonomic studies of Cyanobacteria is very much required. Studies on Cyanobacteria diversity from diverse habitats of Brokenes Peninsula of Larsemann Hills, East Antarctica are still in a very nascent stage. Attempt has been made to study the diversity and factual Cyanobacterial profile from Brokenes Peninsula of Larsemann Hills, East Antarctica.

MATERIAL AND METHODS
The author participated in the 33 rd Indian Scientific Expedition to Antarctica (11.XII.2013-14.IV.2014 to carry out cyanobacterial studies in Broknes Peninsula of Larsemann Hills, East Antarctica during the austral summer and surveyed Broknes Peninsula of Larsemann Hills, Antarctica.

Site deScription
Larsemann Hills, (Figs 1, 2) form a large area free of snow and ice during the austral summer period. During the survey Cyanobacteria samples were collected. All the samples were processed, fixed and maintained properly for study Samples were sampled by towing Phytoplankton net (mesh size 20×) to a distance of 1-5 meter depending up on the depth of water bodies. The samples were preserved in screw cap sampling vials of Tarsons (size 25 × 50mm & 25 × 75mm) by adding 2-4 drops of 4% Formalin solution and labelled with sample number, location, type of water bodies and date of collection. Prior sampling another water body, phytoplankton net was thoroughly washed with water after collection of each sample. Samples were also collected by using forceps, needle, scalper, dropper and brush depending upon the type of the samples and habitat of water bodies.
identification and taxonomic identification Specimens were observed under Leica DM 2500 microscope and photomicrographs of each specimen were taken using DFC 500 digital camera and annotated using Leica QWin V 3.2 Image Processing and Analysis Software and Leica Application Suit V4. The author name of each species were cited in the text as described in 'Authors of Plant Names' (Brummitt & Powell 1992), title of books in citation was cited in accordance with Stafleu & Cowan (1976, 1979, 1981, 1983, 1985, 1986, 1988 and supplements as described by Stafleu & Mennege (1992, 1993, 1995, 1997, 2000, whereas journals, periodicals with botanical content as described by Bridson (2004a, b).

SyStematic identification
The list of identified Cyanobacteria from diverse habitats of Broknes Peninsula of Larsemann Hills, East Antarctica is provided along with details including nomenclature and distribution. deScription. -Cells more or less angular with rounded corners, almost arranged in transverse and vertical series, pale blue-green or olive-green, homogenous or finely granular; sheath very thin, mucilaginous, hyaline; colonies when young 4 cells (Fig. 8C). deScription. -Trichome almost straight, sometimes slightly bent, tapering at the end, not constricted or very slightly constricted, cross-walls granulated; screw like more or less twisted and gradually attenuated at the end; cells sometimes distinctly granulated,; end-cells capitate to sickle shape or obtusely button like flattened or rounded with slightly thickened outer wall, rarely with calyptra (Fig. 8D).
deScription. -Trichome more or less straight, slightly bent from upper side, not attenuated or very slightly attenuated, not constricted at the cross-walls, sometimes cross-walls granulated; end-cell flat rounded, not capitate (Fig. 8E).
environment & habitat. -Freshwater species; planktonic in lake temperature 2°C. deScription. -Trichome straight, not constricted or somewhat constricted, indistinctly granulated at cross-walls, shortly attenuated at the end and slightly bent, one or more terminal cells usually pale, yellowish or yellow green; apical cell convex, widely rounded or somewhat slightly conical rounded, usually indistinctly curved, not capitate, calyptra absent or slightly thickened cell wall (Fig. 8K). deScription. -Trichome dull blue-green to brownish, more or less straight, sometimes slightly curved, not constricted at the crosswalls or slightly constricted; cross-walls usually frequently granulated; end cell flatly rounded or obtuse-rounded with slightly thickened outer membrane (Fig. 8F).  deScription. -Trichome more or less straight or very slightly curved, very slightly constricted or not constricted at the crosswalls; not attenuated at the apices but very slightly rarely curved at the end, not capitate; septa mostly granulated; apical cell more or less hemispherical or rounded; outer membrane sometimes slightly thickened (Fig. 8M).  deScription. -Filament elongate; sheath thin, firm, mucilaginous, colourless, sometime thicker diffluent, sometimes more or less lamellated; trichome slightly constricted or sometimes not constricted at the cross-walls; end not attenuated, not capitate, blue-green; cells not granulated at the cross-walls or sometimes granulated; end cell rounded, calyptra absent (Fig. 8I). deScription. -Trichome more or less straight or cylindrical, not constricted at the cross-walls, not attenuated towards end, capitate at the end; cells distinctly granular at the cross-walls; apical cell capitate, spherical, usually narrower than other vegetative cells (Fig. 8J).
dimenSion. -Cells 3.6-11.3 µm broad; heterocysts 5.0-6.0 µm broad.  (goppertianum), Planktothrix rubescens and Stigonema mesentericum. Gupta (2019) reported cyanobacteria and algae from ice of frozen lake of Stenear Peninsula of Larsemann Hills, Antarctica and recorded maximum species of cyanobacteria in comparison to other group of algae but from Broknes Peninsula recorded more cyanobacteria species in comparison to Stenear Peninsula. This clearly indicates that this area accommodate a rich diversity of cyanobacteria. Lyngbya confervoides, Oscillatoria rubescens (now known as Planktothrix rubescens) and O. tenuis observed from Broknes Peninsula having medicinal and chymotrypsin activity inhibitory properties. (Matthew et al. 2007). Kreitlow et al. 1999 reported that Planktothrix rubescens and O. tenuis having antibacterial properties against Gram-positive Bacteria like Staphylococcus aureus, Bacillus subtilis and Micrococcus flavus. Species found in this area can be used for preparation of safe medicines.

CONCLUSION
Cyanobacterial biogeography in Antarctica offers many challenges and opportunities to study in situ the nature and rates of adaptation of these organisms in harsh climatic conditions and geographically isolated conditions. This study constitutes a first steps towards the assessment of cyanobacterial diversity that should be pursue by conducting phylogenetic inferences to understand in an evolutionary context the adaptive strategies developed by these organisms to thrive in this extreme harsh climatic conditions.