International Journal of Pharmacy and Biological Sciences-IJPBSTM (2019) 9 (1): 139-145 Online ISSN: 2230-7605, Print ISSN: 2321-3272 Research Article | Biological Sciences | Open Access | MCI Approved UGC Approved Journal A Preliminary Study on Biodiversity of Cyanobacteria of Agniar Estuary, Pudukkottai R. Anbalagan and R. Sivakami* PG & Research Department of Zoology, Arignar Anna Govt. Arts College, Musiri -621211, Tamil Nadu, India. Received: 4 Oct 2018 / Accepted: 8 Nov 2018 / Published online: 1 Jan 2019 Corresponding Author Email: [email protected] Abstract In the present study, a total of 38 species belonging to 12 classes were recorded. Among the various classes, Oscillatoriaceae recorded maximum diversity by recording 10 species followed by Phormidiaceae recording five species and Nostocaceae by four species; while Chrococeaceae, Merispropediaceae and Microcystaceae recorded three species each, Scytonemataceae and Pseudoanabaenaceae were represented by two species and classes Dermocarpaceae, Synechoccaceae and Xenococcaceae were represented only by one species each. A familywise comparison reveals that Phormidiaceae and Sycotomateaceae preferred February to record their highest counts, while Dermococcaceae preferred May and Merispopediaceae recorded the maximal counts in June. However, Synechoccaceae registered their maxima in July while Nostococcaeceae preferred July and August and Chrococcaceae recorded their maxima in October. Keywords Agniar estuary, Cyanobacteria, biodiversity, Tamil Nadu ***** INTRODUCTION Due to the unique feature of salinity in the estuaries, Estuaries are unstable ecosystems generally having a both freshwater and marine ecosystems can be limited number of organisms (Selvam et al., 2013). encountered here. However, the different conditions However, they support a high abundance of present in these systems also result in high mortality organisms due to their high productivity. They are of the eggs and larvae of the organisms living in these one of the richest and most productive areas of habitats. Estuaries being unique environments organic detritus and form the base of the food chain. harbour diverse groups of microorganisms due to However, the hydrodynamic conditions in an estuary high amount of biodegradation of organic matter. are quite complex as they are influenced by river Hence, various groups of bacteria and fungi such as flow, tide, wind and density factors. Further, they are nitrogen fixers, phosphate solubilizers, cellulose modified due to earth rotation, bottom friction and decomposers etc. are prevalent in this system the geometric properties of the estuarine system (Holguin et al., 2001). These organisms support these (Srilatha et al., 2012). systems in many ways; on the one hand, they help in DOI: https://doi.org/10.21276/ijpbs.2019.9.1.19 R. Anbalagan and R. Sivakami* 139 www.ijpbs.com or www.ijpbsonline.com ISSN: 2230-7605 (Online); ISSN: 2321-3272 (Print) Int J Pharm Biol Sci. biogeochemical cycling of the nutrients in the system RESULTS AND DISCUSSION and on the other hand act as an important source of In the present study a total of 38 species belonging food for a variety of organisms besides maintaining to 12 classes were recorded. Among the various its positive nature. classes, Oscillatoriaceae recorded maximum In India, the brackish water available has been diversity by recording 10 species followed by estimated to be around 12 million hectares (Heran et Phormidiaceae recording five species and al., 1992) of which about 65,000 ha are under Nostocaceae by four species; while Chrococeaceae, aquaculture. Tamil Nadu has a brackish water spread Merispropediaceae and Microcystaceae recorded of about 63000 ha. A hydrobiological study is a three species each, Scytonemataceae and prerequisite to the assessment of the potentialities, Pseudoanabaenaceae were represented by two distribution of flora and fauna and also to species and classes Dermocarpaceae, understand its realities between the different tropic Synechoccaceae and Xenococcaceae were levels and food webs. It is in this context the present represented only by one species each. study was attempted to assess the cyanobacterial Chrococcaceae recorded only one perennial species diversity of Agniar Estuary system in Pudukkottai (Chrococcus turgidus) while the others were District, Tamil Nadu, India. seasonal. As a group, they preferred October to record their highest count and was dominated by C. MATERIALS AND METHODS turgidus. Study Area Oscillatoriaceae was represented by 10 species The Agniar estuary is situated in the Palk Strait on the belonging to three genera. While the genus East-coast of India (Latitude 10 20 N; and Longitude Oscillatoria was represented by 4 species of which 79 23 E). It is a true estuary and the exchange of two were perennial (O. salina and O. tenus) with O. water occurs between the estuarine and the salina dominating in terms of count. The genus adjoining neritic realm of the Bay of Bengal Lyngbya was represented by 3 species of which only throughout the year. The river mouth is open L. major was perennial. The genus Plectonema was throughout the year. It is highly productive and rich also represented by 3 species of which only P. in fish, prawns, hermit crabs, crabs clams and stagnina was perennial. Among the various species oysters. in this group L. major was the most dominant Cyanobacterial Analysis organism in terms of number closely followed by O. Surface water samples were collected with the help salina. of a satin net (pore diameter 4.5 ) fitted to an The class Phormidiaceae was represented by 5 aluminium frame between 7:00 and 8:00 am for a species belonging to two genera, while the genus period of two years (June 2016 to December 2018). Phormidium was represented by 4 species of which Collection was done on a monthly basis for both the only P. tenne was perennial, the genus water bodies. The samples were immediately Trichodesmium was represented by a single transferred to glass containers for later microscopic perennial species T. erythraeum. Within this group P. analyses. Lugol's solution was also added as a tenue was the most dominant species. As a group, preservative. Care was also taken to observe some the most preferred month was February when they fresh samples. The counting of cyanobacteria was recorded their highest count. done using a Sedgwick-Rafter Counting Cell (Saxena, Nostocaceae was represented by 4 species belonging 1987). Samples were isolated and identified by to the genus Anabaena of which only A. variabilis was standard manuals (Desikachary, 1959; Starmach, perennial and was also the dominating species in 1966; Pennak, 1978; Adoni, 1985; Trivedy et al., terms of count. As a group, they recorded their 1987; Sridharan, 1989). While cyanobacterial highest count in July and August. population was estimated by drop method as Merismopediaceae recorded 3 species belonging to described by Pearsall et al. (1946), further counting 3 genera of which only Synechocystis salina was and identification of cyanobacteria were done by perennial and dominated in terms of count. As a following Pennak (1978), Adoni (1985) and Trivedy et group they recorded their highest counts in January. al. (1987). In addition, diversity indices were also Microcysteaceae also recorded 3 species belonging calculated following Trivedy et al. (1987). Finally, the to 2 genera of which only Microcystis aeruginosa was results obtained in the present study were perennial and dominated over others in terms of statistically treated for a meaningful discussion. number. As a group, they recorded their highest count in September. Rivuleraceae was also represented by 3 species belonging to two genera of International Journal of Pharmacy and Biological Sciences R. Anbalagan and R. Sivakami* 140 www.ijpbs.com or www.ijpbsonline.com ISSN: 2230-7605 (Online); ISSN: 2321-3272 (Print) Int J Pharm Biol Sci. which only Dicothrix bauriana was perennial. As a different effect of hydrographical factors on group they recorded their preference in June by individual species (Gouda and Panigraphy, 1996). recording the highest count. Many scientists also suggest that salinity plays an Scytonemataceae was represented by two species important factor in limiting the distribution of belonging to the genus Scytonema of which only S. organisms as its variation in salinity caused by varium was perennial. As a group, they recorded the dilution and evaporation influences the flora of this highest count in June. Pseudoanabaeneaceae was region (Gibson, 1982; Balasubramanian and Kannan, also represented by two species belonging to the 2005; Sridhar et al., 2006; Saravanakumar et al., genus Spirulina of which only S. major was perennial 2008). A perusal of the correlation between and was also the dominant species. As a group, they Cyanobacteria and salinity reveals a strong positive recorded the highest count in February. correlation (Mugilan, 2017) indicating their The classes Dermocarpaceae, Synechoccaceae and relationship. According to Das and Panda (2010) total Xenococaceae were all represented by a single phosphate, nitrate and chloride contents also play as species. While Dermocarpaceae recorded its highest major role in the distribution of algae. Correlation count in May, Synechoccaceae recorded its peak in between cyanobacteria and phosphate (Sivakami et July and Xenococcaceae registered its peak in July. al., 2017), as well as nitrate (Mugilan, 2017) in the A perusal of literature reveals that marine present study also reveals