Krishnanantham, K.Jayamanne, S.C.Seneviratne, Y. B. M. C. J.2022-01-262022-01-2620159789550481088http://www.erepo.lib.uwu.ac.lk/bitstream/handle/123456789/8231/51-AQT-Preliminary%20study%20on%20mangrove%20diversity%20in%20Irakkandy%20lagoon%2c%20.pdf?sequence=1&isAllowed=yThe term ‘mangrove’ describes both the ecosystem and the plant families that have developed specialized adaptations to live in the tidal environment (Tomlinson, 1986). Preliminary study on diversity of the mangrove stands at Irakkandy lagoon (Trincomalee) was investigated to document the status of the mangrove forest and the mangrove distribution in relation to the soil salinity variation. Due to the past two decades war dilemma and present developmental activities increase the pressure on mangrove ecosystem at an alarming rate Eastern region of Sri Lanka. In addition, Tsunami has collectively contributed to the destruction of mangroves at large in the Eastern province. In this backdrop, this research aims to analyse the diversity of mangrove in the Irakkandy lagoon which further attempts to provide some suggestions to protect mangrove and its ecosystem. Methodology Fifteen transect lines were laid perpendicular to the shore in different sites of the lagoon and sampling was conducted from May 2014 to July 2014 at selected locations. The precise locations were determined by portable GPS unit (ETREX 10) and hydro physico-chemical parameters of each site were recorded over high tide and low tide. Whilemeasuring the mangrove diversity, Temperature and pH were checked using Multiple Test Kit (Thermo scientific) and turbidity was measured using Turbidity meter (Hach model (2100q)) in Nephelometric Turbidity Units (NTU). Salinity was measured using a Refrectrometer (Erma Hand Refractometer, Salinity: 0-100) in units parts per thousand (ppt). Data on floristic composition was identified using standard identification keys. Moreover height of the species was measured by Suunto Clinometer. Three soil samples were collected along the transect line of each site from the edge of the lagoon to end of the mangrove existence. Soil salinity was calculated according to Gibbs, 2000. Shannon-Wiener diversity index and Pielou’s eveness index incorporated in the Primer software version 6.1.2 and Minitab ver.16 used for data analysis and statistical analysis. Results and Discussion Five different true mangrove species and nine mangrove associate plants were identified from the study site. Avicennia marina was the dominant species with Height (H) of 1.392.54m followed by Lumnitzera racemosa (3.131.92m), Excoecaria agallocha (3.282.662 m), Rhizophora apiculata (3.28 4.79m) and Heritiera littoralis was found as rare species with Height of (5.27 2.21m) respectively.enAquaculture and FisheriesBiodiversity – Sri LankaEnvironmental ScienceAquaculture and FisheriesAnimal SciencesOther