ASSESSING THE SATHURUKONDAN MANGROVE ECOSYSTEM IN TERMS OF DIVERSITY, THREATS AND CHALLENGES

Abstract

The present study was carried out form May to October 2023 in mangrove patches (A-J) located on either side of A-15 highway in Sathrukondan area in Batticaloa district within Thannamunai, Sathrukondan and Pillayaradi GN Division chose as study sites. In order to find the check list and calculate the abundance, community skucture and diversity indices (Shannon-Weiner index, Pielou's evenness index, and Margalef index) total of 59 line transects and 99 quadrates were laid for mangroves. The same diversity indices also calculated for associated avifauna by points transect method. Vegetation pattem ofmangrove further analyzedby relative density, relative frequency, dominance and importance value index (IVf. The outcome showed that, the study area, are home to eight true mangrove species belonging to six different families, including Least Concem (LC) namely, Avicennia marina, Aegiceras corniculatum, Excoecaria ogallocha, Rhizophora mucronata and Sonneratia caseolaris and while Near Threaten (NT) species Avicennia fficinalis, Rhizophora apiculata, and Lumnitzera recemosa. Among them E agallocha dominated, while A. corniculatum showed very lowest dishibutions. Similarly, there were 9 mangrove associates were identified, Overall, the selected study Shannon-Weiner diversity showed a lowest value (H' : 1.132), with lowest evenness (J : 0.544) and low richness M:0.794), it could be athibuted to E ogallocha dominance. E. agallogha has the greatest importance value (145.78) due to its high relative density, relative frequency, and relative dominance. subsequently, L. recemosa (IVI : 44.47), S. caseolans (IVI :32.34) R. apiculata (IYI =27 .38), and A. fficiinal,s (IVI :22.41) are next in rank to E. agallocha. A total of 2519 individuals of bird species representing 30 families and 46 species including two migrant species (Gull billed tern and Common sandpiper). Among 26 species of aquatic birds and 20 species of terrestrial birds. Ardeidae (8 species) were the most dominant followed by Rallidae (3 species). The overall Shannon-Weiner Diversity Index for birds of entire study area is H':3.310. In terms of overall species richness and evenness, Margalef s Index and Pielou's Index arc 5.746 and 0.865 respectively. Based on direct field observations, there were many human induced threats noticed those are habitat modification, disturbances, fragmentation, waste disposal and other extractive uses of mangroves. This study indicates that the above threats are in the primary stage and this would be the right time to implement the protective measures.