A Study on Mangrove Diversity in Vankaalai Estuary, Mannar

Abstract

The mangrove along Vangalai coastal area associated with numerous marine flora and fauna
communities remained rarely studied. The present study was carried out during the period
from April to July 2015 to document the status of mangrove distribution of selected sample
sites in Vankaalai estuary, Mannar. Seven belt-transects of 10 m in width were laid
perpendicular to the shoreline. Data were collected on floristic composition and tree height
along the plot of each sites. Mangrove Diversity and evenness were calculated using
Shannon-Wiener diversity index and Pielou‟s evenness index respectively from each sub-plot
(100 m2) in belt transects.

Results revealed that six mangrove species such as Avicennia marina (Avicenniaceae),
Rhizophora mucronata (Rhizophoraceae), Bruguiera cylindrica (Rhizophoraceae),
Sonneratia alba (Sonneratiaceae), Excoecaria agallocha (Euphorbiaceae) and Pemphis
acidula (Lythraceae) were recorded from the mangrove forest in study period. Further, 5
major mangrove associated plants were observed in the study period. The greatest mangrove
diversity (1.296) was observed in sub-plot 14 of transect 5 and the lowest mangrove diversity
(0.453) was recorded in sub-plot 3 of transect 1. The results showed that A. marina was the
dominant species. Species diversity (H‟) of whole mangrove area studied was 1.155 and
evenness (E) was 0.645. It revealed that Vankaalai lagoon should be protected since it
consists of high biological diversity of mangroves.

Keywords: Mangroves, Diversity, Evenness, Transect