A study of salt secretion by mangroves of Rekawa Lagoon, Sri Lanka

Abstract

A method to measure the salt secretion by mangroves which are open to the sea spray was developed and used to measure the salt secretion by mangrove species of Rekawa lagoon, an ecosystem with the highest diversity of true mangroves in southern Sri Lanka. Out of the twelve species of mangroves, only four species i.e. Acanthus ilicifolius, Aegiceras corniculatum, Avicennia marina, and Avicennia officinalis proved to be able to secrete salts. Under the salinity regime (26.2 ± 4.41 ppt) existed during the experimental period, the salt secretion by leaves of these four species were 47.2 ± 18.3, 35.1 ± 16.0, 149.3 ± 45.9, and 81.6 ± 30.5 mg salt cm −2 day −1 respectively. This result corroborates the published records and, hence validates the technique used in this study to measure the salt secretion. These four species exhibited increases in salt secretion with increases in soil salinity, consistent with previous reports. Results of this study also shows that the capacity to secrete salts at any given salinity was different between four species, following an order of Av. marina > Av. officinalis > Ac. ilicifolius, and Ae. corniculatum. The salt secretion by these species immediately after reducing the soil salinity was increased significantly implying an opportunistic removal of salt, which was accumulated in the plant body under high saline condition. Capacity for salt secretion by the four species as well as the magnitude of the increase of salt secretion as a response to increasing soil salinity, vary in parallel to the variations in salt tolerance given in published reports for the same species.

Analysis of the diversity and evenness of mangrove ecosystems in the Pacitan Coast, East Java, Indonesia

“…Like other mangrove plants, A. corniculatum also has a special adaptation to survive in mangrove conditions, namely salt secretion and crypto-vivipary (Feng et al 2021). The increase in soil salinity triggers increasing salt secretion from the A. corniculatum's leaves to remove salt accumulation in the plant body (Jayatissa et al 2006). Furthermore, the crypto-vivipary reproductive system allows the embryo to penetrate the seed coat but cannot penetrate the fruit wall before being in a favorable environment (Elmqvist and Cox 1996;Shi et al 2005;Tomlinson 2016).…”