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Background: Mangroves are one of the key nature-based solutions that mitigate climate change impacts. Even though they are halophytic in nature, seedlings are vulnerable to high salinity for their establishment. This study investigated the effects of different salinities on seedling growth and mineral element composition of two dominant species (Avicennia marina and Rhizophora mucronata). Methods: The study followed a randomized complete block design, i.e., main treatments (growing environment in greenhouse (GH) or net house (NH)) and four sub-treatments under 21 replicates, i.e., irrigation with 100% freshwater (0.4%o—T1), 100% saline water (35%o—T2), 50% saline water and 50% freshwater (18%o—T3), and brine water (60%o—T4). Results: Results revealed that A. marina seeds can optimally germinate and survive well reaching 80% in NH under T1. However, T2 and T4 seedlings had the lowest survival. Mineral element analysis showed that A. marina grown under NH recorded higher levels of Ca, Mg, and K which increased with increasing levels of salinity. The opposite was true with Na levels. R. mucronata on the other hand, recorded completely opposite findings with T1 seedlings reaching 95% in the greenhouse while T3 reached almost 60%. Conclusions: It can be concluded that mangrove species can optimally germinate and grow in both freshwater and 50% saline water, but growth reduction occurs with seawater and complete growth inhibition with brine water.
Kimera et al. (Wed,) studied this question.