Morphology and Structure Adaptation of Avicennia and Sonneratia Growing in Lagoon, Island, and Bay

Abstract Mangrove ecosystems face increasing environmental threats and changes, making it crucial to unravel the complex interrelationship between Avicennia and Sonneratia and their diverse habitats. This study identified the environmental factors, including water salinity and substrate, that impact the distribution and abundance of Avicennia alba, A. marina, A. rumphiana, Sonneratia alba, and S. caseolaris. Three unique mangrove habitats include the isolated rocky island of Pulau Burong, the muddy-sand inland lagoon of Pengkalan Nangka, and the sandy mud to firm mud of coastal Teluk Buih. Pulau Burong is surrounded by marine water of salinity 31 to 35, Pengkalan Nangka is brackish water ranging from 12 to 19, and Teluk Buih is brackish to marine water of salinity 15 to 32. A. alba and A. marina from Pulau Burong have shorter leaf lengths, narrower widths, and thicker leaves compared to Pengkalan Nangka Lagoon and Teluk Buih (p<0.05). Similarly, S. alba from Pulau Burong has a shorter leaf length, narrower width, and thicker leaves than Teluk Buih. Water salinity had perfectly negative correlations with the leaf length of A. alba (r= -0.93) and A. marina (r= -0.91). A. marina leaf width and thickness were strongly negatively correlated with water salinity (r= -0.85 for leaf width and r= -0.84 for thickness). All three Avicenniaspecies' flowering responses, including cyme-like spike inflorescences, were documented. These findings enhance understanding of Avicenniaand Sonneratia ecology in the context of unique ecosystems facing environmental challenges.