Stress-Induced Dwarfism in Avicennia marina Across Coastal Gradients of the Red Sea and Arabian Gulf, Saudi Arabia.

<b>Background and

Objective

</b> <i>Avicennia marina</i> is the dominant mangrove species along the Saudi Arabian coasts of the Red Sea and the Arabian Gulf, where extreme environmental conditions frequently result in dwarf growth forms. This study evaluated regional variation in mangrove growth form and the distribution of dwarf stands across contrasting coastal environments. <b>Materials and

Methods

</b> Field surveys were conducted during the first half of 2026 at 121 sampling sites distributed across the Northern Red Sea (27), Central Red Sea (37), Southern Red Sea (20) and the Arabian Gulf (37). Tree height was measured to classify mangrove growth forms and regional differences were analyzed using one-way analysis of variance (ANOVA) followed by Tukey's honestly significant difference (HSD) test. <b>

Results

&lt;/b&gt; Tree height differed significantly among regions (p<0.001). The Northern Red Sea exhibited the lowest mean tree height (2.49±0.77 m) and the greatest prevalence of dwarf mangroves, whereas significantly taller trees were recorded in the Central Red Sea (3.67±1.22 m), Southern Red Sea (3.63±1.44 m) and the Arabian Gulf (3.68±1.31 m). These results demonstrate pronounced spatial variation in the structural development of &lt;i&gt;A. marina&lt;/i&gt; along the Saudi Arabian coastline. &lt;b&gt;

Conclusion

&lt;/b&gt; &lt;i&gt;Avicennia marina&lt;/i&gt; exhibits marked regional differences in growth form, with dwarf mangroves predominating in the Northern Red Sea. The findings establish a regional baseline for evaluating structural variability in &lt;i&gt;A. marina&lt;/i&gt; and advance current understanding of mangrove dwarfism in arid coastal ecosystems.