Urban development is driving the loss and subsequent fragmentation of mangrove forests in Penang, Malaysia. However, little research has focused on the implications of urbanization onto the biodiversity within mangrove forests. This study investigates and compares both vegetation and crab assemblages between urban and rural mangrove forests. Collectively, 5853 trees were recorded including 15 species from six families: Acanthaceae, Arecaceae, Lythraceae, Malvaceae, Meliaceae, and Rhizophoraceae. Avicennia marina accounted for 88.6% of all trees in the study and held the highest species importance (IV). Although the total number of mangrove tree species varied significantly between urban (14) and rural (7) mangrove forests, the mangrove forest structure based on IV did not vary significantly. In total, 633 crabs were recorded comprising 13 different species from three superfamilies: Grapsoidea, Ocypodoidea, and Paguroidea. Crab species richness did not vary between urban and rural sites, but the biomasses of five and the densities of four crab species varied significantly. Redundancy analysis (RDA) indicated that land use, salinity, and abundance of Avicennia officinalis can best describe the distribution of crab species (r² =32.7). This study indicates that smaller fragmented urban mangroves at the east coast of Penang have a relatively high tree and crab diversity and are worth protecting, in addition to the larger mangrove forests on the west coast. The preservation of small yet interconnected mangrove sites could be critical to the recruitment of their flora and fauna and should be considered in decision-making processes.

城市发展正在推动马来西亚槟城红树林的消失​​和随后的破碎化。然而，很少有研究关注城市化对红树林内生物多样性的影响。本研究调查并比较了城市和农村红树林之间的植被和螃蟹组合。共记录树木5853株，包括针叶科、槟榔科、荔枝科、锦葵科、楝科、根茎科6科15种。海葵占研究中所有树木的 88.6%，具有最高的物种重要性（IV）。尽管红树林树种总数在城市（14）和农村（7）红树林之间存在显着差异，但基于IV的红树林结构没有显着差异。总共记录了 633 只螃蟹，包括来自三个超科的 13 个不同物种：Grapsoidea、Ocypodoidea 和 Paguroidea。螃蟹物种丰富度在城乡之间没有差异，但五种螃蟹的生物量和四种螃蟹的密度差异很大。冗余分析 (RDA) 表明，Avicennia officinalis 的土地利用、盐度和丰度最能描述螃蟹物种的分布 (r ²=32.7）。这项研究表明，除了西海岸较大的红树林外，槟城东海岸较小的城市红树林具有相对较高的树木和螃蟹多样性，值得保护。保护小型但相互关联的红树林地点对于补充动植物群至关重要，应在决策过程中予以考虑。