Mangrove ecosystems in East Java are highly vulnerable to contamination from human activities and marine debris, including plastics. This study examined the shapes and distribution of microplastics (MPs) in sediment, water, and wild crabs across ten mangrove ecosystems in northern and southern East Java. Using digestion and density separation methods, six MP shapes were identified: fiber, fragment, foam, film, pellet, and microbead. Fibers were the most common in water, while fragments were dominant in sediments. Wild crabs contained 48 MP particles in their gills and digestive tracts, with fibers making up over 60% of the total MPs. Correlation analysis showed a significant link between MPs in sediment and their presence in crabs, indicating potential biomagnification risks. Factor analysis highlighted key contributors to pollution in marine protected areas, emphasizing the complexity of coastal contamination and the urgent need for mitigation efforts.