Porifera community structure as a bioindicator of tourism impacts at Iboih Beach, Sabang

This study aims to identify the composition, distribution, and diversity of Porifera species in the coral reef ecosystem of Iboih Beach, Sabang, as a scientific basis for marine biodiversity conservation and the development of invertebrate zoology learning materials in higher education. The research was conducted from June to July 2025 using line transect and 1 m² quadrat sampling methods across three shallow reef zones. A total of 21 Porifera species were identified, predominantly from the class Demospongiae, with Spongia, Haliclona, and Petrosia as dominant genera. Species identification was performed through both macroscopic morphological observations and microscopic analysis of spicule structures. The Shannon-Wiener diversity index (H') ranged from 1.95 to 2.67, indicating a moderate level of diversity. Species distribution was strongly influenced by substrate type, with the highest abundance recorded on hard coral substrates, while sandy areas showed lower diversity. Approximately 20% of sponge colonies were partially covered by fine sediment and macroalgae, especially near snorkeling zones, suggesting ecological pressure from tourism. These findings provide essential baseline data for long-term biodiversity monitoring, promote sustainable marine tourism, and support the contextualization of zoological education through local marine resources.