Biodiversity of Mollusca on Rocky Intertidal Shore of Abu-Qir Bay, Alexandria, Egypt: A Comparative Study

Research on marine biodiversity in Egypt is limited.The present study provides a comprehensive survey and ecological analysis of the biodiversity of Mollusca species inhabiting the rocky shores of Abu-Qir Bay. The diversity, abundance, and frequency of occurrence of the surveyed species were compared with those previously documented 25 years ago by Farag et al. (1999) in the same station to assess the potential impacts of the previously mentioned threats on Molluscan populations. Qualitative and quantitative surveys were conducted from March 2023 to February 2024. The survey recorded a total of 29 molluscan species belonging to two classes, Bivalvia and Gastropoda. The present study recorded an increase in the number of species, species richness (SR), Shannon diversity index (H'), and Pielou's evenness index (J'). The number of species has increased from 17 to 29, species richness (SR) has increased from 1.689 to 3.2534, the Shannon diversity index (H') has risen from 0.1212 to 2.419, and Pielou's evenness index (J') has increased from 0.0428 to 0.718. On the other hand, species abundance decreased from 12969.9 ind. /m² in 1999 to 5465.4 ind./ m². This kind of study is needed for understanding the long-term impacts of threats on biodiversity and for developing strategies to mitigate these effects and protect marine biodiversity.