Seasonal variation of intertidal Gastropoda at rocky and sandy habitats of Umm Al-Namil Island, Kuwait, north-western Arabian Gulf

Gastropoda assemblages were investigated for four seasons in 2016–2017 (autumn, winter, spring, and summer) near Umm Al-Namil Island in Kuwait in rocky and sandy habitats to study the effect of season and habitat type on species richness, abundance, evenness, and diversity. A total of 28 gastropod species belonging to 14 families were identified (26 in sandy, 20 in rocky, 18 in common between both habitats). Clypeomorus bifasciata (31.07%) and Trochus erithreus (21.43%) were the most abundant species in the rocky habitat. Pirenella arabica (27.51%), C. bifasciata (26.15%) and Mitrella blanda (15.66%) dominated the sandy habitat. At the rocky habitat, total abundance ranged from 6.5 ± 4.71 to 40 ± 45.17 ind m⁻² in autumn and summer, respectively. As for the sandy habitat, total abundance varied from 53.0 ± 22.60 to 294.0 ± 316.67 ind m⁻² in summer and winter, respectively. The results of the rocky habitat showed that diversity and evenness were strongly affected by season more than habitat type. Species richness and abundance were strongly influenced by habitat type rather than the season. However, the sandy habitat had a higher value of abundance, diversity, species richness, and evenness throughout the sampling period than the rocky habitat. There was almost a distinction between the species resident in both habitats throughout the study. These findings could be attributed mainly to the feeding habits of these gastropods and their burrowing nature.