The role of monsoon-driven oceanographic variability in recruitment patterns of key intertidal space occupiers on tropical rocky shores on the west coast of Thailand, Indian Ocean

We investigated the influences of oceanographic variables on recruitment patterns of the acorn barnacle Chthamalus malayensis and the rock oyster Saccostrea cuccullata, key space occupiers on tropical intertidal rocky shores. Recruitment data and nearshore environmental variables were obtained at spatial (regional and local) and temporal (monthly) scales on the west coast of Thailand. The relationship between the recruitment of each species and combinations of environmental variables was modeled. The climate of the study sites is influenced by the southwest and northeast monsoons of the Indochinese monsoon system. Observations showed that recruitment of both species and oceanographic variables exhibited differences at either local scale or monthly scale or both. Recruitment of both species was positively related to temperature, while barnacle recruitment was negatively related to salinity, but oyster recruitment was positively related to salinity. Barnacles showed a greater rate of recruitment when south-westerly onshore winds predominated during the southwest monsoon season, while the influence of wind patterns on rock oyster recruitment was not clear. Differential larval delivery regulated by monsoon-driven currents is, therefore, a potential determinant of barnacle recruitment. Our study highlights the roles of monsoon-influenced oceanographic processes as predictors of recruitment patterns of intertidal species in a tropical system. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s10750-023-05256-w.