Assessing the roles of environmental factors in shaping Vibrio-phytoplankton associations in Northern Sarawak, Malaysia

Abstract

The genus Vibrio forms associations with phytoplankton, using algal cells as vectors for proliferation and survival in aquatic environments. These interactions serve as a reservoir for Vibrio species, influencing the ecology of estuarine and potentially affecting the concentration and distribution of pathogenic Vibrio. Despite extensive research on Vibrio and phytoplankton interactions, little is known about their associations with key environmental factors such as temperature, pH, and salinity. This study aimed to determine the concentrations of Vibrio species, environmental factors influencing their proliferation, and analyse Vibrio-phytoplankton interactions. Water samples were collected from two estuaries, with physicochemical parameters recorded in-situ. Phytoplankton abundance was determined microscopically, while Vibrio isolation was conducted using TCBS agar. Molecular identification of Vibrio species was performed using PCR amplification of species-specific genes (OmpW for V. cholerae and ToxR for V. parahaemolyticus). The results showed that 36.7% (n=22/60) of the samples positive for V. cholerae and 31.7% (n=19/60) were positive for V. parahaemolyticus. None of the isolates tested positive for the ctxA and tdh virulence genes. Statistical analysis revealed significant differences (p < 0.05) between Vibrio concentrations, water temperature and salinity, but pH showed no significant effect. Pearson's correlation analysis revealed positive correlations between Vibrio concentrations with high temperature (31.2 – 34.5 ºC) and salinity (28.7 - 31.0 ppt), while exhibiting a negative correlation with phytoplankton concentration. Phytoplankton was influenced by temperature and salinity, with high salinity reducing abundance. The results of this study may provide insights into potential public health risks posed by Vibrio species in estuarine ecosystems and contribute to understanding their ecological dynamics in Northern Sarawak, Malaysia.