Enriched Abundance of Diverse Vibrio parahaemolyticus in the Dead-End of the Ala Wai Canal: A Tropical Artificial Urban Estuary

Vibrio pathogens in marine estuaries pose significant human health risks through recreational water use and seafood contamination. This study used the Ala Wai Canal in Honolulu, Hawaii, as a model tropical urban marine estuary to understand the Vibrio population’s composition and associated environmental health risks. Vibrio-specific 16S rRNA gene amplicon sequencing identified diverse Vibrio populations. Among the 62 major amplicon sequencing variants (ASVs) detected, V. parahaemolyticus-clustered ASVs were significantly more prevalent than those clustered with V. cholerae and V. vulnificus. Spatial distribution of the Vibrio ASVs showed that V. parahaemolyticus-clustered ASVs were highly abundant toward the stagnant end of the canal with higher turbidity and BOD₅ than sites near the freshwater inlets and the ocean outlet. DNA fingerprinting of V. parahaemolyticus isolates obtained from the water showed significant genetic diversity, corresponding to the ASV-based diversity and indicating the presence of diverse environmental niches. The V. parahaemolyticus population in the canal water exhibited a low detection frequency of the virulence factor tdh and an antibiotic resistance profile typical of environmental isolates. The identification of V. parahaemolyticus as the most prevalent Vibrio pathogen and its enrichment within the stagnant terminus of the canal suggest that increased water circulation may change Vibrio ecology and alleviate potential health risks.