PhD Advisor: Professor Carlos M. Duarte

Abstract:
Mesopelagic fish are among the most abundant vertebrates in the ocean, central to food webs and carbon sequestration via diel vertical migration. Yet, their diversity, ecology, and biomass in the Red Sea remain poorly understood. Two dominant species were studied, linking diet, genetics, and biomass to their role in carbon cycling. DNA metabarcoding and ROV observations revealed niche partitioning: both consumed copepods, but lanternfish fed more on benthic invertebrates, while lightfish consumed gelatinous prey, with rare video evidence confirming benthic feeding. A new parasitic copepod was discovered in the lightfish. Genetic analyses uncovered high haplotype diversity, panmixia, recent expansion, and a cryptic lanternfish lineage endemic to the Red Sea and Gulf of Oman. Finally, deep-learning analysis of ROV footage provided the first ground-truthed biomass estimates, highlighting southern Red Sea hotspots. Together, these findings advance understanding of mesopelagic fish ecology, biodiversity, and carbon flux.

Bio:
Kah Kheng Lim is a PhD candidate in the Tarek Ahmed Juffali Research Chair in Red Sea Ecology (TAJRC) group at KAUST. His research focuses on the diet, population genetics, and biomass estimation of the two most abundant mesopelagic fish species in the Red Sea, aiming to better understand their role in carbon sequestration in the Red Sea and beyond.