Chlorophyll Blooms in the Oligotrophic Gulf of Chiriqui, Panama

Nutrient subsidies may influence all dimensions of food-web dynamics: primary producers across ecosystems often face nutrient limitations, and increases in resource supply, generated by nutrient subsidies, enhance producer growth and abundance. The energy produced by primary producers is then propagated through trophic linkages, generating positive bottom-up effects on consumer populations. The Gulf of Chiriqui (GC) in Panama, known for its warm oligotrophic waters, paradoxically supports large migratory species in the Tropical Eastern Pacific. In this study, we analyze 8-day data of satellite remote sensing, including chlorophyll α (Chl-a), sea surface temperature, wind stress, precipitation, and radiation, spanning from 2003 to 2022. We examine the variability and relationships within this data set and its correlations with El Niño Southern Oscillation (ENSO) events. Our results reveal seasonal blooms in Chl-a during April to June and September to October, which appear to be influenced by ENSO events. These productivity peaks occur in the area surrounding the Hannibal Bank seamount in GC. The unique morphology of this guyot, characterized by its steep sides and rugged peaks, may disrupt ocean currents, facilitating the upwelling of nutrient-rich waters. This increase in primary productivity, as revealed by satellite data, coincides with peak dolphinfish capture dates. The findings of this study not only contribute to improved fisheries management but also help to begin understanding the processes that support the biodiversity and the migration of large pelagic species in this understudied region.