THE EFFECTS OF IRON SUPPLEMENTATION ON PRIMARY PRODUCERS IN THE WESTERN EQUATORIAL PACIFIC OCEAN

Abstract

This study investigates the effect of iron (FeCl3) incubation on phytoplankton growth in the western Equatorial Pacific, an area known for its high-nutrient, low-chlorophyll (HNLC) conditions, which limit primary production. The El Niño-Southern Oscillation (ENSO) shifts between El Niño and La Niña, with neutral periods between them. During El Niño, nutrient availability is decreased, leading to a lack of primary production. Iron is an essential nutrient for primary production, and the western Equatorial Pacific is known for its low iron availability. Therefore, I hypothesize that FeCl3 incubation will increase phytoplankton growth. To test this hypothesis, I collected water from various stations in the western Equatorial Pacific and incubated it with FeCl3. I monitored phytoplankton growth and nutrient concentrations through chlorophyll measurements and size fractionation. My results showed that FeCl3 incubation increased phytoplankton growth, supporting my hypothesis. Furthermore, I used a dilute acid test to determine chlorophyll-a concentration in the stimulated chlorophyll colonies. My results suggest that iron is a limiting ingredient in the western equatorial Pacific, and bioavailable iron increased phytoplankton biomass. In conclusion, my study provides evidence that iron incubation can enhance phytoplankton growth in HNLC regions of the western Equatorial Pacific. My findings suggest that iron availability is critical in regulating primary production in these areas. Understanding the biogeochemical processes that control primary production in HNLC regions can provide essential insights into global climate change and biogeochemical cycling.