About This Project

Marine phytoplankton activity is abundant at a global scale and play a major role in the carbon cycle. However, the availability of nutrients is limited in the ocean, thus restraining the activity of phytoplankton. Proposed ocean-based climate solutions include adding nutrients to trigger phytoplankton blooms, but previous research indicates the impact is uncertain. We will address the nutrient requirements and how the cells use these nutrients in phytoplankton.

Ask the Scientists

What is the context of this research?

Tiny marine microbes known as phytoplankton are vastly abundant in the ocean and one of the major primary producers in the ocean. However, nutrient availability such as phosphorus and trace metals may limit phytoplankton growth. Major regions of the ocean are limited in iron, and phosphorus becomes limited at certain times of the year. Growth limiting levels of cobalt and zinc have been measured in oceanic surface levels. Previous research indicates that nutrient limitation in phytoplankton biomass varies depending on the nutrient and region. My experiments aim to identify which nutrients cause productivity, the minimum requirement of each nutrient, and their respective pathways in the cell via proteomics.

What is the significance of this project?

Despite the fact that the ocean has absorbed nearly a third of the atmospheric carbon dioxide, the global climate is on track to exceed a 1.5 degrees Celsius increase. Therefore, scientists are studying ways to store excess carbon dioxide in a timely matter. One proposed solution is to add small amounts of trace nutrients to trigger phytoplankton blooms, specifically additions of iron. However, previous research indicates that variable cellular stoichiometry, rapid turnover of nutrients within the food web, and the differing bioavailability complicate inferences of nutrient limitations. Therefore, it is important to understand which nutrients are prioritized by phytoplankton and their minimal requirements before introducing nutrient additions as an ocean-based climate solution.

What are the goals of the project?

To determine which nutrients propel growth in phytoplankton, I will collect raw samples in one-liter bottles from seawater in the Costa Rica Thermal Dome, which is known for enhanced primary productivity of cyanobacteria, in May 2023. There will be four experiments divided across six treatments repeated three times per treatment: control, iron, cobalt, zinc, iron and cobalt, and iron and zinc. After a period of time, nutrients will be added to each bottle to determine impact of these additional nutrients. Each experiment will be 18 bottles. The biomass of the phytoplankton will be measured to determine how much growth occurred before and after nutrient additions.