How does seawater chemistry shape phytoplankton composition and biogeochemistry?

Biological carbon pump: Influence of changes in seawater chemistry on phytoplankton community composition and organic matter quality and export.

Micro- (e.g. iron, manganese, vitamins) and macronutrients (e.g. nitrate, phosphate) shape phytoplankton composition and primary production. The efficacy of the biological pump critically depends on the quality, quantity and transformation of organic matter originally produced by phytoplankton, and ultimately determines the long-term deposition of carbon at the ocean’s floor.

We lack a mechanistic and quantitative understanding of how trace metal chemistry (controlled by organic ligands) influences nutrient uptake of phytoplankton and vice versa. Carbon export production depends on the chemical composition of organic matter and aggregation rates and binding mechanisms of dissolved organic molecules to particles. Yet, very little is known about these processes, which contribute to the long-term ocean carbon sink.

We study the influence of nutrient limitation on the genetic, metabolic and physiological response of phytoplankton cells in the ocean [ ] and in experiments. We operate trace metal, macronutrient and high-end organic analytics [NMR]. The chemical information is connected to data on genetic, metabolic and physiological cell responses.

Using mathematical models, we want to quantify how phytoplankton composition and organic matter composition and aggregation shapes the vertical organic carbon transport in today’s and the future ocean.