Nutrient Uptake and Growth Kinetics of Novel Environmental Phytoplankton Isolates from the Galápagos Archipelago

Phytoplankton are the foundation of the marine food web, sustaining countless endemic species in the unique ecosystem of the Galápagos Archipelago. Their functional traits—such as cell size, nutrient quotas, growth and uptake rates—shape resource competition and resilience to environmental pressures. Yet, little is known about their kinetic characteristics in this region. Present research explores functional traits of diverse Galápagos eukaryotic phytoplankton spanning two orders of magnitude in size. We evaluated various allometric relationships between metabolic parameters and cell size, identifying deviations. In particular, diatoms exhibited faster growth than similarly sized taxa, suggesting distinct power law-based scaling for diatoms versus non-diatoms. The carbon quotas of larger diatoms were lower than predicted by general allometry due to presence of large vacuoles. Additionally, we explored how diurnal cycles affect physiology of Galápagos diatom Chaetoceros curvisetus. These findings enhance understanding of the effects of environmental changes on primary productivity and biodiversity.