A Lagrangian model for drifting ecosystems reveals heterogeneity-driven enhancement of marine plankton blooms

Marine plankton play a crucial role in carbon storage, global climate, and ecosystem function. Planktonic ecosystems are embedded in patches of water that are continuously moving, stretching, and diluting. These processes drive inhomegeneities on a range of scales, with implications for the integrated ecosystem properties, but are hard to characterize. We present a theoretical framework that accounts for all these aspects; tracking the water patch hosting a drifting ecosystem along with its physical, environmental, and biochemical features. The theory resolves patch dilution and internal physical mixing as a function of oceanic strain and diffusion. Ecological dynamics are parameterized by an idealized nutrient and phytoplankton population and we specifically capture the time evolution of the biochemical spatial variances to represent within-patch heterogeneity. We find that, depending only on the physical processes to which the water patch is subjected, the plankton biomass response to a resource perturbation can vary in size up to six times. This work indicates that we must account for these processes when interpreting and modeling marine ecosystems and provides a framework with which to do so. Modelling a planktonic ecosystem in the ocean is challenging as it is embedded in a patch of water that is continuously moving, stretching, and diluting. This study introduces a new theoretical framework to account for such aspects, tracking a patch of water hosting a drifting ecosystem, along with its physical, environmental and biochemical features.

Automated summary

Marine plankton are essential for carbon storage, global climate, and ecosystem function. This study introduces a new theoretical framework to track and model the dynamics of a drifting ecosystem embedded in a moving and diluting water patch. The research highlights the importance of considering physical processes and patch heterogeneity in interpreting and modeling marine ecosystems.