  Marine plankton play a crucial role in carbon storage, oxygen production,
global climate, and ecosystem function. Planktonic ecosystems are embedded in a
Lagrangian 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 which accounts for all these
aspects; tracking the water patch hosting a drifting ecosystem along with its
physical, environmental, and biochemical features. The model 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 propagation 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
several fold. This work indicates that we must account for these processes when
interpreting and modelling marine ecosystems and provides a framework with
which to do so.
