Multiscaling statistical procedures for the exploration of biophysical couplings in intermittent turbulence. Part II. Applications

Turbulence has widely been recognized as a source of homogeneity in phytoplankton distributions at scales of less than 1 m. However, it is shown here, using univariate and bivariate procedures specifically developed to investigate the properties of single and joint intermittent stochastic processes, that the small-scale phytoplankton distribution investigated in the Eastern English Channel over four tidal cycles is never fully homogenized and presents a differential coupling with temperature, for turbulent intensities ranging from 5×10−7 to 10−4 m2 s−3. More specifically, patchiness increases with decreasing turbulence intensity, and is higher during ebb than during flood tide for similar turbulence intensities. The coupling between phytoplankton and temperature distributions increases with increasing turbulence intensity, and is stronger during flood tide. Taking into account the hydrodynamic and tidal characteristics of the study area, as well as the composition of the phytoplankton community, phenomenological explanations are provided for the observed patterns converging towards a combination of biologically and physically induced patchiness, and turbulence-controlled biophysical couplings. Taking into account the detailed intermittent complexity of marine data sets can lead to a valuable, unique gain in understanding structures and functions of marine ecosystems.