A Review of Secchi's Contribution to Marine Optics and the Foundation of Secchi Disk Science

Linear and nonlinear internal waves are widespread phenomena with important implications for the ocean's ecology. Here, we review the biological impacts of non-breaking internal waves for three broad categories of organisms sessile organisms, passive plankton, and depth-keeping plankton. We use heuristic simulations to contrast the effects of passing internal waves for each of these groups. In the case of irradiance, an isobaric quantity, light availability is only modulated for passive plankton. Wave-induced horizontal transport enhances this effect, because transport in the direction of wave propagation implies that passive plankton spend longer within each wave. This is true for both linear waves, where horizontal transport is due exclusively to Stokes drift, as well as for weakly nonlinear waves, where transport arises from both nonlinearity and Stokes drift. In the case of depth-keeping plankton, a similar effect is seen for isopycnal properties. In a simple example, where we set the vertical distribution of temperature to match that of density, wave-induced horizontal transport alters the overall water temperatures depth-keeping plankton are exposed to. These results emphasize that horizontal transport within internal waves is not only important to dispersal but also modulates the effects of wave-induced vertical disturbances on plankton.