Kelp Hydrodynamics

Researchers: J. Leichter (SIO UCSD), G. Pawlak (MAE/SIO UCSD), S. Monismith (Stanford)

Funding: National Science Foundation

Our research specifically seeks to quantify the wave-dependent drag forces and associated hydrodynamic mechanisms by which one of the most common forms of aquatic vegetation, giant kelp, mediates flow conditions in inner shelf habitats. The frictional drag generated by individual kelp plants and whole kelp forests strongly influence circulation and transport in coastal habitats. However, at present it is not possible to incorporate these effects into coastal circulation models. We are undertaking high-resolution field measurements to develop parameterizations of drag on a whole kelp forest in the presence of coastal currents, surface waves, and internal waves, that will be suitable for use in inner shelf circulation models. Our work is further quantifying the magnitude by which kelp forests affect cross-shore exchange on the inner shelf and to determine the mechanisms that mitigate cross-shore exchange in the presence of kelp so that our findings may be generalized to any kelp forest environment. This is relevant to understanding coastal environmental flows and their interactions with a range of types of aquatic vegetation in both natural systems and for large-scale aquaculture and ecosystem management. 

Kelp forests are common to many mid-latitude coasts, and they are among the most valuable inner shelf habitats for fisheries, recreation, and possibly biological carbon fixation. Understanding their hydrodynamics is thus important to management of coastal waters, as well as to designing natural restoration areas and potential aquaculture systems. Given the rapid development in high resolution circulation models as decision-analysis tools for coastal zone management, including the potentially large hydrodynamic effects of kelp forests can be an essential prerequisite to producing accurate predictions of inner shelf flows.