Chlorophyll increase due to internal waves on the shelf break of Gran Canaria (Canary Islands)

Abstract

This paper shows observational evidence of internal wave generation and mixing in the southwest shelf-breakregion of Gran Canaria Island. Signals of periodic internal motion and related mixing events were detected through largepycnocline variations and subcritical gradient Richardson events. Broad areas of homogeneous dense water over the slope,where the vertical temperature field displays a wave-like pattern, provide further evidences of internal wave mixing in thisregion. The observed diapycnal chlorophyll transport matches with mixing events, suggesting a periodic nutrient supply tothe euphotic zone through internal wave mixing. We postulate that internal wave mixing may be an important mechanismcontributing to the biological enhancement reported southwest of Gran Canaria Island.