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

Abstract

This paper shows observational evidence of internal wave generation and mixing in the southwest shelf-break region of Gran Canaria Island. Signals of periodic internal motion and related mixing events were detected through large pycnocline 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 this region. The observed diapycnal chlorophyll transport matches with mixing events, suggesting a periodic nutrient supply to the euphotic zone through internal wave mixing. We postulate that internal wave mixing may be an important mechanism contributing to the biological enhancement reported southwest of Gran Canaria Island.