Morphometrically induced estuarine phytoplankton patchiness in Pelorus Sound, New Zealand

Abstract

Phytoplankton patchiness in the main channel of Pelorus Sound, New Zealand, is primarily attributed to channel morphometry near the head of the sound. There, a large sidearm retains fresh water from flood events providing sufficient residence time for phytoplankton production to cause a bloom. Subsequent flushing of that elevated biomass, by estuarine circulation and upwelling within the sidearm, displaces parcels of high‐biomass water into the main channel on each outgoing tide. Phytoplankton aggregation along tidal fronts was also observed but only when phytoplankton biomass was high in response to a flood event. The time to reach maximum phytoplankton biomass after a flood event was 7–8 days.

Keywords:

• phytoplankton
• biomass
• chlorophyll
• patchiness
• residence time