If you scroll down the extracts on the right, you will see that the features do indeed arise in a single year -- somewhere in 2007. They appear stronger in the 2007 composite than in the mission-length composite because thay have not been diluted by averaging with the other four and a half years of more typical chlorophyll concentrations.
I continued to look at shorter and shorter time periods and thereby traced the patches of high chlorophyll to a few scattered days during the austral, late winter and spring.
I've singled out two Aqua-MODIS orbits that account for most of the anomalous feature in the chlorophyll composite of the entire mission.
