Patterns of diel vertical migration of zooplankton in acoustic Doppler velocity and backscatter data on the Newfoundland Shelf

Backscatter data from moored acoustic Doppler current profilers (ADCPs) are analysed to quantify the diel vertical migration patterns of zooplankton on the Newfoundland Shelf, Canada. Data from 11 moorings provide long time series (similar to 100 days each) for in-depth statistical analysis. For one deployment, dry weight measurements of zooplankton are used to calibrate the acoustic backscatter. Quantification methods are developed and applied to the backscatter and vertical velocity time series to determine the characteristics of the observed diel migration. We show that the migration responds to changes in light intensity and water column temperature structure. We have sufficient spatial data to show high correlation of migration characteristics over spatial scales of up to tens of kilometres.