Small-scale horizontal distribution of coastal copepods

The horizontal spatial distribution of four species of coastal copepods was investigated by pumping two continuous series of samples and subjecting the data collected to statistical analysis. Sampling was conducted 1.5 km offshore of Moolack Beach, Oregon, at a depth of 7 m. Two small boats, each equipped with a pump of 280 1 min^?1 capacity, were anchored 40 m apart and collected a series of 50 consecutive, paired Zooplankton samples. Current speed and direction were measured at the beginning of each sampling interval. The amplitude and frequency of the fluctuations in copepod densities indicate large changes in density over linear distances of 30 m to a few hundreds of meters. Maxima of abundance occurred simultaneously for most categories of copepods counted. Time series analysis showed that there was a lag of 12 min (equivalent to 159 m) between the occurrence of abundance maxima at the seaward and shoreward boats. This suggests that the variations in zooplankton density occurred in a pattern which is oblique to the direction of the current.