WHITE-NOISE-LIKE DISTRIBUTION OF THE OCEANIC COPEPOD NEOCALANUS-CRISTATUS IN THE SUB-ARCTIC NORTH PACIFIC

Continuous estimates of Neocalanus cristatus abundance were obtained with an electric particle counter along a cruise track in the subarctic western North Pacific in spring. In meso- to megascale observations, with sampling interval 510 m and coverage 2519 km, the number of patches decreased exponentially both with increasing patch size and with density of the copepods in the patch. The maximum patch size and density were 6.6 km and 1230 ind. m-3, respectively. In micro-scale observations, with sampling interval 10 to 30 m, the number of patches also decreased exponentially with patch size and density. Spectral analysis of temperature, salinity, in vivo chlorophyll fluorescense and copepod abundance showed that the copepod did not have the characteristic patch-length or wave-number dependencies observed in the other parameters. These white-noise-like spectra, together with the general observations on micro- to mega-scales, suggested that N. cristatus had patches in all length scales from at least 10 m to 50 km and that patches of a given order were constituted by the gathering of smaller-scale patches.