Biovolume-size spectra of epipelagic zooplankton using a multi-frequency acoustic profiling system (MAPS)

Zooplankton biovolume data from a Multi-frequency Acoustic Profiling System were used to construct biovolume-size spectra for the Gulf Stream and the Southern California Bight. These spectra were linear through most, but not all, of the size range sampled (0.025-4.00 mm, ESR). Analysis of covariance was sometimes a useful tool to distinguish among spectra taken at different times and places. Difference spectra offered an alternative method of visualizing disparities between spectra. We compared our acoustically-derived spectra from the Gulf Stream with those obtained from other oceans with different samplers and those obtained in the same waters with a different sampler. The results indicate that differences attributable to sampler bias within the same system presently make it difficult, if not impossible, to interpret comparisons from different samplers in different ecosystems.