Assessing the utility of a continuous, underway fish egg sampler (CUFES) for sampling zooplankton

Abstract

The accuracy of using a continuous underway fish egg sampler (CUFES) to sample zooplankton was assessed by comparing CUFES samples with those collected using a vertically towed bongo net. Samples were collected concurrently by the two samplers along four inshore–offshore  transects off the south-western coast of South Africa. Frequency of occurrence and abundance estimates of 14 taxonomic groups were compared between samplers. Seven taxa had similar frequencies of  occurrence and there was a significant, positive relationship in zooplankton abundance between samplers. There were consistent differences between day and night samples; night-time abundance in  CUFES samples was generally greater than daytime abundance. Spatial patterns of zooplankton distribution from each sampler were similar for some groups. Species composition was significantly different, with a greater proportion of large zooplankton in the vertical bongo net samples than in CUFES samples. The CUFES appears to be a good sampler for some small zooplankton, including crustacean eggs, juvenile Metridia spp, Oithona spp. and juvenile amphipods.

Keywords: bongo nets; CUFES; vertical migration; zooplankton abundance

African Journal of Marine Science 2009, 31(2): 181–189