Use of laser optical plankton counter and zooscan for determining spatial and temporal variations in mesozooplankton community structure in Brazilian coastal ecosystems

Abstract

New optical technologies, such as the Laser Optical Plankton Counter (LOPC) and the ZOOSCAN yield highly resolved information on the abundance, size distribution and taxonomic composition of zooplankton communities. However, they require careful calibration in a given environmental setting before routine sampling can be achieved. This proposal seeks to demonstrate the ability of the LOPC and the ZOOSCAN to resolve zooplankton community dynamics in relation to the physical environment off Ubatuba, São Paulo coast, and over Abrolhos Bank, Bahia State (Eastern Brazilian coast). These areas are subject to varying physical forcing on the pelagic and benthic communities. In order to adequately relate the biological and physical variability the study areas have to be sampled with the same high spatial resolution. To that respect, the LOPC will be deployed in the framework of a multidisciplinary research program over Abrolhos Bank during winter 2007 and summer 2008 and in monthly intervals on the ANTARES bio-optical monitoring station off Ubatuba. Calibration of the LOPC signal will be achieved via a comparison with concomitantly taken net-samples, for which zooplankton composition will be determined in the laboratory, either by a semi-automated image analysis system or by a novel zooplankton scanning device, the ZOOSCAN. The calibrated LOPC and ZOOSCAN results will be interpreted in relation to the physical and biological variability of the study areas and yield new information on the fine scales on which zooplankton communities (copepods, larvae of benthic organisms and ichthyoplankton) vary spatially and temporally, and on the processes governing this variability.