Pergamon zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHGFEDCBA Deep-Sea Research II, Vol. 43, No. l-8, pp. 1925-1945, 1996 Copyrisht 0 1996 Elsevier Science Ltd Pm s0%7-0645(96)ooo446 Printed in Great Britain. AU rights reserved 0967-0645/96S15.00+0.00 Video Plankton Recorder estimates of copepod, pteropod and larvacean distributions from a stratified region of Georges Bank with comparative measurements from a MOCNESS sampler MARK C. BENFIELD,*t CABELL S. DAVIS,* PETER H. WIEBE,* SCOTT M. GALLAGER,* R. GREGORY LOUGH1 and NANCY J. COPLEY* (Received4 January 1995; in revisedform 29 April 1996;accepted 5 May 1996) Abstract-A two-vessel exercise was conducted over the southern flank of Ge.orges Bank during the onset of vernal stratification in May 1992. The Video Plankton Recorder (VPR), a towed video system, was used to map out the fine-scale distributions of zooplankton to a depth of 70 m along a trackline which described a regular grid (3.5 x 4.5 km) in Lagrangian space. A second vessel following a parallel course conducted Multiple Opening/Closing Net and Environmental Sensing System (MOCNESS) sampling during the last section of the grid, which provided an opportunity to compare data from the two systems. Both the VPR and the MOCNESS provided similar data on the taxonomic composition of the plankton which was numerically dominated by copepods (Calanus, Pseudocalanus, Oithona), pteropods (Limacina) and larvaceans (Oikopleura). The absence of rare (e43.1 mp3) species from the VPR dataset was a consequence of the small volume sampled (0.0694 m3) by the high magnification camera, while fragile gelatinous taxa were undersampled by the MOCNESS. Estimates of copepod and pteropod concentrations were comparable for the two gear types. While the species composition of the plankton did not change statistically along the grid, abundances of the dominant taxa varied along the transect and each taxon demonstrated pronounced fine-scale vertical patterns that appeared to be related to hydrographic features. The VPR represents a powerful tool for rapid surveys of the micro- to fine-scale structure of zooplankton assemblages either alone, or in conjunction with other sampling techniques. Copyright 0 1996 Elsevier Science Ltd INTRODUCTION The patch structure of pelagic macrozooplankton populations reflects heterogeneity in their physical, chemical, and biological environments on scales ranging from millimeters to hundreds of meters (Mackas et al., 1985; Davis et al., 1992a; Donaghay et al., 1992). High- resolution samplers have demonstrated that physico-chemical parameters exhibit substantial fine-scale (l-lOOOm, Haury et al., 1978) variability which is correlated with the distributions of planktonic larvae (Donaghay et al., 1992). Many authors (e.g. GLOBEC, 1979; Marine Zooplankton Colloquium 1, 1989; Davis et al., 1992b; Donaghay et al., 1992; Kils, 1992; Schulze et al., 1992) have pointed out the need for direct measurement of physical, chemical, and biological distributions on ecologically meaningful scales. However, limitations of conventional samplers (e.g. nets, pumps) have *Department of Biology, Woods Hole Oceanographic Institution, Woods Hole, MA 02543-1049, U.S.A. TPresent Address: Coastal Fisheries Institute, Louisiana State University, 218 Center for Wetland Resources, Baton Rouge, LA 70803, U.S.A. 1 Northeast Fisheries Science Center, National Marine Fisheries Service, NOAA, Woods Hole, MA 02543, U.S.A. 1925