Aquatic Sciences Meeting, Albuquerque 2001

CS37 Zooplankton

Date: Tuesday, February 13, 2001, Time: 4:15:00 PM

Location: Aztec

Schneider, J, , University of California, Santa Barbara, USA, schneide@lifesci.ucsb.edu

Quetin, L, B, University of California, Santa Barbara, USA,

Quetin, R, M, University of California, Santa Barbara, USA,

Daly, K, L, National Science Foundation, Washington D.C., USA,

THE USE OF AGGREGATION CHARACTERISTICS TO IDENTIFY DOMINANT ANTARCTIC EUPHAUSIIDS

The Antarctic Pack Ice Seals research cruise was conducted in the eastern Ross Sea and western Amundsen Sea during the austral summer of 1999-2000. Acoustic data was collected with a 120 kHz echo sounder simultaneously with net tows to document the distribution of the three species of euphausiids. A 1-m MOCNESS was used to sample the upper 200-m of the water column in 50-m depth intervals. The acoustic data was analyzed with patch finding software developed by Nero and Magnuson (1989) to identify and characterize aggregations by size, depth and density. Characteristics of single species aggregations, verified by MOCNESS results, were analyzed. In plots of density (mg/m3) versus depth (m), aggregations of E. superba were clustered, with characteristics distinct from those of E. crystallorophias and T. macrura. Aggregations of E. crystallorophias and T. macrura had similar densities with different but overlapping depth ranges. These distinct quantitative aggregation characteristics allow us to identify the dominant species within an aggregation. Thus analysis of acoustic transects, with separation of aggregations by species, is possible even when net validation is not available.

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Aquatic Sciences Meeting, Albuquerque 2001

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