Skip Navigation

This Article
Right arrow Full Text
Right arrow Full Text (PDF)
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Services
Right arrow Email this article to a friend
Right arrow Similar articles in this journal
Right arrow Similar articles in ISI Web of Science
Right arrow Alert me to new issues of the journal
Right arrow Add to My Personal Archive
Right arrow Download to citation manager
Right arrow Search for citing articles in:
ISI Web of Science (5)
Right arrowRequest Permissions
Google Scholar
Right arrow Articles by De Robertis, A.
Right arrow Search for Related Content
PubMed
Right arrow Articles by De Robertis, A.
Social Bookmarking
Add to CiteULike   Add to Connotea   Add to Del.icio.us  
What's this?

Journal of Plankton Research Vol.24 no.11 pp.1207-1220, 2002
© Oxford University Press 2002

Small-scale spatial distribution of the euphausiid Euphausia pacifica and overlap with planktivorous fishes

Alex De Robertis

Scripps Institution Of Oceanography, La Jolla Ca 92093–0208

Email: alex.derobertis{at}noaa.gov

Present Address: Northwest Fisheries Science Center, Hatfield Marine Science Center, Newport Or 97365, Usa

The spatial distribution of zooplankton and planktivorous fish in Saanich Inlet, British Columbia was characterized with a 445 kHz multibeam sonar capable of localizing individual animals in three dimensions. Numerical simulation of data processing procedures indicates that this instrument has sufficient resolution to characterize zooplankton spatial distributions using Lloyd’s index of patchiness and nearest neighbour distance (NND) measures. Zooplankters at this site were dominated by the euphausiid Euphausia pacifica which underwent diel vertical migration (DVM). Fish (mainly herring and walleye pollock) were only abundant at this deep-water station at night. Analysis of 4 m3 volumes over scales of ~100 m indicates that both euphausiids and fish were strongly aggregated in the vertical dimension, but not in the horizontal dimension. In the horizontal dimension, fish distributions were independent of zooplankton abundance, indicating that the fish were not exploiting small-scale horizontal prey aggregations. Analysis of NND at the centimetre scale indicates that euphausiids were not aggregated, but rather, they were approximately randomly distributed. These observations indicate that in this environment euphausiids do not form subsurface social aggregations as has been documented in other locations. DVM and social aggregation are both predator avoidance behaviours that may be redundant, as populations that exhibit pronounced DVM may derive little additional benefit from routine social aggregation.


Add to CiteULike CiteULike   Add to Connotea Connotea   Add to Del.icio.us Del.icio.us    What's this?


This article has been cited by other articles:


Home page
 ICES J. Mar. Sci.Home page
A. De Robertis, C. Schell, and J. S Jaffe
Acoustic observations of the swimming behavior of the euphausiid Euphausia pacifica Hansen
ICES J. Mar. Sci., January 1, 2003; 60(4): 885 - 898.
[Abstract] [Full Text] [PDF]


Disclaimer: Please note that abstracts for content published before 1996 were created through digital scanning and may therefore not exactly replicate the text of the original print issues. All efforts have been made to ensure accuracy, but the Publisher will not be held responsible for any remaining inaccuracies. If you require any further clarification, please contact our Customer Services Department.