TITLE

Spatio-temporal variability in the distribution of epi- and meso-pelagic acoustic backscatter in the Irminger Sea, North Atlantic, with implications for predation onCalanus finmarchicus

AUTHOR(S)

Anderson, C.I.H.; Brierley, A. S.; Armstrong, F.

PUB. DATE

April 2005

SOURCE

Marine Biology;Apr2005, Vol. 146 Issue 6, p1177

SOURCE TYPE

Academic Journal

DOC. TYPE

Article

ABSTRACT

The deep scattering layers of the North Atlantic, including the Irminger Sea, contain many predators of the key copepod speciesCalanus finmarchicus. Previous seasonally restricted studies have described the deep acoustic scattering layers of the Irminger Sea as �ubiquitous�. They have shown that the intensity of the acoustic backscatter varies across the region, and so, by implication, the potential predation pressure onC. finmarchicusalso varies spatially. This paper reports observations of the distribution of epi-pelagic (0-200 m) and meso-pelagic (200-1,000 m) acoustic backscatter in the Irminger Sea, made using a scientific echosounder operating at 38 kHz during four seasonal (winter, spring and summer) cruises. Our study demonstrates that the intensity of the backscatter varies seasonally in regionally distinct ways across the Irminger Sea. The mean acoustic backscatter, both in the upper 800 m and upper 200 m of the water column, varied significantly between the northern, central and southern areas of the central basin (�open ocean�), and within each area between the Greenland shelf slope, open ocean and Mid-Atlantic Ridge subregions. Different patterns of seasonal change in the acoustic backscatter between the upper 800 m and upper 200 m were also seen, indicating both persistent differences in the underlying amount of backscatter in each area, and varying patterns of seasonal increase in the near surface backscatter in the different areas and subregions. These observations could be related to the different oceanographic regimes encountered in each location, and are discussed in terms of their implications for potential predation pressure onC. finmarchicus.

ACCESSION #

16795230

Tags: CALANUS finmarchicus;  CALANUS;  PREDATORY aquatic animals;  PREDATORY animals;  SPATIO-temporal variation;  VARIATION (Biology)

 

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