MEPS 173:267-274 (1998)  -  doi:10.3354/meps173267

Demersal ichthyofaunal distribution in the abyssal North Atlantic revisited: the effect of sample size on ordination

N. R. Merrett1,*, M. J. R. Fasham2

1Zoology Department, The Natural History Museum, Cromwell Road, London SW7 5BD, United Kingdom
2Southampton Oceanography Centre, Empress Dock, Southampton, Hampshire SO14 3ZH, United Kingdom

ABSTRACT: Abyssal benthic trawling is time-consuming and therefore costly. In practice, such sampling to elucidate demersal fish ecology accrues largely opportunistically over long periods. Thus, it was that striking contrasts in fish morphology, ultimate size, feeding pattern and fecundity were identified across a north-south boundary zone in the eastern North Atlantic from 12 samples. The results were later refined with the addition of a further 13 samples. Now, collection of a further 20 samples, making a total of 45, has broadened spatial coverage further. This has led to former sample groupings coalescing to complicate initial indications and published interpretations, although confirming the major findings. Hence, evidence of the influence of latitude on sample composition (together with that on the biological characteristics of the dominant species) was strengthened (consistent with response to changes in overlying productivity suggested initially). Yet the influence of bathymetry on sample composition was considerably weakened, although remaining significant, especially along latitude 31°N close to the zone of ichthyofaunal change.


KEY WORDS: Abyssal ichthyofauna · Distribution · MDS ordination · Sample size · NE Atlantic


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