Comparing abyssal nematode assemblages of physically disturbed and adjacent sites of the eastern equatorial Pacific


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kvopel [ at ] awi-bremerhaven.de

Abstract

The nematode assemblages of experimentally impacted and adjacent sediments in abyssal depths of the eastern equatorial Pacific were investigated seven years after a physical disturbance was set. A total of 3048 nematodes belonging to 68 genera and 26 families were identified. Abundance data were subjected to univariate and multivariate statistical analyses, which discriminate between sites based on their faunistic attributes. The nematode fauna at both disturbed and control sites was dominated by specimens belonging to the genera Acantholaimus, Chromadorita, Thalassomonhystera, Desmoscolex, Halalaimus and Diplopeltula. These genera contribute to about 55 % and 50 % of total nematode fauna in the disturbed and control sites, respectively. The mean relative abundance of the dominant genus Acantholaimus amounted to about 20 %. Generic diversity, evenness and richness at the undisturbed sites do not significantly differ from the corresponding median values at the disturbed sites. Mean k-dominance curves show differences in community structure between treatments. Ordination of Ö- and ÖÖ-transformed family abundances revealed groupings of the disturbed and undisturbed samples (significant at the 5 % level), whereas ordination of genus abundances did not. Sample variability was investigated by inspection of the relationship between variance and mean abundance of genera and families in each sample group and by calculating the comparative Index of Multivariate Dispersion (IMD). There is a clear increase in the standard deviation for a given mean of genus or family abundances at the disturbed sites. A higher variability among the disturbed samples, however, does not appear to be true in the multivariate sense.



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ISI/Scopus peer-reviewed
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Published
Eprint ID
3224
Cite as
Vopel, K. and Thiel, H. (2001): Comparing abyssal nematode assemblages of physically disturbed and adjacent sites of the eastern equatorial Pacific , Deep-sea research part ii-topical studies in oceanography:, 48 , pp. 3795-3808 .


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