Naslov
Recovery of nematofauna after the anoxic stress: the analysis of multivariate and univariate aspects of nematode assemblages structure

Autori
Travizi, Ana

Vrsta, podvrsta i kategorija rada
Sažeci sa skupova, sažetak, znanstveni

Izvornik
Abstracts / Ott, J., Stachowitsch, M., Napetsching, S. - Beč : Pro Mare, 2005

Skup
40th European Marine Biology Symposium

Mjesto i datum
Beč, Austrija, 21.08.2005. - 25.08.2005

Vrsta sudjelovanja
Poster

Vrsta recenzije
Međunarodna recenzija

Ključne riječi
meiofauna; Nematoda; anoxia; stagnation; recovery; structure; dynamics

Sažetak
This study is part of comprehensive investigation of meiofauna recovery at three northern Adriatic offshore sites (SJ 005: 13o08.0'E, 45o18.4'N ; SJ 007: 13o16.0'E, 45o17.0'N ; SJ 107: 13o19.0'E, 45o26.1'N) over the biennial postanoxic period. Previously reported results concerning spatio-temporal recovery of meiofauna pointed out outstanding dominance (88-99%) of free-living nematodes and distinguished them as main promoters of recovery process. Nematofauna density distribution pointed out two distinctive temporal patterns, attributed to periods of stagnancy (6-7 months after the anoxic stress) and subsequent recovery. The first period is characterized by low nematofauna densities (51-356 ind. 10-2), while the second one is characterized by conspicuous monthly oscillations and remarkably higher densities (622-2844 ind. 10-2). In order to reveal the main community attributes associated with observed density patterns, the original data sets (15 samples collected in monthly intervals, and subsequent 4 samples obtained seasonally), as well as pooled data (stagnation vs. recovery) were subjected to statistical analyses. For temporal variability of nematode composition multivariate techniques (hierarchical agglomerative clustering and MDS) were used. The results based on original data sets of species abundance, clearly separated samples attributed to stagnancy from samples attributed to recovery of nematofauna. Stress coefficients (< 0.05) indicated excellent MDS representation, and one-way ANOSIM revealed high R values (RSJ005=1, RSJ007=0.96, RSJ107=0.92) and statistically significant differences (p< 0.1) between samples associated with contrasted periods. Multivariate analyses discriminated two successive nematode assemblages at each location, both using the original and pooled data sets. The latter approach revealed that recovery was influenced by site-specific composition of nematofauna, despite the occurrence of same temporal pattern at all sites monitored. Faunistic affinity between sites SJ 007 and SJ 107 was higher then in comparison with SJ 005. Statistically significant differences of nematofauna composition were established for sites SJ 005 and SJ 107 at p<0.4. Such a finding suggested different relative importance of particular species to recovery occurring at particular sites. To find out the main differences in taxonomic composition, and to reveal species responsible for discrimination of successive nematofauna assemblages, data were subjected to SIMPER analysis. The results will be discussed in presentation. Univariate aspect of assemblages structure was studied by calculating set of common univariate indices, erected to describe species diversity (S, H', H, d, &#61474; ), dominance (D, &#955; ), and evenness (J'). Statistically significant differences of species richness, diversity and dominance were established only for site SJ 005 &#8211; where recovery period was distinguished by increase of species diversity and equitability, as well as decrease of species dominance. At sites SJ 007 and SJ 107 no differences in univariate indices between contrasted periods were found. Recovery of nematofauna at these sites could be attributed to replacement of unstable nematode assemblages dominated by r-selected and tolerant species with more stable assemblages dominated by K-selected species. Such a finding suggests that acute anoxic event is associated with high mortality of competitive dominants and their replacement with opportunistic and tolerant species, that affects total nematofauna density rather than diversity and dominance values.

Izvorni jezik
Engleski

Znanstvena područja
Geologija

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