Short-term response of active microeukaryotic communities to arsenic contamination in silty and sandy subtidal coastal marine sediments
Pede, A.; Gillan, D.C.; Verstraete, T.; Baré, J.; Vyverman, W.; Sabbe, K. (2012). Short-term response of active microeukaryotic communities to arsenic contamination in silty and sandy subtidal coastal marine sediments, in: Pede, A. Diversity and dynamics of protist communities in subtidal North Sea sediments in relation to metal pollution and algal bloom deposition. pp. 133-157 In: Pede, A. (2012). Diversity and dynamics of protist communities in subtidal North Sea sediments in relation to metal pollution and algal bloom deposition. PhD Thesis. Universiteit Gent; Vakgroep Biologie, Onderzoeksgroep Protistologie en Aquatische Ecologie: Gent. 200 pp., more |
| Abstract | We used an experimental approach to assess the effect of acute arsenic (As) contamination on active microeukaryotic communities in two subtidal marine sediment types. Silty sediments from a chronically metal-contaminated marine station and sandy sediments from a reference station were spiked with a range of As levels (KH2AS04; 0-960µg L-I) and incubated in the dark for 2 days. The response of the microeukaryotic communities to the different As contamination levels was analysed by 18s rRNA-based DGGE analysis. We hypothesized that communities from silty sediments would be more resistant to acute metal intoxication due to their contamination history. Ciliates (from 6 different classes), which occurred together with representatives of Cercozoa, Bacillariophyta, Amoebozoa, Euglenozoa, Fungi and Metazoa (2 nematodes) were the dominant active component of the microeukaryotic communities. We detected distinct effects of As contamination on the diversity and composition of these communities. Diversity (~number of DGGE bands) significantly decreased at contamination levels = 480 µg As L-1 in both sediment types, but the decrease was more pronounced in the sandy (43%) than in the silty sediment (32%), suggesting higher tolerance to As contamination in the silty sediment. In addition, a significant shift in community composition occurred at contamination level = 120 µg As L-1 and again at = 480 µg As L-1 in silty sediment. Surprisingly, the effect of As on protist community composition was not significant in the sandy sediment. Fungi responded most sensitively to high As concentrations, while only some ciliates increased in relative abundance with higher As levels. These included representatives from various classes such as the Phyllopharyngea, Spirotrichea, Litostomatea and Colpodea. |
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