Resumen de Thraustochytrids (fungoid protists): an unexplored component of marine sediment microbiota
L. Bongiorni, Luciano Pignataro, G. Santagelo
Thraustochytrids are poorly known fungoid protists able to decompose refractory organic substrates such as cellulose. These microorganisms probably play an important role in the microbial loop of marine sediments. This paper reports a study conducted on thraustochytrids dwelling in a sandy shore of the Eastern Ligurian Sea. One hundred twenty eight samples (1 ml each) were collected, to examine Thraustochytrid spatial distribution, following a nested ANOVA design, that incorporated 3 successively smaller spatial scales (different sampling units ranging from metres to centimetres). Samples were examined by a direct, improved, fluorochrome-count method also suitable for ciliates. Sampling was repeated 4 times in autumn-winter. The average abundance of thraustochytrids (±SE) was 42.3±2.9 ml-1, with no significant decrease over time. The densities of thraustochytrids and ciliates varied significantly but at different spatial scales: the former between squares (3.3 x 3.3 m), and the latter between subplots (0.01 x 0.01m), indicating their tendency to form patches at different spatial scales. A significant correlation was found between the densities of the two protists, suggesting some interaction between them could occur. The thraustochytrid abundance supports the idea that these protists play a an important role in carbon cycling of Mediterranean sandy shores.
