The Importance of Vertical and Horizontal Dimensions of the Sediment Matrix in Structuring Nematodes Across Spatial Scales

Author(s)

Vieira, Danilo Candido ^{[1, 2]} ; Fonseca, Gustavo ^[1]

Affiliation

^[1] Univ Sao Paulo, Ctr Biol Marinha CEBIMar, Sao Paulo - Brazil

^[2] Univ Fed Parana UFPR, CEM, Pontal Do Parana, Parana - Brazil

• Document type: Journal article
• Source: PLoS One; v. 8, n. 10 OCT 30 2013.
• Web of Science Citations: 8

Abstract

Intensive surveys have been conducted to unravel spatial patterns of benthic infauna communities. Although it has been recognized that benthic organisms are spatially structured along the horizontal and vertical dimensions of the sediment, little is known on how these two dimensions interact with each other. In this study we investigated the interdependence between the vertical and horizontal dimensions in structuring marine nematodes assemblages. We tested whether the similarity in nematode species composition along the horizontal dimension was dependent on the vertical layer of the sediment. To test this hypothesis, three-cm interval sediment samples (15 cm depth) were taken independently from two bedforms in three estuaries. Results indicated that assemblages living in the top layers are more abundant, species rich and less variable, in terms of species presence/absence and relative abundances, than assemblages living in the deeper layers. Results showed that redox potential explained the greatest amount (12%) of variability in species composition, more than depth or particle size. The fauna inhabiting the more oxygenated layers were more homogeneous across the horizontal scales than those from the reduced layers. In contrast to previous studies, which suggested that reduced layers are characterized by a specific set of tolerant species, the present study showed that species assemblages in the deeper layers are more causal (characterized mainly by vagrant species). The proposed mechanism is that at the superficial oxygenated layers, species have higher chances of being resuspended and displaced over longer distances by passive transport, while at the deeper anoxic layers they are restricted to active dispersal from the above and nearby sediments. Such restriction in the dispersal potential together with the unfavorable environmental conditions leads to randomness in the presence of species resulting in the high variability between assemblages along the horizontal dimension. (AU)

• FAPESP's process: 09/14019-0 - Free living marine nematodes: taxonomy, systematics and phylogeny
• Grantee: Gustavo Fernandes Camargo Fonseca
• Support Opportunities: Research Grants - Young Investigators Grants