The importance of different spatial scales in determining structural and functional characteristics of deep-sea infauna communities

Abstract

The urge to understand spatial distributions of species and communities and their causative processes has continuously instigated the development and testing of conceptual models in spatial ecology. For the deep sea, there is evidence that structural and functional characteristics of benthic communities are regulated by a multitude of biotic and environmental processes that act in concert on different spatial scales, but the spatial patterns are poorly understood compared to those for terrestrial ecosystems. Deep-sea studies generally focus on very limited scale ranges, thereby impairing our understanding of which spatial scales and associated processes are most important in driving structural and functional diversity of communities. Here, we used an extensive integrated dataset of free-living nematodes from deep-sea sediments to unravel the importance of different spatial scales in determining benthic infauna communities. Multiple-factor multivariate permutational analyses were performed on different sets of community descriptors (structure, structural and functional diversity, standing stock). The different spatial scales investigated cover two margins in the northeast Atlantic, several submarine canyons/channel/slope areas, a bathymetrical range of 700–4300 m, different sampling locations at each station, and vertical sediment profiles. The results indicated that the most important spatial scale for structural and functional diversity and standing stock variability is the smallest one; infauna communities changed substantially more with differences between sediment depth layers than with differences associated to larger geographical or bathymetrical scales. Community structure differences were greatest between stations at both margins. Important regulating ecosystem processes and the scale on which they occur are discussed. The results imply that, if we are to improve our understanding of ecosystem patterns of deep-sea infauna and the relevant processes driving their structure, structural and functional diversity, and standing stock, we must pay particular attention to the small-scale heterogeneity or patchiness and the causative mechanisms acting on that scale

Distribution of Meiofauna in Bathyal Sediments Influenced by the Oxygen Minimum Zone Off Costa Rica

“…Meiofauna community composition (multivariate, square root transformed, Bray-Curtis Similarity) and total meiofauna abundance (univariate, square root transformed, Euclidean Distance) were analyzed with PERMANOVA tests (three-factor design: water depth, sediment depth, core). The random factor 'core 'was inserted as nested in water depth to account for the dependency of the sediment layers within each core; this approach has been used in several studies as a good solution to the sediment layer dependence issue (e.g., Ingels and Vanreusel, 2013;Rosli et al, 2016). This design allows us to investigate differences between water depths and sediment layers simultaneously.…”

“…The importance of food quantity and availability on nematode abundance and diversity in OMZs has also been suggested by Cook et al (2000) for the Arabian Sea. Food availability is a regulating factor along the vertical sediment profile (Ingels et al, 2009(Ingels et al, , 2011Ingels and Vanreusel, 2013). At the Costa Rica margin, meiofauna densities declined with increasing depth in the sediment, a recurrent gradient observed in marine sediments (Levin et al, 2002;Soltwedel et al, 2005).…”

The Whittard Canyon – A case study of submarine canyon processes

“…This lack of bathymetric pattern has been observed in several canyons, independent of geographical region or canyon-scale environmental conditions (Bianchelli et al, 2010;Ingels et al, 2013a;Romano et al, 2013;Leduc et al, 2014;Pusceddu et al, 2013) and is likely reminiscent of canyon heterogeneity and associated environmental variability exerting influence on benthic assemblages. More important are small-scale environmental conditions that act on the scale of meiofauna and nematodes, such as those associated with sediment grain size and sediment depth, or the amount and availability of food (Ingels et al, 2013b, Leduc et al, 2012, 2014b. Ingels et al (2011) water depths (Danovaro et al, 2009, Ingels et al, 2011, Gambi and Danovaro, 2016.…”

Nematode diversity patterns at different spatial scales in bathyal sediments of the Mediterranean Sea

“…This procedure might lead to possibly biased results, as different proportions of the nematode communities could be extracted from different samples. Nevertheless, we adopted this procedure as it is the standard methodology used in practically all nematode studies in the deep sea (Danovaro et al, 2008a, b;Leduc et al, 2012;Ingels and Vanreusel, 2013), thus allowing the comparison of our data with previous studies.…”