The contribution of deep‐sea macrohabitat heterogeneity to global nematode diversity

Abstract

The great variety of geological and hydrological conditions in the deep sea generates many different habitats. Some are only recently explored, although their true extent and geographical coverage are still not fully established. Both continental margins and mid-oceanic seafloors are much more complex ecologically, geologically, chemically and hydrodynamically than originally thought. As a result, fundamental patterns of species distribution first observed and explained in the context of relatively monotonous slopes and abyssal plains must now be re-evaluated in the light of this newly recognized habitat heterogeneity. Based on a global database of nematode genus composition, collected as part of the Census of Marine Life, we show that macrohabitat heterogeneity contributes significantly to total deep-sea nematode diversity on a global scale. Different deep-sea settings harbour specific nematode assemblages. Some of them, like coral rubble zones or nodule areas, are very diverse habitats. Factors such as increased substrate complexity in the case of nodules and corals seem to facilitate the co-existence of a large number of genera with different modes of life, ranging from sediment dwelling to epifaunal. Furthermore, strong biochemical gradients in the case of vents or seeps are responsible for the success of particular genera, which are not prominent in more typical soft sediments. Many

Nematode assemblages from the Kandalaksha Depression (White Sea, 251–288 m water depth)

“…Sabatieria was not found to be abundant over the same depth range in the Arctic Laptev Sea, however (Vanaverbeke et al 1997a). Similar to slope and other shelf studies Vanreusel et al 2010), the genus Desmoscolex was abundant at some stations. This is the first time, however, that the genera Filipjeva and Aponema have been noted as dominant or subdominant.…”

Worldwide Analysis of Sedimentary DNA Reveals Major Gaps in Taxonomic Knowledge of Deep-Sea Benthos

“…Deep-sea habitat heterogeneity at larger spatial scales is poorly understood but is believed to play an important role in the maintenance of benthic biodiversity on the ocean floor (e.g., Levin et al, 2001;Van Gaever et al, 2009;Vanreusel et al, 2010;Durden et al, 2015). Our data suggest a considerable degree of taxonomic differentiation, and hence biogeographic patterning, between the soft-sediment benthic communities that are represented by our eDNA samples (Figures 6, 7).…”

“…Broad spatial distributions are reported among small-sized eukaryotic taxa such as rotaliid foraminifera (Pawlowski et al, 2007;Gooday and Jorissen, 2012), nematodes (Vanreusel et al, 2010;Zeppilli et al, 2011), and harpacticoid copepods (Menzel et al, 2011), as well as certain macrofaunal and megafaunal taxa (Sibuet, 1979;Allen, 2008). However, in some cases, detailed morphological and/or molecular re-examination of putative cosmopolitan species resulted in the recognition of cryptic species having much smaller distribution ranges (Moura et al, 2008;Brandão and Yasuhara, 2013;Krapp-Schickel and De Broyer, 2014;Yasuhara et al, 2014).…”

Drivers of deep Mediterranean megabenthos communities along longitudinal and bathymetric gradients

“…Logistics impaired the retrieval of replicates at 2000 m, and no OTMS sample was available at 2800 m depth; thus, the possibility of heterogeneous habitat cannot be disregarded. In recent years, several studies have shown the importance of habitat heterogeneity in shaping deep benthic communities (Levin & Dayton 2009, Ramírez-Llodra et al 2010b, Vanreusel et al 2010. Further studies in the bathyal and abyssal Mediterranean, including the use of imaging instruments such as remote operated vehicles or autonomous underwater vehicles, are necessary to describe in detail the deep Mediterranean expanse and to identify potential habitat characteristics that could influence heterogeneity.…”