Free-living marine nematodes from hydrothermal sediments:similarities with communities from diverse reduced habitats

Abstract

The meiofauna of hydrothermal deep-sea sediments in the North Fiji Basin (NE Pacific) was investigated. Nematodes were the dominant taxon. The structure of the hydrothermal nematode communities from the Fiji Basin is compared with (1) the communities from adjacent oxic deep-sea sediments. ( 2 ) other hydrothermal vent areas and (3) shallow reduced environments such as cold seeps and subsurface anoxic sediments of eutrophic bottoms. Although the genus composition of the hydrothermal area and the biodiversity on a generic or functional-morphological level did not deviate greatly from the control areas, we found differences at the species level and in the size spectra and the species diversity. None of the species found in the hydrothermal sediments occurred in the surrounding areas. The size spectra of the vent communities was shifted towards larger nematodes, and species diversity was much lower in the hydrothermal area. The similarity in nematode genus composition between hydrothermal sites and control areas stands in contrast with the presence of a specialized endemic hydrothermal macrofauna. The absence of a planktonic life stage, in combination with small size, makes it more difficult for nematode species to migrate between isolated hydrothermal patches.

Rapid colonisation by nematodes on organic and inorganic substrata deployed at the deep-sea Lucky Strike hydrothermal vent field (Mid-Atlantic Ridge)

“…To our knowledge, information on hydrothermal vent nematode biomass is reported exclusively by two studies (Vanreusel et al 1997;Gollner et al 2007). In the deep-sea HV of the North Fiji Basin, the mean weight was between 0.23 and 0.35 μg wet wt in active HVs and 0.15 μg wet wt in inactive sites (Vanreusel et al 1997).…”

“…Several HV habitats, from inactive bare basalts (Gollner et al 2010b) and sediments (Vanreusel et al 1997) to diffuse flow areas colonized by macrofaunal assemblages (Zekely et al 2006a, c), host meiofaunal communities characterized by low abundance and diversity, linked with the abiotic and biotic conditions of the habitat (Gollner et al 2010b;Zekely et al 2006a, c;Degen et al 2012). In most cases, nematodes and copepods are the most abundant meiofaunal organisms (Vanreusel et al 2010;Zeppilli et al submitted).…”

“…In most cases, nematodes and copepods are the most abundant meiofaunal organisms (Vanreusel et al 2010;Zeppilli et al submitted). The nematodes identified in vents can belong to families and genera already known from non-vent habitats (Dinet et al 1988;Vanreusel et al 1997;Zekely et al 2006c;Sarrazin et al in press). In some hydrothermal vents such as at the North Fiji Basin (Vanreusel et al 1997) and IzuOgasawara Arc in the western North Pacific Ocean (Setoguchi et al 2014), none of the nematode species found in hydrothermal sediments occurred in the surrounding abyssal areas.…”

“…The nematodes identified in vents can belong to families and genera already known from non-vent habitats (Dinet et al 1988;Vanreusel et al 1997;Zekely et al 2006c;Sarrazin et al in press). In some hydrothermal vents such as at the North Fiji Basin (Vanreusel et al 1997) and IzuOgasawara Arc in the western North Pacific Ocean (Setoguchi et al 2014), none of the nematode species found in hydrothermal sediments occurred in the surrounding abyssal areas. Conversely, at the EPR, several nematode vent species have been found in abyssal sediments surrounding hydrothermal vent fields (Gollner et al 2010b(Gollner et al , 2015.…”

A new species of Copepoda Harpacticoida, Xylora calyptogenae spec. n., with a carnivorous life-style from a hydrothermally active submarine volcano in the New Ireland Fore-Arc system (Papua New Guinea) with notes on the systematics of the Donsiellinae Lang, 1948

“…For instance, the Dirivultidae Humes and Dojiri, 1980 (Copepoda, Siphonostomatoida), which represent 10% of the vent copepods known worldwide, are reported from vents and seeps only. On the other hand, a different impression is given by the free-living nematodes from hydrothermal deep-sea sediments in the North Fiji Basin, where the genus composition does not deviate greatly from control areas in adjacent oxic deepsea sediments (Vanreusel et al 1997). X. calyptogenae spec.…”