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

Daniela Zeppilli,Florence Pradillon,Sandra Fuchs,Ann Vanreusel,Tristan James,Perrine Mandon,Jozée Sarrazin

doi:10.1007/s12526-015-0348-2

Abstract

Despite the fragmented nature of hydrothermal vent (HV) fields, nascent vent sites are rapidly colonized by a pool of regional species. While succession of large animals at vents is relatively well established, we lack information on the associated meiofauna, in particular, on nematodes. The aim of the present study is to investigate the process of colonisation after 9 months of organic (wood and bone) and inorganic (slate) substrata by nematode assemblages deployed at the Eiffel Tower hydrothermal edifice on the Lucky Strike vent field on the Mid-Atlantic Ridge (MAR), at varying distances from visible hydrothermal activity. Abundance, biomass and diversity of colonising nematodes were compared with the results from an earlier similar two-year experiment. Near the vents, nematodes preferred inorganic substrata while in areas not influenced by vent activity, organic substrata were preferred. Nematode females dominated at almost all sites while numerous females at the ovigerous stage and juveniles were reported near the vent emissions, suggesting that nematode populations reproduce well after just 9 months. Our nine-month experiment on the MAR showed that the type of substratum influenced significantly the composition of colonising nematodes, while after two years, the community structure was instead influenced by hydrothermal activity.

Highlights

Hydrothermal vents (HVs) are extreme environments where percolating cold seawater (∼2–4 °C) penetrates the fractured oceanic crust
We evaluated the relationship after 9 months between nematode abundance, biomass, diversity and environmental variables and type of substrata conducting a non-parametric multivariate multiple regression analysis (DistLM: distance-based linear model) using the PERMANOVA + add-on package for PRIMER6 software (McArdle and Anderson 2001; Anderson et al 2008)
This study followed the previous pilot deployment of paired wood/slate panels in close proximity of hydrothermal emissions on and around the Eiffel Tower hydrothermal edifice performed by Cuvelier et al 2014

Summary

Introduction

Hydrothermal vents (HVs) are extreme environments where percolating cold seawater (∼2–4 °C) penetrates the fractured oceanic crust. Being heated and enriched with reduced chemicals, the hydrothermal fluid emerges from the seafloor at temperatures up to 400 °C (Van Dover 2000). Hydrothermal organisms are adapted to the presence of extreme environmental conditions (high concentrations of reduced compounds, heavy metals and radionucleides, low oxygen level, and elevated temperatures; Sarradin et al 1999; Charmasson et al 2009). Hydrothermal habitats are ephemeral and they have a longevity that is directly related to volcanic, tectonic and magmatic processes (Van Dover 2000). As hot fluid venting is transient, hydrothermal vent sites have ephemeral lifespans ranging from years (e.g. HV 9°50′ N at the East Pacific Rise (EPR); Shank et al 1998; Lutz et al 2008) to decades or, exceptionally, centuries [e.g., the Mid-Atlantic Ridge, (MAR); Humphris et al 2002].

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