Colonization of synthetic sponges at the deep-sea Lucky Strike hydrothermal vent field (Mid-Atlantic Ridge): a first insight

Abstract

The main objective of the present study was to investigate invertebrate colonization processes at deepsea hydrothermal vents in response to environmental factors and to the presence of complex artificial substrata (i.e., synthetic sponges). We set out a pilot experiment at 1700 m depth on the Lucky Strike vent field (Eiffel Tower, Mid-Atlantic Ridge). Synthetic sponges were deployed in 2011 at five sites along a gradient of hydrothermal activity and were recovered in 2013, and the composition of macro-and meiofauna was assessed on four of them. The influence of temperature and fluid inputs on colonizer faunal abundance and diversity was analyzed. Faunal abundance and diversity decreased with increasing distance from vent emission. The colonizers were represented by a subset of species characterizing the natural populations at the Eiffel Tower edifice. Some taxa (e.g., pycnogonids, ophiuroids, cnidarians, foraminiferans) represented new records not yet found on deployed substrata on the Eiffel Tower. Synthetic sponges harbored a high percentage (from 17.5% to 55%) of juveniles and larval stages of polychaetes, molluscs, and copepods. A mature nematode community (mainly Cephalochaetosoma and Halomonhystera) in a reproductive stage was found. Variability in faunal composition was significantly correlated with distance from fluid emission. We hypothesize that the complex structure of inorganic sponge substrata may have favored settlement of juveniles and larvae. Sponge substrata may, therefore, help sample a wider range of organisms than other substrata, and, thereby, provide a more complete picture of vent biodiversity. The results provided in this study might improve our understanding of mechanisms that govern faunal colonization processes at vents.

Potential Mitigation and Restoration Actions in Ecosystems Impacted by Seabed Mining

“…In chemosynthetic habitats, all experiments that deployed artificial substrata were done in the presence of active venting in order to answer diverse ecological questions unrelated to mining impacts (Van Dover et al, 1988;Mullineaux et al, 1998Mullineaux et al, , 2003Mullineaux et al, , 2009Mullineaux et al, , 2010Mullineaux et al, , 2012Tunnicliffe, 1990;Govenar and Fisher, 2007;Kelly et al, 2007;Kelly and Metaxas, 2008;Pradillon et al, 2009;Ivanenko et al, 2011;Gaudron et al, 2012;Gollner et al, 2013Gollner et al, , 2015Cuvelier et al, 2014;Zeppilli et al, 2015;Plum et al, 2017;Baldrighi et al, 2018). To date, there has been no experimental deployment of colonisation of substrata in absence of a local source population (and activity).…”

“…Increasing distance from a heat source allows increased colonisation and intrusions of background fauna which may alter species composition and interactions (Mullineaux et al, 2000(Mullineaux et al, , 2003Micheli et al, 2002;Cuvelier et al, 2014). A couple of studies deployed substrata on basalt or young inactive vents (Van Dover et al, 1988;Mullineaux et al, 1998;Gollner et al, 2013Gollner et al, , 2015Plum et al, 2017;Baldrighi et al, 2018). However, basalt and inactive sulphides (possible target for mining) are two very different habitats for organisms to occupy and do not allow for generalisation among them.…”

Foresight Workshop on Advances in Ocean Biological Observations: a sustained system for deep-ocean meroplankton

“…Critical knowledge gaps on deep-sea connectivity are mainly in the temporal patterns of dispersal and settlement (Metaxas 2004, Mullineaux et al 2010, the vertical trajectories of larval dispersal (Arellano et al 2014, Yahagi et al 2017 and the comparison of larval and juvenile stages to identify post-settlement process (Arellano and Young 2010). Assessment of spatial-temporal patterns is a huge task that can only be tackled by strategic, long-term sampling through the deployment of multiple devices including automated plankton samplers (Doherty and Butman 1990, Lewis andHeckl 1991, O'Hara 1984), low cost tube traps, and recruitment experiments (Baldrighi et al 2017, Cunha et al 2013, Cuvelier et al 2014. Assessing both larval supply and settlement patterns would allow identifying postsettlement processes that are relevant for recruitment success.…”

“…Some of the criteria provided by CBD require an understanding of processes in early life history. However, while "maximising connectivity" is considered a critical design element for all MPAn (WCPA/IUCN 2007), it ranks very low in the scale of criteria most often used by managers (Balbar and Metaxas 2019). Its implementation to date has been extremely limited and hindered by inconsistencies in the terminology and concepts considered in management, which favours landscape connectivity metrics, compared to scientific research, which uses predominantly demographic and genetic connectivity estimates and modelling approaches (Balbar and Metaxas 2019).…”

Biodiversity and ecology of meiofauna in extreme and changing environments

“…The review of Rosli et al (2017) describes trends in the ecology of deep-sea meiofauna with focus on patterns and processes at small to regional spatial scales described in studies published since the last review of deep-sea meiofauna of Soltwedel (2000), and highlights areas needing further research. Zeppilli et al (2017) present an integrated review of the biodiversity, ecology and physiological responses of marine meiofauna inhabiting extreme marine environments, including mangroves, submarine caves, polar ecosystems, hypersaline areas, hypoxic/anoxic environments, hydrothermal vents, cold seeps, carcasses/sunken woods, deep-sea canyons, Baldrighi et al (2017) shows that the complex structure of inorganic sponge substrata may favour settlement of juveniles and larvae, and may provide a useful sampling method for ecological studies. Two studies within this special issue show that meiobenthic and nematode assemblages can be used to determine the ecological quality (EcoQ) of highly impacted areas Chen et al 2017).…”