Abstract
Cold seep areas are extremely reduced habitats with spatial-temporally variation of hydrocarbon-rich fluids seepage, low oxygen levels and great habitat heterogeneity. Cold seeps can create circular to ellipsoid shallow depressions on the seafloor called pockmarks. We investigated two selected pockmarks, characterized by different gas emission, and two sites outside these geological structures at the Mozambique Channel to understand whether and how their environmental conditions affect the kinorhynch fauna in terms of density, richness and community composition. A total of eleven species have been found living in the studied area, of which three are new species: Fissuroderes cthulhu sp. nov., Fujuriphyes dagon sp. nov. and Fujuriphyes hydra sp. nov. Densities outside the pockmarks are low and regularly decrease from the upper sediment layers, whereas inside the pockmarks density reaches its highest value at layer 1-2 cm, strongly decreasing along the vertical profile from this depth. Areas under pockmark influence and locations outside pockmarks are similar in terms of species richness, but kinorhynchs showed a significant remarkable higher density at the pockmark sites. Additionally, species composition changes between habitats (inside and outside pockmarks) and between the two sampled pockmarks, with most of the species restricted to one of the studied habitats, except for Condyloderes sp. and Echinoderes unispinosus present both outside and inside the pockmarks. Echinoderes hviidarum, E. unispinosus and Fi. cthulhu sp. nov., present at sites with gas emission, do not only survive under the specific pockmark conditions (characterized by hydrogen sulphide toxicity, methane high concentration and low availability of dissolved oxygen) but even profit from a habitat with a likely lower competition for space and resources, flourishing and enhancing the density, most likely through the replacement with specialized species. Contrarily, species that only appear outside the pockmarks do not seem to cope with the presence of hydrogen sulphide and methane. Therefore, environmental factors linked to gas emissions have a major role driving the kinorhynch community composition.
Highlights
Worldwide oceans cover about 361.9 million km2 of the earth’s surface, of which ∼70% are deep sea plains (Eakins and Sharman, 2010)
The main aim of the present paper is to characterize the kinorhynch community associated with pockmarks in the Mozambique Channel deep sea to (1) identify and describe the new species inhabiting the area, (2) report potential kinorhynch species as indicators of cold seep areas, and (3) determine possible differences in richness, density, and species composition inside and outside pockmarks and along the vertical profile
Two additional specimens mounted for scanning electron microscopy (SEM), same collecting data as type material, deposited at the Meiofauna Collection of the UCM
Summary
Worldwide oceans cover about 361.9 million km of the earth’s surface, of which ∼70% are deep sea plains (Eakins and Sharman, 2010). Organisms inhabiting cold seeps take advantage of the habitat heterogeneity formed by the variable fluid release intensity and the hydrocarbon-rich fluid concentration of the sediment to occupy extreme, reduced niches that other organisms are unable to inhabit (Levin, 2005; Guillon et al, 2017) These adapted species can reach high levels of abundance and biomass (Rouse and Fauchald, 1997; Levin, 2005; Seitzinger et al, 2010; Vanreusel et al, 2010; Guillon et al, 2017; Sun et al, 2017) as a consequence of few species having evolved the morphophysiological adaptations required to live in such a challenging habitat (Hourdez and Lallier, 2006; Zeppilli et al, 2018)
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
