Abstract
We sampled the Darwin mud volcano (MV) for meiofaunal community and trophic
structure in relation to pore-water geochemistry along a 10 m transect from a seep site on the rim
of the crater towards the MV slope. Pore-water profiles indicated considerable variation in
upward methane (CH4) flow among sediment cores taken along the transect, with highest flux in
the seep sediment core, gradually decreasing along the transect, to no CH4 flux in the core taken
at a 5 m distance. Low sulphate concentrations and high levels of total alkalinity and sulphide
(H2S) suggested that anaerobic oxidation of methane (AOM) occurred close to the sediment surface
in the seep sediment core. High H2S levels had a genus- and species-specific impact on meiofaunal
densities. Nematode genus composition varied gradually between sediment cores, with the
genus Sabatieria dominating almost all sediment cores. However, genus diversity increased with
increasing distance from the seep site. These limited data suggest that the community structure of
seep meiofauna is highly dependent on local (a)biotic habitat characteristics, and a typical seep
meiofaunal community cannot be delineated. Stable isotope values suggested the nematode diet
up to 10 m from the seep site included thiotrophic carbon. The thicker hemipelagic sediment layer
(photosynthetic carbon), the increased trophic diversity, and the heavier nematode δ13C farther
from the seep site suggest a decrease in thiotrophy and an increase in photosynthetic carbon in
the nematode diet.
Original language | English |
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Pages (from-to) | 71-83 |
Journal | Marine Ecology Progress Series |
Volume | 438 |
DOIs | |
Publication status | Published - 2011 |