Original Paper

Marine Biology

, Volume 156, Issue 6, pp 1289-1296

First online:

Open Access This content is freely available online to anyone, anywhere at any time.

Trophic specialisation of metazoan meiofauna at the Håkon Mosby Mud Volcano: fatty acid biomarker isotope evidence

  • Saskia Van GaeverAffiliated withMarine Biology Section, Department of Biology, Ghent University Email author 
  • , Leon MoodleyAffiliated withCenter for Estuarine and Marine Ecology, Netherlands Institute of Ecology (NIOO-KNAW)
  • , Francesca PasottiAffiliated withDipartimento Scienze del Mare, Università Politecnica delle Marche
  • , Marco HoutekamerAffiliated withCenter for Estuarine and Marine Ecology, Netherlands Institute of Ecology (NIOO-KNAW)
  • , Jack J. MiddelburgAffiliated withCenter for Estuarine and Marine Ecology, Netherlands Institute of Ecology (NIOO-KNAW)
  • , Roberto DanovaroAffiliated withDipartimento Scienze del Mare, Università Politecnica delle Marche
  • , Ann VanreuselAffiliated withMarine Biology Section, Department of Biology, Ghent University

Abstract

We report the results of a detailed investigation on the trophoecology of two dominant meiofaunal species at the Håkon Mosby Mud Volcano (HMMV), a deep-sea cold methane-venting seep. Analyses of fatty acids (FAs) and their stable carbon isotopes were used to determine the importance of chemosynthetic nutritional pathways for the dominant copepod species (morphologically very similar to Tisbe wilsoni) inhabiting the volcano’s centre and the abundant nematode Halomonhystera disjuncta from the surrounding microbial mats. The strong dominance of bacterial biomarkers (16:1ω7c, 18:1ω7c and 16:1ω8c) coupled with their individual light carbon isotopes signatures (δ 13C ranging from −52 to −81‰) and the lack of symbiotic relationships with prokaryotes (as revealed by molecular analyses and fluorescent in situ hybridisation) indicated that chemosynthetically derived carbon constitutes the main diet of both species. However, the copepod showed a stronger reliance on the utilisation of methanotrophic bacteria and contained polyunsaturated FAs of bacterial origin (20:5ω3 and 22:6ω3 with isotope signatures δ 13C < −80‰). Instead, the FA profiles of H. disjuncta suggested that sulphide-oxidising bacteria constituted the main diet of this nematode. Therefore, HMMV can be regarded as a persistent deep-sea cold seep, allowing a chemosynthesis-based trophic specialisation by the dominant meiofaunal species inhabiting its sediments. The present investigation, through the determination of the fatty acid profiles, provides the first evidence for trophic specialisation of meiofauna associated with sub-habitats within a cold seep.