Characterisation of the nematode community of a low-activity cold seep in the recently ice-shelf free Larsen B area, Eastern Antarctic Peninsula

• Published in: PLoS ONE
• Main Authors: Hauquier, Freija, Ingels, Jeroen, Gutt, Julian, Raes, Maarten, Vanreusel, Ann
• Format: Article in Journal/Newspaper
• Language: English
• Published: 2011
• Subjects: Earth and Environmental Sciences; MOSBY-MUD-VOLCANO; FREE-LIVING NEMATODES; LITTORAL PERIPHYTON COMMUNITIES; MEIOFAUNA COMMUNITIES; ORGANIC-MATTER; PACIFIC RISE; METAZOAN MEIOFAUNA; MARINE NEMATODES; SEA-ANTARCTICA; WEDDELL SEA; Antarctic; Antarctic Peninsula; Drake Passage; Pacific; Weddell; Weddell Sea; Antarc*; Antarctica; Ice Shelf
• Online Access: https://biblio.ugent.be/publication/1941844; http://hdl.handle.net/1854/LU-1941844; https://doi.org/10.1371/journal.pone.0022240; https://biblio.ugent.be/publication/1941844/file/1941867

Background: Recent climate-induced ice-shelf disintegration in the Larsen A (1995) and B (2002) areas along the Eastern Antarctic Peninsula formed a unique opportunity to assess sub-ice-shelf benthic community structure and led to the discovery of unexplored habitats, including a low-activity methane seep beneath the former Larsen B ice shelf. Since both limited particle sedimentation under previously permanent ice coverage and reduced cold-seep activity are likely to influence benthic meiofauna communities, we characterised the nematode assemblage of this low-activity cold seep and compared it with other, now seasonally ice-free, Larsen A and B stations and other Antarctic shelf areas (Weddell Sea and Drake Passage), as well as cold-seep ecosystems world-wide. Principal Findings: The nematode community at the Larsen B seep site differed significantly from other Antarctic sites in terms of dominant genera, diversity and abundance. Densities in the seep samples were high (>2000 individuals per 10 cm(2)) and showed below-surface maxima at a sediment depth of 2-3 cm in three out of four replicates. All samples were dominated by one species of the family Monhysteridae, which was identified as a Halomonhystera species that comprised between 80 and 86% of the total community. The combination of high densities, deeper density maxima and dominance of one species is shared by many cold-seep ecosystems world-wide and suggested a possible dependence upon a chemosynthetic food source. Yet stable (13)C isotopic signals (ranging between -21.97+/-0.86% and -24.85+/-1.89%) were indicative of a phytoplankton-derived food source. Conclusion: The recent ice-shelf collapse and enhanced food input from surface phytoplankton blooms were responsible for the shift from oligotrophic pre-collapse conditions to a phytodetritus-based community with high densities and low diversity. The parthenogenetic reproduction of the highly dominant Halomonhystera species is rather unusual for marine nematodes and may be responsible for the ...