Diversity of meiofauna at deep-sea hydrothermal vents and cold seeps with particular reference to nematodes

Deep-sea hydrothermal vents and cold seeps are remarkable for their spectacular megaand macrofauna, many of which appear to have a high level of endemism to these chemosynthetic environments. It is not clear whether the patterns of biodiversity, faunal zonation and biogeography documented in these size categories, are also present in the meiofauna. This thesis examines the diversity and density patterns of the meiofauna (with particular reference to nematodes) in quantitative samples collected from: Bathymodiolus mussel beds in a deep-sea hydrothermal vent field on the East Pacific Rise; Bathymodiolus mussel beds at an Atlantic methane seep site; an Atlantic hydrothermal vent sediment mound and a reference non-chemosynthetic sediment site on the Mid-Atlantic Ridge. Results suggested that deep-water chemosynthetic substrata will generally harbour assemblages exhibiting lower diversity and elevated dominance. The densities of meiobenthos appeared to vary in accordance with the presence of macrofauna. From the study of the meiobenthos of hydrothermal vent mussel beds spanning 27 degrees of latitude on the EPR, the nematodes share the same, if not a larger biogeographical province as the macrofauna. From comparison of data collected from the vent mussel beds and the Atlantic methane seep mussel bed, it was evident that the species composition of the nematode assemblage was completely different. Density levels and major taxa composition were very similar as a result of similar local factors acting within the mussel beds. Based on a comparison of data collected from all mussel bed samples and the hydrothermal sediment core, it was evident that the nematode assemblages were significantly different. Factors determining all the observed differences are discussed.EThOS - Electronic Theses Online ServiceGBUnited Kingdo