Diversity at deep-sea hydrothermal vent and intertidal mussel beds

Hydrothermal vents are well-known for their exotic faunas, but common ecological descriptors of communities, apart from species lists, have eluded vent ecologists for decades. Using replicate sampling, we examine species richness, diversity, evenness, and composition within mussel beds at the Lucky Strike hydrothermal vent field on the Mid-Atlantic Ridge, and we compare these measures to those found at intertidal mussel beds along the south-central Alaskan coast using similar sampling efforts. The number of species found at the vent mussel beds is less than half that of the intertidal mussel beds. From calculations of diversity and evenness indices, we find that the lower diversity of the vent mussel beds is a reflection of a reduced number of rare species found there compared to intertidal mussel beds. In contrast to relatively even distributions of deep-sea soft-sediment (non-vent) communities, both vent and intertidal mussel beds share the attribute of very uneven distributions, with a large number of individuals found in a small number of species. Based on comparisons of the Shannon diversity index (H) within vent mussel beds and in a variety of other marine environments, we find that diversity at vent mussel beds is low, but no lower than the diversity measured in certain shallow-water environments. We hypothesize that diversity within the Lucky Strike mussel beds, located on a slow-spreading ridge where the spacing between vents is large, represents the low extreme of diversity at hydrothermal vents. We expect higher diversity at mussel beds on fast-spreading ridges (e.g., on the East Pacific Rise).

Duke Scholars

Author Cindy Van Dover Marine Science and Conservation