Biogeographic Patterns Among Deep-Sea Benthic Megafaunal Communities Across the Drake Passage (Southern Ocean)

• Main Author: Auscavitch, Steven R.
• Format: Text
• Language: unknown
• Published: DigitalCommons@UMaine 2014
• Subjects: Benthic animals; Benthic plants; Drake Passage; Marine Biology; Antarctic; Southern Ocean; Antarctic Peninsula; Cape Horn; Burdwood Bank; Antarc*
• Online Access: https://digitalcommons.library.umaine.edu/etd/2213; https://digitalcommons.library.umaine.edu/cgi/viewcontent.cgi?article=3253&context=etd

The Southern Ocean has long been recognized as a biogeographic discontinuity for marine organisms. The Drake Passage, a region bounded by the South America shelf to the north and the Western Antarctic Peninsula to the south, represents a convergence of several biogeographic sub-regions, yet many benthic communities throughout the region remain poorly characterized. This work seeks to provide a survey and comparison of nine deep-sea benthic communities across the Drake Passage using recently collected seafloor imagery and environmental data from cruises in 2008 and 2011. Over one thousand images across nine sites were examined for species composition, megafaunal density, and seafloor substrate characteristics. Towed camera observations revealed substantial sponge and coral diversity and abundance among several sites throughout Burdwood Bank, Cape Horn, as well as two offshore seamounts. Sars and Interim Seamounts exhibited multiple unique assemblages of invertebrate faunas including cold-water corals, anemones, and sponges compositionally similar to adjacent shelf environments. Multivariate biogeographic analyses among megafaunal communities suggest bathymetric patterns consistent within major Southern Ocean water masses including Subantarctic Mode Waters, Antarctic Intermediate Waters, and Circumpolar Deep Waters. As a result of this exploratory assessment, seamounts should be a focus of further examination of benthic communities throughout the Southern Ocean to provide insight to the role that these features play in defining regional biogeographic patterns.