First insights into the biodiversity and biogeography of the Southern Ocean deep sea.
Shallow marine benthic communities around Antarctica show high levels of endemism, gigantism, slow growth, longevity and late maturity, as well as adaptive radiations that have generated considerable biodiversity in some taxa. The deeper parts of the Southern Ocean exhibit some unique environmental features, including a very deep continental shelf and a weakly stratified water column, and are the source for much of the deep water in the world ocean. These features suggest that deep-sea faunas around the Antarctic may be related both to adjacent shelf communities and to those in other oceans. Unlike shallow-water Antarctic benthic communities, however, little is known about life in this vast deep-sea region. Here, we report new data from recent sampling expeditions in the deep Weddell Sea and adjacent areas (748-6,348 m water depth) that reveal high levels of new biodiversity; for example, 674 isopods species, of which 585 were new to science. Bathymetric and biogeographic trends varied between taxa. In groups such as the isopods and polychaetes, slope assemblages included species that have invaded from the shelf. In other taxa, the shelf and slope assemblages were more distinct. Abyssal faunas tended to have stronger links to other oceans, particularly the Atlantic, but mainly in taxa with good dispersal capabilities, such as the Foraminifera. The isopods, ostracods and nematodes, which are poor dispersers, include many species currently known only from the Southern Ocean. Our findings challenge suggestions that deep-sea diversity is depressed in the Southern Ocean and provide a basis for exploring the evolutionary significance of the varied biogeographic patterns observed in this remote environment.
Brandt
Angelika
A
Zoological Museum Hamburg, Martin-Luther-King-Platz 3, 20146 Hamburg, Germany. abrandt@zoologie.uni-hamburg.de
Gooday
Andrew J
AJ
Brandão
Simone N
SN
Brix
Saskia
S
Brökeland
Wiebke
W
Cedhagen
Tomas
T
Choudhury
Madhumita
M
Cornelius
Nils
N
Danis
Bruno
B
De Mesel
Ilse
I
Diaz
Robert J
RJ
Gillan
David C
DC
Ebbe
Brigitte
B
Howe
John A
JA
Janussen
Dorte
D
Kaiser
Stefanie
S
Linse
Katrin
K
Malyutina
Marina
M
Pawlowski
Jan
J
Raupach
Michael
M
Vanreusel
Ann
A
D000818:Animals; D000864:Antarctic Regions; D044822:Biodiversity; D005843:Geography; D007448:Invertebrates / Q000145:classification / Q000502:physiology; D008386:Marine Biology; D009792:Oceans and Seas; D010802:Phylogeny; D012623:Seawater