Table 1. Cold-seep sites included in this study.

Region	Site	Abbreviation	Latitude (mean)	Longitude (mean)	Depth (mean)	References
Gulf of Mexico	Louisiana Upper Continental Slope	ULS	27°44′N	91°16′W	550m	Bergquist et al. 2003, Cordes et al. 2005
Gulf of Mexico	Louisiana Middle Continental Slope	MLS	27°06′N	91°10W	1500m	Cordes et al. in press
Gulf of Mexico	Louisiana Lower Continental Slope	LLS	26°21′N	94°30′W	2300m	Brooks et al. 1990, Cordes et al. 2007, Cordes et al. in press
Gulf of Mexico	Florida Escarpment	FE	26°01′N	84°55′W	3300m	Paull et al. 1984, Turnipseed et al. 2003, Cordes et al. 2007
NW Atlantic	Carolina margin Blake Ridge	BR	32°30′N	76°11′W	2155m	Van Dover et al. 2003
Barbados Prism	North Barbados Trench	BT	13.8333	−57.6666	4850m	Olu et al. 1997
Barbados Prism	South Barbados Orenoque A	OA	10°21′N	58°51′W	1700m	Jollivet et al. 1990, Olu et al. 1996
Barbados Prism	South Barbados Orenoque B	OB	10°19°	58°37	2000m	Olu et al. 1996
Barbados Prism	South Barbados El Pilar	EP	11°13N	59°21W	1200m	Olu et al. 1996
Gulf of Guinea	Congo basin Regab	Regab	05°46.89′S	09°44.66′E	3170m	Olu-le Roy et al.2007, Olu et al. 2009
Gulf of Guinea	Congo basin Astrid	Ast	4°57′S	10°09.5′E	2830m	Olu et al. unpubl.
Gulf of Guinea	Congo basin,	HH, BH, WH	04°49′S-04°46′S	9°54′E–9°56′E	3100m	Sahling et al. 2008
Gulf of Guinea	Gabon margin, Guiness	Gui	1°34.64′S	8°32.90′E	680m	Olu et al. unpubl.
Gulf of Guinea	Nigeria margin	NIG	4°59′N	4°08′E	1350m	Cordes et al. 2007
Gulf of Guinea	Nigeria margin	NIG	2°58′N	6°38′E	1600m	Galéron, Olu, et al. unpubl.

The underlined sites are included in the similarity and principal component analyses.