1. Fig. S1

2. Fig. S2 a) OceanLocation OTU_01OTU_02OTU_03OTU_04OTU_05OTU_06OTU_07OTU_08OTU_09OTU_10OTU_11OTU_12OTU_13OTU_14OTU_15OTU_16OTU_17OTU_18OTU_19OTU_20 Arctic Ocean 1 32 Arctic Ocean, Svalbard 1 341 1 Pacific Arctic Ocean/ Beaufort Sea 1 177 51 1 Barents Sea 1 5 1 Northern Bering Sea 3 21 562 21 1 Southern Ocean Tide gauge site, Brown Bay, McGrady Cove and Stevenson Cove, Antarctica 242 Terra Nova Bay, Antarctica 27 Bransfield Strait, Antarctica 1 3 Atlantic Ocean Baltic Sea 2 1 141 Eastern Mediterranean Sea 3 22 1 3316 1 2 4 Galicia, Spain 1 27 2 Gulf of Cádiz 1 1 1 Gulf of Mexico 1 1 Jade Bay, North Sea 12 Logatchev hydrothermal vent field/ Mid Atlantic ridge 1 1109 7 1 Mid-Atlantic Ridge 1 21 1 Milazzo Harbor/ Tirrenean Sea 1 Northern Sea 1 Sapelo Island/ Sargasso Sea 1 Trondheimsfjord, Norway/ Norwegian Sea 123 1 1 Wadden Sea 8 1 Santos–São Vicente estuary, Brazil 1 Rio de la Plata 241 362221 362 287 2 Indian Ocean Arabian Sea 1 3 Timor Sea 1 1 Crozet Island Archipelago 491978517 722345133 2141 South West Indian Ridge 2 1 1 Pacific Ocean Cascadia Margin, Oregon 1 Clarion-Clipperton Fracture Zone 2 1231 3 1 2 111 Japan Trench 21 1 Jiaozhao Bay/ Yellow Sea 1 Juan de Fuca segments/ Salish Sea 11 1 4 Monterey Canyon, CA. 2 111 Nankai Trough 1 1 1 1 Yellow Sea 136 1 13 Northeastern Japan Sea 1 12 off Shimokita Peninsula 1 Ogasawara Trench 1 1 Okhotsk Sea 1 1 Pacific Ocean 5 342 531 4 1 31 Northeastern Pacific Ocean 1 2 31 South Pacific abyssal 31 5 3 1 3 Kane’ohe Bay, O’ahu, Hawaii/ South Pacific Ocean 1 1 Pacific Warm Pool/ West Pacific Ocean 1 121 East Pacific Ocean 22 4 Western Pacific Ocean 11 Qiongdongnan basin, South China Sea 1 11 2 11 Ryukyu Trench/ East China Sea 1 4 1 Sagami bay/ Sagani Sea 3 Shane Seep in the Coal Oil Point seep field, offshore of Santa Barbara, CA 13 1 Shiribeshi Seamount, northeast Japan Sea 1 1 South China Sea 21 167 2121 134 East China sea 1 1 Ulleung Basin/ East Sea 11 West Philippine Basin/ Philippine Sea 1 Xiangshan harbor/ East China Sea 13 Yellow Sea 14 3 Yonaguni Knoll IV hydrothermal field/ East China Sea 11 Yung-An ridge, SW Taiwan/ East China Sea 1 East Lau Basin 1 111 1 1 Pacific or Atlantic Ocean Pacific Ocean and the Eastern Mediterranean Sea 33 53 225154 1 1 Pacific or Indian Ocean South China Sea, the Andaman Sea and the Indian Ocean 11 2 1 1 1 Unknown 71416298 9101217 1 2645

3. OceanLocation OTU_01OTU_02OTU_03OTU_04OTU_05OTU_06OTU_07OTU_08OTU_09OTU_10OTU_11OTU_12OTU_13OTU_14OTU_15OTU_16OTU_17OTU_18OTU_19OTU_20 Pacific Ocean Cobb Seamount Juan de Fuca 1 1 East Lau Spreading Center 1 East Pacific Rise 1 1 104 57 3 2 Guaymas Basin 1 Hawai'i South Point X3 1 11 1 Hawai'i South Point X4 8 32 3 3 1 Hikurangi Margin (New Zealand) 1 Japan Trench 1 1 Juan de Fuca Ridge 1 1 Loi'hi Seamount Pisces Peak X2 431 1 Loi'hi Seamount South Rift X3 1 1 Atlantic Ocean Mediterranean cold seep 1 Indian Ocean Southwest Indian Ocean Ridge 1 2 Fig. S2 b)