Dataset: Methane seep hard substrate species collected on RV/Atlantis AT15-44, AT15-59, AT15-68, AT18-10 in the Pacific, off Costa Rica and USA from 2009-2011 (Seep Carbonate Ecology CROCKS II project)

Methane seep hard substrate species collected on 4 RV/Atlantis cruises and lodged at the SIO Benthic Invertebrate Collection.

Samples were taken at methane seeps on the Costa Rica Margin (8o 55.8 N 84o 18.7 W) and at Hydrate Ridge, Oregon Margin (44o 34'N, 125o 9 W).

Field investigations (collections and experiments) were made using the submersible ALVIN on the RV Atlantis at methane seeps on the Costa Rica margin during 2009 (AT 15-44) and 2010 (AT 15-59 funded by OCE 0939557). To compliment the studies of carbonate ecosystems off Costa Rica, but in a lower-oxygen realm, we examined parallel ecosystems and conducted parallel colonization experiments at Hydrate Ridge methane seeps. AT 15-68 was conducted with ALVIN at the northern, southern and southeast summits of Hydrate Ridge from July 30-Aug. 9, 2010, and AT 18-10 was conducted with ROV Jason, to recover experiments placed at Hydrate Ridge in 2010.

Collections from the two Costa Rica cruises yielded 909 lots cataloged into the Scripps Institution of Oceanography Benthic Invertebrate Collection (SIO-BIC), with 1874 whole specimens and 342 tissue samples. DNA has been extracted from 294 specimens and minimally sequenced for Cytochrome oxidase I (some for 16S and 18S as well). Collections from the Oregon Hydrate Ridge cruises in 2010 and 2011 resulted in 488 lots cataloged into SIO-BIC with 682 specimens and 295 tissue samples. DNA has been extracted from about 200 specimens and some sequenced (mainly CO1, but some for 16S and 1S).

The Costa Rica methane seeps hosted about 25 species of gastropods that are likely to be endemic to seeps, this is exceptionally high diversity, twice the normal 8-12 species found at seeps. Among them was the first species of Neomphalidae from a seep, this group was previously known from vents only, and two species of Lepetodrilidae, almost only known from vents.

The diversity of carbonate macrofauna is higher at Costa Rica seeps than at Hydrate Ridge seeps, in both active and inactive settings. Faunal diversity is higher on active carbonates at Costa Rica and Hydrate Ridge than on inactive carbonates or within active seep (microbial mat-covered) sediments.