Survey of Invertebrates at Sea Floor Deployments of Wood in the North Pacific Ocean

Field Museum Of Natural History, Chicago IL

Investigators

Abstract

Survey of Invertebrates at Sea Floor Deployments of Wood in the North Pacific Ocean Perhaps because of the small, well-defined habitats in which they occur, animals at sea floor hydrothermal vents are increasingly well known, but our knowledge of animals that live elsewhere on the vast sea floor continues to be limited. Do species known from vents and their relatives occur in comparable, non-vent habitats in which oxygen is limited? One little-known seafloor habitat, that provided by wood sunken to the sea floor, shares with hydrothermal vents temporal transience, random distributions, ecosystems based on bacterial production. Both hydrothermal vents and sunken wood provide hard substrates on the otherwise sediment-laden sea floor. The earliest deep-sea discovery cruises first reported the very high diversity and unusual animals associated with wood falls trawled from the sea floor, but the composition of the wood fall fauna remain poorly known. Experimental deployments of wood and a control substrate, basalt, will sample this little-known fauna to determine its composition and relationship with the vent fauna. Individual lengths of wood and basalt cubes in a mesh bag will compose deployment units. Four of these units will be tied to a frame constructed from PVC tubing. Two frames with units will be deployed in the North Pacific Ocean from a surface ship using the CTD wire with a transponder at Axial Volcano at 1500 m depth and two deployed on the abyssal plain at 2500 m depth. After one year, half of the deployments at each site will be recovered by a Remotely Operated Vehicle to ascend to the surface ship in a lidded box. The other half will be recovered after two years. Because these sites differ in substrate, depth and proximity to hydrothermal venting, the recovered units will likely carry maximal species diversity. Specimens recovered on-board ship will be deposited in The Field Museum collections where existing collections from North Pacific hydrothermal vents will facilitate direct comparisons. Improving the availability of deep-sea specimens will increase our knowledge of wood fall specialists in the North Pacific Ocean, and of their habitat specificity, especially relative to hydrothermal vents.