Two exploratory cruises to the East Lau Spreading Center (ELSC) will be undertaken to evaluate sites for selection as the Integrated Study Site (ISS) bull's eye for the Ridge 2000 program and to carry out studies necessary for further interdisciplinary research in this area. In addition to exploration and biological mapping, the sites will be carefully evaluated in terms of the relation between the chemistry of the diffuse flow vents and the macro-biology. This is especially important to do at this time because the only available water chemistry data for this region is from high temperature vents and indicates that Zn is very high and sulfide and methane are very low; this is not consistent with the abundant communities of sulfide and perhaps methane-oxidizing symbioses reported in diffuse flow. The reserach is complementary to, and will follow upon, the first two major ISS evaluation cruises outlined in the Implementation Plan for the site.
The first of the two cruises will examine up to 6 sites identified by previous cruises and carry out detailed studies of 3 sites, with a goal of collecting data for finalizing selection of the bull's eye site for the Lau Basin ISS. The 2nd cruise will take place a year later, after selection of the ISS bull's eye, and will characterize the faunal biology and low temperature hydrothermal chemistry in the detail needed for planning the actual ISS experiments. The work for the first cruise includes mapping of the distribution of major community types, measurement of water chemistry in the major community types using an in situ analyzer supplemented with discrete samples, quantitative sampling of major community types, identification and phylogenetic analyses of component species, analyses to determine the reductant used by the symbionts in the major symbioses, measurements of physiological condition of major species in different vent areas, preliminary studies on maintenance of these species alive for further studies, and a variety of ancillary studies. The second cruise will be focused on a single site and studies will examine interactions between chemistry, physiology and ecology within each of the discrete assemblages of animals at the site as well as constructing very high resolution maps of the site, and carrying out experiments on living animals facilitated and guided by results from the first cruise.
