Chemical composition of organisms and hydrothermal fluids from the Guaymas Basin hydrothermal field

Atomic absorption spectrometry (flame and graphite furnace techniques) and instrumental neutron activation analysis were used for determining Fe, Mn, Zn, Cu, Pb, Cd, Ag, Co, Cr, As, Se, Sb, Ba, Au and Hg contents in 25 samples of different tissues and whole organisms inhabiting the southern trough in the Guaymas Basin (Gulf of California) and in several samples of its bottom waters. It is shown that the habitat environment of this hydrothermal field with high primary production of both photosynthetic and bacterial chemosynthetic origin influences the Fe and Mn ratios in waters from microbiotopes and distribution patterns of the metals in external and internal organs of benthic animals. In dominant specialized taxa, maximal bioaccumulation of metals is registered both in organs related to bacterial chemosynthesis (such as trophosomes of Vestimentifera Riftia pachyptila and gills of vesicomyid clams Archivestica gigas) and in other organs. Other organisms, such as the mollusks Nuculana grasslei, actinias Paraphelliactis pabista, Actinaria, Spongia, and crabs Munidopsis alvisca demonstrate high bioaccumulation properties as well. Metal enrichmenr factors are highly variable and vary from 10 to 104. Variations in the molar Fe/Mn ratio imply partitioning of these two metals in the following migration succession: microbiotope water - external organs - internal organs.