Bioaccumulation of some trace elements in the biota of hydrothermal fields of the Guaymas Basin (Gulf of California)

Resumen

Data from the
hydrothermally influenced Guaymas Basin of the Gulf of California
are presented on the concentration and distribution of Ag, As, Au,
Ba, Cd, Co, Cr, Cu, Fe, Hg, Mn, Pb, Sb, Se, and Zn in different
tissues of dominant hydrothermal vent animals such as vestimentifera
Riftia pachyptila and vesicomyid clams Archivesica gigas and other
organisms, including Spongia, bivalve mollusks Nuculana grasslei,
Phelliactis pabista, and crab Munidopsis alvisca. Chemical element
content was measured by atomic absorption spectrometry (flame and
graphite furnace methods) and instrumental neutron activation
analysis. In the dominant specialized taxa, the main target organs
of metals were the trophosome and obturaculae of Riftia pachyptila,
the gills and mantle of Archivesica gigas. The other organisms also
demonstrated high bioaccumulation of metals. Especially high levels
of most of the metals (excluding Mn) were detected in the soft body
of Nuculana grasslei. The highest Mn content was found in the whole
body of Spongia. Bioconcentration factor of the trace metals studied
varies within three orders of magnitude from 5 (Mn) to 3•104 (Cd).
This testifies apparently a selectivity of trace metal
bioaccumulation by the organisms which is determined by metal
bioavailability independently of metal concentration in the water
column. Variability in the molar ratio Fe/Mn allows us to assume
that these metals undergo fractionation during migration from the
hydrothermal fluids to the interior organs of animals. Insignificant
differences between the Cd, Cu, Fe, Hg, Pb, and Zn levels in the
Guaymas Basin vent clams versus that in the bivalve mollusks from
polluted areas of the Gulf of California might suggest that the
metal bioavailability play an important role in the
bioaccumulation.