BIOGEOCHEMISTRY OF HYDROTHERMAL VENT MUSSEL COMMUNITIES - THE DEEP-SEA ANALOG TO THE INTERTIDAL ZONE

Continuous measurements of sulfide, silicate and temperature were made in situ from the submersible Alvin in the Rose Garden and New Vent hy drothermal fields of the Galapagos Spreading Center. Continuous measur ements of temperature also were made for an 18 day period in the Rose Garden field. The results demonstrate several adaptations that appear to have contributed to the success of the vent mussel Bathymodiolus th ermophilus in the Rose Garden. Dense clusters of B. thermophilus can d isperse the hydrothermal fluids laterally for distances of several met ers. This results in a large increase in the area of the redox transit ion zone, where both dissolved oxygen and hydrogen sulfide are availab le. As a result, the animal communities can grow to occupy areas that would not otherwise provide adequate reduced substrates. Measurements of the temperature demonstrate a distinct tidal periodicity. This peri odicity Will result in a large range of environmental conditions withi n the vent community. The mussel can tolerate these wide ranges in con dition because of its ability to accept long periods of anoxia and to filter feed.