INITIAL MICROBIOLOGICAL AND CHEMICAL INVESTIGATIONS 

 OF PELE'S VENT, LOIHI SEAMOUNT 



David M. Karl 1 ' 2 

 Andrew Brittain^ 



and 

 Bronte Tilbrook 1 



1 Department of Oceanography 



University of Hawaii 



Honolulu, Hawaii 96822 



2 Division of Oceanic Biology 



Hawaii Institute of Geophysics 



University of Hawaii 



Honolulu, Hawaii 96822 



3 Department of Microbiology 



University of Hawaii 



Honolulu, Hawaii 96822 



INTRODUCTION 



The discovery of deep-sea hydrothermal vents and their 

 associated bacterial and animal assemblages (Lonsdale 1977; 

 Corliss, Dymond, Gordon, Edmond, von Herzen, Ballard, Green, 

 Williams, Bainbridge, Crane, and van Andel 1979; Galapagos 

 Biology Expedition Participants 1979) has led to a decade of 

 exploration and in-situ experimentation. In 1977, Lonsdale 

 first observed the relationship between the distribution and 

 abundance of deep-sea animal communities and the discharge of 

 hydrothermal vent fluids. His deep-sea bottom photographs taken 

 at the Galapagos Rift revealed freshly-produced oceanic basalts 

 covered with hydrothermal mineral precipitates and an unexpected 

 presence of large benthic invertebrates. Lonsdale formulated 

 two independent, but not mutually exclusive, hypotheses to 

 explain these observations. First, he suggested that the 

 clustering of suspension feeding animals around active 

 hydrothermal vents might be due to the entrainment of bottom 

 water by the rising buoyant plumes. This localized bottom water 

 current could sustain the deep-sea vent community by delivering a 

 steady supply of suspended particulate matter. In this ecosystem 

 model, the particulate materials consumed by the benthic 

 invertebrates living at hydrothermal vents would be derived from 

 phytoplankton production in the surface waters. The deep-sea 

 vent community would, therefore, be supported ultimately by 

 energy supplied to the ocean in the form of solar radiation. As 

 an alternate hypothesis, Lonsdale suggested that vent-associated 

 chemoautotrophic bacteria living at the expense of reduced 



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