Deep-Sea Research I 50 (2003) 1375–1387 Instruments and Methods LAREDO: a new instrument for sampling and in situ incubation of deep-sea hydrothermal vent fluids Howard Phillips, Llyd E. Wells*, Rex V. Johnson II, Steve Elliott, Jody W. Deming School of Oceanography, University of Washington, Box 357940, Seattle, WA 98195, USA Received 15 May 2002; received in revised form 13 January 2003; accepted 25 June 2003 Abstract Wedescribeanewhydrothermalventsampler,LAREDO,designedtocapturehotfluidsandincubatetheminsituat conditions characteristic of deep-sea hydrothermal vents for periods of hours to days. To accomplish this, LAREDO wasengineeredtooperateatambientpressuresto6000-mwaterdepth(600bar),intheflowofhot(to420  C)acidic(to pHof3)effluentwithlargeparticleloadsandfastflowrates(>1ms 1 ).KeyfeaturesoftheLAREDOsamplerinclude thenovelapplication(inthisenvironment)ofatorsionbartogeneratetheenergyrequiredtosealthesamplechambers, independent and continuous temperature records in two of the three sample chambers, and remote (electronic) or manual (by submersible) modes of closure. Results of LAREDO’s first operational field tests on smokers at 9  51 0 N  104  18 0 W along the East Pacific Rise indicated successful capture of vent fluid (up to 91% pure effluent by analysis of magnesium content) without leaks after tests of several different instrument configurations. High-resolution temperature records (a datum every 2s for each thermocoupled chamber) indicated achievement of high temperatures (>150  C)inatleastonechamberonalldives.ThefieldtestsalsopointedtosimplemodificationsofLAREDO’sdesign that will improve its ability to monitor the temperature of the captured fluids and to close autonomously on the seafloor. With these improvements and its demonstrated capacity for in situ capture and incubation, LAREDO represents a useful new tool to expand upon biological and geochemical research in the harsh smoker environment. r 2003 Elsevier Ltd. All rights reserved. Keywords: Hydrothermal fluid sampler; Smokers; Vents; Microbiology; High pressure; Instrumentation 1. Introduction Hydrothermal vents provide unique access to a potentially extensive subsurface biosphere, bounded in part by the maximum temperature and pressure at which life can exist (Gold, 1992; Deming and Baross, 1993). Life may have originated in subsurface vent systems (Corliss et al., 1981; Baross and Hoffman, 1985) or taken refuge there during planetary catastrophes (Chyba et al., 1994). Yet, beyond theoretical considera- tions, little is known about the actual pressure and temperature limits of life, or about how these and other factors interact. The highest known growth temperature of an organism in pure culture is ARTICLE IN PRESS *Corresponding author. Tel.: +1-206-543-0147; fax: +1- 206-543-0275. E-mail address: chimera1@ocean.washington.edu (L.E. Wells). 0967-0637/$-see front matter r 2003 Elsevier Ltd. All rights reserved. doi:10.1016/S0967-0637(03)00127-4