Field Testing of a New IRS Sediment Trap Designed to ExcludeSwimmers

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This proposal is a continuation of a present GOFS long-lead time project to test the effectiveness of poisons and preservatives on preventing the decomposition of organic matter collected in sediment traps. We have completed three field tests of this question and concluded that the best treatments for inhibiting bacterial activity also resulted in the greatest artifact in both flux and organic chemical composition from swimmers. In order to exclude swimmers, we have designed a novel trap with an indented rotating sphere and time-series capability (IRS). We propose to test this new trap design in Dabob Bay, WA, during fall bloom, and at the Hawaii time-series station. The questions being addressed are: 1) Do detailed chemical analyses of materials collected in the new IRS sediment trap indicate that this design excludes swimmers of all sizes more effectively than conventional open collectors? 2) Are the chemical artifacts resulting from swimmers reduced sufficiently by the IRS design to finally allow discrimination between preservation of labile substances in treated traps and the addition of zooplankton swimmers? 3) Can the IRS traps be fitted with dependable subsampling carousels for time-series collections and in-situ experiments? 4) Do the IRS and carousels-adapted (IRSC) traps perform suitably at all depths in the open ocean? 5) Using IRS traps, can we now measure accurately the vertical fluxes of a wide range of organic molecules throughout the ocean? If so, can these data be used to better define particle dynamics and productivity relationships? We anticipate that this new trap will be ready for use in the planned equatorial Pacific GOFS experiment in 1991/1992.