Cruise Plan (as of 4/18/00): Ship: RV Melville Loading August 17/18th in San Diego, CA Offloading September 28/29th in Arica, Chile Dates of the research cruise: August 21st (AM) - September 28th (AM) Departure port: San Diego, CA Arrival: Arica, Chile Locations: See the two attached charts Transects: Entail suface water mapping of a variety of parameters. In addition to the ships surface water sampling system, we will have a clean surface water pumping system deployed and travel at a speed of 4 to 8 knots. We will stop periodically for a quick CTD cast (500 meters maximum depth, commonly only 300 meters depth). The transects will start right after breakfast and end at ~2200 hours. Aug. 17/18th - Loading of all equipment, gear and vans on board ship. Equipment must be loaded this Thursday and Friday. The crew has the weekend off. Aug. 19/20th - (Saturday and Sunday) setting up instruments and work areas, securing equipment. Aug. 21st - Monday morning departure from San Diego Aug. 21-30th - Transit to the Costa Rica Upwelling Dome (~9 to 9.5 days) - stop once or twice enroute for a few hours to test, clean, and condition the sampling systems. Aug. 30/31st - Surface transect within the Costa Rica Upwelling Dome. Sept 1/2nd - Transit to the Equator west of the Galapagos Islands (~2 days) Sept 2nd PM - Equator!!! Pollywogs beware! Sept 3rd ~0800 to ~2300 - Initiate the first Galapagos Transect starting West of the Galapagos Islands. Sept. 4th - Break - hopefully to go ashore in the Galapagos Islands (I have requested permission but I don't know if we will receive it). Sept. 5th ~0800 to ~2200 - Start the second Galapagos Transect to the West of the Islands. Sept. 6th to Sept. 13th ~0800 to ~2200 each day - The major Galapagos Islands to Peru Transect with the clean surface pumping system which will cover ~100 nautical miles each day (possibly more if we need to make up for lost time above). Sept. 14th - Sampling break and transit to the position to initiate the Peru transects Sept. 15-16th ~0800 to ~2200 - Peru Transect #1 with clean surface pump system. Sept. 17th - biological sampling along Peru Transect #1 Sept 18th - transit to the start of Peru Transect #2. Sept. 19-20th ~0800 to ~2200 - Peru Transect #2 Sept. 21st - transit to the start of Peru Transect #3 Sept. 22-23rd ~0800 to ~2200 - Peru Transect #3 Sept. 24th - transit to the start of Peru Transect #4 Sept. 25-26th ~0800 to ~2200 - Peru Transect #4 Sept. 27th - transit to Arica, Chile Sept. 28th - arrive Arica on Thursday morning. Sept. 28-29th - Offload ship and prepare equipment for shipping back to shore labs. Sept 30th - prepare and load containers for shipment of equipment home Oct 2nd - Take care of final details for shipping equipment back home - Monday The exact location of the Surface Transects will be dependent upon sea state and any sea surface temperature and chlorophyll images received during the research cruise. Description of Research: This research cruise, departing from San Diego, California on the morning of August 21st, 2000 and ending in Arica, Chile on September 28th, 2000 will focus on the effect of bioactive trace metals (iron, zinc, manganese, cobalt, copper and cadmium) on phytoplankton and bacterioplankton dynamics. The main emphasis will be on the coastal upwelling regime off Peru, with a secondary emphasis on the equatorial Pacific upwelling regime near the Galapagos Islands and the Costa Rica Upwelling Dome. We will also run a major transect connecting the equatorial Pacific upwelling system with the Peru coastal upwelling regime. The major working hypothesis is that we will observe a mosaic of conditions with high concentrations of macro nutrients such as nitrate and phosphate, but with highly variable iron concentrations ranging from extremely low resulting in severe iron limitation, to high concentrations where iron (and Zn) is not biolimiting. We also predict a range of silicic acid concentrations driven by different assimilation ratios of silicic acid to nitrate dependent upon the ambient iron concentrations. Zinc, cadmium and cobalt may all play a significant role in carbon assimilation. We propose that the trace metal chemistry will be a factor determining whether or not extensive blooms of large diatoms develop in the macro-nutrient rich upwelled waters. Factors responsible for variations in trace metal concentrations have to do with both the magnitude of external sources and the assimilation rates of the bioactive trace metals relative to the macronutrients. The riverine inputs of trace metals to the Peru coastal waters during our investigation are predicted to be minimal. The existence of a wide continental shelf, however, can trap the iron-rich suspendend particles delivered during the previous flood seasons. The continental shelf can then act as an external source of iron (and zinc and manganese) to be entrained with the macronutrient rich upwelled waters. Extensive regions off the Peru coast have only a minimal shelf. We predict that upwelled waters in these regions will have low iron concentrations and will tend to exhibit iron limitation. A wide variety of biological parameters will be examined; ranging from growth rates of phytoplankton, to various physiological indicators, to molecular biological indexes. It is argued that many of these parameters will prove to be sensitive diagnostic indicators of the extent to which the biological communities might be limited by a particular trace or macro-nutrient. There will be a multitude of on-deck incubations occurring throughout the cruise. These incubations will have different amounts of trace metals/organics added in order to examine the response of the phytoplankton and bacteria communities. There will also be a contingent of marine chemists aboard making near real time measurements of the concentrations and speciation of the various trace metals. The bulk of the sampling will be of near surface water during the major surface transects. The surface transects will be carried out at speeds of approximately 4 to 8 knots and will have our clean surface pumping system deployed. We will periodically stop during the surface transects for quick CTD casts down to depths of 300 to 500 meters. We will take advantage of the latest satellite and remote sensing data to help guide our transects. We will also take advantage of what we learn during the surface transects in order to reoccupy a station and sample more intensively at appropriate locations.Email: shipsked@ucsd.edu
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