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Funded byNational Oceanic and Atmospheric Administration, Center for Sponsored Coastal Ocean Research, NGOMEX Hypoxia Studies (Rabalais et al.), and NOAA, Oceans and Human Health Initiative (Senn et al.) Cruise LogJuly 20, 2006 – Day 01900 Prep for cruise, Happy Birthday Melissa July 21, 2006 – Day 10010 Depart Cocodrie on R/V Pelican 1000 Arrive Southwest Pass, Mississippi River Calm, hot, isolated thundershowers 1300 Complete water sampling in Mississippi River Collection of salinity gradient/nutrient concentrations Collection of Miss R end member for methyl mercury study 1400 Deploy towed ADCP 1500 Begin hydrographic stations on transect A' and on to transect Extremely low oxygen levels in bottom waters within the 20- to 25-m isobath Portunid crabs at water surface over hypoxic bottom waters High phytoplankton biomass and supersaturated surface waters (>200%) Mercury methylation box core station 2400 Complete 2 box core stations on transect A July 22, 2006 – Day 2Calm, slight chop, isolated thundershowers 0200 Complete box core station on transect A 0800 Complete transect A and steam to transect B, LUMCON Fourchon camp on the horizon 1800 Complete transect B Hypoxic bottom-waters from 5 to 30 m depth Seas reaching to 2 ft, occasional 3 ft, 9 to 15 kn winds SSW, slowed speed for towed ADCP Several super tankers at the LOOP (Louisiana Offshore Oil Port) facility 1900 Begin transect C Spinner sharks!!! Juvenile flying fish!!! Series of box cores at multiple stations on transect C for microphytobenthos Portunid crabs at the water surface over bottom water with low oxygen. July 23, 2006 – Day 30100 Tow for bulk plankton mercury and methyl mercury determination 0300 Station C6C, site of moored instruments. No diving. Night dives are for the Caribbean, not Gulf of Mexico oil platforms. 0800 Winds 15 kn SSW, choppy 0900 Complete box core series for transect C 1100 Return to C6C to dive and exchange oxygen meter. Frontal passage and squalls as we prepared to dive. Winds 15 kn from the north and building seas. Aborted. 1200 Begin transect D' 1930 Finish transect D' and head west to southern end of transect D. Extensive hypoxia along transect D' to a depth of 35+ m. Value in 42 m was < 3 mg/L. Most of the afternoon in transit was spent outrunning the front as we headed south finishing the station before the frontal margin reached us. Winds 12-15 kn from the SSW then the SSE. 2100 Begin transect D, complete box coring at D3 Continued low oxygen along this transect. Where values between 1 to 2 mg/L, dense population of centric diatom Coccinodiscus on chlorophyll filters Sediment surface at D3 covered with pinnate diatoms July 24, 2006 – Day 40700 Complete transect D nearshore, head west to E1 Hypoxia very close to shore, Isle Dernieres Stalled frontal system, 13 kn SSW, 3 ft swells 1800 Complete transect E, box coring at E2A by the ‘B’ team and E6 by Senn. 2000 Begin transect F, offshore Box core at deepest station, 40 m, Senn Continuation of hypoxia in mid to deeper depths Stalled frontal system turns into 20 kn winds with 4 to 5 ft swells as a tropical depression forms in the southwestern Gulf of Mexico. Watching this as closely as the CTD profiles. July 25, 2006 – Day 5Happy Birthday Kyle! 0200 Box core F3 Pennate diatoms across the sediment surface, evidence of oxidized Fe, Terrebellid and Ampharetid worms at sediment surface, alive but in 0.3 mg/L oxygen 0600 Complete transect F Seas calm after F3, but before were quite high Lower and near anoxic bottom-waters in the mid depth stations of transect F Winds at 19 kn from ESE Ballyhoo in dip net 0800 Begin transect G nearshore, calm but dark clouds to the south in the direction of the low pressure system Fooled us, seas back to 4 ft with higher swells More fooling around, seas up to 6 to 8 ft swells, wind 27 to 30 kn Hypoxia in the mid depth stations of transect G 1700 Head to offshore end of transect H, calm enough to box core H6, Senn Sea cucumbers and a mud crab in single core Hypoxia in mid depth stations of transect H, mixed nearshore July 26, 2006 – Day 60000 Finish transect H, able to box core at H3 0300 Transit to transect I nearshore Inshore stations of transects H and I well mixed 0630 More hypoxia at mid depth stations on transect I More winds, up to 30 kn, more seas, 6 to 8, less words No box coring on transect I 0900 No map as yet, map-maker exhausted . 1000 Seas up to 10 ft, water column mixed to 15 m, still some hypoxia in approx. 20 m depths 1200 Continue on transect J, seas continue 1700 Able to box core transect J at station 4 1900 Hypoxia at mid depth stations on transect J July 27, 2006 – Day 70000 Continue transect J Continued rough seas 0300 Move west to transect K No box coring 0500 Hypoxia mid depths on transect K 0700 Transit to offshore end of transect M and approaching Louisiana/Texas border 1000 Close off hypoxic bottom area on M line 1100 Return to transect K and complete box core 1200 Transit to J5 to CTD, transit to I4 1700 Complete box core transect I, several stomatopods (mantis shrimp) in cores, transit to G3 2300 Complete box core transect G, transit to D3 July 28, 2006 – Day 80500 Box core station D3 0630 Transit to C6C to change oxygen meter at bottom 0930 Dive aborted, dive boat not functional, will try next week 1030 Depart for Cocodrie 1400 Arrive at dock ESTIMATED SIZE OF BOTTOM-WATER HYPOXIA for 2006 is 17,280 square kilometers (or 6,662 square miles) about the size of the states of Rhode Island and Connecticut combined. 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