2006 Daily Log

Jul 20, 2006 – Day 0

1900 –: Prep for cruise, Happy Birthday Melissa

Jul 21, 2006 – Day 1

0010 –

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 A

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

Jul 22, 2006 – Day 2

Calm, 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.

Jul 23, 2006 – Day 3

0100 –

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 pennate diatoms

Jul 24, 2006 – Day 4

0700 –

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 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.

Jul 25, 2006 – Day 5

Happy 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

Jul 26, 2006 – Day 6

0000 –

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

Jul 27, 2006 – Day 7

0000 –

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

Jul 28, 2006 – Day 8

0500 –: 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