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2011 Shelfwide Cruise: July 25 - August 6

Daily Log

Jul 23, 2011 - Day 0
Night Shifters - a.k.a. Leslie Smith 
LUMCON buzzed with excitement, unusual at LUMCON for Saturday evening at 10pm, but not unusual for a research scientist. Science does not stick to the 9 to 5; when itu2019s time, itu2019s time, and at that moment, it was time to load the boat to set out for the 26th annual Shelfwide cruise. Carts were loaded with laboratory supplies to be brought down to the boat, vans of supplies from nearby universities were unloaded, and crates from universities 1300 miles away were opened with care, fingers crossed that the precious cargo had made it safely.

The hush that settled after the excitement of loading, left researchers fidgeting in their seats in the galley, ready to start their adventure and unsure of what to do with themselves until the boat would launch at daybreak. One by one researchers retired to their bunks, a restless sleep to follow with so much anticipation for tomorrow. At 0600, a welcoming resonance of the engines firing roused all from sleep, and the boat started underway. Day shifters woke up to survey the scene, while night shifters tried to catch a few extra hours of sleep before working through the night.

Jul 24, 2011 - Day 1
0500 -  
Depart dock and steam to Southwest Pass
1330 -  
Begin collecting Mississippi River end member water
1630 -  
Leave Southwest Pass and head to first station
1800 -  
Begin sampling on inshore end of A' transect, very low oxygen at A'1 and A'2. Lots of fish larvae and ovigerous blue crabs at surface station A'4. Crabs probably spawning, but also chomping on fish larvae.
2200 -  
Depart A'4 for offshore end of A transect at A6
Jul 25, 2011 - Day 2
0000 -  
Beginning offshore end of transect A. No hypoxia at stations A6 or A5.
0200 -  
Station A4 just at 2.0 mg/l.
0230 -  
Hypoxic at Station A3 and hypoxic all the way to beach. Lots of lesser blue crabs, females at surface, but not spawning, probably avoiding the low oxygen at mid water and shallower at shore. Lots of larval fish, needle fish, and some juvenile flying fish.
0400 -  
Depart to transect B to begin at 7 am or so
Night Shifters 
The beginning of the night shift found the researchers at the end of a transect in the Mississippi River. Very fitting to begin the adventure where the cause for our adventure u2013 the Dead Zone in the Gulf of Mexico - begins. The nutrient-rich Mississippi River discharge, courtesy of Americau2019s breadbasket, leads to increased production in the water column and increased consumption in the bottom water, decreasing oxygen levels to the point where most critters cannot surviveu2026.i.e. an area dead/devoid of life.

With stations coming in rapid succession, the night shifters had no chance to notice the progression of the night and their new nocturnal existence. But their hard work, from station to station, was beginning to build the picture of the Dead Zone. As the sun rose, bleary eyed and full of caffeine, the night shifters ate their breakfast-dinner and went to bed; hearts knowing how important their job was, but feet and back very convincingly arguing for sleep. For the next 12 hours, their tasks would be bequeathed to the dayshifters.

Creature of the Night 
The Lesser Blue Crab. At almost every station numerous mature female blue crabs aka u201cSooksu201d were seen up near the surface laden with thousands of fertilized eggs. Floating lazily along the surface these crabs shoveled clawfulls of small fish and larvae into their mandibles. Though mouths watered at the site of the abundance of crabs, so near within reach from a dip net, the researchers refrained, leaving the multitude of larvae soon to be hatched to build the future populations. Most were ovigerous crabs releasing larvae. Few males were seen. Suspect they were avoiding bottom hypoxia. NR saw juvenile flying fish.
0700 -  
Begin with B1, very low through B7 in 26 m.
1200 -  
Trouble with oxygen probe cable, shorted out twice. Replaced cable, but need to read secondary sensor now.
1400 -  
Finish transect B out of low oxygen in 36 m
1600 -  
Begin offshore stations on transect C. 35 m not hypoxic; 30 m hypoxic
1900 -  
Severely low oxygen, hydrogen sulfide in bottom water, 20 m into 10 m. Eel swimming at surface at C6C, sulfidic water. Pee yew, very sulfidic smell at C4, needlenose and large and small C. similis at surface. Crabs at surface until station C1 where oxygen is 1.6 at 4 m.
2400 -  
Depart to D'1
Jul 26, 2011 - Day 3
0200 -  
D'1 and D'2 very low oxygen. Lots of eels swimming at the surface of Du20192 and Du20193 escaping the low oxygen.
Night Shifters 
The Niskin bottle, a subsurface water collection device, is cracked open and the unlucky researcher is knocked backward, recoiling away as if punched in the face. Rotten eggs! She did not accidentally capture yesterdayu2019s breakfast, rather, the bottom water brought to the surface was full of hydrogen sulfide. Hydrogen sulfide is often observed in areas with little oxygen, as anaerobic organisms are able to use sulfate in lieu of oxygen during metabolism. Hydrogen sulfide is a bi-product of these reactions and is one of the many variables sampled on the cruise as a clue as to what is occurring within the Dead Zone.

Tonight was the sampling of the infamous C-transect, a transect sampled monthly by LUMCON since 1985 (as long as the annual shelfwide cruise). A 27-year observation data set of this resolution is unprecedented in oceanographic research and a great asset in terms of describing changes in the Gulf through time. Operations were turned into high gear during this transect as more depths were sampled and more parameters at each depth were sampled. The most notorious of these stations was the C6C stations, where the Rabalais laboratory has oxygen sensors fixed to the oil rig located at this station. The oil rig itself was a wonder: large enough to house dozens of workers and land a helicopter on top. From the side of the 116-foot Pelican, this metal city left only one reaction: open mouths.

Creature of the Night 
Benthic Eels. With the cry of u201csnake,u201d everyone on the deck raced over to the starboard side to look into the water. This supposed snake was an eel that normally lives in the mud swimming next to the boat, wriggling its way along the surface of the water. These animals were definitely escaping the low oxygen.
0600 -  
Du20194 out of hypoxia, fill out end of transect Du2019
0730 -  
Head to offshore end of transect D and work towards shore
1147 -  
Starting to enter hypoxic area at 20 m and near anoxic by 18 m at D3
1430 -  
Remainder of transect D hypoxic almost to shoreline, station D0 in 4 m below 1 mg/l. Changed DO temp co-efficient for YSI 6820. Still completing Winklers.
1800 -  
Head west to inshore end of transect E which is just above hypoxia cutoff. E1 with Salvinia, large duckweed in water. Large needlefish. Very calm and stagnant feeling
Jul 27, 2011 - Day 4
0030 -  
Middle of transect E is hypoxic,
0200 -  
Leave offshore end of transect E for offshore end of transect F. Strong currents on bottom. Oxygen concentration increasing slightly with depth as temperature decreases. Colder water holds more oxygen at same salinity than warmer water.
0430 -  
Offshore transect F starting at F6, farther offshore than normal for monthly transect F. Not hypoxic. Flying fish, about 4 inches long. Crystal clear water.
Night Shifters 
The rosette of Niskin bottles is lowered into the water, weighed down by the heavy metal cage surrounding it protecting the thousands of dollars worth of sensors strapped below the bottles. Whereas in previous evenings the rosette would immediately disappear into the murky greenish brown water, tonight researchers watch the rosette descend several meters down through clear blue waters. Sampling has moved offshore. With a decrease in turbidity has also come a decrease in fish and larvae previously seen so thick in the water that it textured the surface. The clear water, however, does not preclude the absence of hypoxia, as our map of the Dead Zone stretches further.

By now, the researchers and crew have a rhythm. Each knows their jobs and move together with the fluid ease of a ballet - sending instruments down on the winch, making slight adjustments needed for depth in the water column, or just a few inches of slack to attach another instrument. Bottles and buckets are passed without words to the next person and lab duties are seamlessly filled in, without the need to ask what to do. The night shift has become a well-oiled machine.

Creature of the Night 
Atlantic Needlefish. Of the few fish that were seen, the Atlantic Needlefish was one of this most common. These little saltwater predators have long narrow mouths full of sharp teeth hunting smaller fish and swimming crustaceans. Most likely they were attracted to the side of the boat by the artificial light in the darkness that has been known to excite them. We were fortunate, however, that these pointy jumping fish, were not excited enough to try and jump into the boat.
0530 -  
Continue with transect F, one of the two transects of our hypoxia studies studied since 2001 for a comparative analysis of the relative influences of the Atchafalaya River compared to the Mississippi River along transect C. Focus of many process experiments and rates for modeling work.
0700 -  
Pick up hypoxia at station F4, thin lens, but not much for this transect, which is usually hypoxic.
1200 -  
Remainder of transect F is hypoxic but in a thin lens on the bottom.
1300 -  
Head to inshore end of transect G.
1500 -  
Inshore end of transect G is hypoxic close to the bottom and hypoxia deepens as head farther offshore.
Weather Report 
Tropical Depression now a named Tropical Storm Don. Not expected to reach hurricane speed winds, but will entertain us as we move farther west towards western Louisiana and the coast of Texas. Expected to head to the central Texas coast. Expect winds and waves to pick up tomorrow.
1830 -  
Hypoxia thickens in 20 m at station G4
2000 -  
Out of Hypoxia at G6, head to offshore end of transect H
Jul 28, 2011 - Day 5
0130 -  
Station H6 not hypoxic, but station H5 falls just below 2 mg/l/. Baby sailfish, about 5 inches long, at H5.
0200 -  
Continue inshore on transect H, hypoxia extends to 12 m inshore, then above 2 mg/l into shore
Night Shifters 
A flat calm set upon on the Gulf. Barely a wave moved, only the faintest breath of wind felt. The sunset, breathtaking - reds and oranges reflected off the still water, mirroring the horizon. Murmurs filled the galley and passageways u2013 Tropical Storm Don was approaching. Those watching the marvelous sunset could not help but relay the clichu00e9 calling this the calm before the storm. Eyes inside were glued to computer screens for the storm forecast. Safety of the boat and crew in the coming days will be the highest priority. Wind and waves of the tropical storm do not just affect the researchers sampling the Dead Zone; they will affect the Dead Zone itself. Tropical storm force winds at this point in the season after hypoxia has set in will serve as giant mixer replenishing the oxygen at depth with oxygen rich surface water. Effectively bringing life back in to the Dead Zone. Although this is beneficial for the ecosystem to have a breath of life put back in to the water, it disrupts the Dead Zone mapping, as those places previously hypoxic prior to the storm, will now appear as if they were normoxic the whole time. Researchers patiently wait to see what will have in store for the next night shift, Dramamine at the ready. But not all storms are equal. Some mix it up and some donu2019t.

Still sampling in blue water, the types of creatures drawn to the artificial light of the boat have begun to change. Tonight the water was full of squid, schools of 3 inch long silver fish, and even a baby sail fish; not to mention dolphins (our creature of the night). As the water column gets deeper, there is more time to kill on the deck waiting for the CTD to be lowered 30-40 meters. To fill the extra time, researchers have taken to playing games, searching for critters in the water and trying to take photos. One of the games u2013 Trash or Animal u2013 though disturbing is a frequently used game, trying to figure out if the mass floating just beneath the surface was an animal or just a piece of trash. It is amazing how much debris is seen floating by these stations with no land in sight; a reminder, that our inputs have great reach.

Creature of the Night 
Bottlenose Dolphins. Weaving in and out of the R/V Pelicanu2019s bow waves two dolphins played with reckless abandon. Glancing over at each other, egging the other on they jumped in tandem, darted back and forth on either side of the bow, and cruised along at top speed aided by our waves. Upon sight of the dolphins, the researchers reverted back their 10-year old selves, squealing with delight and taking photos. These dolphins come as a welcome sight after the cetacean unusual mortality event in the Northern Gulf of Mexico over the last year and a half has found hundreds of dolphins and whales dead and stranded on beaches.
Jul 29, 2011 - Day 6
0300 -  
Entering hypoxia on transect H at 22 m, then as approached closer to shore went close to anoxia.
0500 -  
But not to continue, inshore stations on transect H well above 2 mg/l.
0700 -  
Head to inshore end of transect, station I1 below 1 mg/l. Surprise, have to head into shore to close it off at station I0. Then back offshore.
1130 -  
The middle of transect I, 10-20 m is hypoxic. Barely above 2 mg/l in 24 m, but head to offshore end of transect J. Mahi mahi swimming around CTD mid transect, about 5 1-footers.
1800 -  
Another surprise, but similar to 2010, offshore end of transect J, at 27 m is hypoxic. Have to head offshore to close off the contour.
2000 -  
At the end of transect J, in 33 m, no longer hypoxic. Head back inshore. Winds have increased to 14 kn and seas are building, about 3 ft now. Expect more to come as Tropical Storm Don and the R/V Pelican both head west.
2200 -  
Heading inshore on transect J and back into the area of hypoxia, which continues until a depth of 10 m is reached at station J2.
0500 -  
Finish off transect J at station J1, fully mixed water column, seas up to 5 ft now.
0700 -  
Begin the inshore end of transect K at station K1. Tropical Storm Don headed to Corpus Christi and should be there for midnight.
Night Shifters 
The calm of the nights preceding were displaced by swells on our 6th day of the cruise. Waves burst into the side of the deck splashing water on to the feet of the researchers, many unprepared and wearing sneakers. Veterans of the cruise already had on black rubber goulashes, duct taped in places showing reverence to their longevity as a watertight scientific accessory. These swells are not the worse this cruise has seen, nor are they the worse of what is likely to come. As researchers struggled with swaying instruments on deck and in the water, schools of small silver fish just over the gunnels bobbed effortlessly through the swells. Perhaps they are just better at going with the flow.
Creature of the Night 
Juvenile Puffer fish. At about 1 centimeter long the baby Puffer fish seemed meager and small in the waters of the vast Gulf of Mexico. It is a wonder how such a small fish, in such a vast volume of sea water managed to find itself in a 5 gallon bucket hauled up on deck by a night shifter. As we were gazing at the little critter safe in a sample bottle, several needlefish (a predator of such a small fish) were in the water just off the starboard side. Perhaps, it is even more a wonder that such a small thing can survive in such a bitter environment, with a predator at every turn. In fact the vast majority of fish eggs and juveniles die before making it to adulthood, making it ever more important to have a healthy reproducing population.
0900 -  
Move through transect K during the day. Some day shifters down for the count. Seas with 5 ft swells.
1300 -  
One station at 18 m approached hypoxia. Strong bottom currents kept YSI 6820 from reaching the bottom and staying down.
Weather Report 
1500 -  
At end of transect K bottom oxygen well above 5 mg/l. Profiles with no vertical structure.
1800 -  
At end of transect S and moving to inshore. No hypoxia in 25 m. Oxycline at station in 18 m but only as low as 4 mg/l. Sea state definitely up to 6 ft swells. Went inshore as far as station S2 in 12 m. All profiles indicate fully mixed water column. Mostly murky water with a needlenose of two.
Jul 30, 2011 - Day 7
0030 -  
Head to station K5 to reoccupy a few stations.
0630 -  
Arrive K5 and resample a series of stations on transect K.
1100 -  
Head to port
Night Shifters 
A large bang roused night shifters from sleep. Just the waves. The R/V Pelican battled her way through the powerful water, with waves 6 to 7 feet high splashing up against her sides and water visible through portholes in the galley. Since the last night shift, both wind and waves have picked up, sending a salty spray on those sampling on deck. Within the first few hours of the night shift, Tropical Storm Don, the cause of the waves and wind had reached landfall near Corpus Christi. Fortunately, the boat was not caught in the midst of the storm, but the storm still left its mark in the form of elevated wind and waves.

Oxygen! Oxygen everywhere! For the first time since the beginning of our adventure oxygen has become a prevalent feature in the bottom water. This shift was abrupt and suspiciously concurrent with the effects felt from Tropical Storm Don. Though we cannot say conclusively whether the normoxic bottom water had been previously hypoxic prior to the mixing caused by Don, the evidence certainly points in that direction. With hypoxia alleviated, at least temporarily, our westward survey has come to an end. Like several other years in the survey of the Dead Zone, nature found away to camouflage its hypoxia trail, leaving scientists wondering if the water had been normoxic the whole time. We begin our journey back to the east, thankful for the satellite television to entertain us as we (not the royal we) doze in the galley.

Creature of the Night 
5-Gallon Plastic Red Bucketu2026Fish. Perhaps we are not as good at the animal trash game after all, but todayu2019s creature of the night is a plastic bucket. Not just any plastic bucket, but a bucket that has been on the cruise for the last four years. With such a long tenure on the cruise, it seems only fitting to have the bucket set free into the Gulf. This burial was unfortunate, however, for the flabbergasted scientist whose sampling bucket had just broken free from its handle and rope tied to the boat and was floating away taking his sample water and sampling device in one fell snap. This situation was probably not helped by the cackles and pointing of the fellow scientists on deck. We did get our just deserves later, however, as a wave came over the side of the boat and flooded one of the main instigators and her boots borrowed from Wendy (but who shall remain anonymous, but she recently graduated from the University of Rhode Island Graduate School of Oceanography).


  • The final dissolved oxygen data will be corrected, as necessary, from linear regression with the Winkler titrations over a range of 0.22 to 8.43 mg/L. Initial observations indicate correction, but the f-factor for the Winkler standard remains to be verified. Any corrected data will be reflected in other derived measurements.
  • Salinity data not yet verified with PortaSal samples.
  • CTD data remain to be post-processed with ALIGN CTD to be applied.
  • Instrumentation was calibrated pre- and post-cruise according to manufacturer's specifications and standard method procedures were applied for several variables, not yet calculated, according to several LUMCON EPA-approved Quality Assurance Project Plans.
  • Data collected as part of process studies remain to be analyzed and synthesized.
  • Final QA/QC'd data will be submitted to NOAA NODC within two years of collection.