Back home again

Sorry to have waited till our return to finish off the blog, however, we did make it home safely. After finishing the pre-front transects, we spent 24 hours following the drogue and the plankton mimics while the front came in. We successfully recaptured the mimics after their longest open water trial. While we had expected bad storms with the incoming front, we were pleasantly surprised. The temperature did drop considerably, but the seas remained calm all but one evening.

Unfortunately, the crane broke and we were unable to collect cores after Sunday. We also lost the ability to put the small boat over the side in order to do more diving trips until the last day.

We re-occupied the two transects sampled prior to the front. We collected water samples from each of the 8 stations along each of the two transects for net tows and chlorophyll and HPLC filtering and nutrient analyses. Further Acrobat scanning was also performed during this time.

After travelling back toward the port of Pensacola, we attempted to locate a tripod that had been deployed prior to the hurricane season using hydrophones, but to no avail. Blake Schaeffer at the EPA will instead use side scan sonar to locate it. After trying to find the tripod, the divers were able to get out once more near the Port of Pensacola to obtain nutrient samples 2m off the bottom of the water column using the microsamplers.

We unloaded the boat upon our return Tuesday morning and the vans departed. Group 1 arrived back in Raleigh, NC Wednesday morning around 3am after driving straight through. Group 2 had to return via Wilmington to return the UNCW scientists and equipment, and so had a stopover north of Atlanta Tuesday night, and returned to Raleigh around 7pm Wednesday.

Eye on Science...

For people who are wondering, BenDiM2 refers to the Benthic Dinoflagellate Migration project, of which this is the second of three cruises.

Katy Grabowski (Dr. Dan Kamykowski's student) is looking at water samples from the bottom waters. She is examining phytoplankton populations (specifically dinoflagellates) that are the basis of the food chain. We're studying these plankton in the Gulf of Mexico due to the chronic reoccurence of Red Tide blooms in the gulf. Anita McCulloch is also looking at plankton populations, however, she is using HPLC to examine the pigments present in the water to identify plankton species. She is also comparing this data to her work in the Galapagos Islands.

Dr. Carrie Thomas' group is looking at nutrient fluxes in the upper layer of the sediment. They examine the concentration of nitrogen species in porewater. However, the sandy sediment with marled carbonate chunks at the bottom of the Gulf make it tricky to get good cores. When they do obtain good cores, they use flux chambers to monitor nutrients produced in the sediment over time.

Linda Waters-Lindqvist (Dr. Tom Wolcott's student) is looking at Benthic Karenia brevis seed populations and their relationship to benthic nutrient sources. Her project is two-fold. 1) Nutrients coming out of the sediment are measured using a microprofiler to obtain water from the bottom 2m of the water column where dinoflagellates use nutrients to maintain benthic seed populations to determine what is available at what depths for food. 2) Linda is also using autonomous drifters (Mimics) to see how a programmed model of Karenia brevis behavior responds to real light conditions in the water column with simulated nutrient profiles. She is looking to see if, during the course of a 24 hour diel migrational cycle, the Karenia brevis population will stay low enough in the water column to move with the bottom water and be transported on shore in upwelling conditions where additional nutrients are obtained and a toxic red tide bloom can form.

Dr. John Morrison's group is examining the physical oceanographic regime of the Gulf of Mexico to describe the physical properties associated with the waters that the other groups are examining the biology of to understand physical attributes affecting the biological structure.

Pre-Storm Transects

So I believe it is now Saturday afternoon (though we're all pretty tired, so maybe I should check on that). We've been sampling at stations non-stop as we're trying to beat a front approaching. We have sampled 2 transects offshore with 8 stations per transect from Thursday afternoon through Friday afternoon. At each station, we do at least 2 CTD casts to collect water at 2m increment water depths from the bottom to 12m off the bottom, as well as a surface sample. The first cast is sampled for chlorophyll, nutrients, and HPLC samples. 500mL of water is filtered and saved frozen for nutrient analysis, keeping the filter for chlorophyll analysis. Another 1500mL is filtered (500mL per filter) from the bottom water, 10m off the bottom water, and the surface water; the filters from this are stored in liquid nitrogen, and will be extracted and run on an HPLC (high performance liquid chromatography) to analyze pigments from the water to determine what types of plankton were present. The second cast is used for a net tow. 5L of water is poured through a net to isolate plankton at the bottom of the water column. By doing it this way, the sample isn't contaminated by towing the net off the side of the boat and collecting plankton in the water column on the way up. As with normal field work, some problems arose periodically with the CTD, but the ship's crew has been fantastic at getting it working again fairly quickly. Coring (box cores and multicores) has been attempted at several stations, but due to the sandy bottom with quite a bit of coral, there has been a lot of frustration prior to finally collecting some good cores to do flux chamber nutrient analysis. When a good core is obtained, we do a third CTD cast to collect water for the flux chambers off the bottom of the seabed. The flux chambers are being sampled at regular time intervals today (Saturday) for water to be analyzed for nutrients as biogeochemical reactions occur in the sediment and alter the water chemistry.

After the first station, the divers were deployed to dive to 50ft water depth to collect water from every 20cm off the bottom of the seabed using a specially designed micro-sampler controlled by using an air tank to provide pressure to simultaneously pull 16 syringes at 16 different depths off the bottom to collect the water and bring it aboard the ship for collection and freezing for detailed nutrient analysis.

The Acrobat and ADCP were launched overnight Friday to Saturday night, collecting nutrient, oxygen, current, fluorescence etc. data. This morning, we have deployed a drogue drifter to follow the bottom water to see where Karenia brevis populations would potentially be transported given current weather and conditions. We are now preparing to deploy the Mimics (autonomous drifters that mimic Karenia brevis behaviors in the water column) with some snorkelers to follow them. The mimics will be compared with the drogue drifter to see differences in behavior between the autonomous and drag drifters.

Departure

Wednesday, we met at the Port of Pensacola at 8am (some of us spent the night at a hotel, while others of us crashed at Blake's house). Upon port arrival, we had to wait for the ship to finish unloading before we could get set up, so we unloaded the vans. Once it was ready for us, it was time to start carrying in all the equipment, some of which as hand toted while others was lifted aboard by crane. The second group of scientists from NCSU (another 7 people) arrived around 9:30am to finish helping load the ship, and begin the great unpack. We set up the labs, one instrument lab and one wet lab, tied everything down so nothing shifted during transit, and acquainted ourselves with the ship. We finally left port around 4pm, and headed out into the gulf. The Pelican is known for amazing cuisine, and did not disappoint. After dinner, most settled into their bunks for the night or watched the Presidential debates by satellite. During this time (and overnight), we deployed the Acrobat, an instrument which is towed behind the boat to detect various nutrient levels. This helped us determine where we will start sampling, which is set to begin in about an hour (Thursday morning).

Travel Days

We met to pack the vans bright and early at 7:30am on Monday. After pretty rapid packing due to the excellent turnout of helpful graduate students, Chief Scientist Dan Kamykowski and graduate students, Linda Waters and Cathy Thompson drove two hours to Wilmington to pick up Prof. John Morrison, post-doc Wendy Woods, and graduate student Ebenezer Nyadjro from UNCW Marine Lab. We packed the vans there with more instrumentation and then we were off for our long drive (~9.5 hours) to just south of Atlanta, GA where we stopped for the night.

After the 5 hour drive on Tuesday morning, we met Dr. Blake Schaeffer (former graduate student and post-doc at NCSU) at the Environmental Protection Agency in Gulf Breeze, FL, where he is now employed. We toured the facilty while Dr. Geoff Sinclair of LUMCON (former NCSU graduate student) used the laboratory facilities for cruise preparation.

Unfortunately, we learned this afternoon that the ship was delayed coming in to port due to bad weather in St. Petersburg, FL. The ship is unable to make port in Pensacola until early Wednesday morning. So, we made the best of the afternoon preparing gear and chemical solutions, getting dive tanks filled, and making alternate cruise plans. We then had a fresh fish barbeque at Blake's house, complete with a cake to celebrate his first wedding anniversary.