DAY EIGHT (9/24/12)

Over the course of the night while dodging several vessels of a shrimp fleet, the navigators searched for Little Mitch and Four Leaf Clover Banks to no avail.  However, en route to Steamer Bank this morning, we stumbled upon a set of banks that we named Falkor Banks trending to the west of the previously located “Rock.”  We’re quite sure “Rock” has not been mapped in the past.  It is a very interesting site with a rather flat top, fairly low relief, several circular holes, and a very large “blue hole” feature, which might be an ancient lake near a historic coastline.

 

Blue hole

Image credit: Maureen Trnka

Biologist (and closet geologist) Tom Shirley and geologist Andre Droxler pounded open a rock from yesterday’s collection to investigate what critters and geological clues could be revealed.  They found layered red algae, a bright orange worm, a brittlestar, and tiny crabs.

 

Worm found upon breaking rock

Image credit:  Maureen Trnka

Meanwhile, David Hicks, Liana Lerma, and Jonathan Le analyzed the 3D video from Baker Bank recording the number of fish species for biodiversity analyses.

Wes Tunnell spoke at the SASS this afternoon giving an ecological history of coral reefs in the southern Gulf of Mexico.  He told us about the decline of Acropora corals throughout the Caribbean Sea and the Gulf of Mexico and pointed out the similarity in appearance to the staghorn bryozoans that we discovered yesterday at Dream Bank.

Wes Tunnell speaking about coral reefs at SASS

Image credit:  Maureen Trnka

Just before dinner, the Falkor steamed on to map Steamer Bank, which unfortunately was also a disappointment as we only found a tiny bump at the coordinates we researched in advance of the cruise.  We collected CTD data and water samples at Falkor Banks and Steamer Bank and then ended the day with a sunset photo contest.

Day 8 Sunset

Image credit:  Maureen Trnka

Written by Harriet Nash for HRI at TAMU-CC.

DAY SEVEN (9/23/12)

Today our exploration centered on Dream Bank.  Similar to Aransas Bank, the landward side was murkier with suspended muddy sediment in the water column while the seaward side of the bank was quite clear.  Dream Bank has quite a few crevices and some burrows, which serve as refugia for fish escaping the frightening ROV.  The fish assemblage at Dream Bank is similar to that of Aransas Bank.  In addition, we spotted a sea robin, which looks like a winged fish flying near the sea bottom, and a few schools of amberjack.  Other exciting sights were sea stars, a flame box crab, a cleaning station with a fish and a couple of cleaner shrimp, an arrow crab, and several sea serpents and basket stars.

 

Large female basket star with smaller male basket star attached in center
Image credit:  Harriet Nash

While attempting to collect rocks for the geologists, we came upon a fishing weight that was mistaken by one of the rather nerdy scientists in the group as a mermaid’s tassel.  We quickly moved on to collect some soft corals.  As Wes Tunnell put it, collecting soft corals with the ROV’s hydraulic arm is “like collecting a flower with a bulldozer.”  However, we still managed to bring a fine specimen of black coral safely to the lab for analysis.  We also collected a soft coral with basket stars.  A full set of sediment cores was collected for analysis.

The biologists AND geologists all became giddy when the ROV approached a mound of rubble that resembled staghorn coral (Acropora cervicornis).  A mound of dead A. cervicornis would provide strong support for the theory that Dream Bank is an ancient drowned reef and could also be carbon dated.  After looking at a piece of the rubble sample, Wes Tunnell and Tom Shirley determined that the rubble was composed of staghorn bryozoans, which are filter-feeding invertebrates that live in colonies but are not related to corals.  We have not seen any living staghorn bryozoans so the feature could be a mound of fossils.  Another unanswered question:  how did the staghorn bryozoans end up in a mound formation?

Staghorn bryozoans

Image credit:  Harriet Nash

Not far from the mound there was a large crater, which could be the result of groupers digging a large hole or a geophysical phenomenon such as a “mud volcano” or methane geyser producing a hole in the sea floor with steep walls.  The cause of the crater is not certain. 

The mound of ancient A. cervicornis was a dream that did not come true, but don’t fret because science never sleeps.  Dream on, dream on…

Day 7 Sunset

Image credit:  Harriet Nash

Written by Harriet Nash for HRI at TAMU-CC.

DAY SIX (9/22/12)

Data, data, data!  Today we collected CTD data and water samples to profile the water columns above Dream and Mysterious Banks, which are both located in the southern grouping of the South Texas Banks.  Dr. Paul Zimba and doctoral candidate Maureen Trnka will analyze water samples to determine which algal species are present at which depths at the two sites.

Between the CTD dives, the crew conducted a safety exercise by testing the tender boats.  HRI and other students and journalist Mark Schrope rode along for photo opportunities and to collect Sargassum (macroalgae) samples.  It was an exciting ride as pantropical spotted dolphins followed the little excursion.  At least a dozen dolphins swam alongside the boat playing in the wake and jumping into the air. 

Just a little taste of dolphins galore

Image credit: Maureen Trnka

Dr. David Hicks spoke at the afternoon’s SASS and the told the crew and scientists about his biodiversity assessment studies in high salinity environments in an ecological restoration area in south Texas near the Mexican border. 

Dr. Hicks speaking to crew and science party as SASS

Image credit:  Harriet Nash

Throughout the day and into the night we also continued collecting multibeam data for detailed mapping of remaining sites.  As before, scientists took turns processing the incoming data.  Refined maps will be used to guide the next ROV dives tomorrow.

On the lounge deck just before sunset, the crew and scientists wrapped up the day with a lovely “charcoal-based social networking opportunity,” AKA barbecue, complete with a slideshow recapping the first week. 

BBQ Social

Image credit: Harriet Nash

 

 

Day 6 Sunset

Image credit:  Maureen Trnka

Written by Harriet Nash for HRI at TAMU-CC.

DAY FIVE (9/21/12)

To core or not to core? That was the question of the day as the ROV explored Aransas Bank this morning. Scientists jumped to their feet in the labs cheering throughout the vessel when ROV pilot returned the first successful push core safely to its holder full of a muddy sediment sample. Whooping and hollering from the science control room could be heard across the Gulf (well, at least throughout the R/V Falkor). One small tap from a hydraulic robotic arm, one giant push for benthic ecology at Aransas Bank.

ROV hydraulic arm returning core with sediment to the holder.

Image credit: Harriet Nash; Deep Sea Systems International; Schmidt Ocean Institute

After a couple of successful push cores on the landward side of the bank, we did a video transect to the peak.  The ROV followed the same procedure of core sampling and video transect from the seaward side as well.  Visibility on the landward side of Aransas Bank was quite murky, but visibility on the seaward side was much better and similar to that at Baker Bank.  In general, we observed similar biota at Aransas Bank when compared to what we saw at Baker Bank. Several species were common at both sites—Atlantic thorny oyster, long sea whip, tattler basslet, reef butterfly fish, blue angelfish, French angelfish, sponges, and wire coral. Notable differences between sites include no sea cucumbers; fewer Hypnogorgia white sea fans; many more red snapper; and more depressions, ledges, and burrows than at Baker Bank. Aransas Bank is home to more short bigeyes, which darted into burrows when the ROV approached. We also saw a few interesting species on Aransas Bank that we did not see at Baker Bank. They included silky shark, scrawled cowfish, spotfin hogfish, serpent star, a huge hermit crab, jackknife fish, and giant basket stars.

After spending quite a bit of time collecting samples of sponges, rocks, and sea fans, the ROV returned to the mother ship. The crew fixed the ROV in its place on the aft deck, and almost immediately a sponge brittlestar frantically scurried from the ROV across the deck trying to get back to its home. A scientist quickly scooped it up for the collection.

 

We unloaded the completely full sample box and the sediment cores. Once the samples reached the wet lab, the scientists entered a frenzied state of chaotic excitement while sorting and processing samples. The sediment samples were very watery and loose so only a few survived and were stored for later analysis by benthic ecologists and geologists. Living inside sponges and rocks were polychaete worms, tiny shrimps, squat lobsters, juvenile crabs, brachiopods, and white tangled bryozoans.  The scientists turned in for the night quite pleased with the high biodiversity represented in their samples.

Microscopic image of a squat lobster that was extracted from a rock sample.

Image credit: Jonathan Le; Deep Sea Systems International; Schmidt Ocean Institute

 

Day 5 Sunset

Image credit: Harriet Nash

Written by Harriet Nash for Harte Research Institute at Texas A&M University-Corpus Christi.

DAY FOUR (9/20/12)

Today was spent collecting data with a CTD, which is a piece of equipment used to measure conductivity (a surrogate for salinity), temperature, depth, fluorescence (a surrogate for chlorophyll levels), dissolved oxygen, and turbidity.  The CTD was lowered into the water at Baker and Aransas Banks from the aft deck using a crane, and the device profiled the entire water column from the surface to the sea floor.  We monitored real-time graphs from the science control room.   Also, scientists analyzed water samples that came up with the CTD looking for Karenia, which is a genus of algae that causes harmful algal blooms, which was indeed identified in the samples.

CTD being lowered into the water above Baker Bank

Image credit: Maureen Trnka

Additionally, we filled in gaps in the multibeam data for the northern grouping of the South Texas Banks and began collecting sub-bottom profile data to help geologists determine the extent of the site formations below the sea bottom.  Such data are valuable to determine the age and origin of the banks.

 

Pankaj Khanna (Rice University student)

processing sub-bottom profile data

Image credit: Maureen Trnka

Dr. Tom Shirley spoke at the SASS series today.  He talked about serpent stars, deep-sea brittlestars, and their affinity for certain species of soft corals—sea fans in particular. 

Dr. Shirley speaking at the afternoon SASS

Image credit: Maureen Trnka

In the Baker Bank videos yesterday, we saw one species that was wrapped around wire coral reminiscent of a wad of chewing gum.

Deep-sea brittlestar wrapped around wire coral

Image credit:  Deep Sea Systems International; Schmidt Ocean Institute

Wildlife spotted today included yet more playful, leaping dolphins and a gliding peregrine falcon.

Day 4 Sunset

Image credit: Maureen Trnka

Written by Harriet Nash for Harte Research Institute at Texas A&M University-Corpus Christi.

DAY THREE (9/19/12)

More excitement today!  Based on the detailed map from the previous day’s work, we spent the entire day exploring Baker Bank with the ROV.  After a deployment to balance the ROV’s buoyancy, the ROV followed two planned transects for video capture and then collected some samples.  We captured several hours of video, including almost three hours on the first transect and an hour on the second transect.  The transects began on opposite sides (landward and seaward) at the base of the bank and went up to the peak (shallowest depth). 

3D map of Baker Bank with overlay of ship's route while collecting multibeam data.

Image credit:  Harriet Nash; Schmidt Ocean Institute

Crew deploys ROV over Baker Bank.

Image credit: Mark Schrope; Deep Sea Systems International; Schmidt Ocean Institute

In a region known for murky waters filled with suspended mud and silt, scientists were thrilled to have good visibility at 70 meters below the sea surface.  The live video feed revealed a thriving ecological community with high biodiversity at Baker Bank.  Scientists identified several species of sponges ranging in color from white to purple; fields of coiled wire corals; sea fans; black corals; sea whips; crinoids; feather hydroids; branching coralline algae; sea cucumbers; brittle stars; oyster clams; and juvenile and adult reef fishes including butterfly fishes, angelfishes, wrasses, porgies, snappers, and damselfishes.  Unfortunately, videographers also identified a lionfish, which is an invasive species that feeds on native reef fish species.  Technicians used regular video, 3D video, and three different types of cameras to capture images and map sightings throughout the dive.  Scientists will use the imagery and data to describe the community and biodiversity of Baker Bank.

Pilot James Sherwood controls ROV from the ship's navigation room.

Image credit:  Mark Schrope; Deep Sea Systems International

Screen capture of video imaging showing wide-mesh sea fan.

Image credit: Harriet Nash; Deep Sea Systems International; Schmidt Ocean Institute

The ROV pilot attempted twice to collect push core samples of sediment, but the sediment was so fine and loose that it was not compacted enough to remain in the sampling tube.  However, the ROV’s robotic arm did successfully collect a few samples:  two sponges and a black coral sea fan. 

A specimen of black coral that was collected from Baker Bank.

Image credit: Harriet Nash

Microscopic image of the black coral specimen showing six tentacles around each polyp mouth.

Image credit: David Hicks; Schmidt Ocean Institute

Day 3 Sunset

Image credit: Maureen Trnka

After Drs. Shirley and Tunnell charted out the next day’s activities with the captain and technology crew, several scientists gathered in the library to end a long day by watching “The Neverending Story,” the book and movie after which the R/V Falkor and its safety boats were named.

Written by Harriet Nash for HRI at TAMUCC.

DAY TWO (9/18/12)

The mapping continues.  In the middle of the night we made it to the southern end of our initial route for multibeam mapping and turned around after collecting data at Mysterious Bank to head back north for the second pass.  The science party continued 2-hour data processing shifts continuously as the equipment beneath the boat continued to collect more raw data.  Data processing is an important precursor to mapping and planning tomorrow’s ROV dives.

Liana Lerma and Maureen Trnka process multibeam data.

Image credit: Elizabeth Shanks

On the R/V Falkor, the multibeam data collection equipment is housed in a gondola (basket-like attachment) fixed 50 centimeters beneath the hull.  The equipment includes a transmitter that sends out several acoustic signals (“multibeam”) that are reflected off the seafloor and captured by a transducer.  Based on the time the acoustic signal takes to bounce off the bottom and return to the mother vessel, the depth at an exact position can be calculated.  The resulting high-resolution depth, or “bathymetry,” data describe the seafloor at a very fine scale, which allows scientists to create 3-D imagery of the sites.

When not processing data, scientists continued to record wildlife sightings (dolphins, sea turtles, flying fish, and sea birds) from the observation deck.  Additionally, the scientists started a Science at Sea Seminar (SASS) series in the library.  Dr. André Droxler kicked off the SASS series with a talk about geological origin of the South Texas Banks.

Dr. David Hicks (UT Brownsville) on observation deck.

Image credit: Harriet Nash

 

One of the several pods of dolphins spotted near the vessel's bow.
Image credit: Elizabeth Shanks

Dr. André Droxler (Rice University) kicks off SASS series in library.
Image credit: Maureen Trnka

Day 2 Sunset
Image credit: Maureen Trnka

Written by Harriet Nash for Harte Research Institute at Texas A&M University-Corpus Christi