Lisbeth Uribe, August 5, 2008

NOAA Teacher at Sea
Lisbeth Uribe
Onboard NOAA Ship Delaware II
July 28 – August 8, 2008

Mission: Surfclam and quahog survey
Geographical Area: Southern New England and Georges Bank
Date: August 5, 2008

Chief Scientist Vic Nordahl, Chief Boatswain Jon Forgione and Chief Engineer Patrick Murphy discussing the best way to reattach the pump power cable to the dredge.

Chief Scientist Vic Nordahl, Chief Boatswain Jon Forgione and Chief Engineer Patrick Murphy discussing the best way to reattach the pump power cable to the dredge.

Ship Log 

In the last 48 hours the engineers, crew and scientists have had to re-attach the power cable to the dredge (see photograph), fix the cracked face plate of the pump, replace the blade and blade assembly, change the pipe nozzles that direct the flow of water into the cage, and work on the dredge survey sensor package (SSP). Dredging is hard on the equipment, so some mechanical problems are to be expected. The main concern is for lost time and running out of critical spare parts.  So far we have had great success with making the repairs quickly and safely.

Science and Technology Log 

Collecting Tow Event and Sensor Information for the Clam Survey 
Over the weekend I was moved up to the bridge during the towing of the dredge. I was responsible for logging the events of each tow and recording information about the ship and weather in a computerized system called SCS (Scientific Computer System). I listened carefully to the radio as the lab, bridge (captain) and crane operator worked together to maneuver the dredge off the deck and into the water, turn on the pumps, tow the dredge on the seafloor bottom, haul the dredge up, turn off the pump and bring the clam-filled dredge back on deck. It is important that each step of the tow is carefully timed and recorded in order to check that the tows are as identical as possible.  The recording of the events is then matched to the sensor data that is collected during dredge deployment. As soon as the dredge is on deck I come downstairs to help clean out the cage and sort and shuck the clams.   

Lisbeth is working on the bridge logging the events of each tow into the computer system.

Lisbeth is working on the bridge logging the events of each tow into the computer system.

My next job assignment was to initialize and attach to both the inside and outside of the dredge the two mini-logger sensors before each tow. Once the dredge was back on deck I removed both mini-loggers and downloaded the sensor data into the computers. Both sensors collect pressure and temperature readings every 10 seconds during each tow. Other sensors are held in the Survey Sensor Package (SSP), a unit that communicates with onboard computers wirelessly.  Housed on the dredge, the SSP collects information about the dredge tilt, roll, both manifold and ambient pressure & temperature and power voltage every second. The manifold holds the six-inch pipe nozzles that direct the jets of water into the dredge.  Ideally the same pump pressure is provided at all depths of dredge operation. In addition to the clam survey, NOAA scientists are collecting other specimens and data during this cruise.

Two small black tubes (~3 inches long), called miniloggers, are attached to the dredge. The miniloggers measure the manifold (inside) and ambient (outside) pressure and temperature during the tow.

Two small black tubes (~3 inches long), called miniloggers, are attached to the dredge. The miniloggers measure the manifold (inside) and ambient (outside) pressure and temperature during the tow.

NOAA Plankton Diversity Study 
FDA and University of Maryland Student Intern Ben Broder-Oldasch is collecting plankton from daily tows.  The plankton tows take place at noon, when single-celled plants called phytoplankton are higher in the water column. Plankton rise and fall according to the light. Plankton is collected in a long funnel-shaped net towed slowly by the ship for 5 minutes at a depth of 20 meters. Information is collected from a flow meter suspended within the center of the top of the net to get a sense of how much water flowed through the net during the tow. Plankton is caught in the net and then falls into the collecting jar at the bottom of the net.  In the most recent tow, the bottle was filled with a large mass of clear jellied organisms called salps. Ben then filters the sample to sort the plankton by size. The samples will be brought back to the lab for study under the microscope to get a sense of plankton species diversity on the Georges Bank.

An easy way to collect plankton at home or school is to make a net out of one leg of a pair of nylons. Attach the larger end of the leg to a circular loop made from a metal clothes hanger.  Cut a small hole at the toe of the nylon and attach a plastic jar to the nylon by wrapping a rubber band tightly around the nylon and neck of the jar.  Drag the net through water and then view your sample under a microscope as soon as possible.

Biological Toxin Studies 

NOAA Scientist Amy Nau hauls the plankton net out of the water using the A-frame. (Upper insert: flow meter; lower insert: plankton in the collection bottle after the tow).

NOAA Scientist Amy Nau hauls the plankton net out of the water using the A-frame. (Upper insert: flow meter; lower insert: plankton in the collection bottle after the tow).

Scientists from NOAA and the Food & Drug Administration (FDA) are working together to monitor clams for biological toxins. Clams and other bi-valves such as oysters and mussels, feed on phytoplankton. Some species of phytoplankton make biological toxins that, when ingested, are stored in the clam’s neck, gills, digestive systems, muscles and gonadal tissues.  If non-aquatic animals consume the contaminated clams, the stored toxin can be very harmful, even fatal.  The toxin affects the gastrointestinal and neurological systems. The rate at which the toxins leave the clams, also known as depuration rate, varies depending on the toxin type, level of contamination, time of year, species, and age of the bivalve. Unfortunately, freezing or cooking shellfish has no effect on the toxicity of the clam. The scientists on the Delaware II are collecting and testing specimens for the two biological toxins that cause Amnesia Shellfish Poisoning (ASP) and Paralytic Shellfish Poisoning (PSP).

NOAA Amnesia Shellfish Poisoning (ASP) Study 
A group of naturally occurring diatoms, called Pseudo-nitzschia, manufacture a biological toxin called Domoic Acid (DA) that causes Amnesia Shellfish Poisoning (ASP) in humans.  Diatoms, among the most common organisms found in the ocean, are single-celled plankton that usually float and drift near the ocean surface. NOAA scientist Amy Nau collects samples of ocean water from the surface each day at noon. By taking water samples and counting the numbers of plankton cells, in particular the Pseudo-nitzschia diatoms, scientists can better determine if a “bloom” (period of rapid growth of algae) is in progress. She filters the sample to separate the cells, places the filter paper in a test tube with water, adds a fixative to the tube and sets it aside for further study in her lab in Beaufort, NC. 

Scientist Amy Nau filters seawater for ASP causing dinoflagellates.

Scientist Amy Nau filters seawater for ASP causing dinoflagellates.

FDA Paralytic Shellfish Poisoning (PSP) Study 
Scientists aboard the Delaware II are also collecting meat samples from clams for an FDA study on the toxin that causes paralytic shellfish poisoning. When clams ingest the naturally occurring dinoflagellate called Alexandrium catenella, they accumulate the toxin in their internal organs. When ingested by humans, the toxin blocks sodium channels and causes paralysis. In the lab, testing for the toxin causing PSP is a lengthy process that involves injecting a mouse with extracts from shellfish tissue.  If the mouse dies, scientists know the toxin is present. The FDA is testing the accuracy of a new quick test for the toxin called the Jellet Test Kit. After measuring and weighing a dozen clams from each station on the Georges Bank, Ben and Amy remove and freeze the meat (internal organs and flesh) from the clams to save for further testing by scientists back on land. At the same time, they also puree a portion of the sample and test it using the Jellet strips for a quicker positive or negative PSP result.

Personal Log 

Pilot whales sighted off the bow!

Pilot whales sighted off the bow!

The problems that we have experienced with regard to the dredge over the past few days are an important reminder of the need for the scientists and crew to not only be well prepared but also flexible when engaged in fieldwork. All manner of events, including poor weather and mechanical difficulties, can and do delay the gathering of data. The Chief Scientist, Vic Nordahl, is constantly checking for inconsistencies or unusual patterns, particularly from the dredge sensor readings, that might need to be addressed in order to ensure that the survey data is consistent and accurate. The time required to repair the dredge meant I was able to do a load of laundry. Dredging is very dirty work! Good thing I am using old shirts and shorts. I also caught up on a few emails using the onboard computers. Though the Internet service can be slow at times it is such a luxury to be able to stay in touch with friends and family on land. I still have two very special experiences that I wish to share before ending my log.

Late in the evening a couple of days ago, as we steamed toward our next tow station, I was invited to peer over the bow. The turbulence in the water was causing a dinoflagellate called Noctiluca to sparkle and glow with a greenish-blue light in the ocean spray.  The ability of Noctiluca and a few other species of plankton and some deep-sea fish to emit light is called bioluminesense. A few days later we had the great fortune to see five pilot whales about 100 meters away, gliding together, their black dorsal fins slicing through the water, occasional plumes of air bursting upward through their blowholes (nostrils located on the tops of their heads).

Answers to the previous log’s questions: 

1. What is the depth and name of the deepest part of the ocean? The Mariana Trench in the Pacific Ocean is 10,852 meters deep, (deeper than Mount Everest is tall – 8,850 meters).  Speaking of tall mountains, the tallest mountain in the world is not Mount Everest, but the volcano Mauna Kea (Hawaii).  It reaches 4,200 meters above sea level, but its base on the sea floor is 5,800 meters below sea level.  Its total height (above base) is therefore 10, 000 meters!

2.What is the longest-lived animal on record? In 2007, an ocean quahog was dredged off the Icelandic coast.  By drilling through and counting the growth rings on its shell, scientists determined it was between 405 and 410 years old. Unfortunately it did not survive the examination, so we do not know how much longer it would have lived if left undisturbed. This ancient clam was slightly less than 6 inches in width.

Lisbeth Uribe, July 31, 2008

NOAA Teacher at Sea
Lisbeth Uribe
Onboard NOAA Ship Delaware II
July 28 – August 8, 2008

Mission: Surfclam and quahog survey
Geographical Area: Southern New England and Georges Bank
Date: July 31, 2008

“Bob” the Man Overboard Victim

“Bob” the Man Overboard Victim

Ship Log 

Man Overboard Drill 

Just as the day watch started our shift we heard three short blasts of the ship’s horn, signaling a “Man Overboard” drill.  While the crew was on deck (both on the bow (front of the ship) and stern (back), the Chief Boatswains Jon Forgione and Leno Luis put on life vests and safety helmets and were lowered into the water in a rigid haul inflatable boat (RHIB).  When those on board the ship sighted the dummy victim, we raised our arms and pointed in its direction. The rescuers then headed in the direction the crew were pointing.  At the same time, the Operations Officer and Medical Person in Charge (MPIC) Claire Surrey readied her gear to perform life saving measures once the victim was safely brought on the deck.  Rescue protocols are taken very seriously as they are designed to keep all members of the crew safe.  Once the MPIC determined the dummy victim was breathing on their own and required no further medical assistance, the drill was over and the crew returned to their stations or berths (sleeping rooms).

Scuba Divers to the Rescue! 

Not long after the man overboard drill, the dredge rolled when it was being hauled from the sea floor, wrapping the hawser (floating tow line) underneath the cage.  To make matters worse, as the dredge was being lifted up the ramp on deck, the hawser became caught in the ship’s rudder.  Our three NOAA Working Divers, Executive Officer (XO) Monty Spencer, Chief Steward (chef), MPIC Jonathan Rockwell and MPIC Claire Surrey suited up in scuba suits for a dive to untangle the rudder. NOAA Working Divers must complete a 3-week training course. They are skilled at ship husbandry, such as working on the rudder, propellers, zincs (metal zinc objects that are placed on the hull of a ship to attract corrosion), and the bow thruster (a tunnel through the ship with a propeller to help direct the bow when docking).  

Chief Steward Jonathan Rockwell preparing to dive below the ship to untangle the hawser line from the rudder.

Chief Steward Jonathan Rockwell preparing to dive below the ship to untangle the hawser line from the rudder.

The diver breathes air through a mouthpiece, called a regulator, from a scuba tank of compressed air that is strapped to the diver’s back. The regulator, connected by a hose to the tank, adjusts the air in the tank to the correct pressure that a diver can safely breathe at any given depth. Originally called the “aqua-lung”, “scuba” stands for self-contained underwater breathing apparatus. Scuba gear has helped scientists explore the ocean, however, the equipment does have limitations.  The deepest dive that can be made by a NOAA scuba diver is about 40 meters, but the average depth of the ocean is about 3,800 meters.  The increased water pressure of the dive limits the depth of the descent of a scuba diver.

As Monty and Jonathan plunged into the ocean, the rigid haul inflatable boat (RHIB) was deployed with General Vessel Assistant (GVA) Adam Fishbein and Chief Boatswains, Jon Forgione at the tiller arm, to assist in diver rescue operations if needed. On standby in full scuba gear was MPIC Claire Surrey in case the divers ran into any trouble. In no time at all the divers freed the tangled hawser from the rudder and were back on board. At each step of the job, great care was taken to check all gear and ensure the safety of the crew.

Question: What is the depth and name of the deepest part of the ocean?

Mature Atlantic Surf Clam and Ocean Quahog

Mature Atlantic Surf Clam and Ocean Quahog

Science and Technology Log 

As I mentioned in my first log, we are targeting two species of clams during our survey, the Atlantic Surf clams (Spissula solidissima) and Ocean Quahogs (Arctica islandica). They are very easy to tell apart, as the surf clam is much larger (about 18 cm in width) and lighter in color. “Quahog” (pronounced “koh-hawg”) originated from the Narrangansett tribe that lived in Rhode Island and portions of Connecticut and Massachusetts. Atlantic surf clams are a productive species, in that they are faster growing, with a lifespan of about 15 years, with variable recruitment (reproductive cycles). They are much smaller and typically found in more shallow waters (<50 meters) from Cape Hatteras to Newfoundland than the ocean quahog. The Quahog lives in depths of 50-100 meters in US waters (from Cape Hatteras up to the north Atlantic (Iceland), and also in the Mediterranean). Quahogs grow slowly, and typically live for more than 100 years, with infrequent and regional recruitment.

There is a great variety of material, both organic and inorganic that is collected by the dredge providing a snapshot of the habitat below.  At times it is sandy, sometimes the sediment is the consistency of thick clay, in which case we must re-submerge the dredge for a few minutes to clean the cage. At other times large rocks and boulders are captured.

Live clams, shells and other material collected in the dredge.  All the material is sorted, weighed and measured as part of the survey.

Live clams, shells and other material collected in the dredge. All the material is sorted, weighed and measured as part of the survey.

Atlantic Surf Clams and Ocean Quahogs live in a part of the ocean called the subtidal zone. Their habitat is the sandy, muddy area that is affected by underwater turbulence but beyond heavy wave impact. In addition to clams, our dredge is capturing a variety of organisms perfectly adapted to this environment, such as sponges, marine snails and sea stars that are able to cling to hard materials to protect them from being swept away by ocean currents and waves. Marine snails and hermit crabs are also able to cling to surfaces.  Like the clam, many organisms have flattened bodies, thereby reducing their exposure to the pull of waves and currents.  We find flat fish, such as flounder and skate, which avoid turbulence and their enemies by burying themselves in the sand.  Flounder prey on sand dollars, another flat organism living in the subtidal zone.  In many hauls of the dredge, the cage is filled with sand dollars. We have collected lots of other interesting animals, such as hermit crabs, worms, sea jellies, sea mice and, less often, crabs and sea urchins. The Sea Mouse is plump, about 10 cm in length, segmented and covered in a large number of grey brown bristles that give it a furry appearance.

Question: What is the longest-lived animal on record?

Personal Log 

The main difficulty I have with writing this log is choosing what to cover. Each day is filled with new and interesting experiences. I am learning so much, not only about the science behind the clam survey, but also about the ship itself and the skills necessary to operate the ship and conduct a marine survey.  Everyone has been extremely generous with sharing his or her knowledge and experience with me.   While cleaning the inside of the dredge last night one of the wires made a small tear in the seat of my waterproof overalls. Now I know to pack a bike inner tube repair kit if I am lucky enough to be invited to join another survey cruise! One of those small rubber patches would have been the perfect for the job. I was able to find a sewing kit and in short order sewed the tear and sealed it with a layer of duct tape. Now I am ready to get back to work!

Lisbeth Uribe, July 30, 2008

NOAA Teacher at Sea
Lisbeth Uribe
Onboard NOAA Ship Delaware II
July 28 – August 8, 2008

Mission: Surfclam and quahog survey
Geographical Area: Southern New England and Georges Bank
Date: July 30, 2008

NOAA Teacher at Sea, Lisbeth Uribe, in her survival suit next to the dredge

NOAA Teacher at Sea, Lisbeth Uribe, in her survival suit next to the dredge

Science and Technology Log 

Prior to our departure on the survey, all the volunteers attended presentations by NOAA scientists about the work we would be doing. The purpose of the clam survey is to provide consistent, unbiased estimates of the relative abundance for many shellfish in the North East region. The target species for our survey are the Atlantic Surf clams (Spissula solidissima) and Ocean Quahogs (Arctica islandica). We also went to a NOAA storeroom and were outfitted with our foul weather gear (heavy waterproof boots, fluorescent yellow rain pants and rain jacket). While on board we received several briefings about safety and the expectations for behavior during the cruise.  During an emergency drill we each tried on our survival suit. I keep the suit in a bag at the foot of my bed, ready for any emergency!

We set sail at 2:00 pm on Monday, the 28th of July, and headed south towards our first tow location in the Southern New England region. The first 10 survey points or stations of our cruise are repeats of points surveyed in the last trip. This means we will be heading south toward the Long Island region before sailing for the Georges Bank region. We are conducting repeat surveys because after the last survey, the dredge’s electrical cable was replaced with a longer cable (formerly 750 feet, now 1,100 feet long). The added length in the cable results in a voltage drop that is expected to be enough to cause the dredge pump to loose pressure slightly. The pump, attached to the dredge itself, is designed to churn up sediment and shellfish as the dredge is towed along the sea floor. By rechecking the survey data collected in the last trip, the scientists will be able to calibrate the data obtained using the new cable. The scientists and crew are very concerned about accuracy of data collection during all parts of the Clam Survey.  

Problems with the Dredge 

For the first repeat survey station, our CO (Commanding Officer), Captain Wagner, warned the crew that the bottom might be rocky.  Once the dredge hit the bottom and began to be towed, we heard some loud noises indicating that there were indeed rocks on the bottom.  We pulled the dredge out of the water after the standard 5-minute tow time.  Rocks had twisted, bent and even severed various pipes and rods that make up the cage of the dredge. The row of outlet pipes (called nipples) that direct powerful jets of water towards the opening of the cage had been severed at the points in which they screw into the main pump pipe.

Though the damage was a setback in terms of lost time, it was amazing to see the engineers swing into action and make the necessary repairs over the next six hours. Out of the hold came an assortment of tools, such as metal cutters, jacks, soldering equipment, wrenches, pliers, and mesh wiring.  I was put to work extracting the broken ends of pipes and handing tools to the engineers as they either replaced or repaired broken parts.  By the end of my work shift (midnight) the dredge was fully repaired and ready for work again.

Tuesday, July 29, 2008 

I am wearing my bib and overalls, boots, and a hardhat while working inside the dredge to free the clams caught in the corners and cracks of the dredge.

I am wearing my bib and overalls, boots, and a hardhat while working inside the dredge to free the clams caught in the corners and cracks of the dredge.

I am fortunate to be working with a great team on the day shift crew (noon to midnight).  My Watch Chief, Shad Mahlum, and the Chief Scientist, Vic Nordahl, are excellent teachers, patient with my mistakes and quick to offer words of encouragement. There are several work assignments during each station.  I help by turning on and off the power for the pump on the dredge, clearing out the shellfish that get caught in the cage, and weighing and measuring the clams we catch. My favorite job is cleaning out the inside of the dredge. After the dredge has been hauled up the ramp onto the deck, the back door is released and the clams and broken shells tumble onto the sorting table. My job is to climb up inside the cage of the dredge and toss down the shells and organisms that get caught along the edges. I like the challenge of climbing around up high in a small space. We have been lucky to have very calm seas over the past couple of days.  This job will get quite a bit more challenging when the deck starts to move around more.

The dredged material is sorted into different wire baskets, also known as bushels, each contain either clams, other sea life or trash to be thrown back out to sea once we have moved past the survey site. The clams are weighed and measured.  At some stations we also collect meat specimens for further analysis.  All the information goes into the computer, including data collected by the sensors on the dredge.

Personal Log 

As part of the day shift crew, I work from noon until midnight.  It may sound tough working a 12-hour shift, but in reality the time passes very quickly as we are always busy either preparing for a station, processing the clams, or cleaning up after a dredge.  We are not permitted to return to our room until the end of our shift as our roommates are on the opposite shift and are sleeping.

When sailing out in the open water it easy to lose one’s sense of direction.  On the second day of the survey I knew that we were headed south for the repeat dredges, but it was not until one of the crew members showed me the site “Ship Tracker for NOAA” that I realized we were collecting samples just off the coast of Long Island all afternoon—not far from my home town, New York City! We are so busy moving from station to station that I often lose track of where I am.

I am grateful for the clear weather we have had so far on the cruise.  Learning to work with the dredge and scientific equipment would have been much more difficult if the seas were not so calm. Each day brings something new and interesting to learn and experience.

Well, my shift is almost over.  Time to think about eating a late night snack and then getting some rest, – lulled by the gentle rocking of the waves.

Question for the Day 

What is the origin of the word “Quahog”? What is the difference between Atlantic Surf clams and Ocean Quahogs? What is a sea mouse?