Tag: shellfish poisoning

Posted on

Tiffany Risch, August 2, 2008

NOAA Teacher at Sea
Tiffany Risch
Onboard NOAA Ship Delaware II 
July 28 – August 8, 2008

Mission: Clam and Quahog Survey
Geographical Area: South of Long Island, NY
Date: August 2, 2008

Weather Data from the Bridge 

  • Mostly cloudy with isolated showers
  • Surface winds: 5 to 10 knots
  • Waves: Swells 2-4 feet
  • Water temperature:  23o Celsius
  • Visibility:  7 nautical miles
The dredge being brought back up onto the ship after being deployed
The dredge being brought back up onto the ship after being deployed

Science and Technology Log 

As I began my shift, I noticed on the map hanging in the dry lab that we are working our way towards an area southeast of Nantucket called Georges Bank.  Georges Bank is a shallow rise underwater where a variety of sea life can be found. Before long, we were called to the deck for our first station of the morning.  We set the dredge, hauled it back, sorted the catch, measured and recorded data, and moved on to the next station. Recording data and sorting are two of my favorite things to do, especially when it involves shucking the clams for the meat to be measured!  My watch seemed to be on a record pace, as we managed to complete seven hauls all before breakfast at 5:00am.  This process happens around the clock on the DELAWARE II, maximizing the amount of data we collect while at sea for two weeks.  

Later in the day, the winch that is used to haul the dredge back from the water suffered a power problem.  I and the person controlling the dredge noticed this right away, as one of my jobs is to switch the power on to the pump that the dredge uses.  I alerted my watch chief, and also the chief scientist for this cruise who quickly began to assess the situation.  Over the next hour or so, things became very busy on the back deck as the captain, engineers, and scientists tried to solve the problem.  They did manage to get the power back to the winch again, which enabled the dredge to be brought back onboard the ship. The amount of talent exhibited by so many people on this ship continues to amaze me.  They always have answers for everything, and Plan B for any situation is always on their minds!

Collecting and sorting the variety of marine life that we find. Here, TAS Risch holds up some sea stars.
Collecting and sorting the variety of marine life that we find. Here, TAS Risch holds up some sea stars.

Personal Log 

Today was a really exciting day of sorting, as my watch found a variety of different organisms.  I actually saw a live scallop clapping in the bucket after it was hauled up!  Other interesting creatures included a Little Skate (Raja erinacea), which is a fish made of cartilage and is closely related to rays and sharks, a sea robin, sea squirts, hermit crabs, some sea stars, and even a few flounders. One of the more unusual characters that we encountered onboard was called a Yellow boring sponge, otherwise known as a Sulfur sponge or “Monkey Dung”. We take measurements of all of these things and quickly return them to their home in the ocean. Very early this morning, around 1:00am I visited the bridge, or the area where the captain controls and steers the ship from, to see what everything looks like at night. Crew member Claire Surrey was on the bridge tonight, making sure the ship stayed on its course.  The area was very quiet and dimly lit by the various monitors that broadcast

information back to the officer in charge.  The ocean was pitch black, and I could only see faint lights of a few other ships bobbing up and down in the waves very far away.  What a cool experience to see the ocean at night, with a starry sky, and know that all types of instruments are guiding my voyage through the sea!

New Words/Terms Learned 

Min-logs:  sense temperature, depth, and pressure underwater on the dredge, and are brought back to the surface and recorded via computer.

Starboard: the right side of a ship

Port: the left side of the ship

Posted on

Tiffany Risch, July 30, 2008

NOAA Teacher at Sea
Tiffany Risch
Onboard NOAA Ship Delaware II 
July 28 – August 8, 2008

Mission: Clam and Quahog Survey
Geographical Area: South of Long Island, NY
Date: July 30, 2008

Weather Data from the Bridge 

  • Hazy in the morning with less than 6 miles visibility
  • Calm seas with little cloud cover
  • Wind speed = 5 knots
  • Waves = Wind drives waves < 1 foot
  • Water temperature:  23o Celsius
Tiffany uses a measuring board to obtain quahog lengths.
Tiffany uses a measuring board to obtain quahog lengths.

Science and Technology Log 

Today started with an early morning shift, working from 12:00 am to 12:00 pm.  As my watch took over, the DELAWARE II began steaming towards the first station of the day to conduct a survey of the surf clam and quahog size and abundance inhabiting this specific area. In order to complete a survey of the area, a dredge is used to capture any surf clams or quahogs that are pushed out of the bottom sediment.  On the top of the dredge are hoses that push pressurized water onto the bottom to loosen up any bivalves.  A bivalve is an organism that has shells consisting of two halves, such as in a clam or a scallop. The dredge is towed behind the DELAWARE II for five minutes at a speed of 1.5 nautical miles per hour.  Attached to the dredge are sensors which transmit dredge performance information back to scientists in the dry lab to record and analyze.  The accuracy of the survey depends greatly on the credibility of the sensor data, and therefore, scientists must monitor variability of the dredge.  After the dredge is brought back to the surface, the load must be sorted, measured, and then discarded.

After listening to a presentation by Larry Jacobson, I learned a lot of new facts about both Atlantic sufclams (Spissula solidissima) and Ocean quahogs. Surf clams live only about 15 years, grow very fast, and can inhabit ocean waters stretching from Cape Hatteras in North Carolina to Newfoundland.  These bivalves are found in waters less than 50 meters of water. Ocean quahogs on the other hand can live for greater than 100 years, are very slow growing, and are found in ocean waters between 50 and 100 meters deep from Cape Hatteras, around the North Atlantic to the Mediterranean.

Giving power to the hydraulic pump.
Giving power to the hydraulic pump.

Scientists on this cruise are also interested in studying other aspects of the clam populations, such as a condition called Paralytic Shellfish Poisoning. Because bivalves are filter feeders, they eat by filtering food out of the waters around them.  Sometimes, algae can contaminate clams using a toxin that is harmful to humans.  When this happens and humans eat the shellfish, they themselves can become quite sick.  Samples of clam meats are being taken during this research cruise to be studied back at a lab and determine what exactly is happening in regards to Paralytic Shellfish Poisoning.

Personal Log 

Today has been quite interesting, as I moved through the many stations that are involved with conducting this survey. I was trained on how to measure clams in the wet lab, how to apply the power to the dredge in the dry lab, and even how to shuck a clam to retrieve the meat which is also measured.  I was also quite amazed regarding how efficient everyone is on the ship, as we all have a job to do, and it all gets done before we arrive at the next station.

One of my highlights today was overcoming my sea sickness and finally getting my sea legs!  Everyone is so supportive, from the officers, to the scientists, and to the volunteers who are all so nice and helpful. I’m looking forward to my next eight days at sea and learning more about the research being conducted.