Jennifer Fry: March 24, 2012, Oscar Elton Sette

NOAA Teacher at Sea
Jennifer Fry
Onboard NOAA Ship, Oscar Elton Sette
March 12 – March 26, 2012

 

Mission: Fisheries Study
Geographical area of cruise: American Samoa
Date: March 19, 2012

CTD data collection graphs

These charts show levels of salinity, temperature, density of the waters of American Samoa.
Teacher at Sea, Jennifer Fry, Survey tech, Scott Allen, NOAA scientists, Evan Howell, Megan Duncan, Aimee Hoover work on the CTD operations performing 8 casts in the day.
5.Once the crane operator lifts the unit out of the water, scientists guide the C.T.D. onto the deck.
6. The C.T.D. unit is safely back on the deck. Scientists collect an array of data including density, temperature, and conductivity using the C.D.T. unit.
4. Using a crane to lift and a hook to grab, the C.T.D. unit is guided onto the deck.
2. The C.T.D. is ready to be deployed into the ocean. Using a team of scientists, a crane, and crane operator the heavy unit is carefully guided into the water.
3. Once is determined safe, the doors on the side of the ship are opened to deploy the C.T.D. unit into the water.
1. The ocean’s depth is always checked prior to a C.T.D. operation to know how deep the unit can be deployed.

CTD Operations: Conductivity, Temperature, and Depth

The CTD Operations onboard the Sette are conducted by Evan Howell, Pacific Islands Fisheries Science Center, Megan Duncan, Joint Institute for Marine and Atmospheric Research at the University of Hawaii, and Scott Allen, NOAA survey tech. The CTD platform, which resembles a giant wedding cake constructed of painted steel, contains multiple instruments that can measure water characteristics including pressure, temperature, salinity, oxygen levels, and chlorophyll concentration.

Jennifer Fry, Scott Allen, Evan Howell, Megan Duncan, and Aimee Hoover stand behind the CTD.

It takes 30 readings per second as it sinks towards the seafloor.

The CTD records data as it sinks and ascends, but only data from the downcast is used, insuring the instruments are recording data in an  uninterrupted “profile” of the water column.  All data collected helps capture ocean characteristics. The acquired data will be shared with the American Samoa Department of Marine and Wildlife Resources scientists and compared with the data they have collected previously.

Using prior data, current CTD data, and acoustic Doppler current profiler, a  type of sonar detecting water currents, scientists can determine patterns in the oceans of American Samoa and compare them.

Animals Seen:

Short-finned Pilot Whales

Dolphins, possibly Pacific Spinner

Jennifer Fry: March 23, 2012 Oscar Elton Sette

NOAA Teacher at Sea
Jennifer Fry
Onboard NOAA Ship Oscar Elton Sette
March 12 – March 26, 2012

Mission: Fisheries Study
Geographical area of cruise: American Samoa
Date: March 23, 2012

Pictured here is a copepod (right) and a jelly (left) found in the plankton net.
Copepod comprise approximately 85 % of the plankton population
Copepod comprise approximately 85 % of the plankton population.
These copepods images taken with a high-powered microscope with an internal camera.

 Plankton Net Operation

11:00 p.m.

Learning how to work with the plankton net was so interesting.  It required careful, meticulous, and orderly work.  Emily Norton, University of Hawaii at Manoa, Biological Oceanography, is conducting daytime and nighttime tows targeting plankton.  She’s particularly interested in collecting and studying copepods, a type of small crustacean which comprise ~80-90% of the plankton. Plankton is a name for a variety of plants and animals that live in the water column and are found throughout the world’s oceans.  Plankton are important because they are an integral part of the food chain, and they can help scientists better understand currents and transport in the oceans.  Helping with the plankton tow is Megan Duncan, oceanography participant, Joint Institute for Marine and Atmospheric Research at the University of Hawaii.  Together we deployed the net starting around 11:00 p.m.  Due to migration patterns known as diel vertical migration, plankton can be collected more easily at night.

  1. The net consists of a 1 meter metal ring with a fine mesh (200 um) net attached to collect the plankton.
  2.   At the end of the long, conical net is a collection filter tube or “codend.”  This is the final collection point for all of the specimens funneled into the mouth of the net.
  3.   The flowmeter is then connected across the diameter of the metal ring, which measures the amount of water flowing past it.
  4. With a crane operator’s help the net is lowered into the sea with 230 feet wire out which calculates to approximately 200 feet deep.  This is called an “oblique tow” method.
  5. The net remains in the water for 30 minutes.
  6. Once brought to the surface, the net is rinsed with sea water multiple times to ensure all of the plankton are completely  flushed down  into the cod end.
  7. The next step is filtering the plankton-rich seawater through a very fine sieve.
  8. The plankton are either observed under a microscope or immediately preserved using an ethanol solution, 95% ethanol 5% water.
  9. Labels are then placed inside the jar written in pencil on waterproof paper, and outside the jar using indelible marker.
  10. The plankton will be processed at a later date in the lab for quantitative analysis.
  11. In the lab, scientists study the plankton further, making observations and studying the DNA, Deoxyribonucleic Acid using PCR, Polymerase Chain Reaction, and sequencing.  Similarities and differences (i.e. mutations) in the DNA sequences are used by scientists to determine how closely related populations of copepods are.  This helps scientists infer how currents affect connectivity in the ocean.

Animals seen:

Copepods

Pteropods

Baby giant squid

juvenile fish, various species

Euphausiid

 Q:What fish have you had the most interest in and why?

A: The most common fish caught in the net is the lanternfish or myctohid.  They represent nearly 85%  of the ocean’s biomass.  One interesting feature is their photophores which produce light that emit from their bodies.

The myctophid pictured on the top is seen with its scales, compared to the bottom that shows them rubbed off due to being in the Cobb trawl net.

This tray of myctophids or lantern fish make up nearly 85% of the ocean’s biomass. They were the most common fish in our night Cobb Trawl nets.

Q: Have you gone scuba diving?

A:  No, I didn’t do any S.C.U.B.A. (self-contained underwater breathing apparatus) diving on this trip.  There are NOAA ships that focus on research that require diving as their method of collecting data.  We visited the NOAA ship Hi’ialakai that researches the coral reef biome in the American Samoa waters.

The NOAA ship Hi’ialakai conducts S.C.U.B.A. operations researching the coral reefs of American Samoa.