NOAA Teacher at Sea
Onboard NOAA Ship Oscar Elton Sette
March 12 – March 26, 2012
Mission: Fisheries Study
Geographical area of cruise: American Samoa
Date: March 23, 2012
Plankton Net Operation
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.
The net consists of a 1 meter metal ring with a fine mesh (200 um) net attached to collect the plankton.
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.
The flowmeter is then connected across the diameter of the metal ring, which measures the amount of water flowing past it.
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.
The net remains in the water for 30 minutes.
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.
The next step is filtering the plankton-rich seawater through a very fine sieve.
The plankton are either observed under a microscope or immediately preserved using an ethanol solution, 95% ethanol 5% water.
Labels are then placed inside the jar written in pencil on waterproof paper, and outside the jar using indelible marker.
The plankton will be processed at a later date in the lab for quantitative analysis.
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.
Baby giant squid
juvenile fish, various species
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.
NOAA Teacher at Sea Caitlin Fine Aboard University of Miami Ship R/V Walton Smith August 2 – 7, 2011
Mission: South Florida Bimonthly Regional Survey Geographical Area: South Florida Coast and Gulf of Mexico Date: August 6, 2011
Weather Data from the Bridge
Air Temperature: 31.6°C
Water Temperature: 32.6°C
Wind Direction: Southwest
Wind Speed: 4 knots
Seawave Height: calm
Clouds: partially cloudy (cumulous and cirrus clouds)
Relative Humidity: 62%
Science and Technology Log
Many of you have written comments asking about the marine biology (animals and plants) that I have seen while on this cruise. Thank you for your posts – I love your questions! In today’s log, I will talk about the biology component of the research and about the animals that we have been finding and documenting.
We have another graduate student aboard, Lorin, who is collecting samples of sargassum (a type of seaweed).
There are two types of sargassum. One of those types usually floats at the top of the water and the other has root-like structures that help it attach to the bottom of the ocean.
We are using a net, called a Neuston net, to collect samples of sargassum that float. The Neuston net is towed alongside the ship at the surface at specific stations. This means that the ship drives in large circles for 30 minutes which can make for a rocky/dizzy ride – some of the chairs in the dry lab have wheels and they roll around the floor during the tow!
Lorin and other researchers are interested in studying sargassum because it provides a rich habitat for zooplankton, small fish, crabs, worms, baby sea turtles, and marine birds. It is also a feeding ground for larger fish that many of you may have eaten, such as billfish, tuna, and mahi mahi.
The net not only collects sargassum, but also small fish, small crabs, jellyfish, other types of seaweed, and small plankton.
Plankton can be divided into two main categories: zooplankton and phytoplankton. As I said in my last post, phytoplankton are mostly very small plants or single-celled organisms that photosynthesize (they make their own food) and are the base of the food chain. Zooplankton are one level up on the food chain from phytoplankton and most of them eat phytoplankton. Zooplankton include larva (babies) of starfish, lobster, crabs, and fish.
We also use a Plankton net to collect samples of plankton. This has a smaller mesh, so it collects organisms that are so small they would fall through the Neuston net. Scientists are interested in studying the zooplankton that we catch in the Plankton net to understand what larger organisms might one day grow-up and live in the habitats we are surveying. They study the phytoplankton from the Plankton net to see what types of phytoplankton are present in the water and in what quantities.
Today we collected so many diatoms (which are a type of phytoplankton) in the Neuston net that we could not lift it out of the water! This tells us that there are a lot of nutrients in the water (a diatom bloom) – maybe even harmful levels. I am bringing some samples of the diatoms and zooplankton home with me so we can look at them under the microscopes at school!
The marine biologists on this cruise are mainly interested in looking at phytoplankton and zooplankton, but we also have seen some larger animals. I have seen many flying fish skim across the surface of the water as the boat moves along. I have also seen seagulls, dolphins, sea turtles, cormorants (skinny black seabirds with long necks), and lots of small fish.
Working as an oceanographer definitely demands flexibility. I have already mentioned that we chased the Mississippi River water during our second day. After collecting samples, we had to find blue water (open ocean water) to have a control to compare our samples against. We traveled south through the night until we were about 15 miles away from Cuba before finding blue water. All of this travel was in the opposite direction from our initial cruise plan, so we have had to extend our cruise by one day in order to visit all of the stations that we need to visit inside the Gulf of Mexico. This has meant waking-up the night shift so we can all change their airplane tickets and looking at maps to edit our cruise plan!
Many of you are writing comments about sharks – I have not seen any sharks and I will probably not see any. The chief scientist, Nelson, has worked on the ocean for about 33 years and he has sailed for more than 1,500 hours and he has only seen 3 sharks. They mostly live in the open ocean, not on the continental shelf where we are doing our survey. If there were a shark nearby, our ship is so big and loud that it would be scared away.
Today I saw a group of about 4 dolphins off the side of the ship. They were pretty far away, so I could not take pictures. Their dorsal fins all seemed to exit the water at the same time – it was very beautiful. A member of the crew spotted a sea turtle off the bow (front) of the ship and I saw several different types of sea birds, especially seagulls.
Yesterday afternoon we passed through the Gulf of Mexico near the Everglades and there were storm clouds covering the coastline. The crew says that it rains a lot in this part of the Florida coast and that Florida receives more thunderstorms than any other state. It is strange to me because I always think of Florida as “the sunshine state.”
The color of the ocean has changed quite a lot during the cruise. The water is clear and light blue near Miami, clear and dark blue farther away from the coast in the Atlantic Ocean, cloudy and yellow-green in coastal Gulf of Mexico, and cloudy and turquoise in the Florida Bay. Scientists say that the cloudiness in coastal Gulf of Mexico is caused by chlorophyll and the cloudiness in the Florida Bay is caused by sediment.
It has been hot and sunny every day, but the wet lab (where we process the water samples and marine samples), the dry lab (where we work on our computers), the galley and the staterooms are nice and cool thanks to air conditioning! I can tell that I am getting used to being at sea because now when we are moving, I feel as though we are stopped. And when we do stop to take measurements, it feels strange.
Did you know?
NOAA does not own the R/V Walton Smith. It is University of Miami ship that costs NOAA from $12,000 to $15,000 a day to use!
Organisms seen today…
– Many sea birds (especially seagulls)
– 2 cormorants (an elegant black sea bird)
– 10-12 dolphins
– 1 sea turtle
– Lots of small fish
– Lots of zooplankton and phytoplankton (especially diatoms)