NOAA Teacher at Sea
Aboard R/V Walton Smith
December 11-15, 2011
Mission: South Florida Bimonthly Regional Survey
Geographical Area: South Florida Coast and Gulf of Mexico
Date: December 11, 2011
Weather Data from the Bridge
Air Temperature: 24.5 degrees C (76 degrees F)
Wind Direction: 65.9 degrees east northeast
Wind Speed: 15.8 knots
Relative Humidity: 78%
Science and Technology Log
Today is the first day of the research cruise. The R/V Walton Smith left its home port in Miami, FL this morning at about 7:30am. After a delicious breakfast, the crew and scientific party received a safety briefing from Dave, the Marine Tech. We learned about the importance of shipboard drills and we were shown the location of all the safety gear we might need in case of an emergency. This ship works like a self-contained community. The crew of the ship must also be the policemen and firemen (or policewomen and firewomen).
After our safety briefing, the science party went outside to our first station of the day. The first piece of equipment we put into the water was a CTD. The CTD is named after the three factors the equipment measures: conductivity, temperature, and depth. The CTD will be deployed at precise locations along our route. Since they conduct this research cruise twice a month, they can see if conditions are changing or staying the same over time.
Question for students: What is the relationship between salt and electrical conductivity? If the salt content in the water increases, will it conduct electricity better or worse?
The next piece of equipment we deployed was the Neuston Net. This net sits at the water line and skims organisms off the surface of the ocean. The net is in the water for 30 minutes at a time. After bringing the net onto the deck, the fun part starts – examining the contents! Our Neuston Net had two main species: moon jelly (Aurelia) and sargassum. The term sargassum actually describes many species, so the scientists on board will study it carefully in order to classify which kinds they caught in the net. Sargassum is an amazing thing! It is planktonic (which means that it floats with the current) and it serves as a habitat for bacteria and small organisms. Since it is such a thriving habitat, it is also a great feeding ground for many different species of fish.
Once we emptied the contents of the Neuston Net, Lindsey and Rachel, two of the scientists on board, began to measure the quantity of each species they caught. In order to measure the weight of the moon jellies, they used the displacement method. This is because we can’t use regular scales onboard. Here are the steps we took to measure the moon jellies:
1) We poured water into a graduated cylinder and recorded the water level. For example, let’s say that we poured in 100ml of water.
2) We put a moon jelly into the graduated cylinder and recorded the new water level. For example, let’s say that the new water level read 700ml.
3) We subtracted the old water level from the new, and we could tell the volume of the moon jelly we had caught. For example, based on the numbers above, we would have caught a 600ml moon jelly!
Both the CTD and the Neuston Net will be deployed many times over the course of the cruise.
Despite a bit of seasickness, I am having a wonderful time! Everyone on board is very welcoming and happy to answer my questions. Everyone is so busy! It seems like they have all been working nonstop since we arrived on board yesterday.
Answers to your questions
First, let me just say that these are great questions! Good job, Green Acres. Here are some answers, below.
1) How do the currents make a difference in the water temp? The currents play a major role in water temperature. In the Northern Hemisphere, currents on the east coast of a continent bring water up from the equator. For example, the Gulf Stream (which is a very important current down here in Florida) brings warm water from the tropics up the east coast of the United States. This not only keeps the water temperature warm, but it also affects the air temperature as well.
2) How does the current affect the different algae populations? Currents regulate the flow of nutrients (which phytoplankton needs to survive). Strong currents can also create turbidity, which means that it stirs up the water and makes it harder for light to penetrate the water column. As you know, phytoplankton rely on sunlight to grow, so if less light is available, the phytoplankton will suffer. I’m told by Sharein (one of the phytoplankton researchers) that algae are hearty creatures. This means that as long as the turbid conditions are temporary, algae should be able to thrive.