NOAA TEACHER AT SEA
ONBOARD NOAA SHIP OREGON II
JUNE 23 — JULY 4, 2011
Mission: Summer Groundfish Survey
Geographic Location: Northern Gulf of Mexico
Date: June 29, 2011
|Wind Speed||13.90 kts|
|Wind Dir.||71.56 º|
|Surf. Water Temp.||27.80 ºC|
|Surf. Water Sal.||24.88 PSU|
|Air Temperature||29.30 ºC|
|Relative Humidity||76.00 %|
|Barometric Pres.||1013.73 mb|
|Water Depth||26.00 m|
Science and Technology Log
So now that we have an understanding of abiotic factors, let’s talk biotic factors, and for the most part, those biotic factors are going to be fish and plankton. The majority of our plankton (plankton are organisms–plants or animals–that are too small to fight against the current and thus drift along with it) samples come from the neuston and bongo nets. After we have our bongo or neuston nets back on board, the science crew goes to work preserving the specimens.
Something common in the neuston net, is Sargassum a type of brown algae belonging to the Kingdom Protista and the Phlyum phaeophyta (kingdoms and phylums are associated with the science of taxonomy or classification). If you are familiar with kelp, then you are familiar with brown algae. Kelp is a long algae that fastens itself to the bottom of the seafloor with a root of sorts called a holdfast. Sargassum, however, does not hold fast, but rather drifts out in the open ocean. It can stay afloat because Sargassum has little tiny gas-filled floats called pneumatocysts. These clumps of algae can provide much needed hiding places for small marine organisms out in the open ocean. Because so many organism might live in, on or around the mats of Sargassum whenever we capture Sargassumin our nets we have to be sure to wash them down thoroughly in order to ensure that we get as many of the creatures off of the blades as possible.
The currents of the Gulf of Mexico and the Atlantic actually concentrate the Sargassum into a giant mass in the middle of the North Atlantic ocean, commonly referred to as the Sargasso Sea. So significant is the Sargassum, that Christopher Columbus feared for the safe passage of his ships because of the thick mass of algae.
The adventures of Captain Nemo as penned by Jules Verne in the late 19th century even commented on the nature of this floating mass of algae: “This second arm–it is rather a collar than an arm–surrounds with its circles of warm water that portion of the cold, quiet, immovable ocean called the Sargasso Sea, a perfect lake in the open Atlantic: it takes no less than three years for the great current to pass round it. Such was the region the Nautilus was now visiting, a perfect meadow, a close carpet of seaweed, fucus, and tropical berries, so thick and so compact that the stem of a vessel could hardly tear its way through it. And Captain Nemo, not wishing to entangle his screw in this herbaceous mass, kept some yards beneath the surface of the waves. The name Sargasso comes from the Spanish word “sargazzo” which signifies kelp.”
As interesting and important as Sargassum is to the ocean environment, it is not our targeted organism, which is, for the most part fish! Although not a fish, crustaceans are still an important fishery, and few are more significant than Panaeus aztecus (brown shrimp), Panaeus setiferus (white shrimp) and Panaeus duorarum (pink shrimp). Chances are if you are dining on shrimp cocktail you are eating one of these three species.