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
|Surf. Water Temp.
|Surf. Water Sal.
Science and Technology Log
A preserved plankton sample from one of the Oregon II's bongo nets.
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.
Sargassum, a brown algae, provides important habitat for many marine organisms including juvenile fish. Clearly visible are the pneumatocysts, gas-filled floats, that help keep the algae at the surface of the ocean.
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.
One of many (so many) brown shrimp to be measured. We measure from the length of the rostrum (the point part by their eyes) to the tip of their (tail).
(or the red snapper) is another commercially important species that scientists are particularly interested in. Species like the red snapper are of particular concern because, according to NOAA’s Fish Watch website
, the population is currently at low levels prompting NOAA to establish temporary restrictions on fishing this species in past years.
It is the work of the crew aboard the Oregon II to collect the data that helps scientists predict population trends in species such as these which allows government regulations to be based on sound science. Although sometimes unpopular with the local fishing industry the temporary ban on fishing for some species is aimed at providing a long-term sustainable population for future generations.
Prized by the fishing industry and restauranteurs, red snapper are a species of particular concern because of the pressures local fisheries have placed on the species.
Although not a primary target of this fish survey, cartilaginous fish (Class Chondricthyes…there’s that taxonomy again) like sharks, rays and skates are also organisms of particular concern. Unlike the majority of the fish we bring on board, which are bony fish belonging to the Class Osteicthyes, the majority of cartilaginous fish reproduce internally. This means that a female shark, ray or skate, might have much fewer offspring in a given year, but those offspring might be more mature once they are born. Bony fish on the other hand often lay eggs externally by the thousands, but only a small percentage survive.
If you recall, one of the steps of the “scientific method” is to share your results, and there is no better way than to publish your findings in journals for other scientists to read. Although writing a paper may sound simple, this is not your average high school term paper–there is considerably more effort required. Brittany and her fellow authors labored for close to four years to finally draft and submit the paper for publishing.
An example of a cartilaginous fish, the Atlantic angelshark (Squatina dumeril) was brought on board as part of one of our trawls.
Although we may not write anything as extensive at the high school level, good sound scientific investigations will always end up with you sharing your results, and as a result, well-researched background information is always essential. To all my past and future students out there, feel free to take note of the reference section of the paper and remember how important references and good research is in backing up your work!
It has not taken long to get into the rhythm of things aboard ship. Although I thought that the waves might lead to a little sea sickness, I now find them quite soothing, and am curious as to how I might feel once back on shore as I struggle to get my land legs back. Sleeping with the waves is a slightly different story. At times they can lull you off to sleep (or it might simply be the twelve hours of sorting, measuring and weighing the catch that does that); other times they can roll you right into your bunk wall and snap you awake. My bunk is on the top, so the wall is better than the floor I suppose!
Although the waves have been soothing up to this point, we are possibly facing some inclement weather as the first tropical storm of the season, Arlene, is to our southwest heading towards the Mexican coast. If the weather picks up too much we may have to head in shore to work up some of the shallower stations while the Gulf settles back down. Either way we will be kept busy, measuring fish or measuring the waves!
Tropical Storm Arlene, the first tropical storm of the Atlantic season is headed for the Mexico coast in the next few days.