NOAA Teacher at Sea
Aboard NOAA Ship Oregon II
September 17-30, 2017
Mission: Shark/Red Snapper Longline Survey
Geographic Area of Cruise: Gulf of Mexico
Date: September 27, 2017
Weather Data from the Bridge:
Latitude: 28o 10.1’ N
Longitude: 93o 07.8’ W
Visibility 10 nautical miles
Wind speed 8 knots
Sea wave height 1-2 feet
Temperature Seawater 29.2 o Celsius
Science and Technology Log:
As described in the last blog post, fisheries are regulated by different management councils that represent particular regions of the country. Of all the different regions, the Gulf of Mexico arguably has the most distinct boundaries of the eight different management councils. If you look at the Google satellite image below, there are likely a couple of things that jump out at you. First is that the gulf is almost completely surrounded by land. It’s less than 100 miles from Florida to Cuba and only about 120 miles at the closest point between Cuba and the Yucatan Peninsula. This means that there is a lot of potential for the land surrounding the gulf to impact the neighboring waters.
This and the fact that there are some major rivers flowing into the gulf contribute to the formation of what is known as the dead zone. The dead zone extends along the coasts of Louisiana and Texas, and is caused by extreme nutrient levels in the waters of the Mississippi River. The Mississippi contains vast quantities of nutrients from agricultural and urban runoff and so contributes abnormally high amounts of nitrogen and phosphorus to the coastal waters. These nutrients lead to massive algal blooms that create decaying biomass that then deplete the oxygen in the waters where the blooms occur. The map below was created by data collected on the Oregon II and shows the extent of the dead zone in 2011, so called because many organisms cannot survive in such low oxygen conditions. The orange and red areas are regions where shrimp and fish cannot live on the sea floor.
The other noticeable feature of the Gulf as a whole is that there is a lot of shallow water, with the continental shelf extending up to around 200 miles offshore in some areas. It is especially thick along the coasts of Florida and the Yucatan. These shallow areas, help to create warm water temperatures, and this helps to provide the energy for hurricanes. The relatively shallow waters have been a factor in the development of offshore oil drilling, and we’ve passed scores of them along the way.
The NOAA map below gives a better idea of how abundant the rigs really are. The construction of these rigs creates significant risk, as evidenced by the Deep Water Horizon explosion and subsequent oil spill. The explosion happened in April 2010 and the spill continued for nearly three months. NOAA was involved in documenting the impacts of the spill from the earliest days and will be able to use this information to improve containment and cleanup after future spills.
Except where nutrient levels are excessively high because of human influence, the nutrient rich waters of the Gulf support abundant life, and we’ve been experiencing that for sure. I’m realizing that we’re only seeing a small snapshot of the diversity of habitats that are found in the Gulf. There are deep water methane seeps, estuaries, coral reefs, and other reef systems that support different organisms and abundant life. The Gulf is a vital resource that provides healthy fisheries, but it’s also a thriving ecosystem in its own right. By coming out on a yearly basis, the scientists conducting these surveys can get an idea of how these ecosystems are faring…kind of like a report card, I guess.
I have just been loving the sunsets! I make a point to get outside around 7, if I can, so I can check out the latest one. Here are just a couple examples.