The Gulf of Mexico

In this post we will begin a series of articles on the natural history of our marine environment. Many reading this are visiting the Gulf for the first time, others have been swimming in it since they could swim, but many from both groups know very little about the natural history of the Gulf region, and so we will explore it.

The emerald waters and white sands of the northern Gulf coast.
Photo: Molly O’Connor

Let’s begin with the Gulf itself. Step outside or look from your window… the wide-open Gulf… just take at it in for moment. It expands to the horizon. Flat. Maybe you can see a fishing or sailing vessel. Maybe people swimming, snorkeling, or surfing. Light greens and blues. Or, maybe it is a choppy day. Surf is crashing onto the shore. Water is a churned brown color. Birds are calling. This scene has looked like this for eons, though at one time there were sails of Spanish gallons on the horizon instead of surfers on the beach. It seems to go on forever. Actually, it covers over 600,000 mi2 but compared to the major oceans this is small. Many oceanographers refer to it as the “puddle” or the “pond”. But for us it is large.


Look towards the west. You can see the stretch of white sand and buildings extending for miles. The white haze, or glow, caused by wind-blown sand and solar reflection. 60 miles to the west you begin to find marshes instead of white beaches. The marshes continue another 60 miles to the Louisiana delta. They formed from muddy rivers coming from all over the United States. Though muddy and grassy, the marshes are full of marine life. From Bayou La Batre AL, to Biloxi MS, to Houma LA, these marshes and muddy waters support fishing communities who in turn support our seafood crave; 90% of all the shrimp in the U.S. comes from here.


Now look WSW. 650 miles away is the coast of Texas. The bottom of this portion of the Gulf is a large shelf. Here organic material has been deposited by the muddy rivers for eons. Covered with mud and silt, toss in a little pressure and heat, and these organics have formed pools of oil, with pockets of natural gas above them. We have been removing these fossil fuels for many years and they have been important in keeping our nation moving. Unfortunately, this was also the area of the worst natural disaster in country’s history. These productive waters support many forms of marine life. There are numerous whale sightings here, including killer whales. There is also the location of the largest coral reef in the region, the Texas Flower Gardens. Far from shore, and in deeper water, few visit this amazing place – but it is there. This shelf is known for the salt domes. Buried domes of salt that were believed to have formed during a time when sea level was different than it is now. There are also brine lakes here. On the ocean floor, small pockets of very salty water form lakes within the ocean. They are truly amazing and you can see video of these on the internet.


Turn now southwest. 550 miles in this direction is the deepest part of the Gulf of Mexico. Known as the Sigsbee Deep, it is about 12,000 ft. You know the pattern a golf ball makes when it lands in a sand trap? A sort of off-set bowl shape? This is what the bottom of the Gulf looks like and the deepest portion is in this direction. Some say it formed from sinking continental plates. Others think this may have been the site of a major meteor impact. Either way this is the big hole.

The goliath grouper is the largest member of the grouper family reaching weights of 800 lbs.
Photo: Bryan Fluech

70 miles directly south of you is the lip of the De Soto Canyon. A submarine canyon that extends about 100 miles southwest towards the Sigsbee Deep. Known by local fishermen as the nipple, it has been a favorite fishing region for years. Another 300 miles beyond the Canyon you cross a deep portion of the Gulf. The mean depth of the entire system is 4000 feet, which when compared to the major oceans is not that deep but deep enough to attract some of the most bizarre creatures on our planet. Luminescent hatchet fish and gulper eels, eerie shaped jellyfish with a variety of lights, and the vampire squid – which will invert itself in defense. We will discuss several of these in another issue. 600 miles across is the Yucatan Peninsula. Between the Yucatan and Cuba the ocean floor drops even deeper into the Caribbean Sea.


As you turn more to the southeast you are looking directly towards Key West and the Florida Keys; 480 miles away. From here to there the Gulf lies over a large shelf known as the Florida Shelf. 20 miles out lies the USS Oriskany, the Mighty “O”, the largest underwater artificial reef in the world. 230 miles further lie the Florida Middle Grounds, another large natural reef. Eventually you will reach the shallow water reefs of the Florida Keys. These reefs are home to a great variety of marine algae, invertebrates, fish, and sea turtles – certainly a topic for a future issue.


We end out visual tour looking east. Again, we see white sand, haze and buildings. This white sand “miracle strip” runs all the way to Panama City. Slightly ESE lies Cape San Blas and the beginning of the “Big Bend” of Florida. Known for its lush seagrass beds and coastal springs, the Big Bend supports scalloping, great flats fishing, and is the grazing area of the endangered Kemp’s Ridley Sea Turtle.


The Gulf of Mexico is a wonderful place. Whales, sea turtles, manatees, seabirds, 500 species of fish, and untold numbers of invertebrates all call this place home. Some visit for only a season, some are found nowhere else on earth. It supports a commercial fishing, maritime transportation, and fossil fuel industry. We have a lot to write about in this series, but for today – go enjoy the Gulf.


Posted: May 7, 2017

Category: Coasts & Marine
Tags: Coastal Habitats, Gulf Of Mexico

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