Archive for the ‘sharks’ Category

Dry Tortugas

Monday, March 8th, 2010

It seems like everyday we are getting up just a little bit earlier. This morning we were on the road by 6AM, heading to Key West to catch the ferry out to the Dry Tortugas. The Dry Tortugas are a cluster of seven islands about 78 miles west of Key West. They were first described by Ponce de Leon in 1513 and named for the large sea turtle population. Originally described as eleven islands, some have been reclaimed by the sea through hurricanes and the changing currents.

The islands have a long history as a stopover for ships and during the Civil War, the Union forces started work on a grand fort that would protect the southern coastline of the United States. The Civil War tie extends to the assassination of President Lincoln. John Wilkes Booth’s broken leg was set by Dr. Samuel Mudd who was later convicted of conspiracy for providing medical attention, and was confined to the prison at Fort Jefferson. He later replaced the Fort’s physician, who died during a yellow fever epidemic, and was eventually pardoned for his actions in providing care to the stricken. The islands were also an important stopover for commerce that eventually made its way up the Mississippi River.

The boat ride out to the islands is a long two and half hours and some of the students used this time as a chance to catch up on those precious minutes of sleep lost in the morning:

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Trevor Floyd, Dan Klarr and Davide Zailo are all finding the most comfortable napping positions they can.

The rest of the students took advantage of the bracing morning air and rode in the bow for as long as they could stand the cold. The weather did cooperate and the strong north winds subsided for the day, making our voyage free of seasickness!

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Lacie Carter, Jordan Kus, Rachel Leads, Ashley Tewiliger, Sam Yackel and Ashli Wilson in the front of the boat, the Yankee Freedom II.

Once we arrived at the Dry Tortugas, it was time for the obligatory group photo.

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The first thing that we did was take the short historical tour of the grounds. The island is 17 acres with the fort taking up a whopping 12 of those acres.

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Jordan Kus, Cynthia Hanson, Ashli Wilson, Dan Klarr, Lannis Smith and Chris Wardlaw stand in the masonry fort, paying attention to the tour guide.

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The interior parade grounds of the fort are planted with many native trees. In this photo, Dan Klarr and Lacie Carter identify a buttonwood tree as Lannis Smith looks on.

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Davide Zailo and Trevor Floyd pose on the walls with the interior of the fort in the background.

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The fort was built to be part of the southern defenses in the Civil War and was equipped with many cannon. As Dan Klarr shows, they have all been decommissioned.

After the tour of the grounds and a quick lunch, it was time to get in the water for some snorkeling. Even though the water temperature was only 66 F, these students didn’t let that get in their way!

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All geared up and ready to hit the reef!

In 2007, the waters around the Dry Tortugas were designated as a Research Natural Area. This designation prohibits fishing or anchoring in the waters. Dr. Carrier’s research is based in the Tortugas and worked to establish a preserve for the mating sharks he studies, a protection that was granted in 1998. This protected area, along with the adjacent Tortugas Ecological Reserve, creates the largest marine reserve in the US. The area is known to be a hatchery area for several species of marine animals, including fish, sharks and birds. It is hoped that this protected area will build up and protect spawning areas for a wide variety of fish.

On this trip, we had a special guest with us, Wes Pratt. Pratt and Carrier have been collaborating on studies of shark behavior and reproduction for almost 20 years. In the time that it took us to get ready to get in the water, Wes had already found a nurse shark for us to tag.

(Don’t do this at home folks. Carrier and Pratt are a trained scientists who have worked with nurse sharks for 40 years and know how to capture these little beauties without hurting them. If you see a shark while snorkeling, do the right thing and admire from afar. Don’t try to touch!!)

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Dr. Carrier, Pratt, and Trevor Floyd with the newly netted female nurse shark.

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Before too long, Dr. Carrier starts explaining to the group what type of information is usually gathered and calling for volunteers to help him and Pratt with the measurements and the tagging.

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One piece of information that needs to be recorded for each shark is the weight. Here, Jordan Kus helps Dr. Carrier and Pratt to get a mass on this shark.

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The length of these animals is also important for later estimates of growth rates. Rachel Leads and Heather Nobert measure the length from tip of snout to tip of tail while Dr. Carrier steadies “Britony” (as the newly found shark was christened). Pratt, Trevor Floyd and Alison Gailey look on.

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In this photo, Cynthia Hanson takes a small skin sample from the dorsal fin of the shark under Pratt’s expert direction.

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After all of the necessary measurements and samples are taken, the shark is tagged with a permanent tag that will later aid in identifying the animals when it is next encountered. Tagged animals allow investigators to examine growth and migration, and sharks in the Tortugas are often caught many times, many years apart, in very nearly the same area!

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The class with the newest Briton.

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Britony (the nurse shark) was a trooper throughout the entire process but it was time to let her go. Pratt, Dr. Carrier and Trevor Floyd untangle her from the net before releasing her back to the wild. The information gathered here today will add to our growing understanding of these apex predators.

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Even with the excitement with the shark, we still found time to study the botanical beauty of the island. Ashli Wilson, Lacie Carter and Jordan Kus admire the sea grapes.

Tomorrow we are leaving the Keys for the Everglades. It’s another early morning, with lots of driving. We’ll be stopping by the Anhinga Trail and Gumbo Limbo Trail at the edge of the Everglades to observe the differences in the natural habitats and hopefully see some alligators! We also plan to visit the studio of a well-known Everglades photographer, Clyde Butcher, as we continue our study of south Florida, its biology, its natural and cultural history, and its incomparable artistry; truly liberal arts at its best!