Marine Debris Assessment Expedition
July 20-25, 2009
aboard the R/V Manta
Click on a link below to jump to a specific expedition blog or scroll down the page to read them all.
Monday, July 20 - Jennifer DeBose
Tuesday, July 21 - Scott Fowler
Wednesday, July 22 (a.m.) - Emma Hickerson
Wednesday, July 22 (p.m.) - Jeff Reid
Thursday, July 23 (a.m.) - Russ Green
Thursday, July 23 (p.m.) - Marissa Nuttall
Friday, July 24 (a.m.) - G.P. Schmahl
Friday, July 24 (p.m.) - Ryan Eckert
Saturday, July 25 (a.m.) - Greg McFall
Saturday, July 25 (p.m.) - Doug Kesling
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Click here to learn more about the Expedition Team.
Thursday, July 23, 2009
by Russ Green
Thunder Bay National Marine Sanctuary (TBNMS)
Maritime Heritage Coordinator, Technical Diver
Last night Emma and the Flower Garden Banks team briefed us in detail on today's task. This morning we had a quick recap at 7:30 a.m. and were ready to dive at 9. The first dive team was myself, Doug and Jeff, with Emma and Marissa as safety divers. The tasks were straight forward but there were several of them we hoped to accomplish. The idea is to carry everything you need (slates, tapes, biological sample bags, cutting tools, lift bags, cameras) and prioritize the tasks on the bottom as conditions such as visibility and current allow.
|Scott, Mauritius and Greg (left to right) getting ready for the second dive of the morning. Standing in front is Jeff holding one of their extra tanks.
The main task today was to survey and assess a derelict shrimp net covering and destroying a significant portion of the deep reef along the Stetson ring. With video and measurements from this dive the FGBNMS team can determine the best way to ultimately remove the net. Other tasks included taking samples of specific corals. Along with our collection bags we carried handy reference cards. Today we were diving in over 200 feet of water, so taking the guess work out of our sampling is a great idea. Coming back to the surface to ask questions is not an option!
As an archeologist one of the most striking things about this expedition is the potential across the entire sanctuary system for a wide range of scientists to bring their skills to bear on a specific project. Measuring and assessing big stuff (usually shipwrecks) in 200 feet of water is something we do regularly at TBNMS and sizing up the shrimp nets is a bit like that.
The current was running strong, nearly 2 knots (?) so we dropped a marker buoy on the target and the R/V Manta live-boated (was not tied to a mooring buoy) while we made our dive. Gauging the current, the captiain dropped the dive team upstream of the marker buoy. We jumped off the boat and free-fell through 200 feet of water, riding the current through the water column and hoping to end up on the target when we hit bottom. It's a technique we've used while conducting archeology on the USS Monitor in about 230 feet of water off the North Carolina coast. It's tough to do particularly when trying to land on a target as relatively small as a shrimp net.
|Fishing nets snagged on the bottom habitat of Stetson ring.
Today we missed the "drop" and didn't see the net so we spent several minutes looking for coral samples. The visitbility on the bottom was just a few feet and it became clear that we missed the area where we hoped to find the coral samples. We finally aborted the dive and made a 40-minute trip to the surface, drifting through the water column and decompressing along the way.
|Greg, Mauritius and Scott (left to right) drifting along at their 15-foot decompression stop. The divers are on pure O2 at this stop. The diver on the right is holding onto a line that leads to a buoy at the surface so that the RHIB can follow along.
A 7-foot long bull shark stopped by as we drifted, so the dive ended with a bit of excitement for the safety diver/biologist who met us at our first deco stop. This afternoon we'll reassess the sea conditions, adjust our priorities and get the second dive team in the water.
|Marissa (left) and Jenn (right) serving as safety divers for the three technical divers, Mauritius, Greg and Scott (center bottom to top) who are making a 20-foot decompression stop. Jenn is holding one of the scooters that the tech divers were using earlier in the dive. Scott (top center) is holding a line to a buoy on the surface.
NOTE: The role of the safety divers is to assist and monitor the technical (tech) divers as they complete their decompression (deco) stops starting at about 100 feet underwater. The two safety divers work as a team. One safety meets the tech divers at the first deco stop to make sure everyone is OK. The second safety hovers above waiting for the OK signal then returns to the surface to notify the boat. After notifying the boat, the second safety descends again and hovers about 20-30 feet above the deco stop to continue monitoring, while the first safety remains with the tech divers. During the deco stops, the tech divers may also begin handing off some of their gear to the safety divers for transport to the surface.
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Thursday, July 23, 2009
by Marissa Nuttall
Flower Garden Banks National Marine Sanctuary
Research Assistant, Safety Diver
The two afternoon dives today were a great success for biological sampling! The first of these dives, took three technical divers to a patch reef that makes up the western part of Stetson Ring. While not able to find a large shrimp trawl we were targeting, they located and retrieved a small net and took biological samples of some of our target species.
|One of the samples collected by the technical divers from the deeper areas around Stetson Ring. This sample included stony corals, sponges, a squat lobster, and some crabs. Because of its fragile nature, this sample could not have been successfully collected with an ROV.
This included a fan-like black coral that we have been hoping to collect for some time. While this organism appears quite commonly around Stetson Ring, we are not 100% sure what it is. Now that we have a sample, we can send it off to the experts to identify it!
Divers were also able to collect a few samples of a bedspring-like black coral, one of which was over 1m long! As you can imagine, it took two of us to put that specimen into a small collection jar. The final dive of the day brought back a few more samples, including more bedspring-like black corals and a small red gorgonian. The gorgonian looks like it might be one of our unknown target species, so we are excited to find out what it might be!
|Marissa and Emma examining an antipatharian (black coral) collected from the area around Stetson Ring.
It takes a lot of different people to organize and safely send divers down to 200 feet. I am serving as a safety diver for the technical diving team. Essentially, what this means, is that my dive buddy and I meet the technical divers as they ascend from depth and check in that everyone is doing okay and has enough of each gas (a couple of special mixes of air that have different amounts of oxygen) to complete the dive. Then, we monitor the dive team as they slowly ascend and complete their decompression requirements. During this time, the dive team can hand off any extra equipment to us like underwater scooters, stage bottles, and cameras which we take up to a small boat to get out of the way. This makes getting back aboard the R/V Manta easier. The seas have calmed down to 1-2 feet.
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For a general overview of this expedition, please visit the Marine Debris Assessment Expedition 2009 page.
To learn more about the scientists on this expedition, please visit the Expedition Team page.
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