Tuesday, July 10, 2012

French Frigate Shoals

July 7th
We Arrived at French Frigate Shoals at 1300, earlier than expected so we went ahead and did our first dive operation. FFS is the midpoint of the entire Hawaiian archipeligo. You wouldn’t think our ship was inside the shoal just by looking out over the water. With persistent winds creating white caps all over the surface, all you can see in either direction is just the water’s surface, save for one rock that sticks out. The rock is the island of La Pérouse, a 1-acre rock made of dense lava, and the only remainder of what was once a volcanic island like the main Hawaiian Islands. There are three low level, vegetated islands and a few blinding-white bare sand islands that make up the land portion of FFS.
Source: PBS, a satellite view of French Frigate Shoals. White specks of sandy islands and  coral reefs can be seen
Our first dive was at a location called rapture reef. We had to swap out a VR2W receiver and an EAR. Christian and Carl make the receiver swap, an issue came up with my dive buddy so we played the proper safe route and called off the dive, leaving the EAR swap for tomorrow. Though just at the surface I was already surrounded by a school of giant Ulua, and could see two Galapagose sharks 15ft below our boat.
On the second day we swap out the EAR, which turned out to be a agrivating process because our tin snips were not working so we had to manually unscrew each hose clap. We had enough time to install the new one and explore the reef around the area. It was an oasis of biodiversity at this site. Giant Ulua, Galapagose sharks, whitetip reef sharks, Uku (green jobfish, very hard to find at all in the main islands), and a huge abundance and diversity of reef fish that I had never seen before. Many of the reef fish here do not occur in shallow depths (above 100 feet) the main islands, and many of these fish can’t be found in other areas of the world. As a photographer it was overwhelming, there was so much to take photos of, and not nearly enough time for it.
Acropora coral and the EAR (cylindrical instrument). The EAR is recording a wide range of acoustics at this reef and in surrounding areas. Reefs are noisy habitats, different fish and invertebrates create unique sounds and signals for a variety of purposes and behaviors.

Underneath every ledge of acropora (table top shaped coral) were over a dozen reef fish. Coral in this shape provides space and refuge for reef fish, contributing to the high biodiversity and abundance at this reef

Galapagose shark that was circling us on our safety stop, approched us in a very curious manner

July 8th
Second day of work at FFS. We swapped out two more receivers and the ear at Rapture reef. Our second site was inside of the lagoon at FFS so the visibility was somewhat murky. Carl was eager to analyze the data from both sites right away. At the site inside the lagoon we are seeing a seasonal pattern in the aggregations of Ulua and Galapagose sharks in that area. More info on this will be explained later as it comes to light.

Swapping out the EAR
Uku, green jobfish. A popular menu item on the main islands,  extremely rare to see swimming around on the main islands too.

It was also an exciting day for the Maritime hertitage team. Artifacts from a whaling vessel were recovered, including a ceramic bowl, a harpoon tip, a lance, carpentry nails and a fine piece of 18th century glass that was a part of the ship’s barometer.
Artifacts from a whaling vessel

Another team was collecting samples from the water column around coral heads. Here, invertebrates that were sampled from coral heads are examined under a dissecting microscope. This is for a study that examines the bioeroding process of coral from invertebrate communities. Bioerrosion is a process that occurs on coral reefs where the calcium carbonite skeletons of coral are broken down by other marine organisms feeding or burrowing. This project under the lead of Nyssa Silbinger, a graduate student in the Donahue lab at HIMB. You can see what other projects the Donahue lab conducts on coral reef ecology on their website: http://www.donahuelab.com/projects/

July 9th
Christian keeping an eye on a curious Galapagose shark.
They will come very close to you if you take your eye off them
Third day of work at FFS. Swaped out 4 recievers and an EAR. We came really close to a lot of the islands today, including La Perouse. The beaches are blinding white. At every location we spotted at least one Galapagose shark and Ulua. At our safety stop at the second site we had a Galapagose shark circling around us, occasionaly swimming away out of view and then showing up right behind us seconds later when we took our eye off of it. Several Hawaiian monk seals could be seen on every sandy beach. East Island is one of the location we did a receiver swap. This is the infamous island where tiger sharks hunt in very shallow water, preying on fledgling albatross. The young albatross have difficulty learning to fly for the first time; take offs and landing are made difficult with an extremely long wingspan. Failure to pass flight school can mean certain death for these birds. By the time we arrived the fledgling albatross had already gone, only adults could be seen on the island. When we looked at the data from that receiver though, it turns out that there was a 14ft tiger shark in that exact area one hour before we got in the water there.East Island once served as a float plane station for the US Navy before and during WWII. It was then converted to a LORAN station. 

Field station on East Island, also the site of a tiger shark gourge fest when the albatross fail flight school

This is all that remains of what was once a island the size of the main Hawaiian islands. It is now reduced to a 1-acre stub sticking out of the water
There is a lot going on with all of the science teams and with the ship, I will expand on these more in the future, but for now it’s late and there is a lot of work for us to do on the ship when we are not doing dive operations, so check back alter for more updates.

Ending the day talking about our previous tiger shark work on Oahu

No comments:

Post a Comment