We set out for Darwin and Wolf with a goal of collecting 15 coral samples. Long samples. Because in our field, size does matter. The larger the coral, the longer the core, and the longer the climate history. To capture the past couple hundred years, we were searching for a coral that could give us a 2 meter long sample. The Rosetta Coral.
Fortunately, our lab’s mascot “Coral” traveled all the way from Tucson to cheer us on.
|Photo by Gloria Jimenez|
We cruised to Wolf first to get our feet wet where the conditions are typically more calm and better for diving. We returned to the reef where we took samples back in 2010, and broke out Julie’s brand new pneumatic drill system to give it a good ole test drive and make sure everything was working properly and efficiently.
Because if we were going to reach our goal with 5 days of diving, efficiency would be key.
|Photo by Stephan Hlohowskyj|
The drill runs off of compressed air, which can be a major logistical challenge with the strong currents and deep reefs at Darwin and Wolf. To power this type of drill, there are only two options: power it from scuba tanks or an air compressor from the surface, or bring extra scuba tanks down to the bottom to power it.
With many tanks of air needed to take a 1-2 meter coral sample, bringing tanks down isn’t ideal, especially when they begin to float away as you use the air in them! But the other option, though seemingly ideal, requires the boat, or a zodiac or panga, to be anchored right above you, with enough compressor hose to make it down to the depth of the coral without tension. And if there is current or swell, that possibility goes right out the window…as the hose and boat gets tossed and yanked around like a rag doll.
And rough conditions is something these islands do well. When we arrived, the Queen Mabel tried to anchor at the site, and before the anchor could even be set, the boat heaved and the huge steel anchor chain snapped in 2. And the anchor was lost. The first casualty of the trip….
On top of the rough conditions, the large corals at these islands that we want to sample are unfortunately also deep. Typically corals that we sample are in shallow water, but here the big ones are found around 50 feet. This not only means lots of compression hosing, but it also means that lots of nitrogen buildup in our bodies. With 3 to 4 hour long dives per day (dawn pre-breakfast dive, after breakfast dive, and 1-2 afternoon dives), we’re all pushing our decompression limits every day.
|The drill. Photo by Julia Cole|
|Drilling some rock like it ain’t no thing. Photo by Jennifer Suarez|
|Photo by Jennifer Suarez|
For the remainder of the day, while the captain and crew searched for the lost anchor, we went on a search of our own to find the corals we drilled in 2010. We wanted to photograph the health of these corals to show their recovery following the drilling. As a marine ecologist turned paleoclimatologist who went from monitoring health of reefs to poking holes in them to study climate, I was particularly keen on seeing their recovery.
After coring, we fill the holes we create with cement plugs that prevent other organisms from coming in and killing the corals from the inside. These plugs also provide a surface for the coral to re-grow, and many have documented the recovery of corals cored in this way. But I was excited to see this for myself. You know, to sleep at night…
|An example of a plugged sample from this trip. Photo by Julia Cole|
But we looked and looked and looked all around the GPS coordinates of the corals sites, and could not find them. Knowing that we that we likely swam by the corals a few times and couldn’t find any evidence of drilling, I’m happy to know that the corals must have recovered and grown over the holes.
In the wee hours of the morning we cruised the remaining 4 hours to Darwin. I watched the sunrise as we became closer and closer to the picturesque arch off the southeast side of the island.
We cruised around the island to start in the somewhat calmer Arrecife Escondito (“Hidden Reef”) to start to search for large corals to sample.
|Prepping for the dive. Photo by Julia Cole|
On our first pre-breakfast dawn dive we found a coral that was around 2 meters tall and started drilling. We were off to a great start, but would soon come across a number of hurdles with the drill, slowing the coring process. Although a frustratingly slow progress, we continued moving forward (rule number 3!!), and 5 dives and far too many tanks in, we finally got 2 cores out of this coral. Sadly, a big part of our slow progress from this coral is that it turns out it was only an ~half meter coral head growing on top of a large rock. 😦
We named this coral “heart of stone” and continued on in search of the Rosetta Coral.
|“Heart of Stone” coral with the 2 coral samples plugged. Photo by Gloria Jimenez|
We got one more half meter core from another core at this site, but unfortunately this core was riddled with boring clam holes. So we aptly named this sample the $50k pencil holder.
While Julie and I did one last sweep of the reef in search of large colonies, we ended up in a scene straight from Blue Planet (or Finding Nemo!). Suddenly, the ocean went nearly black as we were surrounded by a school of thousands of fish. As they’d move back and forth, the sides of their bodies would temporarily glisten in the sunlight, making shapes in front of us. No directions to the Sydney Opera house, but they were clearly being chased by something. Something big. My excitement quickly faded as I waited for whatever it was chasing them to come out of the darkness. Fortunately, what appeared were HUGE mackerel. It was feeding time! An incredible experience!!!
Meanwhile Stephan and Gloria went to set a temperature logger by the first coral, and in doing so, Gloria got bit by an angry eel 😦 Fortunately, she didn’t lose her thumb and it didn’t hit a major artery, but she is left with a bad wound and will likely need surgery to fix a tendon. But let me tell you, she is one tough chick!!
|Tagging the first drilling target at Aricife Antigua: a ~1.5 meter, but solid head|
|Loading the scuba tanks for our dawn dive. Photo by Gloria Jimenez|
|Stephan and Roby break a piece of sample out of the coral head. Photo by Julia Cole|
|2 meters here we come! Photo by: Gloria Jimenez|
|“Rosie” Photo by Gloria Jimenez|