This Irishman got a bit too much sun the other day. Still, what do you expect when you’re marooned on a tropical atoll?

We traveled to this atoll, Tetiaroa, to get a bit of outside perspective on the viruses in the region. Since Jerome is comparing viruses of different sub-habitats within Mo’orea, it will be interesting to see if those differences can be seen in similar systems nearby. It is possible that the large body of water between the islands creates a geographic barrier which prevents the transmission of viruses from one lagoon to another. But we don’t know yet!

All of French Polynesia is in red, and I’ve boxed the Society Islands, where we are

The Society Islands

To get to Tetiaroa, we took advantage of some new friends we recently made over at a nearby American research station. The station (Gump) is located just in the bay next door to ours, is run by UC Berkeley, and hosts researchers from lots of different American universities. We were planning our own trip to Tetiaroa through CRIOBE, but it turned out that one of the Gump researchers needed volunteers to collect specimens for his own island interconnectivity study. In exchange for helping, we got a free ride!

Part of the Gump team with Mo’orea in the background

An aerial view of the atoll of Tetiaroa (thanks Wikipedia). After helping the Gump-ers, we took water samples at each of the points – a deep inner lagoon, shallow lagoon, reef crest, and fore reef. We also took a sample of water halfway between Tetiaroa and Mo’orea on our way back.

Tetiaroa is a pretty awesome little place. Like all atolls, it consists of a ring of flat, low-lying coral islets which surround an inner lagoon. And it has some interesting history. In recent times, it was privately owned by Marlon Brando, and he allowed researchers to visit regularly. In less recent times, it was a sacred retreat for Tahitian royalty, many of whose remains are buried on the islets. But wayyyy before that, Tetiaroa looked rather different. In fact, it might have looked something like Mo’orea or Tahiti at some point – a single, steep volcanic island surrounded by a shallow lagoon and reef. And before that, maybe something like the Hawaiian or Galápagos islands, which are bigger and have no shallow lagoons surrounding them. This is the natural evolution of many tropical volcanic islands: First, volcanic activity builds up a large mountain. The big island of Hawaii and the islands of Isabela and Fernandina of the Galápagos are still at this stage, actively erupting and growing. Coral reefs are initially less developed near these islands because the only water shallow enough for corals is constantly being replaced by new lava flows. Then, as volcanic activity slows, corals get a chance to build larger structures and form ‘fringing reefs’ immediately beyond the shore of the island. As time passes, two things generally occur to these islands: coral reefs continue to grow, and the island itself begins to sink and erode. Consequently, the original coral reef appears to move outwards from the shore of the island as corals build up on the outer slope. Eventually, the original fringing reef becomes a ‘barrier reef’, and a lagoon forms behind it. This is the stage at which we find Tahiti and Mo’orea. Millions of years later, when the original volcanic island itself sinks below the water, all that is left is the constantly growing coral ring, and we have an atoll like Tetiaroa. The islets around the ring are consequences of relatively recent sea level drop (i.e. thousands versus millions of years), which left the highest points of the reef exposed to air and allowed plants and such to take hold. Of course, as sea level is once again rising, these islets all face the threat of inundation once again.

Another interesting factoid: this theory of islands’ geological histories was first described by Charles Darwin. Although he is of course most well-known for his theories involving biological evolution, this contribution to geological theory was not trivial. In fact, it was initially rejected by many prominent geologists for some of the same reasons biologists rejected natural selection, including the massive amount of time required for these processes to occur. It is not much of a coincidence that Darwin formalized both theories based on the same voyage – once he primed himself to accept gradualism and incremental changes in geology, it was only natural to extend these concepts to biology.

Islands are fascinating! But that was a lot of text, so here are some pretty reef pix from Tetiaroa:

The landing area. Wave in…

… Wave out. We had to swim up to the ledge, which was about 4 feet above our heads when the waves flowed out, and wait for another wave to lift us up onto it. It was kind of neat to be plopped right down on the ledge as the water flows out around you, but then you had to quickly roll along the reef while holding all our sampling gear and taking fins off before the next wave came and dragged you back out!

The deep water beyond the fore reef ledge was shockingly blue

Lots of Pocillopora on the fore reef ledge

Some beautiful Acropora hyacinthus near the crest in the backreef

Porites lobata and Pocillopora verrucosa, chillaxin together like old pals

A crown of Porites lobata on a pedestal of… something my Caribbean-trained self thinks looks sorta kinda like an Agaricia of some sort?

Probably the most beautiful little patch of reef I’ve ever been able to take a picture of. Most of the coral is Porites lobata, but there are like four different color morphs in this picture. The reef crest was just stunning out there. And this sight is even more stunning when full of all the fish, which were just scared away before I could take the picture.

A couple of Blacktip Reef Sharks were circling while we were doing our work.

Giant clams were one of the Gump researchers’ target species

Acanthaster planci, the Crown-of-Thorns Starfish, is very evil looking. Aside from the fact that its spines are extremely painfully toxic, this starfish eats corals and is the direct cause of the devastation of entire reefs in the South Pacific. At this reef, we only saw about three, which is normal and healthy. However, certain conditions can cause outbreaks of thousands, which cause irreparable damage.

So that was our Tetiaroa trip! Thanks go out to the Gumpers for giving us a ride, teaching us about a lot of the local species and such, and for a good time.

Since the trip, we’ve finished up our transects on Mo’orea itself, and we’re ready to relax a little while we wait to wrap up our nutrient experiment in a little over a week. Phew! Fieldwork is exhausting!