16 August 2008

USGS-Southwest Biological Science Center/ Department of Biological Sciences, Northern Arizona University, Rapa Nui Cave Biodiversity Inventory Project

Originally drafted 16 August 2008

Moai. The Moai always face towards a village. These Moai are facing towards our study site. There are numerous house foundations, and fences above ground, while there is an abundance of evidence of ancient Rapa Nui use in the caves below.

The past few days were filled with travel. We drove from San Pedro to Antofagasta on 13 August, flew from Antofagasta to Santiago on 14 August, spent the night in Santiago and then flew out to Rapa Nui on 15 August.

For clarification, the place known as “Easter Island” is actually Rapa Nui. This is the name given to this beautiful place by Polynesians who settled this island. So, all of my blogs for the next week will be using the appropriate name for this place – Rapa Nui.

One of the many carvings on the back of the Moai.

So, it was great to get into the field and begin to explore some of the caves of Rapa Nui. This is a truly magical place. Moai are everywhere. These impressive basalt statues are a testament to a highly advanced ancient Polynesian society. This small island 7 by 14 miles wide at its widest points is perhaps one of the most remote places on the planet. Rapa Nui is truly in the middle of the Pacific Ocean and it really feels like it.

One of the breath-taking views en route to our study area.

If I were ever to choose to “drop out” of society, this is where I would go. The atmosphere is laid back, and, for most, all there is to do is enjoy life and watch the waves break along the coast.

The climate is mild year round, the growing season almost continuous. We saw guava, avocado and bananas growing in the middle of winter. There are flowers in bloom and it’s simply amazing. For the past two days, we’ve had a storm pass over the island – so, we’re receiving quite a bit of rain.

Christina examining roots growing across the floor in one of our study caves.

We have the distinct honor of staying at Hotel Tupa, which is owned and operated by Dr. Sergio Rapu, the island’s chief archaeologist. Sergio is a Fellow of the Explorers Club. Because of my affiliation with the Club, I was fortunate enough to be placed in contact with Dr. John Loret also with the Club. John is the authority on Rapa Nui marine biology.

Sergio has been kind enough to begin to share his vast knowledge of ancient Polynesian culture as it relates to Rapa Nui and the surrounding islands. This is really a once in a lifetime opportunity.

Now for the caves…because Rapa Nui is an oceanic island, it was formed by volcanic activity. So, the caves that exist here are lava tubes. Yesterday, as we were making plans to get the expedition under way, we were given tips by some of the locals regarding how to find caves.

Banana trees growing in the entrance of one of our study caves.

The island is largely covered by grassland due to the near complete deforestation by the people of Rapa Nui nearly 200 years ago. Some seeds of tree species were removed long ago, and attempts have been made to reintroduce some of the native plants. Unfortunately, this reintroduction campaign has been unsuccessful. Today, the flora of the island is largely introduced, and the forests that exist are sparse. So, we were told to look for caves by looking for stands of bamboo and other trees/ shrubs against the rolling green hills. These plants tend to grow within cave entrances, and are often not eaten by grazing cattle and horses.

With this knowledge, we set out to a cave rich area on the northern extent of the island. Our efforts were successful! We explored several caves, and settled upon three (our target for the expedition) to study.

Searching for invertebrates on root masses. Credit: Christina Colpitts.

These caves are in sharp contrast to our study caves in the Atacama Desert. We went from the driest desert on the planet to a semi-tropical paradise. So, we will be studying wet caves! Most of our study sites contain standing pools of water, and water is percolating through the ceiling. Interestingly, while evaluating several caves today, I saw only one arthropod. I was searching for bugs on a piece of wood and found one Collembola. While I have made only one confirmation of arthropods using Rapa Nui caves, this does not mean there is no fauna with these caves. It just means we have observed to find them. I observed evidence of several other arthropods within these caves. I saw numerous spider webs, and I’ve seen numerous spider molts within the entrance of one cave. I also saw a number of isopod (rollie pollies) carcasses within the entrance of one cave. In addition, I found live isopods within a collapse pit of one of the tubes. This was good news for us! This means, arthropods are active year round – so, our efforts here should be fruitful.

Regarding microbes, several of the pools contained what appear to be bacterial biofilms. I’ve also observed Actinomycetes on the floors, walls and ceilings of all these caves, as well as what may be gold and silver colored bacteria on the walls.

Additionally, and of high interest to Armando (Azua), my good friend and our Chilean microbiologist/ investigator on this project, we’ve found what may be the same type of Eukaryotic algae that we’ve identified from a cave along the northern Chilean coast. If this proves to be the case, this could be quite interesting.

Dinner is at 2000hr, and I want to get this blog posted before we eat. Also – the food has been great here. As you might expect, we’re eating a lot of fish

Horses grazing on grass and guava. According to Sergio, guava shrubs are viewed as a nuisance plant. The horses eat a lot of it and disperse it throughout the island.