UCONN GEOSCIENCES IN THE BAHAMAS

Archive for February 2016

Feb 5, 2016

Resilience by Sherry W.

January 6, 2016

Before coming to the United States, I had never heard of caving. Our school group headed to Lighthouse Cavern. This was the very first time I had ever gone caving. The proper term for this hobby is called 'spelunking' which involves exploring cave conduits.

Entrance of Lighthouse Cave. Photo source: https://www.flickr.com/photos/jsjgeology/16321380981

Upon entering the cave, under the darkness of the main chamber, I had a mixture of emotions going through my head. Normally, I would be afraid of such a dark and closed-off environment - one that I'm not familiar with. At the same time, I felt super excited to explore something so foreign and new to me! It was an interesting mix of feelings.

The dry main chamber of Lighthouse Cave is decorated with a beautiful array of thousand-year old speleothems. Columns, draperies, stalactites, stalagmites, and bell holes can all be observed! Photo source: https://www.flickr.com/photos/jsjgeology/15705358684

Transitioning from dry cave to a submerged tunnel was a fun shock. For one, the water here is a mix of salt and fresh that is refreshingly chilly. I followed the others in a single line as my headlamp illuminated ahead of me. The journey was relatively dark, and thoughts of creatures living beneath the water creeped into my head...I was afraid, but the idea of exploring something new propelled me forward.

Entering the submerged phreatic zone of the cavern.

These headlamps were our guiding light!

We trekked further into the cave and into deeper water. At one point, my feet could no longer touch the rock below and began to swim in order to explore further. All over, I could see incredible formations on the cave walls. Once we reached the end of the cave, there was an 'island' of limestone where we were able to rest on. It was here when we turned off all of our headlamps and felt what is was like to be in complete darkness. Nowadays, people rely too much on technology and don't take the time for serenity and meditation. This experience was unique and unforgettable for me.

Feb 4, 2016

Salt Pond by Dana Y.

January 11, 2016

This morning Lisa had a discussion with us about sustainability for San Salvador. We learned that there are nine types of sustainability. They consist of energy, food, jobs, transportation, water, education, shelter, waste management, and outreach. The one I find most interesting and want to do my project on is education. I think that if the education system teaches sustainability from an early age then it can have an impact on the other eight types of sustainability. Learning about all of this was my favorite part of the day.

In the afternoon we did a beach profile of the dunes on Junk Beach. We found that from the hurricane the debris had traveled about 42 meters from the ocean’s edge. This means it had to have traveled up and over the dune, across the road, and deposited on the edge of the hypersaline Salt Pond. Some of the debris consisted of netting, a variety of plastics, some metal scraps, and medications. It was super interesting to see how much this hurricane truly impacts this island.

Salt Pond lake is located on the eastern side of San Salvador Island. It's also interesting to note all of the inland lakes. https://en.wikipedia.org/wiki/San_Salvador_Island#/media/File:SanSalvador_map.jpg

At Salt Pond, we also took core samples. You may notice the water in this inland pond is neither clear nor blue. Why is that? When Salt Pond formed, it was separated from the ocean by dunes that created a barrier to the sea. This cut-off basin then began to collect rain water and even overwash from the sea in times of storms. Who lives in these waters plays an even bigger role in the color of the water. A community of microbial mats call this pond their home and give the water its brownish-red glow. The mats are made of thin layers of bacteria that grow beneath the water surface. They play a role in the dynamics of the pond by influencing the precipitation and dissolution of carbonates.

Microbial mats. You may be familiar with the ones from Yellowstone National Park (left). On the right is an image of a profile of layered mats.

Photograph of Salt Pond. View is to the west. The core sample was taken from this portion of the pond to see the transition of various mats through depth.

In order to understand the microbial mats better, we got a push core of the pond floor. We walked out about 40 ft. into the pond in order to get our core. The bottom of the pond was extremely gucky and difficult to navigate since my feet kept sinking into the floor! We hope to analyze how the mats change in varying water depth.

Feb 3, 2016

Australian Invasion: Casuarina induced erosion by Melissa N.

January 2016

On San Salvador, we looked around the island at everything from rock formations to coral reefs. I was interested to learn about the invasive casuarina. This Australian pine was brought to the island (and all of the Bahamas) in hopes of stabilizing coastal dunes during storms. Sadly this pine had the opposite effect.

Australian pines. Image by Meg Stewart https://www.flickr.com/photos/megstewart/4320102993

The casuarina has a shallow root system that can easily be ripped out under the stress of the frequent hurricanes. Once the roots become dislodged, the dune is ripped up giving way to the processes of erosion. The dune eventually loses its profile and becomes unstable.
The casuarina also has needles that cover the ground below the tree. These needles block sunlight penetration to the soil and acidify the soil surrounding the tree. The casuarina not only rips up the dunes, but also halts the growth of any vegetation that could stabilize the dune.

Figure shows a profile of dune erosion caused by cauarinas. Figure by http://www.geraceresearchcentre.com/pdfs/10thNatHist/113_Sealey_10thNaturalHistory.pdf

Photograph of a foreshore on San Salvador Island. Casuarina trees can be seen in the upper right hand corner of the image.

Image shows beach erosion caused by the Australian pine. Photo by https://casuarinacontrol.files.wordpress.com/2011/07/casuarina1.jpg

So what does all of this mean for the island's future? Dunes serve to protect the land in times of storms. Think of them as buffers for local homes located on the coast. When Hurricane Joaquin struck the island on October 2015, it brought powerful winds and swells that eroded sand away from dunes. Beaches on the eastern side of the island were particularly affected. Australian pines are speeding up the erosion process. What can be done about this? For one, the Australian pine has a very dense and heavy wood that withstands water. The trees could be harvested and made into furniture for export which would boost the island's economy and create a market for Bahamian furniture.

Sources and further reading:

The cycle of casuarina induced beach erosion by Neil Sealey

Snorkel Outings by Logan M.J.

January 2016

I had a fantastic time on the UCONN Bahamas Study Abroad adventure. Although caving and studying beaches was fascinating; the ultimate activity was snorkeling, which luckily we were able to do nearly everyday. Every time our truck stopped, we were all hoping we would be able to bring our snorkeling equipment. I cannot express in words the excitement we felt when we learned we were able to go snorkeling after doing field research. It was the coolest and most refreshing break.

The dark areas in the water pictured above are beds of sea grass (thalassia). They are havens for baby fish and make a great feeding ground for turtles!

Off to the races!

Swimming amongst the colorful reef fish was pretty much one of the coolest experiences of my life. Seeing the bright corals amongst diseased corals was fascinating as well. Knowing that parts of the island were made from ancient coral reefs was really interesting to learn. The weirdest thing was definitely learning all of the coral names throughout the trip, so at the end of the trip I felt like the ultimate coral naming professional!

The highlight of the snorkel trips and maybe the whole trip overall were when were able to swim with multiple sea turtles and when me and my snorkeling buddy spotted a huge stingray! It was very cool, very mind blowing and I hope someday to go back!