The Great Salt Lake
In early January of 2015, Scotty and I took our first ever train trip from New Orleans to Salt Lake City and it was such a wonderful experience. Traveling by train is amazing and eco friendly and we got to explore a bit of Chicago during our five hour layover. It was a grand total of -22 degrees Fahrenheit in Chicago that day, but we were determined to make it to Millennium Park to see the famous Cloud Gate. So with lots of layers and many stops into Starbucks and book stores to defrost, we made it! Back on the train for the long stretch to Salt Lake we met and had conversations with a lot of interesting people, all with different destinations. The scenery traveling through the Rockies was breathtaking, so we spent a lot of time in the observation car. One conductor even let us get off the train briefly at a few stops in the Rocky Mountains to "breathe in the mountain air." Obviously, we are now supporters of train travel and will be taking more train trips in the future!
Once we were in Salt Lake, my favorite part was actually the close proximity to beautiful terrain, nature and hiking trails. We were able complete a few hikes and see a significant amount of snow fall for the first time. One of the hikes we completed was the Buffalo Point hike on Antelope Island in the Great Salt Lake State Park. Antelope Island is the largest of ten islands located within the lake. At first glance the snow covered terrain looked barren and lifeless, but it was beautiful. We took a stroll through the visitors center upon arrival. There was a lot of info about the history of the lake and the life on the island. There were resources available to read about how not to get killed by buffalo during the hike, and even a tiny aquarium to view the little brine shrimp that live in the lake. Unsurprisingly, however, there was no information about the fascinating microbes that make up majority of the living things in the second saltiest body of water in the world. The hike was gorgeous, and I felt nothing but gratitude to be in such an amazing place. Most plant life was dry and snow covered, which made for wonderful frosty photographs! I, of course, was on a hunt to spot lichens living in little rock crevices and I found some quite colorful ones! As we got higher in elevation the terrain became more rocky with huge boulders we couldn't see behind. Turns out the information on not getting killed by buffalo was useful. We had an encounter about 10 feet away from a gigantic, territorial buffalo and had to rapidly descend back the way we came.
Now, let's talk about those unmentioned microbes living in the lake! We couldn't see them, but I admired their wondrous presence throughout the whole adventure on the island in their home. The Great Salt Lake actually has two separate parts, a Northern portion and a Southern portion that are separated by a man-made, somewhat permeable causeway. Antelope Island is located in the southern portion of the lake. Usually lakes have an outlet to an ocean, but The Great Salt Lake does not. It lies in a closed basin and is a terminal lake, the only water leaving is doing so through evaporation. Salts and minerals don't evaporate with water, so they have been left behind to accumulate for thousands of years. Majority of the water that flows into the lake actually comes from the Wasatch mountain range (which we were later able to hike the foothills of). When the lake was divided, it caused the northern portion to have an extremely high salt concentration, while the southern portion has a moderately high salt concentration. This is because most water that flows into the lake enters into the northern region, bringing with it salt and minerals. As the water moves through the semipermeable causeway into the southern portion, a lot of the salts and minerals remain in the northern portion. The northern part gets so salty that sometimes the shores of the lake get encrusted in salt and sparkle in the sun.
Both areas of the Great Salt Lake host microbial life, but the microbes in the northern portion are a bit more fascinating in my opinion. The northern portion has a concentration of salt close to TEN times the concentration of the ocean. This salty water makes a great home for members of the genera Halobacteria and Halococcus, which are actually two types of archaea. Halobacteria and Halococcus are extreme halophiles, which means that they LOVE salt; they actually need high salt concentrations of at least 10% or higher to thrive and reproduce. These tiny creatures do best at salt concentration around 20% and can continue to grow in salt concentrations up to about 36%, which is a lot of salt!
Since water will travel from areas of low salt concentration to high salt concentration, lots of salt is usually rough on living things. Concentrations like that of the Great Salt Lake can pull all of the water out of cells dehydrating them to death. However, the extreme halophiles are able to overcome this salty death by storing up potassium chloride (a type of salt) in their cells. This allows them to maintain the same amount of salt inside the cell as the amount outside in the lake. With this salt equality on both sides of the cell, the halophiles are able to maintain a healthy amount of water within them, staying plump and alive!
My favorite part about the Great Salt Lake is that something quite fascinating happens to it in the warmer summer months... the entire northern portion turns a glorious pink color! Why does this happen? When temperatures rise in the spring and summer months water evaporates from the lake. Salt does not evaporate with water, so less water = an even higher salt concentration. The halophiles, as their name suggests, love this. Their population numbers soar when the weather gets warmer. Cell density in the lake can become so high that all the cells start to deplete the oxygen levels. Normally Halobacteria and Halococcus respire oxygen to get their energy... if all the oxygen gets used up, what are they to do? Luckily some species like Halobacterium salinarum can adapt to using sunlight for energy instead! These little guys don't have chlorophyll to use the sun in the way plants do, instead they use a pigment called retinol paired with a protein to create a light capturing molecule called bacteriorhodopsin. This little light absorbing contraption in their membrane does two things: 1. captures light for energy (of course) and 2. causes the cell membranes to turn a reddish-purple color. Bacteriorhodopsin in the membranes of the Halobacteria is actually the reason for the famous pink appearance of the lake in the warmer months!
Increase in temperature→ evaporation of water & increased concentration of salt → increase in halophile population → decrease in oxygen → increase in species with retinol + bacteriorhodopsin complexes → increase in reddish- purple colored cells →lake appears pink!
Unfortunately we were not able to feast our eyes upon the beautiful pink phenomenon since Utah is quite cold in January, but I was able to get a couple pictures of a Halobacterium salinarum culture from a lab at Louisiana State University! We are planning to be in Salt Lake in July of 2016 for a short stop on the way to our next big adventure, so maybe we will be able to see it!
Peace, love & microbes,