Salty and Sweet

 Photo Credits: Emma Roszkowski

I’ve seen mangroves on the coast of Florida before, plants about as tall as me poking up out of the water. But this was different. This looked like a forest, with tall, straight trees rising to heights of 50 feet or more. But at the same time, it was different from any forest I had experienced. The ground was a soft, dark mud and pockmarked with countless holes. We saw some of the residents, small brown crabs, scurrying around our feet. One of the most immediately noticeable differences was the lack of shrubbery on the ground. Normally, you can’t even leave the trail because of the thick vegetation. Here, the landscape was empty except for the trunks of those trees and the thousands of little sticks that poked up through the mud. The mangrove forest sat between a highway and a wide, brown river that flowed into the Tempisque just downstream. As we ventured off a trail and into the shade of the forest, we heard the occasional rumble of a truck passing juxtaposed with the quiet of the forest, the whine of mosquitos and call of a woodpecker.

After a couple minutes’ walk into the forest we sat in a row along a log, asking questions and trying to understand this new environment, relating it to what we had learned about the dry forest in Palo Verde and the higher elevation moist ecosystem at Las Cruces. Despite the wet, nutrient-dense soil, the conditions in mangrove forests are nearly impossible for plants to handle without a set of special adaptations, explaining the lack of undergrowth. Every plant and animal living in the mangrove must learn to survive the high salinity, the mud, and the flooding. It turned out that those little sticks underfoot came from the roots of the trees, their way of getting air when the dense mud couldn’t provide it.  I immediately felt guilty for crunching so many of them underfoot but they blanketed the ground, making them unavoidable. Mau handed out leaves to each of us, as he had done many times before. I was expecting to identify it but instead he asked us to lick the underside. We trusted Mau, he knew what was safe and what wasn’t, we’d seen him catch scorpions. So we licked it and all immediately made faces. It was almost pure salt. I’ll never forget that the undersides of mangrove leaves excrete salt.

We wandered further into the marsh and, abruptly, the forest changed. Now, tall arching roots formed a maze in front of us, supporting a different kind of tree that formed an even canopy above our heads. At the same time, the mud got softer, and we sank further with each step, yanking our boots out with loud slurps. Everyone began to stumble more than walk, catching ourselves on roots as we tried to pull our feet out of the mud without leaving our boots behind.

“Don’t break the roots! They have little openings that let the trees breathe so you could really damage the tree” Mau called from the front of the procession. We all tried to step gingerly over the roots, only succeeding in getting more tangled. After a couple minutes of scrambling through this maze we stopped to talk about the new part of the mangrove forest. The tree species had changed as a result of higher salinity levels and more frequent flooding, and the mud had gotten deeper because of the silt brought into this area during high tide. We talked about the conservation struggles and the importance of such areas. Mangroves have been receiving more attention recently because of rising sea levels and storm frequencies and their role in buffering inland areas from the effects of climate change. Environmental services, however, are harder to quantify than the beachfront potential and agricultural opportunities this land offers- a pattern we had seen emerge during many talks about conservation. Even though the forest looks simple, we talked about the hidden interactions that happen in the soil and the birds who seek protection among the trees and the fish who swim between the branches of mangroves closer to the shore. I learned for the first time that mangroves actually help to reclaim land from the sea by collecting layer after layer of silt between their roots until they stand on dry land, allowing other species to colonize that area.

After talking, we sat around on various dead logs and thicker roots, pulled out peanut butter and jelly sandwiches and munched away happily, trying not to get too much mud on our food. With the time afterwards, we scrambled around the roots. It kind of seemed like a giant playground, though we knew at that point that it was much more than that. On the way back we repeated the stumbling procession, repeating the mantra “don’t break the roots!” to each other anytime someone stepped on a twig. It was a relief to get back into the area with the tiny little sticks because you could trust the ground wouldn’t give way under you. On the way out of the forest we stopped by the edge of the river and squinted against the sun, trying to spot crocodiles on the opposite shore. A motor boat ran along the far side of the river. Screeching ospreys swooped over the water. Somebody pointed out a crocodile swimming downstream and we all watched the approximately 10-foot-long crocodile pass beneath us and continue on its way. Any desire to swim vanished.

During the bumpy drive back, a couple of us had started to doze off when we stopped and the driver pulled open the back doors. We piled out into the parking lot of a Pops, a Costa Rican ice cream chain. Nobody felt sleepy anymore. It had been a long time since any of us had been inside an ice cream store, or even off a biological station. Cups and cones and sundaes were purchased and we stood in a circle, sweaty and covered in mud, slurping up the quick-melting ice cream. I licked my chocolate cone, enjoying every bit more than I had in a long time.

Nicole Oppenheim

Washington University in St. Louis