Barro Colorado Island is a mecca for tropical ecology. Nestled into the southeastern corner of Panama’s Gatun Lake, the waters around Barro Colorado Island (BCI) teems with crocodiles and massive cargo ships traversing the nearby Panama Canal. On land, BCI boasts a biodiversity far greater than its geographic footprint (a little less than six square miles) would suggest. Everything from howler monkeys and brightly-billed toucans to roughly five hundred butterfly species and colonies of ants that number in the millions live on the island.
This staggering assortment of species has made BCI a hub for researchers for a century. The island is home to the Smithsonian Tropical Research Institute’s (STRI) first research station founded in 1923. This makes these jungles the world’s oldest continuously studied tropical forests. Over the last hundred years, STRI scientists have published over 13,000 studies on this rich ecosystem investigating everything from miniscule microbes to some of the world’s tallest tropical trees.
Scientists from 50 different countries flock to BCI to conduct their research, providing an international perspective on the island’s ecology. “It really is a unique experiment in scientific diplomacy. It's a lot of people who've actually lived their lives together,” said Beth King, communications supervisor for STRI. But many are quick to point out that the expertise of local Panamanian citizens continues to be the cornerstone of the island’s scientific community.
Today, the research center boasts a century of climate data, 40 years of environmental monitoring, and the first large-scale, long-term forest monitoring plot that inspired the international ForestGEO network of tropical research sites. BCI scientists draw on this deep well of prior research to inform their current studies. “They don’t have to reinvent the wheel,” King said.
This October, I made my own pilgrimage to BCI and met scientists, experienced the island’s vast array of wildlife, and explored everything else the research center has to offer. But you don’t have to travel to Panama to learn all about the history of BCI, you just have to visit the Smithsonian National Museum of Natural History’s exhibition: Barro Colorado Island 100 Years of Discovery and Wonder. This immersive experience is the STRI’s first exhibition on the National Mall as well as the NMNH’s first bilingual exhibition.
Arriving on Barro Colorado Island
To reach BCI, I took a boat from Gamboa – a small town about 22 miles from Panama City – to the southeast corner of Gatun Lake. When I arrived at the dock, the sun was shining bright – which is unusual for this time of year. Usually, Panama is in the midst of a long rainy season. But this year, the seasonal El Niño weather event has delayed the region’s rainy season. As a result of the lack of rain, the lake was far lower than usual. But a little over a century ago, the Gatun Lake – and Barro Colorado Island – didn’t exist at all.
In 1914, the Chagres River was dammed to create the Panama Canal, and rising waters surrounded what was previously a forested mountaintop. At the time, U.S. scientists were already stationed in Panama to study the environmental impact of the canal, and they proposed setting aside the newly created island for research. This established BCI.
Today, Gatun Lake makes up a large section of the Panama Canal that carries ships just over 20 miles across the Isthmus of Panama. Short-tailed swifts flew low over the water, catching insects in their tiny beaks. Occasionally, ripples would appear on the surface with no obvious source before the head of a crocodile popped up from the depths.
The short boat ride from Gamboa to BCI was spectacular. As we zoomed across the lake, lush forests whizzed by on either side. Suddenly, bolts of lightning streaked white against the darkening sky, which I took as a good omen. The island is home to numerous scientists studying the effects of lightning on tropical forests , and I was excited to spend the next few days learning about their research.
After arriving on BCI, myself and dozens of scientists gathered for a Bambi seminar. Since 1985, these regular gatherings have given scientists in residence opportunities to present their work and lead discussions on the topics they study. For this installment, forest ecologists Evan Gora and Adriane Esquivel-Muelbert presented research about the mortality drivers of tropical trees. While there are many different phenomena that can cause tropical trees to die, their talk focused mainly on lightning – one of the most prevalent botanical hazards on the island.
The very next day, I would venture into the jungle with Gora and Esquivel-Muelbert to observe these lightning-struck trees up close and immerse myself in BCI’s iconic research forest.
A Day in the Jungle
For light sleepers, there’s no need to set an alarm on BCI. As the sun rises over the lake, the low roar of howler monkeys grows louder and louder. Thankfully, I had to be up early anyway to meet Gora, Esquivel-Muelbert, and a few of their colleagues to prepare for our expedition.
To find the giant, lightning-struck trees they were looking for, we had to hike up and into the jungle. The research campus is at the base of BCI, which was once the peak of a mountain. After only a few minutes of climbing, we were dripping with sweat. But as the lush forest closed in around us, I became distracted by its beauty. In the canopy, dozens of birds called down to us, each singing a different song. Spider, capuchin, and howler monkeys swung from branch to branch. Blue morpho butterflies with their large, iridescent wings flitted to-and-fro, gleaming as they passed through patches of sunlight.
On BCI, “almost every day is magical,” said Hernán Capador, a STRI postdoc studying plant genetics and pathology. After seven years of research, he came to BCI to study the fungal pathogens that infect trees. “I had heard about [BCI], but I only understood how important this place really is once I was here,” he said. “Especially the 50-hectare plot.”
The 50-hectare plot at BCI is a 500 by 1,000 meter rectangle of forest that has been closely monitored since the early 1980s. Every single tree and shrub within its area has been identified, measured, and censused every five years. For plant biologists like Capador, the depth of data provided by this plot is invaluable. Its size allows researchers to take an accurate sample of the total biodiversity of the forest, and long-term monitoring gives insight into how forest dynamics shift over time. BCI was the first research center to ever undertake a forest monitoring project of this scale, but the ForestGEO network has now established similar plots in 29 different countries.
The 40-kilometer network of trails that run through BCI’s forest have guided hundreds of scientists towards discovery. Capador walks the narrow pathways to collect soil and seed samples from trees within the 50-hectare plot. He uses these samples to identify pathogens and study how they infect and damage trees. Already, he and his colleagues have described ten new species of fungal pathogens.
But Gora and Esquivel-Muelbert’s research takes them off the beaten path. The giant trees they study are often hiding deep within the forest. While bushwhacking through the thick understory, we traversed streams, steep valleys, and rocky inclines. Each time we arrived at one of our destinations, I had to catch my breath – only for it to be stolen once again by the magnificent sight of a giant tree.
Tropical trees can grow to be over 250 feet tall and several feet in diameter. When they die, they leave massive holes in the canopy where their crowns once flourished. The lightning-struck trees that we visited were like towering skeletons – their foliage had almost entirely disappeared, and many of their crown structures had been significantly damaged. After years of research, Gora has hypothesized that lightning is the greatest threat to giant trees, and understanding how lightning strikes alter the ecology of tropical forests is critical to their longevity.
While BCI is certainly the most famous of STRI’s research centers, the institute has several other facilities in Panama where scientists conduct groundbreaking studies. On the second day of my trip, I ventured off-island to explore two other STRI research sites: Punta Galeta and Punta Culebra. At each of these sites, Gora and his colleague Jeffery Burchfield, a lightning researcher from the University of Alabama at Huntsville, have placed sensors that monitor each time lightning strikes in the area by detecting changes in the electromagnetic field.
Overlooking the Caribbean Sea, Punta Galeta became STRI’s first marine research lab in 1964. Just four years later, 14,000 barrels of diesel oil were spilled near Galeta after an oil tanker broke up off the Atlantic coast of Panama. 18 years later, another devastating oil spill dumped 75,000 barrels of crude oil near the station. These events were devastating to local biodiversity, but enabled STRI scientists to lead major studies on how ecosystems recover from oil spills.
Today, STRI scientists continue to study ecosystem resilience at Punta Galeta. For 30 years, researchers monitored the impact of the oil contamination on nearby corals. Others have investigated Punta Galeta’s recovery from urban and industrial encroachment. With access to mangrove forests, seagrass meadows and coral reefs, researchers at Punta Galeta are able to see how a diverse array of ecosystems respond to damage from human activities.
On the other side of the isthmus of Panama lies Punta Culebra, overlooking the Pacific Ocean. During the construction of the Panama Canal in the early 1900s, three islands — Naos, Flamenco and Perico — were artificially joined to the mainland creating the Amador Causeway road. In 1964, STRI added Naos to its marine research program and built Naos Laboratories, a cutting-edge marine and terrestrial research lab. 32 years later, STRI expanded their presence on Naos by establishing Punta Culebra Nature Center, a stunning visitors center which attracts more that 70,000 people each year.
Punta Culebra offers scenic walking trails, interactive exhibitions, and an aquarium filled with native marine species like sea turtles and starfish. Along the rocky shoreline, STRI scientists study the evolution and behaviors of intertidal creatures such as crabs, snails, fishes and barnacles.
Gora and Burchfield may not be studying corals or crabs, but the lightning sensors that they have placed at Punta Galeta and Punta Culebra are critical to their research. Keeping a detailed record of lightning strikes along both of Panama’s coastlines allows them to monitor changes in strike frequency over time, and investigate how variables such as temperature, ecosystem type and precipitation influence lightning.
Like all other research conducted at Smithsonian research stations in the tropics, their work will preserve a snapshot of what this environment is like for generations of scientists to come, providing a crucial record of how some of the Earth’s most biodiverse environments are changing.
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