Biology of Beach and Bay: Research Resilience in Puerto Rico

By Todd McLeish ’84, June 7, 2020

Even an earthquake couldn't quell student enthusiasm for a signature program of the biology department.

Six biology students and two faculty members traveled to Puerto Rico in January to conduct research.

(Photo submitted)

Just hours after six Ithaca College students arrived with two professors in Puerto Rico for a 10-day environmental research expedition in January, they were awoken by a powerful earthquake that struck the southwest portion of the island. They felt their hotel swaying, heard the structure creaking, and watched as objects fell from shelves. Two hours later, an aftershock only slightly less powerful than the first earthquake woke them again.

And yet the students weren’t worried at all.

“We had been traveling all day and I was still tired, so I just put a pillow over my head and went back to sleep,” said Sarah Griffin ’20, a senior biology major. “I was too tired to deal with it.”

“I suppose I should have been more scared than I was, but I didn’t think it was that bad,” added classmate Elizabeth Anderson ’20. Her only worry was that the trip was going to be canceled.

“Once we decided we were staying, we had to scrap our research plan on Vieques Island because the ferry to get there wasn’t running. Susan and I sat up from 8 to midnight and came up with an entirely new plan for what we were going to do for the next 10 days.”

Dave Gondek, Associate Professor of Biology

Although the epicenter of the earthquake was 90 miles away, it knocked out power to most of the island. It also put IC biology professors Susan Witherup and David Gondek in crisis mode. They spent hours on the phone discussing the situation with the college’s risk management office, monitoring the potential for more aftershocks, and consulting with the students to make sure they felt safe and wanted to stay. They did.

“Once we decided we were staying, we had to scrap our research plan on Vieques Island because the ferry to get there wasn’t running,” said Gondek. “Susan and I sat up from 8 to midnight and came up with an entirely new plan for what we were going to do for the next 10 days.”

“The best choice was to stay put on the big island and find things to do that were similar to what we had originally planned,” said Witherup.

Invasive Plants and Pollination

Faculty in Ithaca College’s biology department have been bringing students to Puerto Rico every January since 2015 to engage them in hands-on environmental research. The trip evolved from a course called the Biology of Oceanic Islands that Witherup and biology professor Peter Melcher designed and first offered in 2013.

“In the context of developing that course, we talked about giving students an opportunity to go to an island and think about the questions we were talking about in class,” said Witherup, an evolutionary biologist who joined the IC faculty in 1997. “After taking them on a sailing vessel the first year, we decided we wanted to move to a more terrestrial-based research experience. We chose Puerto Rico because it’s easy to get there and easy to give students the kind of off-campus experience we were looking for.”

The research that Witherup and Melcher chose to focus on in Puerto Rico involved an invasive plant that was introduced to the Caribbean as an ornamental beach shrub and is now outcompeting a closely related native species that also grows in coastal dune beach habitat.

“They’re both bushy shrubs, but the roots of the native one grow deep into the sand, and it’s known to stabilize dunes against ocean surge from big storms,” said Melcher. “Young plants of the introduced species have a shallower root system, so we suspect that it’s not as good at being a dune stabilizer. Since the two species are competing in a very similar niche, it provides a unique outdoor lab experiment.”

Melcher, a plant ecophysiologist who previously studied the introduced species in its native Hawaiian habitat, is measuring physiological parameters of the two species — their photosynthesis and respiration rates, how much nitrogen they need to grow, and other factors.

“The invasive species grows faster and can survive with a lot fewer resources, so we’ve been trying to figure out how it does that,” he said. “It turns out it has more leaf area to harness the solar energy potential on a per stem basis compared to the endemic one. It’s building cheaper, thinner leaves and photosynthesizing at a lower rate, but it has so many leaves per stem that its overall carbon gain is much higher than the endemic, and this gives it the potential to outcompete the endemic species.”

Witherup’s research aims to understand the impact of pollinators and pollen movement among the two shrubs. She is also examining the genetic diversity of the two species and using genetics to determine where the invasive species originated.

“The students have to be able to identify what insects come to each plant and quantify those visits while sitting on a beach in the sun during the peak pollination hours."

Susan Witherup, Professor of Biology

“The first question I’m asking is whether the presence of the invasive is helping or hurting the native,” she said. “From the standpoint of pollinator visitations, it looks like it is actually facilitating pollination, which is counterintuitive. The reason is because the invasive is providing a nectar reward that is not very different from what the native is offering, and it’s offering a lot more of it.

“The invasive plants are really big and fast growing, and they make a ton of flowers and a ton of fruits, so it’s capable of taking over an area really quickly,” Witherup added. “But because these giant shopping malls of flowers offer this huge attraction to pollinators, the native species that grow nearby get pollinated, too.”

In each of the last three years, the 6 to 10 students that travel to Puerto Rico in January have spent hours observing both shrub species and counting and identifying the bees that visit to pollinate them.

“It’s a great experience for the students to do research in a tropical environment and understand the challenges of working in the field. They’re also becoming immersed in a different culture, so they get to work with people of different backgrounds, learn how they live, and learn about island ecosystems. There are a lot of hidden nuggets of experience they’re getting.”

Peter Melcher, Professor of Biology

“The students have to be able to identify what insects come to each plant and quantify those visits while sitting on a beach in the sun during the peak pollination hours,” Witherup said. “I also had a couple students comparing the nectar reward between the native and invasive. They looked at the sugar concentration in the nectar and the nectar volume to see whether they were different.”

When Hurricane Maria blew through the island in September 2017, it added another element to the research. The storm destroyed much of the dune habitat and the plants the research team had been studying, so Melcher created another experiment from the devastation. As the shrubs grow back from seeds that are dispersed to beaches from the wind and ocean currents, Melcher and the students are evaluating how the plants compete throughout their life cycle when both species are starting from a clean slate. They are also assessing how their growth affects other species that grow and live in the shade of the shrubs.

“It’s a great experience for the students to do research in a tropical environment and understand the challenges of working in the field,” Melcher said. “They’re also becoming immersed in a different culture, so they get to work with people of different backgrounds, learn how they live, and learn about island ecosystems. There are a lot of hidden nuggets of experience they’re getting.”

Bioluminescence in Laguna Grande

Anderson enrolled in Witherup’s class on the Biology of Oceanic Islands last fall and was excited about the opportunity to visit Puerto Rico and get her first experience conducting field research. She was also looking forward to being in a warm climate in the middle of winter. “Mostly I just wanted to collect data in a natural environment,” she said.

Griffin, too, was excited about getting involved in field work and pleased to be invited to join the trip. “I was nervous that everyone would know more than I would because I was the only one who hadn’t taken the class,” she said. But after the earthquake struck and the research plan changed, none of that seemed to matter.

Since much of their research equipment had been shipped to Vieques in advance of their arrival, they were forced to improvise with simple or home-made devices.

“One of the things I learned from the trip is that there are a lot of ways to do science,” said Anderson. “We were able to do almost the same things we had planned for on Vieques but with a mop bucket and a handpump and foldable microscopes. We were able to MacGyver it.”

In addition to collecting data on the pollination of the native and invasive shrubs, the students also helped Gondek learn about the tiny organisms that live in a bioluminescent bay.

Puerto Mosquito on Vieques Island is one of the brightest bioluminescent bays in the world. The tiny single-celled organisms called dinoflagellates that live there have evolved a mechanism to illuminate whenever there is a disturbance in the water. Gondek seeks to understand how the bacteria that also live in the water may affect the ability of the dinoflagellates to bioluminesce.

“There have been lots of studies on the dinoflagellates, but nobody has asked questions about the bacteria,” he said. “We’re starting with asking what kind of bacteria is there and what they’re doing, and then we’ll have more ideas about why they’re there and what’s going on.”

It’s an important phenomenon to understand. When Hurricane Maria struck, the bay went dark for several months after the bioluminescent organisms died. Climate change may also be having an effect.

“It’s critical from a biological standpoint to understand what’s happening,” said Gondek. “But it’s also the driving force of the economy of the island. People rely on that money coming in from tourism, so if the bioluminescent lights go out, it could have a tremendous economic impact.”

But since the research team couldn’t get to Vieques Island in January, Gondek took them to a different bioluminescent bay, Laguna Grande, which is now allowing him to conduct a comparative analysis of the bacteria in the two bays.

Students gather samples on the beach.

(Photo submitted)

Trip Takeaways

For the students, every day in Puerto Rico was a new and different experience. They learned to identify bees and made pollination observations, collected leaf samples for genetic analysis, pumped water from the bioluminescent bay through filters to capture bacteria, and took photos of the invasive and native shrubs.

“We got to do a lot of different things, which is what I liked the best,” said Anderson. “Every day we tried something new, and every night we’d work on another project. We even got to go to the rainforest.”

“It was fun to be able to do research in such a beautiful area,” Griffin added. “It was hard to be out in the sun for that long at times, but it was a great way to do something you feel like was a great learning experience. And the whole time, we were with people who were fun to be around.”

The students agreed that the trip was especially useful simply to get a better understanding of how to conduct research in the field.

“I’ve learned so much about creating a project, learning by trial and error, understanding that things are bound to go wrong, and working through it. This project has empowered me to pursue a career in science. I’ve had so much personal growth and confidence come from it that I feel like I can definitely make it my career.”

Alexandra Stalica ’20, a senior environmental science major

“It was great to be able to know how to prepare for a day out in the field and learn how to adapt to changing circumstances,” said Griffin. “And during our down time, we got to learn some lab techniques that we can now use back on campus.”

After each trip to Puerto Rico, the research team returns to Ithaca with plenty of samples for testing and data needing to be analyzed, allowing many additional students to become involved in the projects.

Alexandra Stalica ’20, for instance, has been analyzing the overhead photographs of the native and invasive shrubs as part of Melcher’s research. Based on what she sees in the images, she assesses how much area each shrub covers and records what other plants are present in each plot to calculate a diversity index for the two shrubs.

"I’ve learned so much about creating a project, learning by trial and error, understanding that things are bound to go wrong, and working through it,” said Stalica, a senior environmental science major who traveled to Puerto Rico during spring break to collect additional data. “This project has empowered me to pursue a career in science. I’ve had so much personal growth and confidence come from it that I feel like I can definitely make it my career.”

Future Research for the Birds

In the future, a fourth research project will be added to the mix of activities that students will engage in during the trip to Puerto Rico. Ornithologist Nanda Cortes, who joined the IC faculty in 2018 after serving as a postdoctoral researcher in the biology department the two prior years, is studying a brightly colored Venezuelan bird called a troupial that has been introduced to Puerto Rico and several other Caribbean islands. She is seeking to learn how the bird’s populations in Puerto Rico differ genetically from those that live in Venezuela and elsewhere.

“The bird is super pretty with a black head, yellow-orange breast and orange back, and the males and females sing a duet together, which is really unusual for birds,” said Cortes. “I want to learn about their genetic makeup to see how long they have been evolving in these different areas and how different they are from each other. I wonder if they were to get in touch again if they would reproduce or interbreed.”

In Puerto Rico, the birds are found in two disjunct regions — in the southwest part of the island and in the north. Cortes first plans to determine how different these two populations are and whether they ever come in contact with each other before comparing them to the Venezuelan birds. To do so, she and students on next year’s trip will capture birds from each population and take blood samples for DNA analysis.

Cortes plans to launch a research project tied to the invasive shrub studies led by Witherup and Melcher. She wants to learn which birds feed on the fruit of the shrubs and if that feeding helps spread the plant to new areas.

“The plant can be difficult to grow because we think the seeds might first have to go through the digestive system of a bird or other animal,” Cortes said. “When the birds eat the fruit, the acids in their stomach might break down the shell of the seed, which could make it easier for the seeds to germinate. That’s what I want to investigate.”

There may be additional research projects and other faculty members involved in the initiative in Puerto Rico in the future as well.