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Marooned for the Sake of Science
Katy Heath is not about to complain about the long hours she logged in the laboratory recently. Who would when the laboratory was a Caribbean island and lunch breaks were devoted to snorkeling?
Travel to such exotic locales is not normally a staple of the undergraduate experience, but it is a lucky perk for some students who work as research assistants. Heath, a senior in ecology, ethology, and evolution, had the opportunity to spend two weeks this past June and January exploring the barrier reefs of Belize. Heath's trip to Belize came about because of research she had been doing on mangroves for a UI plant physiologist and head of the Department of Plant Biology, John Cheeseman, who is a member of a five-year, seven-institution team funded by the National Science Foundation that is studying mangrove ecology.
The tiny Central American country of Belize, which dips its white, sandy beaches in the Caribbean Sea and backs its rugged western flank up against Mexico and Guatemala, possesses stunning natural beauty. In addition to rainforest-garbed mountains, it has a barrier reef second in length only to the Great Barrier Reef off Australia.
Mangroves populate the intertidal waters between the reef and the coastline. These gnarled trees form dense thickets that protect the shoreline from wind and waves and shelter an extraordinary diversity of animal life: some 500 different species of birds alone nest in the mangrove stands of coastal Belize.
The trees' niche of paradise, though, is surprisingly harsh. In addition to the blazing tropical sun, the trees combat low soil nutrients, salt water, and the thick layers of mud over their submerged roots. Understanding how the mangroves have overcome these obstacles to survive, says Cheeseman, "will teach us a great deal about how plants fight back against changes in the environment, whether natural or human-induced."
The small island, or cay, on which Cheeseman and Heath conducted their research is an example of the mangroves' ability to adapt to conditions far from ideal because the cay itself was initially formed, and is now preserved, by the mangroves. It is composed entirely of peat, or decayed plant matter, specifically mangrove roots, that has accumulated over the past 7,000 years. Of keen interest to the scientists is that the island has accreted at precisely the same rate as the sea level has risen.
Equally impressive, and the reason for Cheeseman and Heath's trip to the islands, is the trees' adaptation to the intense tropical sunlight. "Have you ever set your plants outside in the spring, trying to give them fresh air after winter?" asks Cheeseman. "The usual result is a plant with white, dead leaves." To understand how these super sunbathers avoid the bleached look, Heath squished across the island each day, avoiding sink holes and boa constrictors, collecting the red mangrove leaves from trees she found growing under optimal and minimal conditions. At the end of each day, she and Cheeseman boated to a nearby island where the Smithsonian Institution maintains a laboratory where they could analyze their leaf samples. This not-so-primitive spot also featured a kitchen (and a cook!) and bunks.
They were measuring the concentration in the leaves of compounds called antioxidant phenolics and the enzymes that metabolize them. Bleaching is a response to high doses of ultraviolet light. In smaller doses sunlight drives photosynthesis, but once a plant reaches capacity, the extra light energy proves harmful by producing hydrogen peroxide instead of glucose.
Cheeseman believes the mangroves detoxify the peroxide (H2O2) by converting it to water (H2O) and excess oxygen (O), which is absorbed by the phenolic compounds. The data he and Heath collected in Belize and from mangroves grown in a greenhouse on campus may eventually demonstrate how these compounds perform under different environmental conditions.
Heath won't be around for the results—the January trip to balmy Belize was her last lab shift as a UI student. Not a bad end to a college career.
By Holly Korab
Winter 2001