Penn State is home to one of the world’s largest collections of microalgae that live within the cells of corals. The vast collection of coral symbionts supports the research of scientists at Penn State and around the world.
“I’m frequently sending culture strains to scientists all around the world,” said Hannah Reich, a graduate student in biology in Todd LaJeunesse’s lab who helps manage the collection. “And when someone gets a new species into culture, they send us a copy.”
Many microalgal coral symbionts can be cultured in a glass tube with seawater and nutrients. This allows researchers like Reich to directly investigate the biology of the symbionts in an inexpensive way. Members of the LaJeunesse lab are planning to take advantage of both the collection and the Huck Institutes of the Life Sciences’ Microscopy Facility on campus to get a better look at the structure of coral symbionts.
Reich’s interest in marine ecosystems spawned from periodic visits to coastal Rhode Island when she was young.
“I saw how the beach had been eroding through my lifetime,” she said. “When I started college, I knew I wanted to study environmental biology; it was just a matter of what topic. And as a competitive swimmer, I was drawn to the water.” A formative study abroad experience allowed her to survey coral bleaching in the Turks and Caicos Islands in the Caribbean, which solidified her desire to pursue a doctoral degree studying coral reefs.
The culture collection at Penn State is one of the many resources that support Reich’s research. She uses a diverse set of species from the collection to study how symbionts rely on trace metals, like iron, to survive.
“People take vitamins to get important nutrients to maintain their health, and sometimes they might take a supplement for essential metals like iron and zinc when sick,” said Reich. “Corals and their symbionts also need these nutrients to survive. Iron in particular is often limited in ocean ecosystems, and we wanted to know how access to these nutrients might affect how a symbiont responds to warming waters.”
Studying trace metals requires a precise clean room setup, so Reich traveled to Taiwan to work with collaborators in the Marine Biogeochemistry lab at Academia Sinica—the national academy of Taiwan—who have the necessary facilities and expertise. She conducted a series of experiments over two summers, addressing how iron concentrations affect symbiont growth and how this relationship is affected by temperature.
“None of the symbiont species can grow without iron, but following the addition of iron they all behave differently,” said Reich. “In two species, we see that the combination of iron and heat stress can affect survival of the symbiont. When symbionts have little access to iron and are exposed to heat stress, they do not survive. But their counterparts with access to a lot of iron can survive at high temperatures. They struggle, but they can still survive.”
Reich’s work reveals how trace metals are interwoven in the complex relationship that symbionts have with water temperature, which may have implications for how the symbionts, and the corals they inhabit, respond to climate change.
After obtaining her degree, Reich plans to continue studying how trace metals affect coral symbionts with her global network of collaborators.