Carol Thornber
University of Rhode Island
Associate professor; marine population and
community ecology, algal ecology
RI NSF EPSCoR lead principal investigator
SURF program mentor

Undergraduate student to postdoc, seaweed to mysid shrimp — the Rhode Island NSF EPSCoR grant runs through the people and projects of Carol Thornber’s research work.

“EPSCOR has touched nearly everything in my lab,” says Thornber, named lead principal investigator of RI EPSCoR in the summer of 2014. “The support has been incredibly helpful. It’s provided the opportunity to do a lot more than I would have been able to do otherwise, and has stimulated other grants to the NSF, EPA and other agencies.”

SURF students, graduate fellows, Ph.D. candidates, and postdocs. Travel to conferences and poster presentations. RI Science and Technology Advisory Council (STAC) awards and collaborations; research that cuts across disciplines and institutions. Cutting edge technology at shared core facilities.

Although not exclusive, nor direct, the supplemental nature of the EPSCoR funding helps sets the stage for Thornber’s research into the impact of climate change on harmful algal blooms and mysid shrimp, both of which play significant roles in the Narragansett Bay ecosystem.

The projects range from bringing greater understanding of seaweed blooms, investigating reproductive biology and gene expression, to how mysid shrimp species respond to different water temperatures and the affect of ocean acidification on predator cues.

Collaboration with URI colleague Stephen Licht, assistant professor, ocean engineering, focuses on developing aerial imagery to monitor and map seaweed blooms. Work on a Rhode Island Sea Grant-funded project looks at an invasive red algal species with an impact north and south of Cape Cod, and its influence on marine communities. An EPA collaboration investigates the effects of ocean acidification on coastal systems.

Other projects explore algal bloom dynamics (how will species respond to increases in water temperature), chemical defenses (does Ulva chemically inhibit growth of other species), and herbivore control (the impact of snails on blooms).

Anyone who goes for a walk along the Rhode Island coast or swims or fishes understands the importance and impact, the effects of the blooms disrupting leisure activities and clogging and tearing fishing nets. And, once the seaweed dies, the large decaying masses drive down oxygen levels and cause fish kills.

“Algal blooms are a natural part of marine communities and they play a vital role in the marine ecosystem,” Thornber explains. “We expect to see them. But, where we run into problems is when there is above average abundance.”

Thornber says her first STAC grant in 2008, which sequenced genes to identify species in blooms, provided the framework to ask more sophisticated ecological questions: “If we know what species there are, we can predict what the response will be as climate warms and changes. Will we still see these blooms or what time of year will we see them?”

Conducting monthly surveys since 2005 at eight sites in Greenwich Bay, Thornber has found Ulva in abundance and incredible variability, with growth of the bloom biomass partly dependent on temperature and in correlation with precipitation and salinity levels. The next step is to tease apart whether those factors are responsible for growth or increased nutrients.

Thornber’s lab experiments grow the seaweed at higher temperatures and have found that one species in particular, Ulva compressa, grows faster under temperature increases of three degrees Celsius. Curious about what happens during the winter, Thornber looked at how Ulva — a transient species that floats around — responds to the cold. The species can survive long periods of negative temperatures by entering a state of dormancy.

Her research also explores the role snails may play, putting the herbivores in buckets with Ulva to gauge if and how they inhibit algal growth. Although common sense suggests that the amount of Ulva would decrease with consumption, the grazing actually increases the biomass.

Meanwhile, another species, the invasive Dasysiphonia japonica, enjoys both a rapid growth rate and the distaste of snails, which makes it a good invader that has grabbed attention because it washes ashore in big, stinky mats and decays fairly quickly.

Taking all of these factors into account — seaweed species, snails, temperature, acidity and salinity levels — Thornber concludes that bloom dynamics cannot be predicted by a single factor, but rather the synergy of several variables.

Invasive species have shown they can model successful strategies for long-term persistence. Based on what the research shows, the blooms will continue in the face of climate change, but may shift their timing.

“The challenge,” Thornber says, “is how can marine communities retain their key ecosystem functions?”

Story by Amy Dunkle | RI NSF EPSCoR