By: Dyllan Furness, Director of Communications
Pamela Hallock finds little comfort in climate change.
Hallock, a biogeological oceanographer and Distinguished University Professor at the USF College of Marine Science (CMS), has spent her career studying the ocean. She leads the Reef Indicators Lab at CMS and is no stranger to the impacts of human activities on marine environments.
Still, she couldn’t help but notice a bright spot in the results of her recent paper on a species of single-celled organisms called foraminifera (forams).
“These forams have been increasing in numbers in suitable environments,” Hallock said. “Now they’re so prolific that they’re becoming an economic resource in regions with warm waters and high alkalinity because they’re building beaches.”
The foram species in question, Amphistegina lobifera, found favorable conditions in the warm, nutrient-poor waters of the Mediterranean Sea after traveling north through the Suez Canal 60-80 years ago. A. lobifera populations have since proliferated in the eastern Mediterranean and spread westward, raising concerns about its invasive potential in the region.
IMAGE ABOVE: The coastal areas of the Mediterranean Sea shown in yellow indicating regions where A. lobifera can live abundantly if water quality is suitable. Credit Olga Koukousioura.
Despite these concerns, A. lobifera may be boon for tourism in countries like Turkey, Hallock said. Their calcium carbonate skeletons make excellent beach sand. Shorelines once covered in jagged volcanic and limestone rock have accumulated a half meter or more of sand comprised of dead foram skeletons and other shells.
“The rate at which these forams are building beaches in the region is comparable to the rate of sea level rise,” Hallock said.
IMAGE ABOVE: This figure shows alkalinity in the Mediterranean. Note the high alkalinity in surface waters in the eastern basin. Credit Olga Koukousioura.
There’s reason to believe A. lobifera may continue to flourish in a warming world replete with atmospheric CO2. The genus Amphistegina emerged on Earth during a period of higher atmospheric CO2 concentrations, Hallock noted in her paper, and warm waters with elevated alkalinity increase their rates of metabolism and shell formation.
While A. lobifera may currently be considered invasive in the Mediterranean Sea, its presence in the region is really a return to ancestral waters.
“These are a kind of critter that previously inhabited the region,” she said. “Now, through our influence on the environment, we’re making the habitat once again suitable for them.”
LEFT IMAGE: Amphistegina lobifera. Credit Olga Koukousioura. RIGHT IMAGE: Sand sample from Elafonisos, Greece, with abundant A. lobifera shells, as well as shells and shell fragments from snails and other organisms. Credit Olga Koukousioura.
The recent study published in the Journal of Foraminiferal Research offers a unique perspective about the impacts of humans on marine environments, and vice versa.
As Hallock and her co-authors state in the study, “Might this return of prolific shallow-water carbonate production ultimately prove at least locally beneficial as climate change progresses?”