Bangia atropurpurea, a 160 million-year-old red algae, has quietly taken over the rocky shorelines of the Great Lakes. Replacing a species that is a staple in the food chain, the new invasion may be hiding a more serious problem.
We don’t know if it’s replaced other native algae,” says Kirsten Müller, a Biology Professor in the Faculty of Science. “In fact, we don’t even have a baseline of native algal species. And that’s disturbing now that we’re seeing such a dramatic change in the algae population.”
Müller is concerned about our lack of knowledge regarding this species and, more importantly, about the native algae that have been potentially lost, since little is known about the Great Lakes’ algal communities before 1970.
Algae can be just as destructive as other invaders
A relative of the edible variety of seaweed in sushi, this red algae grows mostly during the winter. Although it’s not toxic and has had no measurable impact on the Great Lakes so far, Müller is concerned about the invasion.
Some invasive species, like zebra mussels, have more of an indirect effect on the environment by disrupting the ecosystem balance. Red algae’s sudden appearance may tip a fundamental scale.
Bangia were first spotted around the Great Lakes in 1964. Müller, an expert in algae taxonomy, first characterized Bangia in 1998 and traced its lineage to Bangiamorpha, a 1.2 billion-year-old fossil that is identical to the living Bangia and the oldest taxonomically resolved eukaryote. The modern freshwater variety Bangia atropurpurea split off from marine Bangia more than 160 million years ago.
Using genetic marker analysis, she and her colleagues traced Bangia from Europe and Asia. The species likely entered the Great Lakes via commercial shipping.
More research needed into how algae moves
In addition to DNA sequencing analysis, Müller also uses morphology (physical) characteristics, taxonomy, and biological geography to understand why certain species are where they are.
“It’s important to be able to identify species correctly,” says Müller. “Even the same genetic markers can be shared by very different species.”
Bangia’s sudden appearance and proliferation suggests it’s been spread with the help of humans via transoceanic shipping. Experts like Müller are still trying to determine if this was a single invasion or if Bangia have been brought over multiple times.
Recent restrictions on ballast water exchange aims to limit the number of potential invaders making the transatlantic journey, but algae like Bangia can circumvent these safeguards. Not only are they seawater tolerant, they can attach themselves to the outside of ships, which are not cleaned between journeys.
According to Müller, algae can spread easily and if Bangia can make the journey, other more potentially destructive species could travel as well.