The Microbe Condos
Seaweeds provide great homes for microbes, but different microbes like different neighborhoods.
The fall of each tide on Calvert Island’s West Beach leaves remnants of a thriving underwater community high and dry. Washed-up seaweed can tell a fascinating story if you look closely—very closely.
“Most of life on Earth is microbes, yet we know very little about them,” says Matt Lemay, a postdoctoral student in botany at UBC and a Hakai Scholar. His project, supervised by assistant professor Laura Wegener Parfrey, is part of the Hakai Institute’s Microbes-to-Macrophytes program, which is trying to learn more about the communities of microbes that live in the ocean.
To start to figure out which microorganisms live on which species of seaweed, the program researchers combed the beach for pieces of seaweed and swabbed them, taking note of what species the sample came from.
The results are still preliminary, but one thing is already apparent.
“The microbial communities on the seaweeds aren’t random,” says Lemay.
Seaweed is a generic term for three distinct groups of plant-like algae—brown, red, and green—each with unique evolutionary origins. Seaweed is like a microbe condominium. In the same way different kinds of people live in different kinds of condos depending on price, size, and aesthetics, different species of seaweed seem to host different microbial communities.
“Every species [of algae] we’ve looked at has a unique complement of microbes,” says Lemay.
“It doesn’t matter where on the beach we’ve found them, the microbes have been similar,” he adds.
This is especially interesting given that the microbes found on the surface of the algae were different from those dwelling on the adjacent rocks and sand—and also different from what’s living in the water.
“In terrestrial systems, when you look at microbial communities, they vary from place to place, but in the marine environment they’re largely the same,” says Mary O’Connor, an assistant professor at UBC and a member of the Microbes-to-Macrophytes program.
The next step is to figure out what the patterns are, and what is affecting these relationships. Seaweed species with similar shapes may have similar microbes living on them. Or it may be that more closely related species have similar microbial communities.
As well, the effects of the microbes on their algal “condo” could be different across species. Microbes are known to be vital to the function of most host organisms, but the specific effects are still being worked out.
“[Microbes] are important for carbon cycling, for moving nutrients up the food chain,” says Lemay. “Everything we think the seaweed does, a microbe is probably doing most of the work.”