In the changing climate, coral colonies are often out-competed by surrounding algal mats, and being able to characterize their interactions could be the key to saving them. By studying the microbes that live in and around the coral across 3D space, our goal was to characterize the colony and its interactions with other species. Using a multi-omic approach, we created 3D models of the coral colonies to demonstrate our findings. We discovered organisms and chemicals that were found all around the coral but not in the algae. Additionally, we investigated the microbes that were able to live at the interface and how the coral was defending against them.
Summary figure from 3D coral publication showing interactions between coral and algal mats. From Little et al. (2021) Three-Dimensional Molecular Cartography of the Caribbean Reef-Building Coral Orbicella faveolata.
Marine Midge Microbiomes
Although insects are incredibly widespread, few have managed to invade marine habitats and they are generally found close to the surface. So in 2018 when researchers from the Keeling LabLinks to an external site. discovered marine midge larvae more than 100 feet below the surface, it was quite a surprise. My Honours thesis focused on determining whether these midges derive their microbiome from the environment or inherited it from their terrestrial ancestors. I found that the midges maintained tight control of their microbiota, with over 70% of their bacteria being absent from their surroundings. They shared some broad similarities with terrestrial insects, but more work is needed to compare their microbiomes. The midges live in filamentous algal mats but they appear to be preferentially eating diatoms. They contained many potential parasites and I discovered that midge body size decreases with depth.
Collection of marine midge larvae and algal mats. (A) A map of the Caribbean island of Curaçao with the sample collection sites Westpunt, Buoy One, and CARMABI indicated as red points. (B) Algal mats on a Curaçao reef. Note, the coral colony, Agaricia agaricites, invaded by an algal mat, with the algal mat coming in from the bottom right as indicated by the black arrow. (C) Composition of algal mats include filamentous green and red algae along with sediment. No magnification available. (D) A marine midge larva sampled from the algal mats. Scale bar indicates 0.1 mm.
Coralline algae are calcified red algae that play many important ecological roles like providing structure for coral reefs and giving invertebrate larvae a place to settle. Even though we know that many species of corallines play different roles in their ecosystems, they are often difficult to identify because they are cryptic species. This means that they can't be identified based on morphology because they look similar to something else. In my research, I developed tools for scientists to differentiate two cryptic coralline species. I also helped to characterize a species that Charles Darwin misidentified as a subspecies due to its cryptic morphology.
Images of coralline algae from Soren Huber's Master's Thesis. (A) Corallines on a rock. (B) An arrow pointing to articulated intergeniculum "joint" (C) Coralline algae in a tidepool. (D) Diagram showing coralline morphology, arrows indicate intergenicula.
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