Symbiosis

I study the complex interactions between microbial symbionts (like the orange cyanobacterial cells in the sponge tissue above) and benthic marine invertebrates like sponges and corals. This research combines manipulative experiments with biochemical and molecular analyses to:

Characterize the microbial symbionts present within a host and determine how these associations vary across different host species.
Identify the benefits of these interactions. These benefits are usually nutritional, with the host gaining access to new sources of carbon and nitrogen. In return, the microbial symbionts are provided a safe, nutrient-rich habitat within the host.
Determine how these interactions change under different environmental conditions.

Xestospongia bocatorensis in Bocas del Toro, Panama. This sponge hosts filamentous cyanobacteria

Vase sponge with "sparse" microbial symbiont community in Belize

A very common rope sponge in the Caribbean that hosts abundant microbial symbionts

Symbiotic sponge in Moorea, French Polynesia

Pigment analysis allows me to quantify the abundance of particular symbiont groups within different sponge species

High chlorophyll a concentration (green vials) implies that these sponges host abundant photosymbiont or cyanobacterial communities.

Photosymbionts like cyanobacteria can also visualized using fluorescence microscopy

A photo-transect of cyanobacterial symbionts (orange dots) in a cross section of a Caribbean sponge

Shading experiment (transparent or control canopy) in Bocas del Toro, Panama.

Shading experiment (shade or treatment canopy) in Bocas del Toro, Panama.

Shading experiment setup on a shallow reef in Bocas del Toro, Panama

Gorgonians on a shallow reef in Belize

Hardbottom community near Carrie Bow Cay in Belize

We also use short term incubations to investigate symbiont and host C, N, and H metabolism

These incubations couple classic light/dark bottle experiments with seawater laced with C, N, or H "tracer" compounds and have been conducted with sponges, hard corals, octocorals, and Cassiopeia jellyfish.

Many co-occurring sponge species host unique microbial communities. These unique interactions may allow some species to utilize novel nutrient sources within reef communities and support the coexistence of diverse organisms within these systems.

Metabolic diversity across co-occurring sponge species may have an important role in supporting diverse and complex reef communities like these in the Miskito Cays of Honduras.

Symbiosis

Photographs taken by George Stoyle Photography, myself, or colleagues