Species interactions & microbes
I am interested in exploring how species modify interactions by influencing the microenvironment around participants and directly affecting one or both organisms via physically, chemically or microbially mediated mechanisms.
Several projects revolve around interactions among algal turfs (small, filaments of algae), Porites corals, and the large vermetid snail called, Caerasignum maximum. Vermetid snails are sessile (stationary) marine snails that produce a mucus net which allow them to collect particles in the water column for feeding. While casting their net, corals (and algae) are frequently trapped beneath the net. Because of this - I've explored the direct effects of the net on corals and algae, as well as the indirect effects that the net has on coral-algal interaction (does it make algae overgrow corals more than when algae are alone).
Using the coral-algal-vermetid system I am able to explore not only a little-understood interaction, but also explore questions about habitat modification, chemical ecology, microbial ecology that are germaine to community interactions, especially in coral reef ecosystems. I use field experiments, field surveys, lab experiments and molecular methods to explore community interactions involving these key players
vermetid
coral
algal turfs
Direct and indirect effects of algae and vermetids on coral
Direct and indirect effects of vermetids and algae on corals through chemical, physical and microbial mechanisms
1. Water flow influences coral-algal interactions
2. By changing oxygen dynamics between corals and algae
3. Vermetids create low flow, thick boundary layer conditions
4. Algae, and to a lesser extend vermetids, lead to changes in microbial communities on coral surfaces
A neat interaction Julie Zill (undergrad assistant) and I observed was that predatory muricid snails consume vermetids and deposit their eggs inside the emptied vermetid tubes!
Check out the reef site in Coral Reefs and our paper in Marine Ecology Progress Series.
In 2015 Ceraesignum maximum experienced a massive die-off across French Polynesia. We documented the die-off, and are continuing to monitor its extent. So far, C. maximum are dead across the Society Islands, the Tuamotus, and the only known populations in French Polynesia are in the Gambiers and the Australs.
Species Loss: predation and die-off
The extended phenotype and corals
Experimental design
Some corals have vermetids and some coral do not...WHY? I used a field experiment where I removed corals from reefs with vermetids and corals from reefs without vermetids and transplanted them back on each other.
After 3 months, and collecting data on growth, tissue thickness, microbial communities, and host genetics - I discovered corals with vermetids were GENETICALLY DIFFERENT from corals without vermetids.
Why? Well, I think it's because they have different traits, especially different tissue thicknesses, which influences how they respond to disturbance. This is an example of the long reach of the gene - or the extended phenotype of the coral.
Figure: (a) Coral transplanted to a reef without vermetids, and (b) corals transplanted to reefs with vermetids, (c) reef without vermetids, (d) reef with vermetids
Effects of species across scales: macroalgae and coral
How much does algal cover on reefs versus algal contact affect coral health? I plan on asking this question across reefs that differ in algal abundance, and across islands that differ in population size (regional scale) and on corals that are near and far from algae (local scale).
This work is in collaboration with Amy Briggs, a PhD student in the Osenberg lab. We have collected samples in Moorea and Mangareva in French Polynesia. I am also looking at this question in the Caribbean
