I’ve been wondering over the last week what I should talk about next. I figured I should potentially tell you a bit about my research huh? I’m a Chemist by training, so a lot of this is still very new for me. I’ve spent two years attempting to get my head around the wonderful world of molecular biology and let me tell you, I have new-found respect for it.
So if you asked me at a party or if I was saying hi on the street, I would say something like “I look at the biochemistry of corals and their response to environmental stress”. Boring, but concise. Never fear; I have a long version.
In the last 3 decades, the Great Barrier Reef (GBR) has lost almost 30% of its coral coverage and reports show this trend is continuing. Losing the reefs is a more frightening possibility than you might think. In fact, many small Island nations throughout the tropics rely on the reefs for their food, protection and their cultural identities. In Australia, about two million tourists visit the GBR each year, accounting for a hefty chunk of Queensland’s revenue.
The loss of coral cover is linked to an increase in what we refer to as “mass bleaching events”. Environmental stress factors like increasing Sea Surface Temperatures (SSTs – have a look at the IPCC website) and light intensities have been known to cause these events. Environmentally, we understand what’s happening, but it’s a different story from a molecular point of view, and we need to know what’s going on at this level in order to get some idea of how to help them respond to their changing surroundings.
At their core, scleractinian, or reef-building, corals are a symbiotic relationship between the host coral and a micro-algae known as zooxanthellae. These algae are photosynthetic and so they can provide the coral host with essential nutrients like organic carbon. In return, the corals provide the zooxanthellae with protection and inorganic nutrients they can’t produce by themselves. It’s a mutually beneficial partnership which, unfortunately, is very delicately balanced and extremely susceptible to environmental change. When conditions become unfavourable or stressful, the coral will expel the zooxanthellae and they lose their main source of organic carbon. Sometimes the corals can recover and get their algae back, but sometimes they can’t. If the environmental stress lasts for a long time, they eventually starve and die. This is traditionally not awesome.
There’s currently a large amount of research into how the zooxanthellae’s photosynthetic systems work and my lab (C3) is responsible for a good portion of it. We know that under stress, they can experience a build-up of toxic oxygen radials that overwhelm the photosystem proteins. But we’re not sure why that happens in the first place. The underlying molecular triggers for the bleaching response are still eluding us but bit-by-bit, we’re filling the holes in our knowledge. Why do some types of zooxanthellae appear to be more tolerant to an increase in temperature? Why do some species, like massive corals, resist bleaching when others, like branching corals are pansies that seem to die when you breathe on them?
The answers to these questions could have something to do with their biochemical composition.
Proteins, carbohydrates and lipids play a critical role in ‘maintaining the status quo’ within any organism. By that I mean the amount of energy available drives biochemical processes that keep cells functioning properly; it’s why we need to eat. Within the coral symbiosis, the host and zooxanthellae exchange essential nutrients. In fact, the algae are sometimes responsible for up to 90% of the host’s organic carbon requirements. This exchange keeps them healthy and may affect their resilience to environmental change.
My research focuses on the symbiotic partnership from a biochemical point of view. To do that, I’m using a technique that has only recently started to be applied to biological and environmental questions things like this. It’s called Fourier Transform Infrared Spectroscopy. Essentially, every molecule in the universe is vibrating at characteristically different frequencies. FTIR spectroscopy picks up on these vibrations and plots them in a graph of a series of peaks called a spectrum. Each peak corresponds to a specific molecular bond within a sample. This means that I can map the protein, carbohydrate and lipid content in the corals in very little time and with very little sample preparation. We can use these spectra to model the shifting biochemistry within the organisms and how they respond to elevations in temperature or light intensity.
I have very limited experience within the world of science, but in my opinion, the scope of this technique and the things we can potentially do with it are very exciting. Modelling the biochemistry in response to environmental factors can not only add to our understanding of bleaching, but it could also result in a way of predicting mass bleaching events.