BY PAUL HERRIDGE
The Southern Gazette
It sounds a little like piecing together a jigsaw puzzle spanning hundreds of million years.
A group of researchers at Memorial University are studying the rocks at Fortune Head Ecological Reserve as part of a project to learn more about the impact of burrowing animals such as worms, shrimp, clams and snails.
According to Dr. Liam Herringshaw of the school’s Department of Earth Sciences, certain types of such burrowers, which have been set up in tanks to observe their activities in the lab, create large networks below the surface.
In doing so, they develop new, irrigated space.
The researchers are looking for similar examples in the fossil record to help understand their impact on sediment properties and marine ecosystems.
He noted the province – particularly eastern and central areas – has many examples of rocks showing the period where life in the seas began to get more complex, and burrowing animals started to have a bigger impact.
“We started wondering, ‘Well, can we use what we’ve got from the modern systems and our modern experiments to try to understand what changed and how it changed in these sort of critical intervals in earth history?’”
Dr. Herringshaw noted the rocks at Fortune Head, which cross the boundary between the ‘Precambrian’ and ‘Cambrian’ eras, are now recognized as the global standard by which all other equivalent successions are compared, and was the obvious place to see if changes in the types of burrows could be identified.
The group also did some research at Grand Bank Head, where examples of burrowing animals can also be seen.
“It seemed like a sensible place, both in terms of geographical location – it was close to home – but also because it is the global standard.”
Dr. Herringshaw indicated many animals or organisms, such as beavers or corals, have a large impact on the environment from structures they produce – biologists dubbed it ‘ecosystem engineering’ in the mid-1990s.
“It basically refers to animals that, either through their physical presence or through structures that they make, engineer new environments that can then be exploited by other creatures. Burrowing animals essentially do the same king of thing by excavating networks in the sediment.
“It seemed like a sensible place, both in terms of geographical location – it was close to home – but also because it is the global standard.” - – Dr. Liam Herringshaw
“They create space, which can be exploited, but they also move nutrients about and bring nutrients down into the sediment that otherwise wouldn’t be there and allow things to colonize.”
Dr. Herringshaw explained changes appear in the types of burrows across the Precambrian-Cambrian boundary that records the behaviour of the animals at the time.
In Precambrian rocks, all burrows are horizontal, sort of two-dimensional “surface trails,” as he described them. Later, at the beginning of the Cambrian era, the animals were starting to burrow down into the sediments creating a more three-dimensional world.
Unfortunately, the animals themselves can’t be identified because they are not preserved.
The group hopes to be able to link particular types of burrows to changes in diversity and ecosystem function.
“The idea basically is to say ‘Can we connect these kind of structures, similar to what we have in the modern environment, into diversity?’ Does the Cambrian explosion, as it’s often referred to, relate in some way to the development or the evolution of these key behaviours and key animals?”
Dr. Herringshaw noted offshore oil companies, which could also benefit from understanding the impact the burrows have on the properties of the rock from which they are trying to get oil, have also provided partial funding for the project.
“As we know that in the modern world these burrow networks are utilized by lots of other species, by virtue of the space and the nutrients coming through, was it the same in the past? There’s still quite a lot of uncertainty.
“We don’t have the definitive answers yet, but we’re certainly going to base everything that we’re doing as a test case on the Fortune Head area and then be able to go to other areas of the world with similar aged rocks, but also other periods of time, and say ‘Do we see clear evidence of this kind of engineering? Can we really pinpoint it to a particular burrow type?’”
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