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Research Interests

"Science is not about the answers we find... it is about the questions we ask." — unknown

Research focus:

Marine systems are threatened by human activities and there is a need to understand the state of these ecosystems prior to human impact so that we can minimise our impact effectively. While reefs are vertically complex structures, soft-sediments preserve shelled molluscs (and the skeletons of other biomineralised organisms) in a more straight-forward stratigraphic package, simplifying temporal reconstruction and spatial correlation. We are presently working to quantify the history of molluscan communities on the Great Barrier Reef (GBR) and estuaries in the greater Sydney area, New South Wales (NSW).

We have dug large (0.25m2 area by over a metre deep) excavations from GBR and NSW sediments. These large samples allow us to examine spatial and temporal changes in taxonomic richness, eco-morphological (functional) group composition, and abundance distribution. In doing this we will be able to quantify the historical variability of molluscan assemblages on the GBR and in NSW.

Accomplishing this goal requires a few key elements:

Strand 1: Dating Holocene fossils
The fundamental pre-requisite for using fossils to provide quantitative baselines for conservation biology is being able to determine the age of individual fossils. We use calibrated Amino Acid Racemisation dating, the technique of choice for determining the age of Holocene fossils for conservation palaeoecology, taphonomy and time-averaging studies. I have well-established collaborations with Darrell Kaufman at Northern Arizona University (NAU, AAR dating) and Quan Hua at ANSTO (Carbon-14 dating).

Strand 2: Quantifying the preservation potential of fossils
The second key requirement for using fossils in determining conservation baselines is understanding the sampling biases in the fossil record (e.g. preservation or taphonomic biases). We are leaders in quantitative taphonomy, especially in tropical reef systems. We use both a live-dead comparative approach as well as dating based modeling approaches to estimate per-capita preservation potential.

Strand 3: Using fossils to understand pre-colonisation marine communities
Using the chronology determined in strand 1 and the estimates of preservation probability of strand 2 it is possible to examine community change through time. These palaeoecological approaches provide the most promising means of quantitatively assessing the past composition, structure and variability of benthic marine systems as well as how human activities have altered these systems.

Strand 4: Macro-benthic ecology of biomineralised marine invertebrates
This is a relatively recent strand of my work, but it links my palaeontological research with more traditional ecological studies. It is work I have done mainly through the supervision of HDR students. Julieta Martinelli (graduated) has examined the importance of drilling predation to the One Tree Reef molluscan community as part of her thesis. Gabriel Dominguez is preparing two papers on growth-rates and mortality estimates for bivalve molluscs from Sydney Harbour as part of his thesis. Increasingly we plan to use ecological changes observed in the historical record to generate testable hypotheses for experiments to determine the mechanistic basis of anthropogenic impact on these ecosystems.

Additional interests:

Evolution of Ecological Communities:

Complex ecological systems function, and continue to function despite dramatic environmental and evolutionary changes. This fascinates us. Ecological systems change due to major evolutionary events, such as the origination and radiation of predators, as well as to physical events, both profound, such as continental movements and asteroid impacts, and subtile, such as changes in sedimentation and global temperature. Understanding how ecological systems change in response to these sorts of factors is key to our understanding of biological diversity and ecosystem function, as well as more applied questions of conservation biology. Working with both modern and fossil communities offers the greatest potential for drawing strong conclusions about ecological changes as well as offering the possibility of applying these results to the management of marine systems.

Evolution and Ecological Systems:

There is no question that ecological processes can drive evolutionary changes, but the reverse is also true. Evolutionary changes alter ecological systems, and quantifying these effects is important to understanding marine ecosystems. We are intrigued by changes in ecological community composition during time periods of evolutionary innovation. See: Kosnik 2005 and Wagner et al. 2006 for examples of some of this research.

Ecosystem Variability:

Modern communities are a snapshot of the dynamic history of biodiversity, and ecologists have collected quantitative data for only the last few decades. These short data-series, combined with significant natural variation, make it difficult to evaluate the long-term trends caused by the impact of human activities on marine systems. These data-series can be extended by exploiting the skeletal remains in marine sediments that preserve a record of ecological change and past variability. The time-averaged nature of fossil assemblages smooths out seasonal to annual variation, but captures the longer (century to millennial) time scales at which the cumulative effects of human activities and long-term ecological trends occur. Palaeoecological data provide the most promising means of quantitatively assessing the past composition, structure and variability of benthic marine systems as well as how human activities have altered these systems.