Marine Studies Institute

Our expert: Associate Professor Ana Vila-Concejo

Our partner: NSW State Government

Sandy beaches in estuaries and bayes (BEBs) front and protect many coastal properties and infrastructures in the world. Many major cities have been built around estuaries.

One example is Sydney, where three estuaries are the core of some of the most densely populated and developed parts of the city: Botany Bay, Port Jackson (Sydney Harbour), and The Pittwater (Broken Bay).

The nature of estuarine beaches and their critical functions vary with distance from the mouth of the estuary, which is the source of wave and tidal energy, as well as often the dominant source of sand. Little research has been done in this field.

The management of sandy beaches is underpinned by morphodynamic classification models that were developed for “high energy” sandy beaches – beaches exposed to the full force of ocean swell (open ocean beaches). These models provide the framework for predicting beach response, for example to coastal engineering intervention, or to changes in wave energy and sea level.

Results from few published studies suggest that the wave energy gradient inside estuaries is the major control on the morphodynamics of sandy estuarine beaches. And that further research focused around this gradient is necessary to establish a final classification model for estuarine beaches that can inform management directed at sustaining beneficial roles of these beaches as storm buffers, recreational facilities, wildlife habitat, and protection of critical coastal wetlands.

We're investigating BEBs morphodynamics, evolution, and response to climate change as part of an expanding international consortium studying BEBs in Australia, New Zealand, Brazil, USA and Spain.

We have multiple projects in different BEBs and are undertaking:

• beach surveying using state-of-the-art techniques such as RTK or drones
• beach bathymetry using kayaks fitted with echosounders and RTKs
• sediment analyses and sediment transport studies
• hydrodynamic measurements waves and currents
• decadal and seasonal studies using GIS

Our experts: Professor Maria Byrne, Associate Professor Ana Vila-Concejo, Dr Thomas Fellowes, Dr Tristan Salles

Coral reefs around the world are irreversibly transforming due to unprecedented rapid environmental change. Recent mass bleaching events have shown the impact of climate change driven marine heatwaves for coral reef health and the demise of reef structure.

Because returning coral reefs to their past healthy state is no longer an option, there is a pressing need to understand, quantify and model the impact of new environmental conditions on coral reefs. Coral reefs (and reef islands) are not inert features that will simply get destroyed or flooded with climate change.

While there is research that predicts a future of flooding and inhabitability for reef islands, other studies show that reef islands can even grow under climate change and advocate for more detailed eco-morphodynamic modelling.

This is of important for Australia as we are the custodians of some of the largest and most important coral reef regions on Earth – the Great Barrier Reef (GBR) and the Coral Sea. Many reef islands in these regions are threatened by climate change and are internationally important as the legal ‘baseline’ from which Australia’s maritime zones are drawn.

Recent years have shown the vulnerability of the corals (and coral islands) is widespread with episodes of bleaching, ocean acidification, sediment plumes, cyclones, and, threatening species such as crown of thorns starfish.

With climate change, reefs face accelerated changes that will affect ecosystem services such as coastal protection. The health of coral reefs and sediment producing organisms will be less impacted by incremental global warming and acidification than by increasingly frequent marine heatwaves and storms.

There are key knowledge gaps in quantifying carbonate sediment budgets and productivity, wave dissipation and sediment transport, and reef and island resilience. This needs to be addressed using multidisciplinary approach using field data, remote sensing and numerical modelling.

We aim to understand coral reef morphodynamics, wave dissipation and sediment transport by examining:

• decadal studies using GIS
• surveying using state-of-the-art techniques, RTK and drones
• hydrodynamic measurements (waves and currents)
• sediment analyses and sediment transport studies
• numerical models of wave dissipation on coral reefs

Our expert: Dr Bree Morgan

Formation of dolomite [CaMg(CO3)2], a highly-stable carbonate mineral, has been central to maintaining the stability of Earth’s global climate over geologic timescales.

There's a disproportionate paucity of dolomite in modern times comparative to its widespread abundance in the deep past, referred to as the ‘Dolomite Problem’, one of the longest standing unresolved mysteries in the natural sciences.

The overarching objective of this project is to decipher a trace element signature for the formation of low temperature dolomite, with the goal of gaining wider insight into the mysterious mechanisms promoting dolomite formation in modern and ancient sediments.

The target samples are dolomite-containing, Pleistocene-aged sediments collected from a mesohaline seep (Leg 182) in the Great Australian Bight.

We will complete a detailed assessment of (i) bulk Mg, Ca and trace element (Mn, Sr, Re, As, Sb, Ba, Cd, Mo, Ni, Cu, Zn, V, Cr, Co, U, Y & REE) concentrations in samples by ICP-MS analysis of selective digests, (ii) μ-scale distribution of trace elements in sediments by μ-XRF and LA-ICP-MS analysis of sample thin sections, and (iii) high resolution crystallographic information (quantitative mineral abundances, d104 peak position values of dolomite, crystallite size, and morphology) using XRD, SEM and TEM.

Our findings intend to complement current funded research into the trace element signatures of rare Holocene dolomite, forming in saline playa lake sediments in South Australia and British Columbia.