Current Projects include:

I. Marine Ecosystem Ecology

The Reef Ecosystem Evaluation Framework (REEF): Managing for Resilience in Temperate Marine Environments

Resilience is the ability of natural systems to resist or recover from disturbance without the loss of essential ecosystem function. In general, a broad body of evidence suggests that ecosystem “engineers”, species that create or modify habitat, can have profound effects on associated biodiversity and ecosystem function. As greater diversity often leads to greater resilience, as different species and functional groups may respond differently to different kinds of disturbance, it is important that we understand how pre- and post-recruitment processes influence the population dynamics of ecosystem engineers and other key functional groups if we are to identify the drivers of resilience and which management policies/actions are most likely to increase or safe-guard resilience of temperate reef ecosystems. To achieve this objective, we are:
I. Developing an understanding of the influence of sedimentation and nutrification on the structure and composition of temperate reef ecosystems.
II. Identifying the causes of urchin barren formation and the impact of sedimentation and nutrification on this process.
III. Estimating regional connectivity for key functional groups (macroalgae, macro-invertebrate grazers, and fish) using genetic and environmental markers.
IV. Determining the important life-history, ecological, and environmental drivers of connectivity and the ability of reef communities to recover from disturbance.

Collaborators: Craig Johnson (UTas), Neville Barrett (UTas), Paul Hamer (DPI, Victoria), Greg Jenkins (DPI, Victoria), Maria Byrne (USydney), Sean Connell (UAdelaide), Bayden Russell (UAdelaide), Craig Sherman (Deakin Uni), Mick Keough (Melbourne Uni), Melinda Coleman (NSW MPA)

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II. Fish and Fisheries Ecology

Maelstrom in the matrix: extreme environmental heterogeneity necessitates a novel conceptual framework for marine metapopulations

Marine reef organisms often reside in highly fragmented patchworks of populations interconnected by movement of larvae through a hyper-variable ocean matrix. Understanding how and why such fragmented populations fluctuate is essential to predicting extinction risk and responses of populations to environmental change, management strategies, and harvest.  Importantly, such understanding requires we look beyond individual populations to demographic connections among populations.  One important way that populations of marine reef organisms are connected is through movement of larvae. Young larvae may routinely be “lost” from parental populations and “captured” by distant populations.  We know virtually nothing about true movement potential of the young of most marine species.  This vital information has remained elusive for two key reasons:  1) the small size—microns to millimetres—of most marine larvae makes tracking their movements exceedingly difficult; and 2) the ocean matrix through which these larvae must move is vast, turbulent, and patchily populated with food and predators.  Our work uses “environmental fingerprints” contained within the ear bones of larval fish as markers of their geographic origin.  We are developing novel approaches to sample larval assemblages simultaneously with ocean matrix features, and integrate ocean physics and biology in a computer simulation to explore for the first time, the effects of ocean matrix features on larval movements, survival, and hence connectivity among fragmented marine populations.

Collaborators: Jeff Shima (Vic Uni, Wellington NZ), Stephen Chiswell (NIWA)

What drives recruitment variability in Snapper? Application of a novel theoretical and empirical approach to predict fluctuations in fisheries

Understanding the causes of fluctuations in the recruitment of young to fish populations is an essential scientific need for sustainable fisheries management. This project is uniquely combining physical and biological information on the early life stages of snapper, a key fishery species in southern Australia that shows highly variable recruitment, into a sophisticated modelling framework that will identify the underlying processes driving fluctuations in recruitment. This information will allow predictions of future trends in fishery recruitment in the short term based on measurements of climatic variables, and in the long term based on climate change predictions, with broad applicability to many socio-economically important fisheries.

Collaborators: Greg Jenkins (DPI, Victoria), Paul Hamer (DPI, Victoria)

Linking freshwater flows, salt wedge dynamics and fisheries productivity in estuaries

Freshwater needs of Australia’s estuaries are poorly understood. Freshwater flows influence productivity and dispersion of salt wedges (fresh-saltwater interface), which are important nurseries for larval fish in estuaries. Estuaries also support valuable juvenile fish habitat (e.g. seagrass). Coincidence of productive salt wedges with optimal fish habitat may enhance fisheries by improving the growth and survival of early life stages. This project is integrating hydraulic models and information on the early life history of fish to determine links among freshwater flows, salt wedge dynamics and fisheries production. Findings from this project will be important in allocating freshwater flows to sustain Australia’s estuarine resources.

Collaborators: Jeremy Hindell (DSE, Victoria), Greg Jenkins (DPI, Victoria), Andrew Western (Melbourne Uni)

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III. Evolutionary Ecology of Fishes

How connected are marine populations? Comparing life histories of endemic and non-endemic reef fishes to investigate the mechanisms behind self-recruitment

 
Recruitment of pelagic larvae plays a fundamental role in benthic marine populations, yet the sources and destinations of recruits are unknown for nearly all marine species. Because endemic species rely on retention of locally spawned larvae, they provide a novel opportunity for investigating the mechanisms allowing self-recruitment.  We are comparing the life histories and microchemical signatures in larval otoliths of endemic and closely related non-endemic reef fishes to determine the mechanisms and prevalence of self-recruitment. The results will broaden our understanding of how marine populations are replenished, information critically needed for marine conservation and resource management.

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IV. Ecotoxicology

The Victorian Centre for Aquatic Pollution Identification & Management (CAPIM)

Aquatic systems are increasingly under threat from pollutants that are very difficult to identify, and whose effects are hard to separate from other sources of habitat degradation.  CAPIM is developing and implementing innovative approaches to determine where aquatic ecosystems in inland waters and estuaries are affected by pollutants, identifying pollution sources, developing a mitigation strategy, and developing biotic and chemical systems to monitor remedial actions. 

Within estuaries, we are establishing, developing and validating (through cross-theme and inter-agency collaboration) new methods for detecting and managing effects of pollutants in Victoria’s estuaries.  Specifically we are:
• Developing new measures of individual health for estuarine animals in response to exposure to heavy metals and Endocrine Disrupting Chemicals (EDCs);
• Applying these new techniques in assessments of demonstration estuaries; and
• Using new measures of individual health and existing expertise in measuring connectivity to determine risks of single-estuary impacts extending beyond estuary boundaries.

Collaborators: Mick Keough (Melbourne Uni), Nicole Barbee (Melbourne Uni), Kathryn Hassell (Melbourne Uni), Myumi Allinson (Melbourne Uni), Graham Allinson (DPI, Victoria)

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page authorised by

Stephen Swearer