The influence of larval quality on dispersal outcomes
It is well known that the vertical position of a dispersing larva in the water column can influence its dispersal trajectory, due to the difference in the strength of the currents from the surface to the ocean floor. However, little is known about what controls or influences this vertical positioning. To investigate this unknown, I used 24-hour depth stratified sampling to collect larvae of the southern hulafish from 4 depths throughout the water column, then examined the phenotypic characteristics (based on otolith microstructure) of larvae collected from each depth to see if larval quality might influence an individuals vertical position.
Do fish stick together during dispersal?
Larval dispersal is critical for determining patterns of recruitment, population structure, and metapopulation dynamics, however, our inability to track individual larvae through this phase has left details about what occurs during the pelagic larval period largely unknown. One question that remains unresolved is whether dispersal is an independent event for individual larvae, or if larvae interact in some capacity during dispersal and settlement. To investigate this question, I used otolith elemental signatures from the dispersal period of hulafish collected from reefs around Port Phillip Bay, Australia, to explore the spatial heterogeneity of their dispersal histories. If fish that originated from the same reef and settled to the same site have similar environmental 'fingerprints', it would suggest that these fish in fact travel together during early life-stages.
Does the use of sensory cues help fish make better settlement decisions?
Habitat selection by animals that migrate or disperse ultimately determines the environment they will experience and the organisms they will interact with throughout their life. Intuitively, for habitat selection to be adaptive, animals should respond positively to cues produced by habitat characteristics that will improve their fitness in the new environment, however, there are many examples of dispersing animals where individuals are attracted to cues produced by factors that reduce their fitness after arrival (e.g. attracted to reefs that have high numbers of predators). Using laboratory and field based experiments on artificial reefs, I set out to examine the relative importance of habitat-associated cues in habitat selection decisions for the southern hulafish, and assess whether use of these cues is adaptive across early life stages.
CURRENT RESEARCH
EARLY LIFE-HISTORY DRIVERS OF CONNECTIVITY IN MARINE POPULATIONS
I am currently investigating factors that influence the dispersal, settlement and survival of the southern hulafish Trachinops caudimaculatus, a temperate reef fish, to shed light on what drives patterns of recruitment and metapopulation dynamics in marine systems. Within this overarching research aim there are a number of projects that I am working on:
THE INFLUENCE OF EARLY LIFE-HISTORY ON BEHAVIOUR
I am very interested in behavioural ecology, and understanding how individual behaviour and environmental factors interact to influence individual fitness and survival, and drive population level dynamics. I am currently working on two research projects that fall under this umbrella:
How does the reef environment influence shoaling behaviour?
Group living is a common social strategy found throughout the animal kingdom, and is common amongst marine and freshwater fishes, including the southern hulafish. Shoaling can provide similar or even greater anti-predator benefits as shelter, and the benefits of shoaling generally increase with group size. I set out to investigate how shoaling behaviour might vary on reefs with different environmental and social contexts; for example, does reliance on either physical shelter or shoaling for protection shift with either the quality of reef habitat or the abundance of hulafish present on the reef?
Does larval quality influence post-settlement performance in a territorial Damselfish?
This work is a collaboration with Davina Poulos (James Cook University), investigating the role of larval growth history in determining post-settlement competitiveness and aggression in the territorial ambon Damselfish, Pomacentrus amboinensis. This research, conducted at the Lizard Island Research Station on the northern Great Barrier Reef, aims to tackle the age-old 'nature vs. nurture' question, as we try to tease apart the influences of individual variability and environmental factors on behaviour.
THE IMPORTANCE OF HABITAT FOR ECOSYSTEM FUNCTION AND RESILIENCE
Over the past few years, I have worked in a number of marine systems including seagrass meadow, coral reef, and temperate rocky reef systems in Australia. In this short time I have seen significant changes to these key habitats (i.e. coral reef degradation, shifts from macroalgal dominated reef to urchin barrens, and significant loss of seagrass cover). These changes will have significant impacts on the biological communities these habitats support, and for the productivity and resilience of the systems. This awareness of our changing ecosystems has spurred a research focus on understanding the role of key habitats, or ecological engineers in maintaining the function and resilience of the ecosystem. I am currently using artificial reefs to investigating the impacts of kelp restoration on the fish community assemblages. This information is critical to design and implement effective habitat restoration projects and better manage our marine landscapes.
IMPACTS OF ARTIFICIAL LIGHT AT NIGHT ON FISH
The impacts of artificial or anthropogenic light at night (ALAN) have become an increasing focus in terrestrial ecology over the past few decades, and research has shown light pollution can have significant impacts on everything from individual organismal physiology to landscape level changes in population and community demographics. However, research on the impacts of ALAN on species living below the ocean's surface is almost entirely lacking. I am currently working with a team of researchers at the University of Melbourne, Australia, Carleton University, Canada, and CRIOBE, French Polynesia, to address basic but fundamentally important questions regarding the impact of ALAN on the behaviour, physiology, and fitness of reef fishes, as well as impacts on community level change.
